No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Structure of a near-polar latitude forest from the New Zealand Jurassic
Abstract
A tidal platform at Curio Bay near the southernmost point of the South Island, New Zealand, preserves the petrified remains of an in situ Middle Jurassic forest. The forest grew close to the palaeo-polar circle, but data are not precise enough to tell on which side it lay. A mapped portion of the forest floor provides data on tree density and population structure, allowing comparison with recent forests and with records of other fossil forests. The forest has tree densities similar to many forests growing in low to mid-latitudes today; it appears to have had emergents projecting through a low canopy, and a well-developed undergrowth of smaller gymnosperms and osmundaceous ferns. No aspect of the forest structure uniquely distinguishes it from that of non-polar latitude forests. An extended discussion is given on reconstructing tree height from stump diameter. On the basis of this, a reinterpretation of the structure of an Early Cretaceous fossil forest from Alexander Island, Antarctica, is offered.
... In 1994, the second approach was proposed by Niklas based on the manner in which woody stems taper in girth along their length; this resulted in a curvilinear equation for estimating overall fossil plant height (Niklas 1994). The third approach was taken five years later by Pole, who looked at the diameter and height data for three extant species of Araucaria growing in natural forests in Australia and New Guinea (Pole 1999) and used a power function with an exponent fixed to 0.67 for the height-diameter relationship. As the normalization constant of Pole's equation (1999) is about two to three times that of the Mosbrugger equation for conifers, Pole concluded that the heights of living trees are distinctly taller for any given diameter than the Mosbrugger curve would predict. ...
... We compiled datasets on tree height-diameter information from three Araucaria species: A. bidwillii (Pole 1999), A. cunninghamii (Gray 1975;Pole 1999) and A. hunsteinii (Paijmans 1970;Gray 1975). These datasets had originally been collected to determine the size composition of natural stands, describe forest structure, or analyse height-diameter relationships. ...
... We compiled datasets on tree height-diameter information from three Araucaria species: A. bidwillii (Pole 1999), A. cunninghamii (Gray 1975;Pole 1999) and A. hunsteinii (Paijmans 1970;Gray 1975). These datasets had originally been collected to determine the size composition of natural stands, describe forest structure, or analyse height-diameter relationships. ...
To reconstruct a fossil forest in three dimensions, an accurate estimation of tree height is crucial. However, modelling the height–diameter relationship of ancient trees is difficult, because the trunks of fossil trees are usually fragmentary, which makes direct height measurements impossible. One practical approach for reconstructing ancient tree height is to use growth models based on the height–diameter relationships of the nearest living relatives of the fossil taxa. Here we apply 19 models to describe height–diameter relationships of living Araucaria trees for establishing appropriate models for ancient Araucariaceae trees. Data come from four living populations of Araucaria: Araucaria bidwillii and A. cunninghamii in Queensland, Australia, and A. cunninghamii and A. hunsteinii in New Guinea. According to an AIC-based model selection, a Power model with an exponent of 0.67 (termed here the modified Mosbrugger model) is found to be the most appropriate for each population and for the entire dataset (157 trees), but normalization constants differ across populations. To find the most appropriate models for the genus Araucaria, 100 random samples (each population generating 25 random samples) from the entire dataset are used. Based on 100 curve fitting results on each model and multiple performance criteria, three median models are generated from the medians of their parameter estimates. Of these, the median Power model works best for Araucaria, but the modified Mosbrugger and Curtis models perform nearly as well. In a case study, we revise tree heights of Upper Jurassic araucariaceous logs in Utah, USA, by applying these three models.
... In many cases, the use of recent techniques applied to living communities has proven to be effective in the fossil record allowing comparisons between past and modern vegetation arrangements, facilitating a better understanding of the evolution of terrestrial plant ecosystems (Williams et al., 2003). Additionally, several paleoclimatological and paleogeographical implications have emerged from such studies providing a dynamic approach to the study of fossil plants (Pole, 1999;Cúneo et al., 2003). ...
... It is noteworthy that a good number of paleoforest analyses has been directed to studying high paleolatitude examples (Jefferson, 1982;Francis, 1991;Taylor et al., 1992;Basinger et al., 1994;Pole, 1999;Falcon Lang et al., 2001;Cúneo et al., 2003;Williams et al., 2003;Thorn, 2005; among others). This is particularly relevant because present vegetation at high latitudes (above 60 • ) is uncommon (particularly in the southern land masses), illustrating paleoecological and paleoclimatological shifts in the colonization of land through Earth history. ...
... It is important to remark the effect of bark on fossil tree diameter. As pointed out by Pole (1999), it is clear that any diameter measurements (and other calculated parameters using these data; e.g., tree heights) will represent a minimum when compared with living trees where the bark is included in the diameter. Depending on species, bark thickness in modern araucarians may vary from less than 1% up to 5% of the diameter (Ntima, 1968;Montaldo, 1974;Smith and Butler, 2002), providing some indication of the underestimations of tree characters in the fossil examples. ...
The structure and taphonomy of araucarian stumps and logs from the Jurassic of Patagonia are analyzed. Density measurements of these trees indicate that they were organized into woodlands that occupied extensive paleosurfaces affected by repetitive volcanism from nearby areas. At least two episodes of araucarian woodlands were identified, both terminated by explosive volcanism. As a result, fallen trees and stumps were immediately covered by massive ash falls that favored rapid silicification. The abundance of Araucaria mirabilis seedcones in the surroundings suggests that araucarian woodlands produced this type of cone. Paleoecological, sedimentological, and paleoclimatical data are used to better understand the life history of one of the best well preserved examples of Jurassic tree vegetation. The continuous association of araucarian trees with cheirolepidaceous conifers during most of the Jurassic and Early Cretaceous suggests that the Patagonian landscape was covered by open woodlands or closer forests as the dominant plant formation.
... The geological record is replete with high polar fossil floras demonstrating fully wooded ecosystems at paleolatitudes as high as 79 • N (62,142,163,165) and 75 • S (36,47,53,80,115,118), ranging in age from 290 Mya in the Permian Antarctic (153) to approximately 23 Mya (early Miocene) in the Arctic (71) and to approximately 37 Mya in the Antarctic (late Eocene) (Figure 2) (156). Collectively, these polar fossil forests demonstrate that fully wooded terrestrial ecosystems with tree densities similar to modern forests, occurring today at temperate and tropical latitudes (115,165), can be sustained in the high Arctic and Antarctic when the global atmospheric CO 2 concentration is >500 ppm (Figure 2 and references therein) and greenhouse-induced forcing of 5 W/m 2 is evident (52). ...
... The geological record is replete with high polar fossil floras demonstrating fully wooded ecosystems at paleolatitudes as high as 79 • N (62,142,163,165) and 75 • S (36,47,53,80,115,118), ranging in age from 290 Mya in the Permian Antarctic (153) to approximately 23 Mya (early Miocene) in the Arctic (71) and to approximately 37 Mya in the Antarctic (late Eocene) (Figure 2) (156). Collectively, these polar fossil forests demonstrate that fully wooded terrestrial ecosystems with tree densities similar to modern forests, occurring today at temperate and tropical latitudes (115,165), can be sustained in the high Arctic and Antarctic when the global atmospheric CO 2 concentration is >500 ppm (Figure 2 and references therein) and greenhouse-induced forcing of 5 W/m 2 is evident (52). The presence of high-latitude forests in the geological past also highlights the extreme vulnerability of the contemporary tundra biome, which is notable for its apparent absence for millions of years of Earth history during times of high global warmth and elevated CO 2 concentrations (Figures 1 and 2). ...
... Based on overwhelming paleobotanical evidence, it is highly likely that the current northward migration of woody tree and shrub taxa into the Arctic, along with the general greening (reviewed in 28, 107), will continue and, in doing so, will drive positive feedback of the climate system that will further accelerate the warming and wetting of the Arctic (74,163). In the past, high polar forests had carbon sequestration potentials (13,115,131,165) equivalent to those of the much lower temperate latitudes, and they impacted the hydrological cycle sufficiently to alter ecological dominance patterns within oceans (8,27). These findings from paleobotanical studies suggest that the role of Arctic vegetation in the global biogeochemical cycling of water and carbon will become increasingly important if we continue on a path of intense petroleum use. ...
Human carbon use during the next century will lead to atmospheric carbon dioxide concentrations (pCO2) that have been unprecedented for the past 50–100+ million years according to fossil plant-based CO2 estimates. The paleobotanical record of plants offers key insights into vegetation responses to past global change, including suitable analogs for Earth's climatic future. Past global warming events have resulted in transient poleward migration at rates that are equivalent to the lowest climate velocities required for current taxa to keep pace with climate change. Paleobiome reconstructions suggest that the current tundra biome is the biome most threatened by global warming. The common occurrence of paleoforests at high polar latitudes when pCO2 was above 500 ppm suggests that the advance of woody shrub and tree taxa into tundra environments may be inevitable. Fossil pollen studies demonstrate the resilience of wet tropical forests to global change up to 700 ppm CO2, contrary to modeled predictions of the future. The paleobotanical record also demonstrates a high capacity for functional trait evolution as an additional strategy to migration and maintenance of a species’ climate envelope in response to global change.
... Perhaps the most powerful attribute of a general allometric model is that it provides the basis on which to build quantitative ecological models. Because the WBE model offers a mechanistic hypothesis for many observed anatomical and physiological allometries at the level of the individual, it also offers a basis from which to construct mechanistic connections between these organismal processes and their ecological consequences (Enquist et al. 1998, 1999. The biological and physical principles imposed on vascular networks powerfully determine the space over which plants utilize resources and the rates of whole-plant resource use. ...
... which shows quantitatively how numerous biological and abiotic factors can influence plant population density per size class. Nonetheless, biometric and physiological data indicate no differences in the mean values of C B , C A and ρ across tropical and temperate tree species or with variation in species richness (Whittaker and Woodwell 1968, Brown 1997, Enquist et al. 1998, 1999. This invariance indicates that total community biomass is likely to be insensitive to species diversity, even though C m can vary in response to a variety of environ-mental factors (e.g., temperature, precipitation) known to influence R m . ...
... Recent analyses by provides preliminary evidence suggesting that the -2 scaling rule for forests has apparently not changed over hundreds of millions of years of plant evolution. Assembling diameter distributions for in situ fossil forests for an Early Tertiary forest (dominated by species within the Taxodiaceae, Cupressaceae, Pinaceae, Ginkgoaceae, Fagaceae, Juglandaceae, Menispermaceae and Ulmaceae (see Basinger et al. 1994)), and a middle Jurassic forest (dominated by conifers of extinct taxa likely related to Arucariaceae and Podocarpaceae (see Pole 1999)), provides a unique window by which to assess allometric scaling across ancient communities containing extinct taxa ( Figure 6). Within each fossil community the sizes and spatial positions of stumps have been preserved so as to preserve the size distribu- Figure 6, which was omitted from statistical analysis). ...
A general theory of allometric scaling that predicts how the proportions of vascular plants and the characteristics of plant communities change or scale with plant size is outlined. The theory rests, in part, on the assumptions of (1) minimal energy dissipation in the transport of fluid through space-filling, fractal-like, branching vascular networks; and (2) the absence of scaling with plant size in the anatomical and physiological attributes of leaves and xylem. The theory shows how the scaling of metabolism with plant size is central to the scaling of whole-plant form and function. It is shown how allometric constraints influence plant populations and, potentially, processes in plant evolution. Rapidly accumulating evidence in support of the general allometric model is reviewed and new evidence is presented. Current work supports the notion that scaling of how plants utilize space and resources is central to the development of a general synthetic and quantitative theory of plant form, function, ecology and diversity.
... Numerous well-described Mesozoic (e.g., Jefferson, 1982;Pole, 1999;Cúneo et al., 2003;Thorn, 2005); and Cenozoic (e.g., Basinger et al., 1994;Williams et al., 2003Williams et al., , 2009 forests document prolific forest growth at high latitudes and constrain paleoclimate during these periods. For example, high southern latitude Jurassic fossil forests in New Zealand have high biomasses that reflect warm to cool temperate conditions with high seasonal rainfall (Pole, 1999;Thorn, 2005;Williams, 2007). ...
... Numerous well-described Mesozoic (e.g., Jefferson, 1982;Pole, 1999;Cúneo et al., 2003;Thorn, 2005); and Cenozoic (e.g., Basinger et al., 1994;Williams et al., 2003Williams et al., , 2009 forests document prolific forest growth at high latitudes and constrain paleoclimate during these periods. For example, high southern latitude Jurassic fossil forests in New Zealand have high biomasses that reflect warm to cool temperate conditions with high seasonal rainfall (Pole, 1999;Thorn, 2005;Williams, 2007). Relatively warm climates at northern high latitudes existed into the Cretaceous, as evidenced by large logs, in situ stumps, and floral composition (Parrish and Spicer, 1988;Spicer and Herman, 2010). ...
... Stand density of fossil forests was calculated by determining the number of in situ stumps in a given area and converting it to trees per hectare (t ha −1 ; Jefferson, 1982;Francis, 1991;Basinger et al., 1994;Greenwood and Basinger, 1994;Pole, 1999;Falcon-Lang et al., 2001). Although we knew the number of trees in LP1 and LP2, we were uncertain of the location of the forests' boundaries. ...
... (3) Density of the tree-sized stems was estimated using the forestry definition of a "tree" as stems having a breast-height diameter N 7.5 cm or, in some cases, N10 cm; stems having smaller diameters are considered undergrowth (Pole, 1999). In previous studies of fossil forests (Jefferson, 1982;Mosbrugger et al., 1994;Pole, 1999), workers sometimes recorded all stems N 1 cm diameter, but only counted these as trees if they fit the forestry definition of a tree in terms of diameter. ...
... (3) Density of the tree-sized stems was estimated using the forestry definition of a "tree" as stems having a breast-height diameter N 7.5 cm or, in some cases, N10 cm; stems having smaller diameters are considered undergrowth (Pole, 1999). In previous studies of fossil forests (Jefferson, 1982;Mosbrugger et al., 1994;Pole, 1999), workers sometimes recorded all stems N 1 cm diameter, but only counted these as trees if they fit the forestry definition of a tree in terms of diameter. In order to provide density data that are more directly comparable to those of modern forest stands, we also calculated density when only stems with diameters of N7.5 cm and N 10 cm are counted. ...
... Their plot of number of stems per size class as a function of diameter showed similar slopes for the two forests. The Jurassic forest was dominated by gymnosperms (conifers) with a well developed undergrowth of osmundaceous ferns (Pole, 1999). The early Tertiary forest comprised mostly gymnosperms and angiosperms (Basinger et al., 1994), including some extant genera. ...
Natural molds of 165 stems were found in life position in a 1 m-thick sandstone bed, lower Permian (Wolfcampian), Sangre de Cristo Formation, northern New Mexico. The sandstone represents a single flood event of a river sourced in the Ancestral Rocky Mountains. Most of the flood-buried plants survived and resumed growth. The stem affinities are uncertain, but they resemble coniferophytic gymnosperms, possibly dicranophylls. Stem diameters (N = 135) vary from 1 to 21 cm, with three strongly overlapping size classes. Modern forest studies predict a monotonically decreasing number (inverse square law) of individuals per size class as diameter increases. This is not seen for fossil stems ≤ 6 cm diameter, reflecting biases against preservation, exposure, and observation of smaller individuals. Stems ≥ 6 cm diameter obey the predicted inverse square law of diameter distribution. Height estimates calculated from diameter-to-height relationships of modern gymnosperms yielded heights varying from ~ 0.9 m to > 8 m, mean of ~ 3 m. Mean stand density is approximately 2 stems/m2 (20,000 stems/hectare) for all stems > 1 cm diameter. For stems > 7.5 cm or > 10 cm diameter, density is approximately 0.24 stems/m2 (2400 stems/hectare) and 0.14 stems/m2 (1400 stems/hectare). Stem spatial distribution is random (Poisson). Mean all-stem nearest-neighbor distance (NND) averages 36 cm. Mean NND between stems > 7.5 cm and > 10 cm diameter is approximately 1.02 m and 1.36 m. NND increases in approximate isometry with stem diameter, indicating conformation to the same spatial packing rules found in extant forests and other fossil forests of varying ages. Nearest-neighbor distance distribution passes statistical testing for normality, but with positive skew, as often seen in extant NND distributions. The size-frequency distribution of the stems is similar to those of Jurassic, early Tertiary, and extant woodlands; the early Permian woodland distribution line has the same slope, but differs in that the overall size range increases over time (Cope's rule). The early Permian woodland is self-thinning; its volume versus density relationship shows a self-thinning exponent between − 1.25 and − 1.5, within the range seen in some extant plant stands (− 1.21 to − 1.7).
... Likewise, the biomechanical approach has been used to reconstruct Jurassic and Miocene age fossil plant heights (Mosbrugger et al. 1994;Creber and Francis 1999;Pole 1999). This method is based on the early work of Greenhill (1881) and predicts maximum stem length based on critical buckling length as it relates to basal stem diameter (see Table 1, equation 5). ...
... In practice, these values are estimated from modern wood, because actual values are unlikely to be determined from fossil material. The height estimates predicted by this method tend to be overestimates of actual tree height (Pole 1999;Williams, Johnson, LePage, Vann and Taylor 2003). This discrepancy has been interpreted as a design safety factor against mechanical failure (Niklas 1992). ...
... Growth rings indicate that most of the trees were no older than 70 years, although the largest trees were around 200 years old. Pole (1999) notes that the fossil logs were essentially unbranched and had very little stem taper, similar to modern Araucaria growing in a closed canopy setting. He speculated that the fossil forest was also closed canopy. ...
... Although the stand densities in modern conifer forests vary widely as a result of factors such as the population dynamics of the community, site disturbance regime and stand age (Pole 1999, Donoso 1993, neotropical and tropical extant forests (Pole 1999) show density values similar to the Darwin Forest. The Andean forests of Patagonia are defined as 'temperate forests' and are dominated by broad-leafed angiosperms (Nothofagus being its most important component) in association with a few conifers such as Araucaria araucana. ...
... Although the stand densities in modern conifer forests vary widely as a result of factors such as the population dynamics of the community, site disturbance regime and stand age (Pole 1999, Donoso 1993, neotropical and tropical extant forests (Pole 1999) show density values similar to the Darwin Forest. The Andean forests of Patagonia are defined as 'temperate forests' and are dominated by broad-leafed angiosperms (Nothofagus being its most important component) in association with a few conifers such as Araucaria araucana. ...
... The age of conifers was estimated using the radius of stumps and growth-ring widths (Frangi 1976, Pole 1999). On the basis of 86 trunks, the average estimated age was 146 years (the maximum age was 244 years, and the minimum was 41 years). ...
Brea, M., Artabe, A. & Spalletti, L.A., December, 2008. Ecological reconstruction of a mixed Middle Triassic forest from Argentina. Alcheringa 32, 365–393. ISSN 0311-5518.
The palaeoecology of an in situ Middle Triassic forest known as the Darwin Forest, from the Paramillo Formation of Argentina, is described based on palaeobotanical, sedimentological and spatial analyses. The palaeoforest grew on an andisol soil that developed on volcaniclastic floodplain deposits. The volcanic detritus and the rhythmic amalgamation of upper flow-regime tractional deposits overlying the andisol indicate that the forest was buried rapidly by a subaerial, cool and wet pyroclastic base surge flow. The plant community was reconstructed by quantitative mapping of the fossilized stumps integrated with taxonomic and sedimentological information. The Darwin Forest had a tree density of 427–759 per ha, with an upper stratum (20–26 m) of corystosperms and a second stratum (16–20 m) of conifers. Estimated biomass is equivalent to modern dry monsoonal forest. The understorey was composed of ferns (Cladophlebis spp.). Quantitative growth-ring analysis of Araucarioxylon protoaraucana suggests that these trees were evergreen and, together with vegetation structure and sedimentary data, indicate that the forest developed under dry, subtropical, strongly seasonal conditions.
... 46839 0 48 00 ; E. long. 169805 0 43 00 ) has been previously investigated by Edwards (1934), Kidston and Gwynne-Vaughan (1907), Raine and Pole (1988), Tidwell (1994) and Pole (1988Pole ( , 1990Pole ( , 1999 Westermann, 1996 (1); Stevens, 1997 (2); Hudson et al., 1987Hudson et al., , pers. commun., 1998Marwick, 1953and Spath, 1923. ...
... The Curio Bay fossil forest crops-out on the shore platform as an extensive horizon of in-growth-position fossilised tree stumps and prostrate trunks in¯at-lying strata. The macro¯ora and micro¯ora of the site have been described in previous studies, notably, Pole (1999), Edwards (1934) and Raine and Pole (1988). The fossil wood present is similar to the Kawhia Harbour wood and has been described as primarily of Dadoxylon±Araucarioxylon and Protopinaceae type. ...
... The fossil wood present is similar to the Kawhia Harbour wood and has been described as primarily of Dadoxylon±Araucarioxylon and Protopinaceae type. Pole (1988Pole ( , 1999 also is Equisetites hollowayi, a representative of the horsetails (Equisetales). A pilot study of ®ve samples of ®ne-grained lithologies from the sea-cliff fossil forest horizons at Curio Bay yielded a well-preserved micro¯ora assemblage. ...
Fossil evidence of a high southern palaeolatitude (approximately 75–78° South) Middle Jurassic (Temaikan) forest from Gondwana is investigated from the Murihiku Supergroup exposed at Kawhia Harbour, North Island, New Zealand. Horizons of fossilised tree stumps, preserved in growth position and rooted within coal-rich layers at bedding contacts, are exposed within cross-bedded medium-grained sandstone on the present-day shore platform. Interbedded siltstone and fine-grained sandstone contain terrestrial palynomorphs, fossilised leaves and other macroflora material (including cones and seeds).
... Since the Middle Devonian forests have been greening the Earth (Stein et al. 2007). There are studies on early tree shapes (Daviero & Lecoustre 2000;Meyer-Berthaud & Decombeix 2007) but very little is known about the architecture of Mesozoic trees (Philippe & Daviero 2000), as well as the forests they formed (Pole 1999). During most of the Mesozoic conifers dominated canopies, whereas ginkgos, cycads and pteridosperms were mainly low-to middle-sized trees and shrubs. ...
... Pioneering studies on fossil logs from Patagonia (Calder 1953), Alexander Island (Antarctica; Jefferson 1982) and the Isle of Purbeck (UK; Francis 1983) gave the first indications of tree shape and forest density in the Mesozoic, but were subsequently questioned (Pole 1999). Other famous fossil forests, such as that of Curio Bay (New Zealand), or fossil log assemblages, such as that of Petrified Forest National Park (Arizona), were also investigated in an architectural perspective (Pole 1999;Ash & Creber 2000;Savidge & Ash 2006). ...
... Pioneering studies on fossil logs from Patagonia (Calder 1953), Alexander Island (Antarctica; Jefferson 1982) and the Isle of Purbeck (UK; Francis 1983) gave the first indications of tree shape and forest density in the Mesozoic, but were subsequently questioned (Pole 1999). Other famous fossil forests, such as that of Curio Bay (New Zealand), or fossil log assemblages, such as that of Petrified Forest National Park (Arizona), were also investigated in an architectural perspective (Pole 1999;Ash & Creber 2000;Savidge & Ash 2006). Work relevant to the spacing and structure of Mesozoic trees has been described by Creber & Chaloner (1985, and references therein). ...
Trees are an obvious component of most landscapes. Artists' views of Mesozoic landscapes regularly feature modern trees such as firs (Abies and Picea) and monkey-puzzle trees (Araucaria araucana). However, these reconstructions are highly hypothetical and, in reality, very little is known about the silhouettes of Mesozoic trees. In Mesozoic (Middle Jurassic to Early Cretaceous) strata of Thailand, large conifer logs with different types of architecture are evident, a rare opportunity for architectural studies. Various methods to estimate the original diameter and height of the trees are assessed. Among our material some trees have the classical Christmas-tree shape, whereas others are more oak-like in silhouette. All these trees lived in forest environments. Tree shape is strongly related to environment, and is still under-used as a palaeoecological tool. Reconstructing trees and vegetation has wide implications, from evaluating dinosaur herbivory to calculating elements of the carbon cycle.
... More than a century from the earliest study, Mildenhall (1970) evaluated the taxonomic legitimacy of all New Zealand plant macrofossils listing many Jurassic species as invalid. Recent work on New Zealand's Jurassic floras has included an unpublished MSc thesis (Broekhuizen 1984), a fieldtrip guide (Grant-Mackie 1995), a review by Grant-Mackie et al. (2000), the work of Pole (1999Pole ( , 2001 and Thorn (2001Thorn ( , 2005 on fossil forests, including palynology and sedimentology, and a concerted effort to develop a palynological zonation (de Jersey & Raine 1990& Raine , 2002. Raine et al. (2008) have also provided an atlas of palynomorphs for the New Zealand region encompassing Jurassic forms. ...
... The exact position has potential ecological implications, for instance, in determining whether the terrane and associated flora lay in a polar position or not. Pole (1999) regarded the Middle Jurassic (Bathonian -Callovian, late Temaikan local stage; based on palynology, J.L. McKellar, J.I. Raine, and N. de Jersey, pers. comm. ...
... The most common Taeniopteris species in New Zealand and Australia, T. daintreei, is generally accepted as the foliage of the pentoxylaleans (Drinnan & Chambers 1985), and this is supported by the presence in New Zealand of pentoxylalean cones, Carnoconites (Harris 1962) and permineralised stems known as Pentoxylon. Pole (1999) illustrated in situ tree stumps in the fossil forest at Curio Bay, which show the distinctive polyxylic architecture of Pentoxylales. The group (or something closely related) is also clearly present in a private collection; R. Jackson, Christchurch, collected from the Slope Point area, south of Curio Bay; M. Pole, pers. ...
New Zealand's Jurassic plant fossils are known from non-marine settings in two terranes: the Murihiku forearc basin and from a small area on the Rakaia Terrane, an accretionary prism. These terranes lay in relatively high latitudes along the Gondwana margin but their precise location, latitude and position with respect to each other is unclear. The flora was dominated by conifers, ferns, bennettitaleans, pentoxylaleans and locally equisetaleans, but it is relatively depauperate, perhaps reflecting a high latitude position. Most climate indicators suggest a warm temperate climate with rainfall that was not especially high and that might have been seasonal at times. Revision of the New Zealand Jurassic flora is overdue, and while new genera may be discovered, species numbers may well decrease.
... At Curio Bay, fossilised fallen tree trunks and in situ stumps of a diverse Jurassic (c. 180 Ma) flora, including a variety of large canopy gymnosperms with an understorey of ferns, are exposed at low tide on a wave-cut platform (Pole 1999). These grew on abroad coastal plain in a humid, moderately warm climate. ...
... These grew on abroad coastal plain in a humid, moderately warm climate. Of the fossil flora preserved here, most are coniferous, likely of podocarp and araucarian affinity (Pole 1999). estimated mean tree height was interpreted to be 12 m (Pole 1999); this is less than the tree found at Coombs hills although the Coombs hills tree may have been large relative to surrounding vegetation, in part explaining its preservation. ...
... Of the fossil flora preserved here, most are coniferous, likely of podocarp and araucarian affinity (Pole 1999). estimated mean tree height was interpreted to be 12 m (Pole 1999); this is less than the tree found at Coombs hills although the Coombs hills tree may have been large relative to surrounding vegetation, in part explaining its preservation. A fossil conifer forest at Kawhia (Thorn 2005) includes stumps rooted in coal-rich layers; the mean overall stem diameter here is 0.3 m corresponding to a tree height of 21m. ...
An upright, partly rooted tree stump preserved within a late Early Jurassic basalt flow of the Ferrar Group, Coombs Hills, is described from southern Victoria Land, Antarctica. The wood structure allows the tree to be identified as a conifer (possibly Podocarpaceae) that from the stump diameter of 35–40 cm was c. 24 m tall. The possibly transported tree may have survived the lava flow because the stump was waterlogged or already mineralised. Conifers of similar age (early Middle Jurassic) are known from fossil forests at Curio Bay and Kawhia Harbour in New Zealand, and this discovery extends the known distribution of forests living in moderately warm, humid climates at very high southern latitudes during the late Early Jurassic.
... The general allometric equations (e.g., seeTable 1, equation 4) presented by Niklas (1994) perform reasonably well when compared to other methods of tree height estimation (Williams, Johnson, LePage, Vann andTaylor 2003). Likewise, the biomechanical approach has been used to reconstruct Jurassic and Miocene age fossil plant heights (Mosbrugger et al. 1994; Creber and Francis 1999; Pole 1999). This method is based on the early work of Greenhill (1881) and predicts maximum stem length based on critical buckling length as it relates to basal stem diameter (seeTable 1, equation 5). ...
... These equations were used to validate the volume approach to biomass estimation discussed above (Williams, Johnson, LePage, Vann and Taylor 2003). Whereas species and site-specific regression equations will generally yield the most accurate estimates of whole tree biomass, universal equations have been applied in fossil forest biomass reconstruction (Murray 1927, as cited by Pole 1999; Thorn 2005). An ideal general biomass equation is one that applies equally well to every stem (regardless of species) in the forest of interest . ...
... Others have countered this claim, however (Pole 1999), and newer interpretations indicate taller trees that lived more than 200 years (Falcon-Lang and Cantrill 2000). The application of three different methods to estimate tree height results in the wide range of reported height estimates (4 to 5 m [Jefferson 1982], 7 to 10 m [Pole 1999] and 14 to 29 m [Fal- Lang and Cantrill 2000]). Others have tried to estimate the wood volume production of Jefferson's (1982) forest and these also differ significantly , ranging from 5.6 to 17.6 m 3 · ha –1 · yr –1 (Creber and Francis 1999; Falcon-Lang et al. 2001). ...
Throughout much of earth history globally warm intervals prevailed over ice age conditions. Without the constraints imposed by cold climates, forest vegetation populated high-latitude land masses. There are no modern analogs for these biomes, thus fossil remains provide information vital to understanding the structure and function of these forests. This paper reviews methods (some common in neoecology) by which forest structure, biomass and productivity can be quan- tified from analysis of fossil remains. Common metrics of forest structure, such as stand density, stem diameter, basal area and tree height, can be de termined for most fossil forest localities using the methods described herein. When fossils are preserved as in situ forest layers (so-called fossil forests), additional analyses involving detailed stem measurement or the application of allometric regression models may yield estimates of aboveground biomass. Annual growth rates, when paired with estimates of stem wood volume production, provide an enhanced view of ecosystem energy flow. A review of published studies on polar fossil forests indicates that forest vegetation has occupied high-latitude landmasses since the Late Permian. Although these forests seem to be structurally similar to modern day forests, they differ in that they sequestered large amounts of biomass in warm polar climates. Middle Jurassic forests from New Zealand and early Cenozoic Metasequoia-dominated forests from the Canadian Arctic seem to have sequestered similar amounts of biomass despite differences in plant community taxonomic composition. The lack of dramatic differences between fossil and modern forest ecosystem structure and function may point to general constraints on forest biology that are supported by theoretical models.
... Studies of in situ stumps and logs have revealed general information about the ecology of forest trees growing in different environmental settings at different times in earth history (e.g., Francis 1991;Taylor et al. 1998;Pole 1999;Lehman and Wheeler 2001), but very few studies have rigorously defined the basic paleoecosystem attributes related to carbon accumulation-productivity and biomass. Under appropriate conditions, the combination of tree stumps preserved in growth position and careful analysis of fossil log remnants can be used to characterize the structure, developmental history, biomass, and productivity of an ancient forest ecosystem. ...
... Fossil logs sometimes undergo vertical collapse during burial. Nevertheless, it is usually assumed that the width of a compressed fossil log is equivalent to its original diameter (e.g., Pole 1999;Retallack 1999;Williams et al. 2003a). This assumption is valid if the object undergoes pure vertical collapse where the surrounding matrix prevents lateral expansion of the fossil despite vertical compression (Rex and Chaloner 1983;Niklas and Banks 1992). ...
Abundant fossil plant remains are preserved in the high-latitude middle Eocene deposits of the Buchanan Lake Formation on Axel Heiberg Island, Nunavut Territory, Canada. Intact leaf litter, logs, and stumps preserved in situ as mummified remains offer an opportunity to determine the structure, biomass, and productivity of two Taxodiaceae-dominated forests that grew north of the Arctic Circle (paleolatitude 75–80°N). We excavated fossil tree trunks and treetops to develop equations that describe the height, structure, and mass of the aboveground components of Eocene-age Metasequoia trees. We combined those data with surveys of in situ stumps to determine the structure, biomass, and productivity of two fossil forests, “N” and “HR.” We calculated a canopy height of 40 ± 3 m for the N forest and 25 m ± 2 m for the HR forest. Buried knots in dissected logs and abundant branch-free bole wood indicate that these were tall, closed-canopy forests. Stem tapers indicate that the overstory was of uniform height. Stem volume equaled 2095 m 3 ha −1 and stem biomass was 628 Mg ha −1 in the N forest. Volume and biomass in the HR forest were much smaller, 211 m 3 ha −1 and 63.3 Mg ha −1 , respectively. We estimated understory tree biomass to be 40 Mg ha −1 in the N forest and 3.5 Mg ha −1 in the HR forest. Recovery of seven fossil treetops with exposed branch stubs enabled us to make estimates of branchwood and foliar biomass using allometric equations derived from modern, plantation-grown Metasequoia glyptostroboides . Estimated stand-level branch biomass was 13 and 6.7 Mg ha −1 in the N and HR forests, respectively. Standing foliar biomass was estimated to be 3.2 and 2.1 Mg ha −1 in the N and HR forests, respectively. Using annual ring widths, the reconstructed parabolic stems, and wood density of modern Metasequoia , we calculated annual wood production to be 2.3 Mg ha −1 yr −1 for the N forest and 0.55 Mg ha −1 yr −1 for the HR forest Assuming that the ancient Metasequoia were deciduous like their living relatives, annual aboveground net primary productivity was 5.5 Mg ha −1 yr −1 for the N forest and 2.8 Mg ha −1 yr −1 for the HR forest. Our estimated biomass and productivity values for N are similar to those of modern old-growth forests of the Pacific Northwest of the United States and old-growth coastal Cordillera forests of southern Chile.
... Studies of in situ stumps and logs have revealed general information about the ecology of forest trees growing in different environmental settings at different times in earth history (e.g., Francis 1991;Taylor et al. 1998;Pole 1999;Lehman and Wheeler 2001), but very few studies have rigorously defined the basic paleoecosystem attributes related to carbon accumulation-productivity and biomass. Under appropriate conditions, the combination of tree stumps preserved in growth position and careful analysis of fossil log remnants can be used to characterize the structure, developmental history, biomass, and productivity of an ancient forest ecosystem. ...
... Fossil logs sometimes undergo vertical collapse during burial. Nevertheless, it is usually assumed that the width of a compressed fossil log is equivalent to its original diameter (e.g., Pole 1999;Retallack 1999;Williams et al. 2003a). This assumption is valid if the object undergoes pure vertical collapse where the surrounding matrix prevents lateral expansion of the fossil despite vertical compression (Rex and Chaloner 1983;Niklas and Banks 1992). ...
Accurate reconstruction of the biomass, structure, and productivity of ancient forests from their fossilized remnants remains an interesting challenge in paleoecology. In well-preserved Tertiary fossil Metasequoia forests of Canada's Arctic, in situ stumps and fragments of stems, treetops, and branches contain substantial information about tree dimensions that can be used to determine tree height, stand biomass, and other characteristics such as canopy depth and structure, and the history of stand development. To validate a method for reconstructing the biomass of the Eocene floodplain Metasequoia forests of Axel Heiberg Island, we measured stump diameters and spacing, and stem, branch, and treetop characteristics in living Metasequoia glyptostroboides and Chamaecyparis thyoides stands in ways that simulate the limited measurements that can be made in well-preserved fossil forests in Canada and probably elsewhere. We used those limited measurements to estimate tree height and volume, branch and foliar dry weights, and tree biomass. The estimates derived from the limited data set are usually within 15% of the estimates derived from the methods currently used in forest ecology for determining those metrics in modern forests. Under appropriate conditions, the biomass of ancient forests can be estimated with reasonable confidence.
... The growth ring parameters measured were: number of rings, mean ring width, the width of the narrowest ring and widest ring. The age of the fossil trees was estimated using the relationship between the stump radius and growth-ring widths (Frangi 1976;Pole 1999). ...
... The age of the trees was estimated using the radius of the stump and the average width of First Prumnopitys-like fossil wood record 5 growth rings (Frangi 1976;Pole 1999). The ring width indicates an average annual growth rate in the order of 2.08 mm and the radius of the stump is 121 mm. ...
The main objective of the present paper is to describe a new genus and species of Podocarpaceae fossil wood from the Upper Cenozoic Ituzaingó Formation, Paraná Basin, Argentina, based on a detailed description of the secondary xylem. This specimen, Prumnopityoxylon gnaedingerae Franco & Brea gen. nov. & sp. nov., is the first fossil wood referable as coniferous from northeastern Argentina. This fossil resembles extant Prumnopitys Phil. (Podocarpaceae), sharing the following anatomical features: slightly distinct growth rings; the absence of axial parenchyma; uniseriate and homocellular rays; uniseriate or biseriate, opposite or sub-opposite, separate or contiguous tracheid pitting; and cupressoid or taxodioid cross-field pitting. The presence of this Podocarpaceae fossil from the Ituzaingó Formation indicates that the distribution of this family was more widespread and probably continuous in South America in the past. It also provides new evidence for the hypothesis of its wide distribution in northeastern Argentina during the Cenozoic.
... Near Curio Bay, the terrestrial deposits are primarily fluvial, often including coarse conglomerates, and they interfinger with marine sediments. The fluvial deposits contain petrified forests (Pole, 1988(Pole, , 1999(Pole, , 2001(Pole, , 2004, which occur within couplets consisting of (1) paleosols preserving the underground bases of trees and ferns preserved in growth position and (2) fluvial A u s t r a l i a N e w Z e a l a n d (Mortimer et al., 1999) is along the south coast of eastern Gondwana and is now called the Median Tectonic Zone. Modified from Grant-Mackie et al. (2000) and Briggs et al. (2004). ...
... Superimposed layers of these petrified forest couplets are widespread in the False Islet Formation but are best exposed from the Nature Preserve along the shoreline at Curio Bay eastward some 10 km to Black Point. At Curio Bay waves exhumed one of the petrified forests exposing conifer, pentoxylalean, and osmundaceous axes associated with well-preserved leaf, stem, and cone impressions (Arber, 1917;Edwards, 1934;Parris et al., 1995;Pole, 1999). Our study utilizes a single New Zealand specimen (CM 2006.33.1), collected by Ray Jackson, consisting of a slice of the base (stump) of a permineralized axis, found on a modern cobblestone beach. ...
A new genus and two new species of an incertae sedis spermatophyte are erected based on large, petrified and permineralized axes from Middle to Upper Jurassic strata of central Queensland and northeastern New South Wales in Australia and the South Island of New Zealand. Specimens of this genus were previously considered by some to be a form of the Indian taxon, Pentoxylon. The new genus, Donponoxylon, however, differs from Pentoxylon and other spermatophytes in having very small, round (in cross section) sympodial strands characterized primarily by centrifugal secondary xylem development in individual segments. Furthermore, these segments form a complex anastomosing system that branches and coalesces throughout the stem. Donponoxylon consists of two species: Donponoxylon bennettii and Donponoxylon jacksonii. D. bennettii is diagnosed by atypical secondary growth with continuous or discontinuous concentric outer vascular rings, and by a generally irregular arrangement of vascular segments around the pith. D. jacksonii differs from D. bennettii in having the vascular segments regularly arranged around the pith and the absence of the outer vascular rings. In the absence of attached foliage or reproductive structures, the phylogenetic relationships of Donponoxylon remain uncertain beyond its assignment to Spermatopsida. Donponoxylon was an arborescent component of Middle to Late Jurassic high-latitude forests along the southeast coast of East Gondwana where it thrived in moist, volcaniclastic-derived soils.
... Artabe et al. (2007) describe a forest density of 727-1504 trees per hectare. Pole (1999) described an in situ mixed fossil forest of conifers (Araucariaceae and Podocarpaceae), Pentoxylales and ferns (Osmundaceae) from the Middle Jurassic of New Zealand. The conifers, about 100-year-old, were at least 10 m high but some reached 200 years and probably exceeded 30 m in height. ...
... This estimation could be over-inflated as all casts and moulds were count yet some of them may have been upturned roots and not stems. For his calculation, Pole (1999) took into account only those stumps which were more than 80 mm in diameter, and Jefferson (1982) only those exceeding 100 mm in diameter. Here, all vertical casts displaying perpendicular root bases were considered. ...
A level with fern stumps was discovered in the Aptian Douiret Formation, South-Tunisia. These stumps are preserved as external moulds or casts, without any preservation of anatomical structures. These stumps are considered to be affiliated with the numerous fossil plants assigned to the fern genera Alstaettia and Piazopteris that are widely distributed in coeval strata from the same region, either as leaf imprints or as permineralized remains. The record of in situ fossil forests for the Southern Hemisphere reveals that their systematic components are different, i.e. mainly corystosperms and/or conifers, and rarely under tidal influence. The way this fern grove settled in a margino-littoral environment is discussed.
... A less complex woody gymnosperm assemblage appears to have been present in Jurassic coal-forming environments, dominated by isopimaroid-secreting members. This appears to be supported by studies of the fossil remains of Jurassic forests in North (Thorn 2001) and South (Pole 1999) Islands of New Zealand, which have suggested a woody flora dominated by conifers with a probable araucarian affinity. This characteristic appears to be shared with other contemporaneous, high southern paleolatitude, fossil floras (Thorn 2001). ...
... This characteristic appears to be shared with other contemporaneous, high southern paleolatitude, fossil floras (Thorn 2001). The relatively elevated abundance of compound Y in sample G47/f51 from Curio Bay may reflect slightly different woody gymnosperm contributions from the other Jurassic coaly samples, or it may be due to different diagenetic conditions resulting from the frequent sheet floods that deposited volcanic sediments (Pole 1999). ...
The previously erected chemostratigraphy for Late Cretaceous‐Eocene coaly sediments in Taranaki Basin, New Zealand, has been extended to the Jurassic, primarily using samples from the South Island. Biomarker analysis by selected ion GC‐MS indicates that the abundance of angiosperm‐derived triterpanes and gymnosperm‐derived diterpanes are lower relative to hopanes in samples from the mid‐Cretaceous Trichotomosulcites subgranulatus Assemblage (miospore superzone TS) than younger coaly sediments, and exhibit a significant degree of variation in diterpane distributions and ratios of angiosperm to gymnosperm biomarkers. The two samples from the mid‐Cretaceous Lycopodiacidites bullerensis‐3 Zone (LB3) have similarly relatively low amounts of woody plant derived terpanes, but almost identical diterpane distributions. Jurassic coals show the expected absence of biomarker contribution from angiosperms. They exhibit the simplest diterpane distributions, dominated by isopimaroids, and suggest a fairly uniform woody gymnosperm community. The characteristic Jurassic biomarker zone is designated CD*, after the Australian Callialasporites dampieri Superzone that spans the mainly mid‐Jurassic interval sampled. The angiosperm‐gymnosperm index is not readily extended to include samples older than the Late Cretaceous (Phyllocladidites mawsonii Assemblage, PM), because of the variable and sometimes high values exhibited by samples from the TS and LB3 miospore zones. However, various parameters can be derived from the distributions of woody‐plant terpanes that, when used in combination, permit reasonable discrimination of the CD*, LB3, and TS Zones from each other and three younger groups of zones—PM2, PM3‐MH1, and MH2‐NM. The chemostratigraphy can be applied to correlating terrestrial oils with their sources, with four main groupings of floral zones being recognised in New Zealand—LB3+TS, PM2, PM3+MH1, and MH2+MH3+NM. The previously tentative identification of 18‐norisopimarane is revised.
... Studies of in situ stumps and logs have revealed general information about the ecology of forest trees growing in different environmental settings at different times in earth history (e.g., Francis 1991;Taylor et al. 1998;Pole 1999;Lehman and Wheeler 2001), but very few studies have rigorously defined the basic paleoecosystem attributes related to carbon accumulation-productivity and biomass. Under appropriate conditions, the combination of tree stumps preserved in growth position and careful analysis of fossil log remnants can be used to characterize the structure, developmental history, biomass, and productivity of an ancient forest ecosystem. ...
... Fossil logs sometimes undergo vertical collapse during burial. Nevertheless, it is usually assumed that the width of a compressed fossil log is equivalent to its original diameter (e.g., Pole 1999;Retallack 1999;Williams et al. 2003a). This assumption is valid if the object undergoes pure vertical collapse where the surrounding matrix prevents lateral expansion of the fossil despite vertical compression (Rex and Chaloner 1983;Niklas and Banks 1992). ...
Accurate reconstruction of the biomass, structure, and productivity of ancient forests from their fossilized remnants remains an interesting challenge in paleoecology. In well-preserved Tertiary fossil Metasequoia forests of Canada's Arctic, in situ stumps and fragments of stems, tree-tops, and branches contain substantial information about tree dimensions that can be used to de-termine tree height, stand biomass, and other characteristics such as canopy depth and structure, and the history of stand development. To validate a method for reconstructing the biomass of the Eocene floodplain Metasequoia forests of Axel Heiberg Island, we measured stump diameters and spacing, and stem, branch, and treetop characteristics in living Metasequoia glyptostroboides and Cha-maecyparis thyoides stands in ways that simulate the limited measurements that can be made in well-preserved fossil forests in Canada and probably elsewhere. We used those limited measurements to estimate tree height and volume, branch and foliar dry weights, and tree biomass. The estimates derived from the limited data set are usually within 15% of the estimates derived from the methods currently used in forest ecology for determining those metrics in modern forests. Under appro-priate conditions, the biomass of ancient forests can be estimated with reasonable confidence.
... This call for caution in the use of MS for the palaeoecological interpretation of fossil woods should not obscure the fact that they can be validly used to for a range of palaeoenvironmental applications, including: estimating ancient forest stature and productivity (e.g., Williams et al. 2009;Pole 1999), tree architecture (Steart et al. 2023), insect, fungal, and bacterial interactions (Feng et al. 2019;McLoughlin and Mays 2022;Greppi et al. 2022), tracking taphonomic pathways (Philippe et al. 2022), growth disturbances from volcanic activity (Cuneo 2021), palaeoseismicity (Minor and Peterson 2016) and insect defoliation (Dechamps 1984), detecting palaeo-rainshadow effects (Oh et al. 2020) and biogeographic patterns (Philippe et al. 2004). ...
The growth rings of fossil wood provide valuable data on tree ecology. As many of the parameters controlling width are
climatic, it is tempting to use these rings as an indicator of climate. This is what has been done, with great success, by
dendrochronological studies of archaeological wood. For wood dating from before the Pleistocene, however, the task
is more uncertain. Since around 1980, researchers have relied mainly on a statistical parameter, the mean sensitivity, an
average of the difference in width between two consecutive rings. However, there has never been a critical examination
of utility and significance of this parameter for fossil wood. I compiled 63 studies that used mean sensitivity for
palaeoclimatological inferences. An analysis of this compilation is presented here. Despite its ups and downs since the
1980’s, mean sensitivity is increasingly used by palaeobotanists. However, it has been used in very different ways. The
values obtained for the same fossil can vary greatly from one researcher to another, but also according to the radii of
the woody axis considered. Within fossil wood assemblages, average sensitivity varies widely, but rarely consistently.
Overall, mean sensitivity values are continuously, normally and unimodally distributed, and therefore are unsuitable for
characterising discrete climate classes. Finally, it seems that the most recent studies are also the least cautious when it
comes to interpreting the values obtained.
... Alternatively, to the curves of Mosbrugger (1990) and the here employed formula from Niklas (1993Niklas ( , 1994, other equations have been proposed to estimate tree height from the diameter of fossil trunks (e.g. Pole, 1999;Philippe et al., 2009). Philippe et al. (2009) apply a useful alternative equation to calculate minimum heights of the original trees from partial log. ...
The Valcheta Petrified Forest is located in the northeast of the Río Negro Province, Argentina. This work provides a geological characterization of the site and a survey of the fossil logs exposed on the surface and their systematic study. The fossiliferous levels bearing the silicified logs are here referred to the Allen Formation (middle-upper Campanian – lower Maastrichtian, Malargüe Group). These deposits crop out in patches in the study area, and have been deposited on a paleorelief carved in Eopaleozoic rocks of the Nahuel Niyeu Formation being mostly covered by thin layers of Quaternary sediments. The Valcheta Petrified Forest was developed on the margins of a braided fluvial system. Numerous silicified logs have been located at the site. They consist of large axes, not found in life position, with monopodial growth, some of which retain the bases of lateral branches and flared-like base. The estimated height and ages of these trees suggests that it consisted of a mature forest. No other associated vegetative or reproductive structures have been found. Anatomically, a single xylological type has been distinguished and assigned to Podocarpoxylon mazzonii (Petriella) Müller-Stoll et Schultze-Motel, (Podocarpaceae). This taxon has been previously identified from other localities of the Upper Cretaceous to the Danian of Patagonia although never preserved in such complete tree grow architecture. This shows that, along others conifers, cycads and palms, P. mazzonii would have constituted an important element of the arboreal strata in the North Patagonian forest communities during the Campanian-Danian interval producing monotypic patches in some areas.
... Cretaceous and Palaeogene woods from high palaeolatitudes (e.g. from the Antarctic Peninsula) differ by having predominantly complacent ring sensitivities (average MS of 0.184 for the Cretaceous and 0.228 for the Palaeogene), some rings up to 9 mm wide, abrupt transitions to a narrow band of latewood, and no false rings (Francis 1986;Falcon-Lang & Cantrill 2001). Similar differences are evident between the Korsaröd woods and the high-latitude Mesozoic woods from Australia (Frakes & Francis 1990) and New Zealand (Pole 1999), and Eocene woods from the Canadian Arctic (Francis 1991), which have complacent mean sensitivities, at least some relatively broad rings and abrupt latewood development. Permian high-latitude Antarctic woods from the Gondwanan continental interior, by contrast, have wider average growth rings (up to 3.87 mm) and more variable mean sensitivities (0.190 -0.475: Weaver et al. 1997). ...
Central Skåne (Scania) in southern Sweden hosts evidence of extensive Jurassic volcanism in the form of mafic volcanic plugs and associated volcaniclastic deposits that entomb well-preserved macro-plant and spore–pollen assemblages. Palynological assemblages recovered from the Höör Sandstone are of Hettangian–Pliensbachian age and those from the overlying lahar deposits are dated as Pliensbachian–early Toarcian (?). Palynomorph assemblages from these units reveal significantly different ecosystems, particularly with respect to the gymnospermous components that represented the main canopy plants. Both palynofloras are dominated by osmundacean, marattiacean and cyatheacean fern spore taxa but, whereas the Höör Sandstone hosts abundant Chasmatosporites spp. pollen produced by plants related to cycadophytes, the volcanogenic deposits are dominated by cypress family pollen (Perinopollenites) with an understorey component rich in putative Erdtmanithecales (or possibly Gnetales), and collectively representing vegetation of disturbed habitats. Permineralized conifer wood attributed to Protophyllocladoxylon sp., belonging to plants that probably produced the abundant Perinopollenites grains, is abundant in the volcanigenic strata, and shows sporadic intraseasonal and multi-year episodes of growth disruption. Together with the relatively narrow but marked annual growth rings, and the annual and mean sensitivity values that span the complacent–sensitive domains, these features suggest growth within Mediterranean-type biomes subject to episodic disturbance.
... Cretaceous and Palaeogene woods from high palaeolatitudes (e.g. from the Antarctic Peninsula) differ by having predominantly complacent ring sensitivities (average MS of 0.184 for the Cretaceous and 0.228 for the Palaeogene), some rings up to 9 mm wide, abrupt transitions to a narrow band of latewood, and no false rings (Francis 1986;Falcon-Lang & Cantrill 2001). Similar differences are evident between the Korsaröd woods and the high-latitude Mesozoic woods from Australia (Frakes & Francis 1990) and New Zealand (Pole 1999), and Eocene woods from the Canadian Arctic (Francis 1991), which have complacent mean sensitivities, at least some relatively broad rings and abrupt latewood development. Permian high-latitude Antarctic woods from the Gondwanan continental interior, by contrast, have wider average growth rings (up to 3.87 mm) and more variable mean sensitivities (0.190 -0.475: Weaver et al. 1997). ...
Central Skåne (Scania) in southern Sweden hosts evidence of extensive Jurassic volcanism in the form of mafic volcanic plugs and associated volcaniclastic deposits that entomb wellpreserved macro-plant and spore-pollen assemblages. Palynological assemblages recovered from the Höör Sandstone are of Hettangian-Pliensbachian age and those from the overlying lahar deposits are dated as Pliensbachian-early Toarcian (?). Palynomorph assemblages from these units reveal significantly different ecosystems, particularly with respect to the gymnospermous components that represented the main canopy plants. Both palynofloras are dominated by osmundacean, marattiacean and cyatheacean fern spore taxa but, whereas the Höö r Sandstone hosts abundant Chasmatosporites spp. pollen produced by plants related to cycadophytes, the volcanogenic deposits are dominated by cypress family pollen (Perinopollenites) with an understorey component rich in putative Erdtmanithecales (or possibly Gnetales), and collectively representing vegetation of disturbed habitats. Permineralized conifer wood attributed to Protophyllocladoxylon sp., belonging to plants that probably produced the abundant Perinopollenites grains, is abundant in the volcanigenic strata, and shows sporadic intraseasonal and multi-year episodes of growth disruption. Together with the relatively narrow but marked annual growth rings, and the annual and mean sensitivity values that span the complacent-sensitive domains, these features suggest growth within Mediterranean-type biomes subject to episodic disturbance.
... Calculation of tree height, stem volume, biomass, and productivity followed the forest mensuration methods as summarized in Williams (2007). The map of the fossil forest and measurement data of the individual tree stumps allow me to produce parameters used for characterizing forest structure: tree diameter, basal area, height, volume, dominant, subdominant and suppressed individuals, age/diameter relationships, trunk density, annual wood production, aboveground biomass (Mosbrugger et al., 1994;Pole, 1999), and a centennial trend of CO 2 -sequestration under a greenhouse climate (Osborne & Beerling, 2002). ...
... In situ fossil forests that range in age from the Holocene (11,700 years before AD 2,000) to the Carboniferous (359.2 to 299 Myr) provide a wealth of information including forest biodiversity, structure, biomass, productivity, environmental setting, paleoclimate, water-use ef fi ciency, and plant-fungal and plant-insect interactions (Figs. 14-18 ;Jefferson 1982 ;Francis 1984Francis , 1988Francis , 1991Creber and Chaloner 1985 ;Creber 1990 ;Taylor and Osborn 1992 ;Scott and Calder 1994 ;Pole 1999 ;Falcon-Lang and Cantrill 2000 ;Poole 2000 ;Labandeira et al. 2001 ;Jagels and Day 2003 ;Williams et al. 2003aWilliams et al. , b, 2008Williams et al. , 2009Creber and Ash 2004 ;Thorn 2005 ;Williams 2007 ;Vassio et al . 2008 ;Akkemk et al. 2009 ) . ...
Climate change could have profound impacts on world wetland environments, which can be better understood through the examination of ancient wetlands when the world was warmer. These impacts may directly alter the critical role of wetlands in ecosystem function and human services. Here we present a framework for the study of wetland fossils and deposits to understand the potential effects of future climate change on wetlands. We review the methods and assumptions associated with the use of plant macro- and microfossils to reconstruct ancient wetland ecosystems and their associated paleoenvironments. We then present case studies of paleo-wetland ecosystems under global climate conditions that were very different from the present time. Our case study of extinct Arctic forested-wetlands reveals insights about high-productivity wetlands that flourished in the highest latitudes during the ice-free global warmth of the Paleogene (ca. 45 million years ago) and how these wetlands might have been instrumental in keeping the polar regions warm. We then evaluate climate-induced changes in tropical wetlands by focusing on the Pleistocene and Holocene (2.588 Myr ago to the present) of Africa. These past ecosystems demonstrate that subtle changes in the global energy balance had significant impacts on global hydrology and climate, which ultimately determine the composition and function of wetland ecosystems. Moreover, the history of these regions demonstrates the inter-connectedness of the low and high latitudes, and the global nature of the Earth’s hydrologic cycle. Our case studies provide glimpses of wetland ecosystems, which expanded and ultimately declined under a suite of global climate conditions with which humanity has little if any experience. Thus, these paleoecology studies paint a picture of future wetland function under projected global climate change.
... The Winton Formation of central-western Queensland, which spans the Early to Late Cretaceous, has produced a significant palaeobotanical assemblage. Many studies have been conducted on the flora, including Bose (1955), White (1966White ( , 1974, Peters and Christophel (1978), Peters (1985), Dettmann et al. (1992), McLoughlin et al. (1995, Pole (1999aPole ( , 1999bPole ( , 2000aPole ( , 2000b, Pole and Douglas (1999), Dettmann and Clifford (2000) and Clifford and Dettmann (2005). At least 50 macrofossil taxa are present, from 10 orders, showing a co-dominance of conifers and angiosperms (McLoughlin et al. 2010). ...
Although there is a broad knowledge of Cretaceous climate on a global scale, quantitative climate estimates for terrestrial localities are limited. One source of terrestrial palaeoproxies is foliar physiognomy. The use of foliar physiognomy to explore Cretaceous assemblages has been limited, and some of its potential sources of error have not been fully explored. Although museum collections house a wealth of material, collection bias toward particular taxa or preservation qualities of specimens further magnifies existing taphonomic bias to cold temperatures. As a result, specific collection for foliar physiognomy can be necessary. Here, we conduct three foliar physiognomic analyses on the early Late Cretaceous Lark Quarry flora and assess the results in the context of other proxies from the same formation. Our results suggest that the climate at the Cenomanian–Turonian boundary in central western Queensland was warm and had high precipitation (leaf-area analysis: 1321 mm + 413 mm – 315 mm mean annual precipitation; leaf-margin analysis: 16.4 C mean annual temperature, 5.3 C binomial sample error; climate leaf-analysis multivariate program: 16 +/- 2 C for mean annual temperature, 9-month growth season, 1073 +/- 483 mm growth-season precipitation). Our analysis also gave higher mean annual temperature estimates than did a previous analysis by climate leaf-analysis multivariate program, based on museum collections for the Winton Formation.
... Furthermore, pronounced eustatic sea-level fluctuations throughout the Jurassic indirectly suggest episodic polar or extensive montane ice accumulation (Price, 1999). Nevertheless, the majority of the Jurassic appears to have been characterized by warm and equable conditions, allowing plants and their dependent fauna to colonize even polar latitudes (Pole, 1999;Rees et al., 2004;Vajda and Wigforss-Lange, 2009). These relatively warm, highlatitude, terrestrial environments experiencing strong annual changes in photoperiod have no modern analogues (Creber and Chaloner, 1985) and are of interest in terms of forecasting the biotic response to future global warming (Meehl et al., 2007). ...
A survey of Australian Jurassic plant fossil assemblages reveals examples of foliar and wood damage generated by terrestrial arthropods attributed to leaf-margin feeding, surface feeding, lamina hole feeding, galling, piercing-and-sucking, leaf-mining, boring and oviposition. These types of damage are spread across a wide range of fern and gymnosperm taxa, but are particularly well represented on derived gymnosperm clades, such as Pentoxylales and Bennettitales. Several Australian Jurassic plants show morphological adaptations in the form of minute marginal and apical spines on leaves and bracts, and scales on rachises that likely represent physical defences against arthropod herbivory. Only two entomofaunal assemblages are presently known from the Australian Jurassic but these reveal a moderate range of taxa, particularly among the Orthoptera, Coleoptera, Hemiptera and Odonata, all of which are candidates for the dominant feeding traits evidenced by the fossil leaf and axis damage. The survey reveals that plant-arthropod interactions in the Jurassic at middle to high southern latitudes of southeastern Gondwana incorporated a similar diversity of feeding strategies to those represented in coeval communities from other provinces. Further, the range of arthropod damage types is similar between Late Triassic and Jurassic assemblages from Gondwana despite substantial differences in the major plant taxa, , implying that terrestrial invertebrate herbivores were able to successfully transfer to alternative plant hosts during the floristic turnovers at the Triassic–Jurassic transition.
... All the logs display elliptical cross-sections, a flattening typical for fossil logs, but which might also be, at least partly, original. Much has been published on how to estimate original tree diameter from flattened logs (Pole, 1999). Two methods were applied here (Table 1), one assuming the fossil log width as similar to the original one (Clifford, 1996), and another giving more conservative estimates (Philippe et al., 2009). ...
Giant fossil trees from the Middle Pleistocene of Thailand are described. The longest log is measured at 72.2 m. Morphological analysis suggests that the original trees towered to more than 100 m, in a wet tropical forest. As contemporaneous archaic pebble tools were reported in the same area, the subtropical rainforest was no impenetrable ecological barrier to a population of Homo erectus.
... Map of the fossil forest and measured data of individual trees allow to produce parameters used for characterizing forest structure: tree diameter, basal area, height, volume, dominant, subdominant and suppressed individuals, age/diameter relationship, trunk density, annual wood production, aboveground biomass (MOSBRUGGER et al. 1994;POLE 1999), and centennial trend of CO 2 -sequestration under a greenhouse climate (OSBORNE & BEERLING 2002). ...
The oldest, standing forest preserved as wood has been found at Bükkábrány, Hungary. An open-pit mine working Upper Miocene (Pannonian) lignite revealed sixteen stumps, 1.8 to 3.6 m diameter at base, preserved up to 6 m height, standing on top of the coal bed. Suddenly rising water level of Lake Pannon drowned the forest 7 Ma ago. Sand of a prograding delta covered the landscape, preserving the trunks in waterlogged condition. A brief review of the environment allowing preservation is provided here, and investigations in progress are outlined.
... For the Jurassic and much of the Cretaceous, New Zealand was probably within or close to the polar circle (e.g. Lawver et al. 1992, Pole 1999, McLoughlin 2001, Schellart et al. 2006, implying significant seasonal variation in light and climate, and thus in biological productivity (plant growth). Further, by about 85 Ma (Piripauan; Cooper 2004), the Tasman Sea was opening, and the New Zealand landmass was presumably physically isolated from other parts of Gondwana. ...
... The accuracy of the results was not affected by the measurement technique, since the diameter at the preserved height of both lying trunks and standing stumps should not vary markedly from the dbh, as could be observed in the two complete horizontal trunks; the shape of the trunk above the collar is in fact almost columnar. Similar techniques for diameter measurement were previously adopted in reconstructions of Mesozoic fossil forests (Artabe et al., 2007;Cúneo et al., 2003;Pole, 1999;Thorn, 2005) and demonstrated to be trustworthy for biometric calculations. ...
... Suggate et al. (1978) regarded the Waikawa flora as Early Temaikan (Bajocian) in age. However, palynological data from Curio Bay, west of Waikawa, suggest a Late Temaikan age (Bathonian-Callovian age; Pole 1999Pole , 2001. ...
New results on the stratigraphy and sedimentary environment of the Middle Jurassic strata of the Murihiku Terrane in the Waikawa district, Southland, New Zealand, are presented. This area has not been subjected to study for a long time, although the Murihiku Terrane is important to understand the Mesozoic geology of New Zealand. Stratigraphically, from bottom to top, the sequence consists of lithofacies associations A, B, C, and D, distinguished by their lithology. Lithofacies association A (250 m thick) is composed of boulder?grade conglomerate, coarse?grained massive sandstone, trough cross?stratified sandstone, and minor fine?grained sediments. Lithofacies association B (90 m thick) contains alternating beds of sandstone and siltstone and fossil?bearing massive siltstone. Lithofacies association C (280 m) consists of poorly to moderately sorted pebble?cobble conglomerates and trough or planar cross?stratified sandstones. The characteristic lithofacies of lithofacies association D (>140 m) are planar cross?stratified sandstone, planar horizontally stratified sandstone, grey siltstone, and carbonaceous beds. The depositional age was deduced from bivalve fossils in lithofacies association B, which indicate a Middle Jurassic (Temaikan: Bajocian?Callovian) age.
Paleocurrent flow directions were from the southwest in lithofacies association A and from the southeast in lithofacies associations C and D. Clast compositions also differed between lithofacies associations A and C; andesite volcanic clasts were dominant in A, and rhyolite volcanic clasts were dominant in C.
The major sedimentary environments were terrestrial and shallow marine and were affected by sea?level changes. The sediments of lithofacies association B were deposited during periods of transgression and high sea level, and the boundary between lithofacies associations B and C is a depositional?sequence?bounding unconformity. Fluvial sedimentation became dominant in lithofacies associations C and D. Due to progressive aggradation of the sedimentary basin, the gradient became gentle, and the fluvial pattern changed from a braided to a meandering river. The sediment source, as determined from paleocurrent analyses and clast compositions, was also different from that of lithofacies association A. Thus, the Waikawa district sediments apparently were derived from multiple sources. The provenance of the Murihiku Terrane sediments was probably a primitive volcanic or continental margin arc. Volcanic activity in the hinterland fed large amounts of volcanic detritus to the region by flood, debris flow, and fluvial transport.
... There are no modern analogues to the high-latitude fossil forests (Francis, 1991), although other high-latitude paleoforests have been documented (e.g. Dawson et al., 1975;Pole, 1999). The paleolatitude of the arctic Cenozoic forests was possibly as high as 78°N (McKenna, 1980), far above the present-day treeline. ...
Hawke, M.I. and Stasiuk, L.D., 2000: Organic petrography and Rock-Eval characteristics of the Cenozoic fossil forest litter of Axel Heiberg Island, Nunavut, and their implications for hydrocarbon generation; Geological Survey of Canada, Current Research 2000-B5, 9 p. (online; http:// www.nrcan.gc.ca/gsc/bookstore) Abstract: An investigation of the organic petrography and hydrocarbon generative potential of the Eocene fossil forests of Axel Heiberg Island was conducted. Huminite (39-75%) and liptinite (17-42%) are the dominant macerals. Rock-Eval pyrolysis indicates moderate hydrocarbon potential in selected samples. Neither Rock-Eval pyrolysis nor organic petrography alone can adequately assess the hydrocarbon generative potential of terrigenous source rocks. Rock-Eval pyrolysis measures anomalously high oxygen indices for unhumified samples. Organic petrography data do not necessarily directly correlate with the hydrocarbon potential of the fossil-forest sediments. When results from both methods are examined in combination, however, a more accurate interpretation of the nature of the organic matter and its hydrocarbon generative potential is possible.
... The taxon represented is M. libanoticum and it formed large stands or forests of trees. Following the modi¢ed equations described by Pole (1999) to estimate tree height from trunk diameters, we estimate that these trunks with diameters in excess of 0.60 m would have had a height of 35^50 m. We collected a representative sample of fossil trunk specimens, six of which were used for thin sectioning and all of which remain the property of the Centre National de la Recherche Scienti¢que et Technologique, Bamako, Mali. ...
Examination of an extensive deposit of silicified fossil wood in Continental Intercalaire rocks of northeastern Mali suggests that the logs found at this locality were deposited under high energy conditions sometime between the Late Jurassic and the Early Cretaceous. The woods have been identified as Metapodocarpoxylon libanoticum (Edwards) Dupéron-Laudoueneix and Pons, an extinct member of the Podocarpaceae which has a restricted geographic and stratigraphic distribution: northern Gondwana and Tethys from Late Jurassic to Early Cretaceous time. Anatomical analysis indicates that the tree rings are indistinct, which supports previous suggestions that West Africa was under an equable climate during this part of the Mesozoic.
... High latitude fossil forests have been reported from the Permian to the Neogene and from both the Southern Hemisphere (e.g. Je¡erson, 1982; Francis, 1986; Taylor et al., 1992; Francis et al., 1994; Pole, 1999) and the Northern Hemisphere 0031-0182 / 02 / $ ^ see front matter ß 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 3 1 -0 1 8 2 ( 0 1 ) 0 0 4 5 2 -7 (e.g. ...
Fossil wood is abundant in Cretaceous and early Tertiary sediments of the northern Antarctic Peninsula region. The wood represents the remains of vegetation that once grew in high palaeolatitudes when the polar regions were warmer, during former greenhouse climates. Fossil wood is a unique data store of palaeoclimate information. Analyses of growth rings and anatomical characters in fossil wood provide important information about temperature, rainfall, seasonality and climate trends for this time period in Antarctica. Climate signals from fossil wood, supported by sedimentary and geochemical evidence, indicate a trend of cool climates during the Early Cretaceous, followed by peak warmth during the Coniacian to early Campanian. Narrower growth rings suggest that the climate cooled during the Maastrichtian and Palaeocene. Cool, wet and possibly seasonal climates prevailed at this time, with tentatively estimated mean annual temperatures (MATs) falling from 7°C to 4–8°C respectively, determined from dicotyledonous (dicot) wood anatomy. The Late Palaeocene/Early Eocene was once again warm, with estimated MATs of 7–15°C from dicot wood analysis, but conditions subsequently deteriorated through the latter part of the Eocene, when cold seasonal climates developed, ultimately leading to the onset of Cenozoic ice sheets and the elimination of vegetation from most of Antarctica.
In the Murihiku Terrane of New Zealand, U-Pb detrital zircon ages in Murihiku Supergroup sandstones of Late Triassic, Jurassic and possibly earliest Cretaceous age have a marked youngest age component that is close to, and sometimes coincident with, established biostratigraphic ages, thus reflecting contemporary volcanism. However, youngest Huriwai Group samples yield 137-142 Ma zircon age components (earliest Early Cretaceous) in conflict with palynofloras that suggest only a latest Jurassic age. This is resolved if the age of the Jurassic/Cretaceous boundary is lowered to ca. 140 Ma. Older, reworked zircons are mainly Early Jurassic, Late Triassic and Late Permian reflecting an enduring exhumed magmatic arc source nearby. This might be in the adjacent Median Batholith but as a Murihiku sediment source its Jurassic, Triassic and Permian elements are not well-matched in terms of extent, age and bulk compositions. A connection between the Murihiku (proximal forearc) and Waipapa Composite (distal accretionary wedge) terranes is probable, with a common magmatic arc, speculatively situated in the New England Orogen, eastern Australia.
Fossil-bearing Late Jurassic to Early Cretaceous volcaniclastic sandstones and siltstones from the Murihiku Supergroup are described from the Kaimango Syncline South Auckland, New Zealand. These constitute the youngest known sedimentary succession within the Murihiku Supergroup (Murihiku Terrane). We concentrate on the youngest Matira Siltstone Formation which has yielded a rich but relatively low-diversity macroflora of ferns and gymnosperms, diverse miospore palynofloras, with fair to good preservation, and sporadic occurrences of bivalve and gastropod faunas. Collectively, the paleontology and sedimentology of this formation is interpreted to represent paludal and lacustrine deposition, with intercalated sandstones thought to represent fluvial channelised or deltaic settings. U-Pb dating of detrital zircons (DZ) from sandstones in the youngest formations, Mangatara Measures and Matira Siltstone, have provided significant components in the age range 140 to 143 Ma, possibly straddling the Jurassic-Cretaceous boundary, although miospores suggest a Late Jurassic correlation. Lacustrine and paludal depositional environments have not previously been recognised from the Murihiku Supergroup and this raises the prospect of their enhanced petroleum source rock potential in frontier basins to the north and east of New Zealand.
This research focuses on the three-dimensional reconstruction of an in situ forest based on fossil
wood assemblages recovered in the Rancahué Formation (Upper Oligocene), Neuquén, Argentina.
Atherospermataceae, Lauraceae, Nothofagaceae, Eucryphiaceae, Cunoniaceae and Myrtaceae
specimens are described. The mapping of a forest floor section and in situ tree diameters enabled
the estimation of the following palaeoecological quantitative data: tree density, dominance, basal
area, biomass, diametric classes, canopy height, and age classes. Palaeoclimatical data was
determined on the basis of physiognomic anatomical features using multivariate anatomical
analyses. These results were compared with other proxies including Carlquist’s index, Coexistence
Approach (CA), Nearest Living Relatives (NLRs), and growth-rings analyses. The structural data
from the Aluminé forest inferred from these analyses includes: tree density of 463–701 tree/ha,
mean height of 15.22 m, dominance of the genus Nothofagoxylon ( 89.66 m2/ha), total basal area of
158.20 m2/ha, biomass between 43 and 712 tn/ha and mean age of 223 years (specimens between 31
and 700 years old). These results are comparable to those of mature low-to-middle altitude extant
forests dominated by Nothofagus and developed under humid-temperate conditions. Based on the
NLRs method, the Aluminé forest has a floristic composition similar to the present-day Valdivian
forest. The persistence of Nothofagus as the dominant element in temperate rainforests correlates
with regimes where large-scale disturbances, such as volcanism and earthquakes are prevalent. The
fossil taxa are closely related to the extant Laurelia, Persea, Eucryphia, Nothofagus, Weinmannia,
Myrceugenia and Luma. The forest shows intermixed deciduous and evergreen elements, and taxa
with shade-intolerance and intermediate shade tolerance. Also, the majority of these taxa need soils
with available water. The integrated analysis of multiple sets of proxy data suggests that the late
Oligocene forest grew under temperate and humid climate, while the eco-anatomical features and
sedimentary data provide information about the environmental stress conditions of its development
and the violent causes of burial.
The terrestrial biogeography of Gondwana during Jurassic – Early Cretaceous times is poorly resolved, and the flora is usually considered to have been rather uniform. This is surprising given the size of Gondwana, which extended from the equator to the South Pole. Documenting Gondwanan terrestrial floristic provincialism in the Jurassic – Early Cretaceous times is important because it provides a historical biogeographic context in which to understand the tremendous evolutionary radiations that occurred during the mid-Cretaceous. In this paper, the distribution of Jurassic – Early Cretaceous fossil wood is analysed at generic level across the entire supercontinent. Specifically, wood assemblages are analyzed in terms of five climatic zones (summer wet, desert, winter wet, warm temperate, cool temperate) established on the basis of independent data. Results demonstrate that araucarian-like conifer wood was a dominant, cosmopolitan element, whereas other taxa showed a greater degree of provincialism. Indeed, several narrowly endemic morphogenera are recognizable from the data.
The terrestrial biogeography of Gondwana during Jurassic–Early Cretaceous times is poorly resolved, and the flora is
usually considered to have been rather uniform. This is surprising given the size of Gondwana, which extended from the
equator to the South Pole. Documenting Gondwanan terrestrial floristic provincialism in the Jurassic–Early Cretaceous times
is important because it provides a historical biogeographic context in which to understand the tremendous evolutionary
radiations that occurred during the mid-Cretaceous. In this paper, the distribution of Jurassic–Early Cretaceous fossil wood is
analysed at generic level across the entire supercontinent. Specifically, wood assemblages are analyzed in terms of five
climatic zones (summer wet, desert, winter wet, warm temperate, cool temperate) established on the basis of independent
data. Results demonstrate that araucarian-like conifer wood was a dominant, cosmopolitan element, whereas other taxa
showed a greater degree of provincialism. Indeed, several narrowly endemic morphogenera are recognizable from the data.
Finally, comparisons with Laurasian wood assemblages indicate strong parallelism between the vegetation of both
hemispheres.
The leaf longevity of trees, deciduous or evergreen, plays an important role in climate feedbacks and plant ecology. In modern forests of the high latitudes, evergreen trees dominate; however, the fossil record indicates that deciduous vegetation dominated during some previous warm intervals. We show, through an integration of palaeobotanical techniques and isotope geochemistry of trees in one of the earliest polar forests (Late Permian, c. 260 Ma, Antarctica), that the arborescent glossopterid taxa were both deciduous and evergreen, with a greater abundance of evergreen trees occurring in the studied forests. These new findings suggest the possibility that deciduousness was a plastic trait in ancient polar plants, and that deciduous plants, migrating poleward from lower latitudes, were probably better adapted to high-disturbance areas in environments that were light-limited.
Forests are expected to expand into northern polar latitudes in the next century. However, the impact of forests at high latitudes on climate and terrestrial biogeochemical cycling is poorly understood because such forests cannot be studied in the modern. This study presents forestry and geochemical analyses of three in situ fossil forests from Late Permian strata of Antarctica, which grew at polar latitudes. Stem size measurements and stump spacing measurements indicate significant differences in forest density and canopy structure that are related to the local depositional setting. For forests closest to fluvial systems, tree density appears to decrease as the forests mature, which is the opposite trend of self-thinning observed in modern forests. We speculate that a combination of tree mortality and high disturbance created low-density mature forests without understory vegetation near Late Permian river systems. Stable carbon isotopes measured from permineralized wood in these forests demonstrate two important points: (i) recently developed techniques of high-resolution carbon isotope studies of wood and mummified wood can be applied to permineralized wood, for which much of the original organic matter has been lost and (ii) that the fossil trees maintained a deciduous habit at polar latitudes during the Late Permian. The combination of paleobotanical, sedimentologic, and paleoforestry techniques provides an unrivaled examination of the function of polar forests in deep time; and the carbon isotope geochemistry supplements this work with subannual records of carbon fixation that allows for the quantitative analysis of deciduous versus evergreen habits and environmental parameters, for example, relative humidity.
A Middle Jurassic fossil forest, thought to have been growing at high southern palaeolatitudes on the Gondwana margin, is described from New Zealand. Fossil stump horizons are exposed in stratigraphic section within the Urawitiki Measures Formation, Murihiku Supergroup. Tree bases were preserved by silica permineralisation in a sandy braided river setting. Fossil wood is referred to ‘abietinean-type’ and Agathoxylon. A total of 238 stumps were mapped with measured diameters allowing tree height estimates of 9–40 m. A two-dimensional area (102 m2) allows an interpretation of tree density (2353 trees/ha), biomass (579 t/ha) and stand basal area (146 m2). This horizon is interpreted as a highly productive, young, dense tree stand probably actively regenerating on a flood-cleared surface. Annual growth rings suggest a clearly defined growing season with a rapid onset of favourable temperature, light and water supply conditions at the start and a similarly rapid deterioration at the end. Mean ring width is 1·10 mm and the maximum 9·67 mm. Mean Sensitivity values suggest both ‘complacent’ and ‘sensitive’ growth patterns. Broad palaeoclimate interpretations suggest a humid, warm regional climate throughout the growing season.
A central goal of evolutionary biology is the development of a general predictive theory that incorporates the various forces structuring biological diversity. In this article, we argue that a focus on allometry and metabolic scaling theory provides the basis to begin to mechanistically link and understand patterns observed at ecolog-ical and evolutionary timescales. To make our case, we draw on and review several recently published papers and present new analyses. We argue that together, this synthesized work supports the notion that selection has maximized the scaling of resource exchange surfaces (e.g., photosynthetic surface areas) yet simultaneously minimizes the scaling of transport times and resistances. As a result, the scaling of plant metabolism, in turn, has profoundly influenced the evolution and ecology of plant form, function, and diversity, probably since the inception of the chlorophytes. In particular, we discuss preliminary support for the notion that stabilizing selection for 3/4-power scaling of metabolism, in addition to competition for similar limiting resources, has led to the emergence of regular ecological patterns that have likely been prevalent throughout plant evolution.
The terrestrial biogeography of Gondwana during Jurassic–Early Cretaceous times is poorly resolved, and the flora is usually considered to have been rather uniform. This is surprising given the size of Gondwana, which extended from the equator to the South Pole. Documenting Gondwanan terrestrial floristic provincialism in the Jurassic–Early Cretaceous times is important because it provides a historical biogeographic context in which to understand the tremendous evolutionary radiations that occurred during the mid-Cretaceous. In this paper, the distribution of Jurassic–Early Cretaceous fossil wood is analysed at generic level across the entire supercontinent. Specifically, wood assemblages are analyzed in terms of five climatic zones (summer wet, desert, winter wet, warm temperate, cool temperate) established on the basis of independent data. Results demonstrate that araucarian-like conifer wood was a dominant, cosmopolitan element, whereas other taxa showed a greater degree of provincialism. Indeed, several narrowly endemic morphogenera are recognizable from the data. Finally, comparisons with Laurasian wood assemblages indicate strong parallelism between the vegetation of both hemispheres.
A palaeoecological study of a standing Late Triassic forest containing 150 silicified stumps from the Río Blanco Formation of Mendoza province, Argentina is described. A mapped portion of the forest floor provides quantitative data — tree density, mean separation of trees and basal area per stump — which, along with taxonomic and sedimentologic information, allowed the reconstruction of a plant community that grew along river banks and within proximal floodplain environments. Analysis of architectural and phenological data from monotypic forest indicates an evergreen community composed of a corystosperm genus with a canopy height of c. 13–21 m. The corystosperm taxon: Elchaxylon, like Rhexoxylon, has polyxylic axes with centripetal secondary xylem but does not generate perimedullar bundles and the centrifugal secondary xylem produces an undivided solid pycnoxylic cylinder. Vegetation analysis shows that the forest has a clustered distribution pattern with high density. Forest density ranges between 727 and 1504 trees/ha but there are first order clusters with elevated density (mean nearest neighbour distance of 1.85 m). The histogram of diameter classes based on 131 stumps suggests an earlier colonization by few older pioneers (the largest ones) followed by establishment of a large younger cohort of coeval trees. Based on 9 series and 139 rings, the mean ring width and mean sensitivity (MS) were 3.47 mm and 0.31 respectively. MS values and the presence of false rings indicate the forest community responded to stressed ecosystems. The growth rings are very erratic and range from 0.27 to 8.94 mm. For fossil growth analysis it was assumed that wider rings would suggest a warmer climate and the considerable range in growth rates would indicate variability in the limiting factors among subsequent cycles.
Three hectares of Amazonian terra firme forest and an adjacent one-half hectare of várzea forest were quantitatively inventoried
at O Deserto, on the Rio Xingu, Pará, Brazil. In the terra firme forest, 1420 individual trees greater than ten cm dbh, in
39 families and 265 species, were inventoried. In the várzea forest, there were 220 individual trees, in 17 families and 40
species.Cenostigma macrophyllum andOrbignya sp. were the most important species in the terra firme forest;Mollia lepidota andLeonia glycycarpa were most important in the várzea forest. Among one-hectare subplots of the total three-hectare terra firme sample, the number
of trees ranged from 393 to 460, the number of families was a constant 33, and the number of species ranged from 118 to 162.
This variation indicates that one-hectare samples are too small to be used to estimate the species richness of the total forest.
The terra firme forest was richer in species and had a greater stature than the várzea forest.
An open access copy of this article is available from the publishers website. Twenty five plots of mature kauri Agathis australis (D. Don) Lindl., covering the range of the species in northern New Zealand, were sampled for density, basal area, and species composition using a modified point-centered quarter technique. Two increment cores were taken from at least ten trees at most sites, and used to estimate tree ages and growth rates. The density of kauri stems ^ 10 cm d.b.h. ranged from 17 to 416 ha~', and the basal area from 23 to 127 m2 ha~' in the 25 stands. Diameter distributions ranged from highly skewed and unimodal to flat and multi- modal, with all size classes represented in most plots. Combined frequency distributions suggest that two or three kauri generations (cohorts) may be present on many sites. There is only a weak relationship between age and diameter; individuals in the same 10 cm diameter class may vary in age by 300 years, and the largest individual on the site is often not the oldest. Mean annual diameter increments range from 0.15 to 0.46 cm yr~'on different sites with an overall average of 0.23 cm yr~>, equivalent to 8.7 annual rings per cm of core, about half the com- monly quoted figure for growth rate. Periodic mean annual increment and mean annual increment curves are presented. It is concluded that the "normally attainable age" is >600 years. Individuals >2 m d.b.h. probably often exceed 1000 years, but there is no reliable evidence for trees >2000 years in age. individuals in the same 10 cm diameter class may vary in age by 300 yr, and the largest individual on the site is often not the oldest. Mean annual diameter increments range from 0.15-0.46 cm yr-1 on different sites with an overall average of 0.23 cm yr-1, equivalent to 8.7 annual rings per cm of core. The "normally attainable age' is >600 yr. Individuals >2 m dbh probably often exceed 1000 yr, but there is no reliable evidence for trees >2000 yr in age.
This striking book provides a handy summary of the ecology of the world's vegetation. The introductory chapters provide a basic back-drop to the subject. The subsequent chapters examine sequentially the form and function of each major biome throughout the world.
The Glenham Porphyry comprises an andesitic suite of terrestrial flows and small sub-volcanic intrusions of Late Triassic to early Jurassic age within Murihiku Supergroup sediments of E Southland. The rocks have a stable, reversed-polarity thermoremanent magnetisation (TRM) component overprinted by a strong secondary component of normal polarity and low coercivity, that is removed in a demagnetising A.C. field of 30mT. The mean TRM, corrected for tectonic tilt, is D = 343o, I = +78o (alpha95 = 5.6o K 29) giving a paleomagnetic N pole position at 24oS, 162oE (dp = 9.2o, dm = 10.2o), and a paleolatitude fo 66o. When rotated back to Antarctica, the reconstructred paleopole position, at 43oS, 218oE is close to the Jurassic pole positions of other Gondwana continents.-Authors
Polar climate exerts a strong influence on global atmospheric and oceanic conditions, and therefore a sound knowledge of the thermal regime, precipitation/evaporation, and the presence òr amount of ice at high latitudes is essential for understanding a wide range of global systems. Probably the most sensitive indicator of atmospheric conditions, and one that bequeaths an extensive and abundant fossil record, is land vegetation. Accurate reconstructions of polar vegetation through time, and appropriate interpretations of the climatic signal contained in the resultant plant fossil record, is therefore critical to our understanding of global paleoclimate, the evolution and distribution of global biotas, and successful retrodiction of sources of fossil fuels and climate-related mineral deposits.
Description and quantitative evaluation of various cycles of leaf production in the rain forest of Gabon, especially focussed on the availability of young shoots and leaves
Fossil forests preserved within the Middle Eocene sediments of eastern Axel Heiberg Island represent an environment of floodplains adjacent to a large river system, over which dense forests of deciduous conifers (principally Metasequoia) and broad-leaved angiosperms became established intermittently. Several hundred tree stumps are exposed in over 30 forest layers at this locality. Fossil forests at such high latitudes represent a unique environment not present on earth today. Wide growth rings in the fossil wood illustrate that ambient temperatures were warm and favourable for forest growth, and that trees were adapted to the extended periods of daylight and darkness and the predominantly low-angle sunlight present at that time. Organic productivity was high. -from Author
The headwaters of the Ok Tedi, Fly and Sepik Rivers are located in the middle of the island of New Guinea and are populated by the Mountain Ok people. The basin of the upper Ok Tedi rises from 500 to 2900 m and has been an isolated rain forested region of great antiquity. It is the wettest region within the southern mid-altitude fringe of New Guinea with over 7000 mm of rainfall annually. There are four natural vegetation zones of which only one, Lower Montane Rain Forest, in regularly inhabited and cultivated by people though all zones are exploited for natural resources. The flora and fauna are rich and diverse. Heavy rainfall and persistent cloudiness compresses ecological zonation producing extremely diversified biota in a comparatively small area with high levels of locally endemic species. Although flora and fauna show moderate levels of similarity to other localities in eastern New Guinea, the available comparisons indicate that biogeographic relationships in many respects are more to the west.
(1) Two species of Araucaria occur in Papua New Guinea: A. cunninghamii and A. hunsteinii. Their ranges overlap but almost invariably one species predominates in a given site, A. hunsteinii most often at lower elevations and on gentler topography. (2) A. hunsteinii generally has the greater mature height with a maximum of 76.9 m in this study and a record figure of 88.9 m. This is the highest tree reliably recorded for the tropics. The maximum DBH is usually similar in the two species (c. 1.5 m) but the record is held by A. cunninghamii (1.73 m). (3) The size (diameter) distribution in two large plots covering 1000 trees of each species was very similar (strongly positively skewed). (4) Regeneration was also abundant in eight other plots 50 m square though there was very little or no regeneration directly beneath large trees within the layer of parent litter around the bole. (5) In the study area the mature trees of A. cunninghamii are denser than those of A. hunsteinii but the reverse is true of small seedlings (<15 cm). (6) Complicated differences are also found in growth rates of seedlings and trees. Experimental studies are badly needed.
Productivity studies have shown that plants with marked vertical extension of photosynthetic crown can be more productive per unit area of land or water occupied than plants whose photosynthetic surface is spread in a thin horizontal sheet on the earth's surface if environmental factors are not otherwise limiting. Geometric models including a flat disc and cones of several heights but constant base radius show that heightening cones intercept progressively more light. Amount of chlorophyll displayed per unit area of earth's surface can also increase greatly with vertical extension of aerial crown. These observations suggest that thickness, geometric configuration, and chlorophyll content of the photosynthetic portion of the vegetation per unit area of earth's surface, and light intensity incident on surfaces at right angles to sun's rays should be measured and described as basic data in primary productivity studies.
Results are described of a detailed enumeration and comparison of four sample plots in tropical rain forest in New Guinea. The plots are 2 ac (0.8 ha) each in size and range in altitude from 1975 to 3700 ft (600-1125 m). Plots 1 and 2 are in forest on moderately steep hill slopes, and Plots 3 and 4 are on a gently sloping plateau surface, Plot 4 being on the break of slope towards a nearly level river terrace. Stratification of tree heights was studied by means of profile diagrams, height histograms, and graphs showing total crown width plotted against height class. With the exception of a dense layer of small trees between 15 and 25 ft (5-8 m) no clear evidence of layering was found. An examination of the accuracy of profile diagrams by comparison with measurements made during and after felling indicated considerable errors in the initial diagrams. Various structural features, notably tree density, girth distribution and buttressing, are correlated with topography and show a trend from the two hill forest Plots 1 and 2 to Plot 3 on the plateau surface proper thence to Plot 4 on the transition to river alluvium. Araucaria hunsteinii in Plot 2 seems an element additional to the mixed broad-leaved forest; it is responsible for the large number of trees in the highest height class, for the high average girth, and for a total basal area almost double that of broad-leaved forest alone. Excluding Araucaria from Plot 2 for the sake of comparison, Plot 4 has the highest average girth, and the lowest number of trees, while basal areas do not differ greatly between plots. The relationship between tree girth at breast height and crown width proved to be practically linear for crown diameters between 25 and 45 ft (7.5-13.5 m), and within this range crown diameters are from twenty-three to twenty-one times as large as bole diameters. With increasing tree height the frequency of cylindrical and conical crowns decreases, and that of round and flat crowns increases. The percentage of cylindrical and conical crowns is positively correlated with tree density. The number of species per 2 ac sample plot is above average for tropical lowland rain forest. Additive species/area curves show little sign of flattening out, and no `minimum area for adequate sampling' could be established. None of the plots shows family or species dominance, species diversity between plots is high, and so far as the data go the flora seems to vary continuously. Most species tested for group forming were found to be more or less randomly distributed, but instances of pattern occur in each plot.
(1) Stand structure and mean weight-density relations of nearly pure, dense, even-aged, natural stands of Prunus pensylvanica and Abies balsamea in the north-eastern U.S.A. were examined and related to allometric growth. Values for the exponents of allometric and mean weight-density equations were estimated by principal components analysis of logarithmically transformed data. (2) It is proposed that soon after a stand of woody plants becomes established the size frequency distribution is a negatively skewed, bell-shaped curve; the distribution subsequently becomes positively skewed, and eventually approaches normality after substantial thinning. Maximum positive skewness occurs at the time self-thinning begins. (3) The weight-frequency distribution undergoes a parallel series of stages: roughly normal at first, but quickly changing to lognormal, with maximum skewness attained at the time thinning begins. These curve-forms are proposed only as approximations to empirically observed distributions. A consistent tendency toward bimodality is one commonly-observed departure from the idealized distributions. (4) The calculated exponents of the mean weight-density equations for Prunus pensylvanica and Abies balsamea were -1.46 and -1.22, as compared to the proposed value of -1.5 (-3/2 power `law' of self-thinning). In general, weight changes in plant parts during self-thinning did not parallel those for whole plants; in particular, the mean weight-density exponent for foliage was approximately -1.0. The exponents of mean weight-density equations for total roots and total shoots, however, approximately equalled the exponent for whole plants. (5) It is concluded that observed patterns of allometric growth are incompatible with mean weight-density equations for whole plants, unless a mutual adjustment between allometry and stand structure is assumed.
Antarctic vegetation is today mostly restricted to non-vascular plants, with a few small angiosperms clinging to the Antarctic Peninsula. However, probably as recently as the mid-Late Pliocene woody angiosperms were present in inland Antarctica, suggesting an overall presence of complex and diverse vegetation. Angiosperms were introduced into Antarctica during the Cretaceous from South America and possibly also Southeast Asia via Australia. These angiosperms speciated rapidly at the prevailing high latitudes and were an important source for the developing angiosperm-dominated vegetation of the Southern Hemisphere. The migration and evolution of early angiosperms in Gondwana was probably facilitated by a high level of disturbance caused primarily by the rifting of the supercontinent. This high-latitude region was an important source of evolutionary novelty during the Late Cretaceous-Paleogene. As the climate deteriorated during the Cenozoic, the angiosperm flora was reduced in biomass and diversity, finally being restricted to the current remnants. The timing and nature of this major regional extinction is still poorly understood.
Park Volcanics Group is proposed for igneous rocks, either shallow intrusive or extrusive, emplaced in the Murihiku Terrane during Triassic‐Jurassic times. The term replaces Park Intrusives of Mutch, some members of which are shown to be extrusive rather than intrusive. Formation status within the group is given to Gowan Andesite and Pinney Volcanics (new names) in western Southland, Glenham Porphyry in eastern Southland, and Barnicoat Andesite (new) in the Richmond area, Nelson.Gowan Andesite is a porphyritic feldspar two‐pyroxene andesite with a glassy or microcrystalline groundmass. A suite of low‐grade metavolcanic rocks which forms the main mass of Malakoff Hill and which has formerly been included in the “Park Intrusives” is here excluded and ascribed to the Takitimu Group; representative chemical data are given. Glenham Porphyry is typically a porphyritic feldspar two‐pyroxene andesite texturally similar to the Gowan Andesite but with significant geochemical differences. Two volumetrically minor members are recognised, Habukinini Trachydacite and Kenilworth Rhyolite. In the north of its outcrop area, Glenham Porphyry is emplaced on or into Late Triassic terrestrial beds; in the middle it overlies Kaihikuan (Middle Triassic) and is overlain by Otapirian (latest Triassic) marine beds; and in the southeast it is directly overlain by Ururoan (late Early to early Middle Jurassic) conglomerates and marine sandstones.Pinney Volcanics are restricted to a very few, probably one, massive conglomeratic horizon in the Oretian Stage. The commonest rock type is a two‐pyroxene trachydacite, modified by very‐low‐grade burial metamorphism. Auto‐brecciation is characteristic and rock types change over short distances. Hornblende‐rich variants occur as well as more felsic varieties including rhyolite ignimbrite. These may have been erupted onto a bouldery floodplain or shallow‐marine surface, but alternatively may have been mass‐emplaced by debris avalanche resulting from flank collapse of a volcano lying beyond the present terrane boundary.In its unaltered condition, Barnicoat Andesite was an olivine two‐pyroxene andesite, distinctly more tholeiitic than the Gowan and Glenham andesites. A previously reported occurrence of “Park Intrusives” in the southern Taringatura Hills is discredited, as is the presence of Jurassic strata in that area. Weetwood Formation, in the eastern flanks of the Takitimu Mountains, is provisionally excluded from the Park Volcanics.Radiometric data indicate a Late Triassic or Early Jurassic age for the Gowan, Glenham, and Barnicoat andesites. Excluding the Pinney Volcanics, no more than 5 unequivocal volcanic events are recognised during more than 80 million years of sedimentation in the Murihiku Basin. A minimum volume of 7.5 km is estimated for the Glenham Porphyry and about one‐third of that figure for the Gowan Andesite. The volume of Pinney Volcanics and Barnicoat Andesite appears to be much less. Medium to high K2O in the Park Volcanics suggests that the locus of Murihiku sedimentation was a back‐arc or possibly intra‐arc rather than a fore‐arc basin.
The existence of a temperate Antarctic flora in the Permian, Mesozoic and early Tertiary poses a number of problems that are not soluble by reference to any environmental situation obtaining at the present day (i.e. in which plants live in a regime where a warm summer is followed by a winter without sunlight).
Certain characteristics of the polar climate during a number of geological periods can be deduced from the remains of forests which grew at very high latitudes where tree growth cannot take place at the present day. The demands of tree growth of the order of 3 to 4 mm increase in trunk radius each year are such that an input of light energy of at least 3000 MJ m ⁻² a ⁻¹ would be necessary.
Light energy inputs of this magnitude have been measured at very high latitudes in both North and South polar regions and it would appear that polar forest growth would be possible today if the ambient temperatures were sufficiently raised above their present levels. It is also significant that the forest productivity of about 10 t ha ⁻¹ as estimated for the Lower Cretaceous forest on Alexander Island (Palaeolat. 70°S), is a terrestrial productivity that is only matched at the present day in a variety of temperate and subtropical regions of the world.
The evolution of photoperiodic ecotypes in tree species must have facilitated the colonization of polar regions by tree varieties adapted to make all of their annual growth during the long summer light period. There is evidence also that these photoperiodic ecotypes have a high rate of cambial activity concentrating the more rapid growth of wood into the polar summer.
The record now available gives a general picture of transition from widespread, very diverse rainforests in the early Tertiary, to predominantly open vegetation with rainforest restricted to wetter regions. The development of sclerophylly may go back as far as the Eocene, with Banksia and Acacia how having records that extend back that far. The development of open vegetation types was probably linked with changing fire regimes; by the mid-Miocene, heath-like vegetation was established locally in coal swamps. Rainforests of drier aspect were established early too, probably first at inland localities, and there are hints of wet sclerophyll forest by the late Miocene. The history of grasslands and savanna remains sketchy, and no modern analogues can be identified for vegetation types in the Pliocene that were rich in Asteraceae and grasses. The history of the eucalypts, and their links to specific fire regimes, is a more recent story. -from Author
In the mid-Cretaceous, around 105$pm$5 Ma, the tectonic regime in New Zealand changed significantly. From the Permian to the Early Cretaceous most rocks formed under the influence of convergent margin tectonics and comprise incomplete remnants of magmatic arcs, forearc basins, trench slope basins, and accretionary complexes. This tectonic pattern was ended by the approach and collision of the spreading ridge between the Phoenix and Pacific plates. Crustal extension, leading eventually to fragmentation of the continental crust, commenced immediately after ridge collision. Precollisional and syncollisional events deformed and thickened the accretionary prism, with concurrent folding and thrusting of more arcward elements. Cretaceous granulites in southwest New Zealand are thought to result from the closure of a small backarc basin or marginal sea slightly earlier than the main ridge collision. Postcollisional block faulting led to thick nonmarine sedimentation in new basins that cut across old terrane boundaries, except in the outboard area where a thick wedge of marine rocks was deposited over the subsiding accretionary prism. After oblique ridge trench collision along the New Zealand margin, the Phoenix-Pacific Ridge propagated to the southwest to link with zones of incipient spreading in the Tasman Sea and south of Australia. Subsequently, the eastern part of the ridge continued to migrate south with increasing offset along the Udinsev Fracture Zone. In the Late Cretaceous a duplicate ridge developed. The southern branch continued to move southward and collided with the trench west of the Antarctic Peninsula in the Cenozoic. The northern branch is the extant East Pacific Ridge.
Marie Byrd Land (MBL) is the western keystone of West Antarctica. Recent palaeomagnetic results from Lower Cretaceous (c. 117 Ma) plutonic and volcanic rocks from MBL in conjunction with a previous palaeomagnetic result from New Zealand suggest that eastern MBL and the Eastern Province of New Zealand originated in a position adjacent to Weddellia (Antarctic Peninsula, Thurston Island, and Ellsworth-Whitmore Mountains blocks) as part of a continuous Pacific convergent margin. This is far from their previously assumed position adjacent to the Western Province of New Zealand and North Victoria Land. The 117 Ma palaeomagnetic pole for eastern MBL constrains the last movements of the Weddellia blocks related to spreading in the Weddell Sea to postdate the initial opening phase of the Weddell Sea. A c. 100 Ma pole for the amalgamated mid-Cretaceous MBL is consistent with like age poles from the Thurston Island and Antarctic Peninsula blocks but all are significantly offset from a newly constructed apparent polar wander path for East Antarctica. From this it is concluded that there has been palaeomagnetically resolvable post-100 Ma motion between East Antarctica and the Pacific-bordering blocks of West Antarctica as a result of extension in the Ross Sea, Ross embayment, and Byrd Subglacial Basin. ... This 250-word extract was created in the absence of an abstract.
The Late Triassic to Early Jurassic Park Volcanics Group comprises minor shallow intrusive and extrusive bodies emplaced during mainly marine sedimentation of the Murihiku Terrane, southern New Zealand. Gowan Andesite in western Southland and Glenham Porphyry andesites in eastern Southland are high‐K andesites. Glassy examples have commonly lost K during alteration. Orthoclase contents of Or3.6–3.7 in plagioclase phenocrysts at An50 confirm the high‐K nature of the melts at the time of phenocryst crystallisation. The Gowan andesites have higher Fe/Mg than the Glenham and related differences in minor element chemistry suggesting lower fO2during fractionation of the parent magma. Pinney Volcanics in western Southland are mostly high‐K trachydacites but, like Glenham Porphyry, include minor rhyolite. Barnicoat Andesite in the Nelson area is medium‐K olivine andesite, marginally tholeiitic in terms of its FeO*/MgO versus SiO2behaviour, but otherwise is typically calc‐alkaline, as are the Gowan, Glenham, and Pinney. Analyses of pyroxenes (augites, orthopyroxenes, reaction rim and groundmass pigeonites) reveal xenocrysts recording an early stage of magma fractionation, slight iron enrichment in the andesite stage, and lowered Fe/Mg and increased Ca contents in augites of the most felsic rocks. Titanian tschermakite and litanian magnesio‐tschermakite of deep‐seated origin participated in fractionation leading to the Pinney Volcanics, and magnesio‐hornblende, edenite, and biotite crystallised as minor late stage minerals following high‐level emplacement of Gowan Andesite and siliceous Glenham Porphyry members. Low Sr/Sr ratios (c. 0.7034–0.7037), REE and multi‐element distribution patterns, and the mineralogical features collectively suggest fractionation of the andesites from parental basalt originating in an enriched mantle wedge above a subduction zone, with minimal contamination by continental crust.High‐K andesites appear to be unknown in clearly established forearc basins whereas they are characteristic of back‐arc sites. At the time of emplacement of the Park Volcanics, the southern Murihiku sedimentary basin is therefore unlikely to have occupied a forearc setting. The volcanic arc that provided detritus and ash deposits to the basin at that time was probably sited on a strip of largely Proterozoic continental crust detached from the Gondwana mainland by a marginal sea with a subduction zone dipping away from that marginal sea under the volcanic arc, with the Murihiku sedimentary basin towards the rear on the proto‐Pacific side. Drumduan Group, with a low‐temperature, high‐pressure metamorphic overprint, and other largely volcaniclastic terrane fragments in the Median Tectonic Zone of southern New Zealand, may be arc‐front remnants of the same arc system.
New evidence, provided by bracketing marine molluscan faunas, suggests a Late Albian age for fossil forests in the upper part of the Fossil Bluff Group of Alexander Island. These in situ forests are underlain by Late Aptian and Late Albian strata containing faunas including ammonites (the last of which is Lechites), inoceramid bivalves, dimitobelid belemnites and trace fossils. The tree-bearing levels occupied a fluvial dominated environment, subject to periodic major floods. They were transgressed during late Albian time by returning marine conditions with diverse faunas, including hamitid and puzosiid ammonites. The increased precision in dating of the fossil forests will improve palaeobotanical contributions to climate and environmental studies.
Low-temperature alteration of glassy andesites of the Park Volcanics Group of southern New Zealand has involved the addition of relatively radiogenic Sr, the loss of Rb and K, and the degassing of Ar. These combine to increase the measured RbSr age and lower the KAr age. Holocrystalline and least-altered glassy samples from the Glenham area, Southland, give broadly similar RbSr mineral-whole-rock and KAr total-rock ages close to 207 Ma. This date is ∼ 15 Ma older than that suggested in earlier stratigraphic studies, but is not incompatible with current field observations. Barnicoat andesites from Nelson and Gowan andesites from western Southland may be broadly coeval, although subtle geochemical and petrographic differences rule out cogenesis.
To any dynamical system equipped with a metric, we associate a class of well approximable sets. In the case of an expanding rational map of the Riemann sphere acting on its Julia set, we estimate and in some cases compute the Hausdorff dimension of the associated well approximable sets. The methods used show a clear link between distortion properties and the type of results obtained in this paper, via ergodic theory and ubiquity.
The structure and species richness of the Late Cretaceous (Santonian-Maastrichtian) vegetation in the Otway Basin, southeast Australia is reconstructed based on knowledge of palaeolatitudes, palaeotemperatures, plant taxa identified from fossil spores and pollen, and ecophysiological relationships established for present-day ecosystems. The vegetation, which grew at palaeolatitudes of 60–65°S and at mean annual palaeotemperatures of 16.5–19°C, comprised tall open-forests (Foliage Projective Cover 60–70%, height about 30 m) containing austral conifer and proteaceous taxa having coriaceous, notophyll-sized leaves. Today the taxa (Podocarpus, Dacrydium, Dacrycarpus, Knightia, Gevuina, Macadamia) from a minor component of upland closed-forests (usually termed rainforests) of tropical northeast Australia and New Caledonia. A conical-shaped crown to the trees of the tall open-forests situated in high latitudes during the Cretaceous would enable some light to penetrate the canopy to a shrubby understorey (of Proteaceae, Winteraceae, Trimeniaceae, Nothofagus, and Ilex) and a ground stratum of diverse cryptogams. On nutrient-poor, waterlogged sites fringing the forest, sclerophyllous leaved taxa (Adenanthos, Stirlingia, Epacridaceae, and possibly Beauprea) developed, with wetland swamps of Callitriche, ferns and some epacrids.In cooler localities in New Zealand and Antarctica, the productivity of the forests would have been greater, and the canopy taxa mainly with coriaceous, microphyll-sized leaves. Austral podocarps and Proteaceae occurred in the canopy of New Zealand forests, whereas the canopy of Antarctic forests contained podocarps and Nothofagus.
The Fossil Bluff Group of south-east Alexander Island contains strata ranging from Kimmeridgian to Albian in age and represents the infill of a fore-arc basin to the west of the Antarctic Peninsula volcanic arc. Recent field work has identified approximately 2800 m of younger rock above the 4000 m already defined, including the top of the previously described Pluto Glacier Formation. A new unit, the Rhea Corner Member is defined, near the top of the Pluto Glacier Formation. The sequence above this is named as the Neptune Glacier Formation, comprising three members, the Deimos Ridge, Triton Point and Mars Glacier members. They represent the youngest part of the Fossil Bluff Group. Both the Deimos Ridge and Mars Glacier members are fully marine, but the Triton Point Member, which is late Albian in age, contains the only record of emergent conditions in 6.8 km of strata. It is a fluvial unit and contains extensive fossil forest horizons, with standing trees up to 5 m tall preserved by widespread flood deposits. The Neptune Glacier Formation therefore records a significant regression-transgression cycle of Albian age.
Palaeovegetation reconstructions, particularly of fossil forests, are generally restricted to scant information on the taxonomic composition, relative abundance of individual taxa, or on tree density. We have developed new techniques for the analysis of stump horizons that result in a relatively detailed three-dimensional reconstruction of ancient forests. In addition, a rough estimate of their above-ground standing biomass can be calculated. These techniques are applied to an in-situ Miocene peat forest preserved in the Lower Rhine Embayment, northwestern Germany. In a study area of 2500 m2, 476 stumps were mapped and used in the forest reconstruction. Additionally, pollen samples and leaf remains have been analysed. The peat forest consists primarily of conifers (in particular Taxodiaceae and Pinaceae) with Sciadopitys being the most common genus. The only angiosperms in the wood flora were palms, but in the pollen flora, evidence for the Myricaceae, Mastixiaceae, Ericaceae and a few other angiosperms is also present. The forest was relatively dense with 1904 trees/ha and a basal area of 164 m2. Mean trunk diameter was 28 cm, while mean tree height is calculated to have been 9.9 m. Height, diameter and density distribution are illustrated using contour and three-dimensional surface plots. Estimated above ground biomass is 750 t/ha, but this value also includes dead or partly dead trees. This peat forest does not closely compare with previous reconstructions of Miocene peat forests. Its three dimensional structure and biomass differ from those of modern bald cypress swamps.
Observation reveals a linear relationship between the logarithm of the circumference of a tree, branch, or leaf stem, and the logarithm of the weight of the tree, branch, or leaf. The bearing of this on the angles of branching in trees is discussed.
A statistical description of the branching patterns of trees is proposed in the context of a power-law tapered beam model. Depending on the exponent which describes tapering of the depth of the beam, the model either preserves geometric, elastic, or static stress similarity. A detailed study of the morphometry of three oak, one poplar, one cherry, and one white pine corroborates the stationarity of these branching structures and fits the elastically similar model. A separate study of the natural frequencies of branch segments and whole trees within four species also agrees with the predictions of the elastically similar model.
Arguments based on elastic stability and flexure, as opposed to the more conventional ones based on yield strength, require that living organisms adopt forms whereby lengths increase as the (2/3) power of diameter. The somatic dimensions of several species of animals and of a wide variety of trees fit this rule well. It is a simple matter to show that energy metabolism during maximal sustained work depends on body cross-sectional area, not total body surface area as proposed by Rubner (1) and many after him. This result and the result requiring animal proportions to change with size amount to a derivation of Kleiber's law, a statement only empirical until now, correlating the metabolically related variables with body weight raised to the (3/4) power. In the present model, biological frequencies are predicted to go inversely as body weight to the (1/4) power, and total body surface areas should correlate with body weight to the (5/8) power. All predictions of the proposed model are tested by comparison with existing data, and the fit is considered satisfactory. In The Fire of Life, Kleiber (5) wrote "When the concepts concerned with the relation of body size and metabolic rate are clarified, . . . then compartive physiology of metabolism will be of great help in solving one of the most intricate and interesting problems in biology, namely the regulation of the rate of cell metabolism." Although Hill (23) realized that "the essential point about a large animal is that its structure should be capable of bearing its own weight and this leaves less play for other factors," he was forced to use an oversimplified "geometric similarity" hypothesis in his important work on animal locomotion and muscular dynamics. It is my hope that the model proposed here promises useful answers in comparisons of living things on both the microscopic and the gross scale, as part of the growing science of form, which asks precisely how organisms are diverse and yet again how they are alike.
The tectonic significance of palaeomagnetic results from the Triassic and Jurassic Murihiku sedimentary rocks of the Kawhia region
- P J Oliver
Oliver, P.J., 1994. The tectonic significance of palaeomagnetic
results from the Triassic and Jurassic Murihiku sedimentary
rocks of the Kawhia region, North Island, New Zealand.
In: Van der Lingen, G.J., Swanson, K.M., Muir, R.J. (Eds.),
Evolution of the Tasman Sea Basin. Balkema, Rotterdam, pp.
67-82.
Diversity and floristic composition of lowland tropical forest in Africa and South America
- A H Gentry
Gentry, A.H., 1993. Diversity and floristic composition of lowland tropical forest in Africa and South America. In: Goldblatt,
P. (Ed.), Biological Relationships Between Africa and South
America. Yale Univ. Press, New Haven, pp. 500-547.
On the Jurassic rocks of the Hokonui Hills
- J Park
Park, J., 1887. On the Jurassic rocks of the Hokonui Hills,
Mataura, and Waikawa. New Zealand Geol. Surv. Rep. Geol.
Explor. 1886-1887, 141-153.
Physiognomy and phytosociology of the international woodlands research sites
- R L Burgess
Burgess, R.L., 1981. Physiognomy and phytosociology of the
international woodlands research sites. In: Richle, D.E. (Ed.),
Dynamic Properties of Forest Ecosystems. Cambridge Univ.
Press, Cambridge, pp. 1-35.
The Curio Bay scientific reserve
- Pole
Pole, M.S., 1990. The Curio Bay scientific reserve. Geol. Soc.
N. Z. Newsl. 89, 34-37.
Geometrical study of a cast of Lep-M
- H T Clifford
Clifford, H.T., 1996. Geometrical study of a cast of Lep-M. Pole / Palaeogeography, Palaeoclimatology, Palaeoecology 147 (1999) 121–139 tophloeum australe (McCoy) Walton from Queensland. Mem. Queensl. Mus. 39, 227–230.