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Tree age estimation for the tropics: a test from the Southern Appalachians
Ecological Applications
Abstract
The lack of annual growth rings in the majority of tropical tree species greatly limits our understanding of the long‐term dynamics of tropical forests. To address this problem, several methods have been developed to estimate the age of tropical trees from diameter growth data. These past approaches, however, suffer from two major flaws: (1) they assume a deterministic age–size relationship for a tree species, and (2) they have not been verified with independently derived age data. In this paper, I present a new approach that uses diameter growth rates, independent of tree size, that are stratified by crown class to estimate the age of individual trees. Past approaches have assumed that when present‐day canopy trees were juveniles they grew at rates similar to conspecifics currently in the understory. In contrast, the crown class model assumes that present‐day canopy trees have grown at rates similar to conspecifics in the same crown class, irrespective of size, throughout ontogeny.
The crown class model was compared to a periodic annual increment (PAI) model typical of past approaches in mixed oak‐hardwood forest in the southern Appalachians, USA. Tree ages were obtained independently from tree cores from three stands of differing age structure. Comparisons between the two models were made for species' population age structures (independent of stands) and stand age structures (independent of species).
Age estimation errors for the crown class model were lowest for relatively shade‐intolerant species such as yellow poplar ( Liriodendron tulipifera ) and chestnut oak ( Quercus prinus ), but increased with the increasing shade tolerance of the species. The PAI model followed the opposite pattern, providing the most accurate age estimates for shade‐tolerant species. These results were consistent with the underlying ecological assumptions of each model.
When predicted age distributions for individual stands were compared to the true age distributions, the PAI approach had higher estimation errors than the crown class model in almost every case. In addition, the PAI model had a strong tendency to overestimate tree ages. A mixed model that used crown class age estimates for shade‐intolerant species and PAI model age estimates for shade‐tolerant species generated the most accurate estimates of stand age distribution. The results of this study suggest new opportunities for the study of long‐term dynamics in tropical forests and underscore the importance and utility of validating models with independent data.
... We provide here a brief description of each approach. For a detailed discussion of the models, their rationales, and their relative advantages see Baker (2003). We used the age estimates in two ways. ...
... While this may be true for shade-tolerant species that can survive in the low-light environment of the understory and subcanopy of the forest, many shadeintolerant species cannot survive under such conditions . Consequently, the PAI-regression model provides better age estimates for shade-tolerant tree species (Baker 2003). Mixed model.—Given the differences in estimation accuracy of the crown-class and PAI-regression methods relative to shade tolerance, we used a third approach for estimating stand-level age structure based on species' relative shade tolerance. ...
... While both species are capable of reaching the upper canopy, Neolitsea is more shade tolerant and can endure in low-light conditions for extended periods, whereas Chukrasia is shade intolerant and rarely found in the low-light conditions of the forest understory. Based on validation results for tree species in the southeastern United States (Baker 2003), we expected the crown-class method to provide better age estimates for Chukrasia and the PAI-regression method to better predict the ages of Neolitsea. ...
Disturbances influence forest dynamics across a range of spatial and temporal scales. In tropical forests most studies have focused on disturbances occurring at small spatial and temporal scales (i.e., gap dynamics). This is primarily due to the difficulty of reconstructing long‐term disturbance histories of forests in which most tree species lack annual growth rings. Consequently, the role of past disturbances in tropical forests is poorly understood. We used a combination of direct and indirect methods to reconstruct the historical disturbance regime and stand development patterns in mature and regenerating seasonal dry evergreen forest (SDEF) in the Huai Kha Khaeng Wildlife Sanctuary in western Thailand. Direct estimates of long‐term establishment and growth patterns were obtained from 12 tree species that form annual growth rings as a consequence of the region's strong intra‐annual rainfall seasonality. Indirect estimates of establishment patterns were obtained from analyses of stand structure and individual tree architecture and application of age‐estimation models to 10 dominant canopy‐tree species using demographic data from a large‐scale, permanent forest‐dynamics plot.
The combination of direct and indirect methodologies revealed a complex disturbance history in the seasonal evergreen forest over the past 250 years. In the mid‐1800s, 200–300 ha of forest were destroyed by a catastrophic disturbance, which led to the synchronous establishment of many of the trees that presently dominate the forest canopy. Since then widespread disturbances of variable intensity have occurred at least three times (1910s, 1940s, and 1960s). These disturbances created discrete temporal pulses of establishment in small to large gaps in the forest matrix across several square kilometers. Background mortality and gap formation were evident in every decade since 1790, but these varied in intensity and frequency.
The SDEF retains a distinct structural and floristic legacy from the catastrophic disturbance of the mid‐1800s. The single‐age cohort that established after the disturbance has developed a complex three‐dimensional structure as a consequence of differences in interspecific growth patterns of the canopy‐tree species and subsequent disturbances of moderate and low intensity. While no single methodological approach provided a complete picture of the disturbance history and stand development patterns of the seasonal evergreen forest, taken together they offered new insights into the long‐term dynamics of a primary tropical forest. In particular, the study highlighted the role of disturbance at multiple spatial and temporal scales and varying intensities in determining the structure and composition of a complex, species‐rich tropical forest and raises important questions about the role of rare, catastrophic events on tropical forest dynamics.
... Such a juvenile selection effect implies that fast-growing juveniles have higher chance of reaching the canopy compared to slow-growing juveniles in these species. Age estimations from growth models can be much improved by comparing outcomes with observed ages from tree-ring data for the same trees or tree species (Baker 2003; Brienen et al. 2006; Chien 2006). Baker (2003) developed age estimation methods for tropical trees based on such comparisons by testing them for temperate species with a varying degree of shade tolerance. ...
... Age estimations from growth models can be much improved by comparing outcomes with observed ages from tree-ring data for the same trees or tree species (Baker 2003; Brienen et al. 2006; Chien 2006). Baker (2003) developed age estimation methods for tropical trees based on such comparisons by testing them for temperate species with a varying degree of shade tolerance. Results of age projections can be improved by accounting for autocorrelated growth, which results in higher, more realistic, variation in tree ages (Brienen et al. 2006 ...
... Similarly, the disturbance history of a seasonal tropical forest in western Thailand was reconstructed by Baker et al. (2005), using a combination of treering analysis and age estimations from growth projections (cf. Baker 2003). The stand structure data of the Huai Kha Khaeng Wildlife Sanctuary showed a single cohort of canopy trees and the simulated age distributions showed that the cohort of canopy trees established in the 1800s and showed that there was a pulse in establishment for the shade-intolerant species in the mid-1900s. ...
Over the last decade the field of tropical dendroecology has developed rapidly and major achievements have been made. We reviewed
the advances in three main themes within the field. First, long chronologies for tropical tree species were constructed which
allowed climate reconstructions, revealed sources of climatic variation and clarified climate–growth relations. Other studies
combined tree-ring data and stable isotope (13C and 18O) measurements to evaluate the response of tropical trees to climatic variation and changes. A second set of studies assessed
long-term growth patterns of individual trees throughout their life. These studies enhanced the understanding of growth trajectories
to the canopy, quantified autocorrelated tree growth and yielded new estimates of tree ages. Such studies were also used to
reconstruct the disturbance history of tropical forests. The last set of studies applied tree-ring data to growth models.
Tree-ring data can replace diameter measurements from research plots, provide additional information to construct population
models, improve timber yield models and validate model output. Based on our review, we propose two main directions for future
research. (1) An evaluation of the causes and consequences of growth variation within and among trees and their relation to
environmental variation. Studies evaluating this directly contribute to improved understanding of tropical tree ecology. (2)
The simultaneous measurement of widths and stable isotope fractions in tree rings offers the potential to study responses
of trees to climatic change. Given the major role of tropical forests in the global carbon cycle, knowing these responses
is of high priority.
KeywordsTree rings–Climate–growth relations–Tropical forest dynamics–Long-term growth patterns–Tree age–Growth modelling
... Slow-growing juveniles experience higher mortality rates (Wyckoff & Clark, 2002) and remain longer in the understorey where risk of damage from falling debris is high (Clark & Clark, 1991). They may therefore have a much lower chance of reaching the canopy, compared with fast growers (Enright & Hartshorn, 1981; Swaine et al., 1987; Baker, 2003). If fast growers preferentially reach the canopy , this implies that extant canopy trees will on average have grown more rapidly as juveniles compared with extant juveniles (Fig. 1a); or, when expressed against time, that juvenile growth rates realized in the distant past (i.e. in extant adults) will have been higher than those attained in the recent past (i.e. in extant juveniles; Fig. 1b). ...
... Ó The Authors (2009) Journal compilation Ó New Phytologist (2009) New Phytologist (2009) www.newphytologist.org 1997; Baker, 2003; Brienen & Zuidema, 2006). To our knowledge, our study is the first to actually test this hypothesis for tropical tree species through a direct comparison between current and historical juvenile growth rates. ...
... However, the degree to which growth rates need to be adjusted depends on the shade tolerance of the species. Baker (2003) found that for shade-tolerant species mean growth rates may give relatively accurate estimations of tree age, whereas the use of mean growth rates for shade-intolerant species will greatly underestimate long-term growth rates and hence overestimate tree age. To accurately predict long-term growth rates and model growth dynamics, species-specific data on the relation between growth and mortality are needed (e.g. ...
Long-term juvenile growth patterns of tropical trees were studied to test two hypotheses: fast-growing juvenile trees have a higher chance of reaching the canopy ('juvenile selection effect'); and tree growth has increased over time ('historical growth increase'). Tree-ring analysis was applied to test these hypotheses for five tree species from three moist forest sites in Bolivia, using samples from 459 individuals. Basal area increment was calculated from ring widths, for trees < 30 cm in diameter. For three out of five species, a juvenile selection effect was found in rings formed by small juveniles. Thus, extant adult trees in these species have had higher juvenile growth rates than extant juvenile trees. By contrast, rings formed by somewhat larger juveniles in four species showed the opposite pattern: a historical growth increase. For most size classes of > 10 cm diameter none of the patterns was found. Fast juvenile growth may be essential to enable tropical trees to reach the forest canopy, especially for small juvenile trees in the dark forest understorey. The historical growth increase requires cautious interpretation, but may be partially attributable to CO(2) fertilization.
... Most studies of tropical tree demography have focused on size, but in many cases the link between size and age remains the more important ecological question with consequences at both the ecosystem and population levels. For example, understanding this link is required at the ecosystem level to determine rates of forest turnover (Martinez-Ramos and Alvarez-Buylla 1998, Baker 2003, Vieira et al. 2005), and at the population level, for comparisons among species of longevity, time to reach the canopy, and age patterns of mortality (Baker 2003, Easdale et al. 2007). Despite the importance of quantifying and qualifying this link, there are relatively few estimates of the time it takes for trees of tropical wet forests to reach important demographic milestones, such as escaping juvenile mortality, reaching the canopy, reaching maximum size, and dying. ...
... Most studies of tropical tree demography have focused on size, but in many cases the link between size and age remains the more important ecological question with consequences at both the ecosystem and population levels. For example, understanding this link is required at the ecosystem level to determine rates of forest turnover (Martinez-Ramos and Alvarez-Buylla 1998, Baker 2003, Vieira et al. 2005), and at the population level, for comparisons among species of longevity, time to reach the canopy, and age patterns of mortality (Baker 2003, Easdale et al. 2007). Despite the importance of quantifying and qualifying this link, there are relatively few estimates of the time it takes for trees of tropical wet forests to reach important demographic milestones, such as escaping juvenile mortality, reaching the canopy, reaching maximum size, and dying. ...
... The new modeling framework we introduce here is the first to explicitly include the dynamics of light environment (via an index of crown illumination, CI) in the estimation of the time to attain particular sizes and life expectancy of tropical trees from size-dependent annual growth and survival data. Problems with previous approaches were reviewed by Baker (2003) and Martinez-Ramos and Alvarez-Buylla (1998); one key limitation is that many earlier formulations were deterministic. Lieberman et al. (1985) did introduce stochasticity but did not include the sampling effect of mortality (Wyckoff and Clark 2002), or the role of known environmental factors such as light (Baker 2003). ...
In tropical rain forests, rates of forest turnover and tree species' life-history differences are shaped by the life expectancy of trees and the time taken by seedlings to reach the canopy. These measures are therefore of both theoretical and applied interest. However, the relationship between size, age, and life expectancy is poorly understood. In this paper, we show how to obtain, in a dynamic environment, age-related population parameters from data on size and light transitions and survival of individuals over single time steps. We accomplish this goal by combining two types of analysis (integral projection modeling and age-from-stage analysis for variable environments) in a new way. The method uses an index of crown illumination (CI) to capture the key tree life-history axis of movement through the light environment. We use this method to analyze data on nine tropical tree species, chosen to sample two main gradients, juvenile recruitment niche (gap/nongap) and adult crown position niche (subcanopy, canopy-emergent). We validate the method using independent estimates of age and size from growth rings and 14C from some of the same species at the same site and use our results to examine correlations among age-related population parameters. Finally, we discuss the implications of these new results for life histories of tropical trees.
... First, a modification of the crown-class model as described by Baker (2003) was employed. This model uses dbh and crown class to estimate the age of individual trees. ...
... For larger trees, the crown-class model would have difficulty distinguishing between similar-sized individuals in non-overlapping age groups (Figure 7). Investigations into temporal dynamics and tree age in tropical forests in other parts of the world have relied heavily on extrapolations from short-term growth trends within permanent forest plots (Baker 2003). Efforts to obtain tree ages from tropical trees have been slowed by their widely reported lack of annual growth rings (Lang ...
In this study I document the growth rate and age of trees in an old-growth montane Hawaiian wet forest and use these results to evaluate the cyclic succession model for forest dynamics. I used two methods to estimate the age of trees - the crown-class model and radiocarbon dating. Over 6000 trees belonging to eight species were tagged and measured over 7 y on Hawaii Island. Growth rates for the dominant tree (Metrosideros polymorpha) were relatively low (mean = 1.3 mm y1) and varied with tree size and crown class. 14C-based age estimates for 27 M. polymorpha trees loosely corroborated estimates based on the crown-class method. The oldest tree dated by 14C had a median age of 647 y BP, placing it among the oldest documented angiosperm trees in the northern hemisphere. 14C dating revealed that the upper canopy may be comprised of three distinct age groups of M. polymorpha trees of similar size, with the median age of each group separated by 200-250 y. The high density of large, very old trees in multiple groups is unusual for a tropical forest and indicates that forest development may occur through gap-phase regeneration at a fine scale and stand-level mortality at a coarser scale.
... Similarly, age estimates have been obtained from projections using short-term data (Clark & Clark 1992, 2001) that are poorly validated (cf. Martinez-Ramos & Alvarez-Buylla 1998; Baker 2003). Such estimates may be biased, as successful trees may have grown at above-average growth rates (cf. ...
... Slow growing juveniles have a higher probability of mortality as they stay longer in the understorey (Swaine et al. 1987; Terborgh et al. 1997; Arets 2005) and juvenile mortality is higher for suppressed trees (Kobe et al. 1995; Wyckoff & Clark 2002). Such selection of fast-growing trees may explain the discrepancy in passage time, but direct comparisons of age values obtained for the same species with different methods are required to confirm this (Bormann & Berlyn 1981; Martinez-Ramos & Alvarez-Buylla 1998; Baker 2003). To the extent that the above explanation holds, our results show that the use of median or mean growth rates tends to overestimate tree ages and that tropical forest canopy trees are younger than hitherto assumed. ...
Cited By (since 1996): 40, Export Date: 6 May 2012, Source: Scopus
... Precise sampling methodologies, combined with techniques to correct age determination in samples taken above the root collar or with missing the pith have been proposed by several authors (Duncan 1989;Villalba and Veblen 1997b). In the case of shade-tolerant species, combining the above methods with crown class models, which, in turn, take into account the diameter of the individuals, helps to determine the date of establishment or total age (Baker 2003). ...
The study of forest dynamics over large temporal and spatial scales has widely benefited from dendrochronological techniques. Patagonia is home to several long-lived tree species (Austrocedrus chilensis, Araucaria araucana, Fitzroya cupressoides, Nothofagus dombeyi and N. pumilio) with well-defined tree rings suitable for reconstructing tree establishment, mortality, spatio-temporal growth patterns and disturbance regimes with annual resolution. The first dendrochronological studies in the region date back to the 1950s and had a strong emphasis on hydroclimatology. It was not until the last few decades that studies using dendroecological techniques began to emerge. In this chapter, we review the experience gained by the tree-ring lab at IANIGLA (CONICET, Mendoza, Argentina) and colleagues from other institutions over the past 30 years applying dendroecological techniques to understand the role of climate and disturbances (insect outbreaks, snow avalanches, windblows, fires and decline) on forest dynamics. For each case, we summarized the process, and the dendrocronological methods used. In this way, it was possible to detect those gaps of knowledge that still can be explored using dendroecological methods in the Patagonian forests of Argentina.
... In fact, growth estimates of forest trees are typically made by using measurements of DBH, which are scaled to the whole tree via allometric equations derived from destructive sampling (Sillett et al., 2010). The relationship between DBH and tree age is consistent with preliminary results from Wunder (2010), and could provide acceptable results to be used in the design of management actions in P. undulatum dominated stands, since diameter is an easy and inexpensive measurement to obtain, and in many cases such data already exist (Baker, 2003). Our results demonstrated that models with cubic terms were among the best. ...
Pittosporum undulatum Ventenat (Pittosporaceae) is an invasive tree of forests and woodlands in several regions of the world. In the Azores archipelago it occupies about 30% of the forested areas and efforts to valorize its biomass are underway. Implementing sustainable forest management requires basic information on tree age and growth rate, yet this information was lacking. We used tree-ring analysis to obtain accurate age estimates and growth rates from a total of 982 live trees (1318 samples: 646 increment cores and 336 pairs of stem discs) that were sampled in São Miguel, Terceira and Graciosa islands. Pittosporum undulatum showed distinct annual growth rings with an increase in cell-wall thickness and a decrease in cell lumen of the Fibers, from early to latewood. We found trees with ages at base and at breast height ranging from 5/4 to 131/108 years, respectively. Samples taken at tree base and at breast height allowed to estimate a diameter growth rate of 0.38 cm.year⁻¹, with an average of 8 years needed to attain breast height, and a rotation period of 26 years to reach the average diameter of 7 cm presently found at the stands. Allometric equations relating tree age and diameter at breast height, tree height, basal area and biomass were found to be significant. Among the models with lowest AIC, equations predicting tree age from diameter at breast height or from biomass showed the best fit (R² = 0.65 and for R² = 0.70, respectively). The developed methods and the obtained results can now be used to support management of biomass valorization projects but also to better understand invasion dynamics at conservation devoted areas.
... Moreover, as there are typically few contemporary ground observations that record the extent of burnt areas, retrospective methods are needed to infer the dates of past fires. Tree stem diameters are potentially useful proxies for time since fire (TSF), i.e. the time since the last fire, in species in which aerial stems are killed by fire (Barker 1988;Baker 2003;Burley et al. 2007;Rumpff et al. 2009;Clarke et al. 2010). Other techniques (e.g. ...
In fire-prone landscapes, knowing when vegetation was last burnt is important for understanding how species respond to fire and to develop effective fire management strategies. However, fire history is often incomplete or non-existent. We developed a fire-age prediction model for two mallee woodland tree species in southern Australia. The models were based on stem diameters from ∼1172 individuals surveyed along 87 transects. Time since fire accounted for the greatest proportion of the explained variation in stem diameter for our two mallee tree species but variation in mean stem diameters was also influenced by local environmental factors. We illustrate a simple tool that enables time since fire to be predicted based on stem diameter and local covariates. We tested our model against new data but it performed poorly with respect to the mapped fire history. A combination of different covariate effects, variation in among-tree competition, including above- and below-ground competition, and unreliable fire history may have contributed to poor model performance. Understanding how the influence of covariates on stem diameter growth varies spatially is critical for determining the generality of models that predict time since fire. Models that were developed in one region may need to be independently verified before they can be reliably applied in new regions.
... First, the number of trees removed at each DBH (Diameter at Breast Height) was based on Holmes et al. (2002). Second, DBH was used to infer tree-age based on the relationship developed in Figure 2 (Baker, 2003; Korning & Balslev, 1994; Lieberman & Lieberman, 1987; Lieberman et al., 1985). Once the estimated age for trees was found, Tilley's (1999) agespecific estimate of the solar transformity of forest trees (Figure 3) was applied to each age-class to derive a solar emergy for each age-class (Figure 4). ...
Sustainable forestry production systems, such as certified forestry, re-duced impact logging or sustainable forest management, have become an important part of tropical countries' strategy to oversee their forest re-sources. Particularly, certification of forest products has become a widely adopted practice as a response to a growing international concern over the ecological and economic sustainability of harvesting natural tropical forests because of the benefits on reducing excessive and unnecessary construction of forest roads, reducing excessive use of heavy machinery, diminishing excessive collateral damage, and improving the inefficient milling processes and wasting of residues. To accomplish the aim of this study, which is to compare conventional and certified forestry we used a systems analysis tool that could integrate various benefits of certified forestry including, stand age, wood harvest, soil losses and economic gain or loss. We found that the affected area under uncertified logging practices is twice the area of certified forestry because conventional prac-tices require more roads, more logging decks and more skid trails. Also, the rate of soil erosion between uncertified logging (154 Mg/ha/yr) and certified logging (66 Mg/ha/yr) is different. Based on these data, we es-timated that the total emergy removed from certified forests was 40% less than the forest under conventional forestry. The fact that certification does a better job of preserving forest while removing wood was also demonstrated through the Environmental Loading Ratio (ELR). We also found that certification leaves forests with a 30% better chance to recover after logging because less wood is removed. But forestry using certifica-tion showed a lower Emergy Yield Ratio (EYR) because the lower yield and the extra cost of certification. Certification is also favored for the higher price for certified wood in international markets. Then, when Bo-livia exports uncertified wood, it obtains a positive benefit, but lower than using uncertified wood domestically (EYR = 20.4). In other words the worst thing the country could do is certify wood for their domestic market and sell uncertified wood abroad.
... This information is crucial for planning sustainable management of this species and sustainable production of frankincense. Assessment of age-diameter relationship is crucial to estimate population-age structure and is enabled by the rapid development of dendrochronology to apply it on tropical tree species (Baker, 2003; Rozendaal and Zuidema, 2010; Steenkamp et al., 2008; Trouet et al., 2006, 2010; Worbes, 2002). Dendrochronological application is species dependent (Brienen and Zuidema, 2005; Worbes and Fichtler, 2010) and it has not been assessed yet for B. papyrifera. ...
... 4 Ϯ 0 . 2 leaves year - 1 ; mean Ϯ SE ) and that growth rates are affected by proximity to canopy gaps ( Webber 2005 ) . This is consistent with what is known about other shade - tolerant species , which often have extended periods of growth suppression during their lifetime , leading to nonlin - ear growth trajectories ( Harper 1977 ; Baker 2003 ) . ...
The distribution and spatial patterns of plant populations in natural ecosystems have recently received much attention; yet the impacts of human-induced disturbances on these patterns and underlying processes remain poorly understood. We used the sub-canopy tree, Ryparosa kurrangii (Achariaceae), to explore the possible effects of such disturbances on stand structure and spatial patterning in an Australian tropical rainforest. We studied three populations that differed in their extent of habitat modification: anthropogenic disturbance (proximate settlement and roads) and internal damage by an invasive alien species, the feral pig (Sus scrofa). Populations were mapped, characterized, and three size cohorts (seedlings, saplings, trees) were analysed using a suite of spatial point pattern analyses (univariate: Diggle's G and F and Ripley's K; bivariate: Diggle's G and Ripley's K). Ryparosa kurrangii has a typical stand structure for a sub-canopy tree species, but occurs at high densities locally (>400 stems ha−1). At all sites, the tree cohort were randomly distributed and saplings were spatially aggregated at distances of up to 2–3 m. Between sites there were distinct differences in the size structure and spatial pattern of seedlings, the cohort most affected by recent habitat modification. That is, the least disturbed site had no aggregation among seedlings, the site with the greatest anthropogenic disturbance had many small, clustered seedlings that were spatially associated with trees, and the site with pig damage had clustered seedlings that had no spatial relationship with trees. We propose that habitat modification by anthropogenic and pig disturbance disrupts seed dispersal and establishment regimes, which leads to altered seedling spatial patterns. These disturbances could have long-term implications for the population structure and health of R. Kurrangii.
... Our results confirm the idea that the faster growing part of the population should be used for growth projections, although we found only strong differences between the lifetime and plottype growth data for Cedrelinga. This finding is consistent with the results of Baker (2003), who showed that adjustments would particularly be needed for light-demanding species. Several studies already presented growth projections using growth rates from the fastest growers to estimate future timber yield (Condit et al., 1995a; Rondon et al., 2009), and tree ages (O'Brien et al., 1995; Terborgh et al., 1997; Laurance et al., 2004). ...
Most growth and yield models for tropical tree species use diameter growth data obtained from permanent sample plots. A potential disadvantage of this data source is that slow-growing, suppressed juvenile trees are included of which only a small fraction will attain harvestable size. If this is the case, the average growth rate of extant juvenile trees will be lower than the historical, juvenile growth rate of trees of harvestable size. Thus, if juvenile growth rates are obtained from permanent plots, future timber yield may be underestimated. To determine the magnitude of this effect we simulated tree growth based on two types of diameter growth data: long-term tree-ring data from harvestable trees (‘lifetime growth data’) and growth data of the last 10 years from trees of all sizes (‘plot-type growth data’). The latter data type is a proxy for growth data from permanent sample plots. Second, we evaluated which percentage of harvestable timber volume at initial harvest is available at second harvest using lifetime growth data. We obtained tree-ring data from 89 to 98 individuals of three Bolivian timber species over their entire size range. Based on these data tree growth simulations were performed for two scenarios: a second harvest in 20, and in 40 years. A realistic degree of growth autocorrelation was incorporated in the growth projections, for both the lifetime and the plot-type growth data.
The growth trajectories of trees are not fully understood due to their long life span. We characterized the population dynamics of the canopy tree Castanopsis cuspidata (Thunb.) Schottky in a Japanese warm‐temperate forest over 49 years (1966–2015). Our study was initiated approximately 50 years after our study site was clear‐cut. The forest had a closed canopy for the first 23 years of the study. Strong typhoons in 1991 and 1993 seriously damaged the forest, and since then the forest has been recovering from these disturbances. The diameter distribution of this species was bell‐shaped in 1966, suggesting that the trees emerged simultaneously after the clear‐cut in the 1910s, and the recruitment of trees has remained unchanged since then. The lack of recruitment of C. cuspidata before the typhoon disturbance supports this conclusion. Assuming that the C. cuspidata trees in 1966 were cohorts that were established soon after the clear‐cut, the size differences reflect differences in growth rate, with small trees corresponding to slow growers and large trees corresponding to fast growers. Before the typhoon, slow growers had low survival, and the mortality rate of fast growers was low. Many fast growers were uprooted or snapped by strong winds by the typhoons. However, their mortality rate did not differ from that of slow growers because many slow growers were killed by large fallen trees. The growth of some slow‐growing survivors increased after the typhoon, which allowed them to rapidly reach the canopy. Therefore, the typhoon altered the distribution of canopy trees among slow and fast growers. Survivors experienced faster growth than trees that died during the census period, suggesting that growth rate provides a robust indicator of future survival. Before the typhoon, the survival of fast growers was higher than that of slow growers. This suggests that fast growers disproportionally contribute to reproduction compared with slow growers. However, no recruited tree was observed in this subperiod, suggesting that fast growers made no contribution to reproduction. Fast growers might not play a more significant demographic role than slow growers in this species.
Leadbeater’s possum (Gymnobelideus leadbeateri) is a critically endangered arboreal marsupial found primarily in the mountain ash forests of Victoria’s Central Highlands in southeastern Australia. It has two very specific and well-known habitat requirements: a dense, connected lower stratum of Acacia spp. for foraging and movement within the forest and hollow-bearing trees for nesting. Early habitat suitability models for Leadbeater’s possum focused primarily on the dynamics of the hollow-bearing tree component, assuming that sufficient Acacia persisted throughout the development of the stand. Recent research has highlighted the transient nature of the Acacia component in these forests and shown that old-growth forests are relatively poor habitat for Leadbeater’s possum. The stand dynamics of mountain ash forests mean that the presence and abundance of Acacia and hollow-bearing trees are largely independent of one another. This presents a fundamental conundrum for the conservation of Leadbeater’s possum – the Acacia component is associated with young, post-disturbance forests, whereas hollow-bearing trees are associated with older forests. Conservation-oriented silviculture needs to accommodate these dynamics and focus on the provision of both habitat elements in close proximity to each other in time and space. A landscape-scale approach that focuses on long-term habitat restoration and management will be critical to the long-term viability of Leadbeater’s possum, particularly in a warming climate.Keywords
Acacia dealbata
Eucalyptus regnans
Habitat suitabilityConservation-oriented silviculture
Accurate knowledge of individual tree ages is critical for forestry and ecological research. However, previous methods suffer from flaws such as tree damage, low efficiency, or ignoring autocorrelation among residuals. In this paper, an approach for estimating the ages of individual trees is proposed based on the diameter series of Cinnamomum camphora (Cinnamomum camphora (L.) Presl), Schima superba (Schima superba Gardn. et Champ.), and Liquidambar formosana (Liquidambar formosana Hance). Diameter series were obtained by stem analysis. Panel data contains more information, more variability, and more efficiency than pure time series data or cross-sectional data, which is why diameter series at stump and breast heights were chosen to form the panel data. After choosing a base growth equation, a constraint was added to the equation to improve stability. The difference method was used to reduce autocorrelation and the parameter classification method was used to improve model suitability. Finally, the diameter increment equation of parameter a-classification was developed. The mean errors of estimated ages based on the panel data at breast height for C. camphora, S. superba, and L. formosana were 0.47, 2.46, and −0.56 years and the root mean square errors were 2.04, 3.15 and 2.47 years, respectively. For C. camphora and L. formosana, the estimated accuracy based on the panel data was higher at breast height than at stump height. This approach to estimating individual tree ages is highly accurate and reliable, and provides a feasible way to obtain tree ages by field measurement.
Growth Simulation, an analytical modeling technique, has been increasingly used in ecological studies and practical forestry applications where dendrochronology is not applicable. The technique uses randomly sampled diameter increments from tagged trees over a known time interval to assemble a statistical sample of lifetime growth trajectories. We carried out a validation of Growth Simulation using a temperate species in order to compare indirect model outputs with direct tree ring analysis. Rings were measured on sample disks cut from 55 pine branches ranging in age from 8–36 years. Assessments included lifetime growth rates, growth rate with respect to diameter and age, periodic annual increment (PAI), cross-referencing of rings by date, and autocorrelation of growth over successive periods. Tree ring analysis and Growth Simulation showed close correspondence for all parameters tested (maximum, median, and minimum growth rates; longevity estimates). Growth Simulation is found to be a robust and informative technique for studies of tropical tree growth, and is especially useful where analysis of tree rings is not feasible or when bootstrapping analysis of ring data is of interest.
The Colchic rainforest of the Western Caucasus is one of the few temperate rainforests dominated by broadleaf deciduous trees. Understanding natural dynamics of broadleaf-dominated temperate rainforests is essential for their conservation and management. Here, we investigate for the first time the structure, natural disturbance, and recruitment dynamics of a mixed Colchic old-growth rainforest, dominated by Fagus orientalis and Picea orientalis. We used forest inventories and dendrochronological analysis of tree growth in five 30-m-radius plots to quantify forest structure, growth, and disturbances. For the last 400 years, the forest experienced a mixed disturbance regime dominated by frequent small gaps superimposed onto medium disturbances with about a 25-year recurrence period, with no evidences of stand-replacing disturbances. This disturbance regime favored the dominance of shade-tolerant, late successional species with slow tree canopy access through multiple growth releases. These dynamics impose low growth rates and continuous recruitment of spruce and beech, and contributed to a high heterogeneity of tree ages and sizes that result in stable forest structure, as suggested by the low stand slenderness. Spruces were the oldest (up to 427 years) and fastest growing trees in the forest, suggesting that their low presence in the forest is due to low disturbance rates that limit their recruitment. Spring climate conditions that promoted beech growth were detrimental for spruce growth, suggesting that interspecies interactions may condition the effect of climate on forest growth and development. The dynamic equilibrium state we reconstructed in this old-growth forest could likely be disrupted by anthropogenic disturbances or management.
Information on long-term growth rates, ages, and survival of dominant tree species is vital to understand forest dynamics. In this study, tree-ring analysis was used to reconstruct lifetime growth patterns and to examine age–diameter relationships of selected tree species from the dry Afromontane forest fragments in northern Ethiopia. Ring width measurements were based on increment core samples and stem discs collected from three tree species (Juniperus procera, Olea europaea subsp. cuspidata, and Podocarpus falcatus). Standard dendrochronological methods were used for data collection and analysis. Overall, across species and sites, significant mean radial growth differences were found. P. falcatus trees showed the highest mean annual radial growth (2.45 mm/year), while O. europaea trees showed slow growth rates, with average annual growth ranging between 1.6 mm in Desa’a and 2.0 mm in Hugumburda. The mean ring width of an individual J. procera tree ranged between 1.8 mm/year (in Desa’a site) and 2.3 mm/year (in Hugumburda site). Many trees of the sampled species exhibited more or less sigmoid growth curves. Age variation is mainly determined by the variation in passage time through the smaller diameter classes (juvenile classes). In general, the results obtained in this study have important implications for understanding growth dynamics of tropical dry Afromontane forests and for planning conservation and restoration activities. This study has to be supported by eco-physiological studies to further understand the responses of these and related main tree species to the varied environmental gradients to better explain the dynamics in relation to emerging environmental changes.
The Brazil nut tree (Bertholletia excelsa) is an iconic and economically valuable species that dominates vast swathes of the Amazon Basin. This species seems to have been an important part of human subsistence strategies in the region from at least the Early Holocene, and its current distribution may be a legacy of past human settlement. Because B. excelsa is a long-lived pioneer tree it requires natural or human disturbances to increase light availability in the understory for a successful establishment. However, it remains unclear how the long-term population dynamics of this species have been shaped by pre-colonial and post-colonial human practices. Here, we use tree-ring analyses to look at changes in growing conditions over the past 400 years in a Brazil nut tree population in Central Amazonia. We identify changes in tree recruitment and growth rates associated not only with regional climatic variability, but also major political and socio-economic activities recorded by historical documents in the vicinity of Manaus. We demonstrate that the expansion of a post-colonial political center (Manaus) from the middle of the 18th century onwards coincided with a reduction in recruitment of B. excelsa. We argue that this hiatus suggests the interruption of indigenous management practices, probably due to the collapse of pre-Columbian societies. A second recruitment pulse, and unprecedented cycles of growth release and suppression, aligns with a shift to modern exploitation of the forest into the 20th century. Our findings shed light on how past histories of human-forest interactions can be revealed by the growth rings of trees in Amazonia. Future interdisciplinary analysis of these trees should enable more detailed investigation of how human forest management has changed in this part of the world, through pre-colonial, colonial, and industrial periods of human activity, with potential implications for conservation.
Ruizia cordata Cav., a native species of Réunion Island, is critically endangered as 4 individuals are known to be left in the wild at the dawn of 2015. Today, the success of ex situ programs initiated in the past 30 years is undeniable, ensuring available genetic strains conservation for the generations to come. The finding of a well-shaped new individual in February 2015 in the North coastal cliffs of the island has made a new genetic strain available for ex situ collections. As such, the perspective of discovering other natural individuals still stands as a hope for the long term conservation of R. cordata.
Quesions
What were the long‐term disturbance rates (including variability) and agents in pristine Norway spruce‐dominated ( Picea abies (L.) Karst.) forests? Have soil moisture conditions influenced disturbance rates across this boreal spruce‐dominated forest? Were the temporal recruitment patterns of canopy dominants associated with past disturbance periods?
Location
Interfluvial region of Northern Dvina and Pinega rivers, Arkhangelsk, northwest Russia.
Methods
We linked dendrochronological data with tree spatial data ( n trees = 1659) to reconstruct the temporal and spatial patterns of canopy gaps in a 1.8‐ha area from 1831–2008, and to develop a growth‐release chronology from 1775–2008.
Results
No evidence of stand‐replacing disturbances was found within selected forest stands over the studied period. Forest dynamics were driven by small‐ to moderate‐scale canopy disturbances, which maintained a multi‐cohort age structure. Disturbance peaks were observed in the 1820s, 1920s, 1970s and 2000s, with decadal rates reaching 32% of the stand area disturbed.
Conclusions
The overall mean decadal rate was 8.3% canopy area disturbed, which suggests a canopy turnover time of 122 yr, with a 95% confidence envelop of 91–186 yr. Bark beetle outbreaks (possibly exacerbated by droughts) and wind‐storms emerged as the principal disturbance agents. Recruitment of both Norway spruce and downy birch was associated with periods of increased canopy disturbance. Moisture conditions (moist vs mesic stands) were not significantly related to long‐term disturbance rates. The studied spruce‐dominated boreal forests of this region apparently exhibited long‐term forest continuity under this mixed‐severity disturbance regime. These disturbances caused considerable structural alterations to forest canopies, but apparently did not result in a pronounced successional shifts in tree species composition, rather occasional minor enrichments of birch in these heavily spruce‐dominated stands.
Tree growth estimation is a challenging task as difficulties associated with data collection and inference often result in inaccurate estimates. Two main methods for tree growth estimation are diameter tape measurements and increment cores. The former involves repeatedly measuring tree diameters with a cloth or metal tape whose scale has been adjusted to give diameter readings directly. This approach has the advantage that diameters can be measured rapidly. However, because of the substantial error involved during tape measurements, negative diameter increments are often observed. Alternatively, annual radius increment data can be obtained by taking tree cores and averaging repeated measurements of the ring widths. Acquiring and analyzing tree cores is a time-consuming process, and taking multiple cores may have adverse effects on tree health. Therefore, radius increment data are typically only available for a subset of trees within a stand. We offer a fusion of the data sources, which enables us to accommodate missingness and to borrow strength across individuals. It enables individual tree-level inference as well as average or stand level inference. Our model recognizes that tree growth in a given year depends upon tree size at the start of the year as well as levels of appropriate covariates operating in that year. We apply our modeling to a fairly large dataset taken from two forest stands at Coweeta Hydrologic Laboratory in the southern Appalachians collected from 1991 to 2011. Copyright © 2014 John Wiley & Sons, Ltd.
A growth study of Prioria copaifera (Caesalpinaceae) using dendrochronological techniques. The Cativo (Prioria copaifera) forms very homogeneous forests called cativales in the flooded plains of some rivers from Costa Rica to Colombia. For over 70 years Cativo has been the main base of the timber industry in the Colombian Darien area. Because of high productivity and high-dominance of Cativo trees, they represent one of the most prone tropical forests for sustainable forest management. The objective of this research is to model diameter and timber volume growth and growth rates (absolute, mean and relative) of Cativo as a function of age, using tree ring data derived from dendrochronologycal techniques. We evaluated the annual nature of the tree rings by radiocarbon analysis and crossdating techniques. Besides, the diameter and volume growth was modeled using von Bertalanffy’s model. As of our results, we estimated the life span of Cativo in 614 years as the time required to reach 99% of the asymptotic diameter. By the mean value we have found that the mean rate of diameter growth is 0.31cm/y. The species requires 90 years to reach 40cm in diameter, the regulated cut diameter in Colombia. We find that Cativo reaches maximum current annual increment (ICA) in diameter at 40 years and in volume at 90 years with rates of 0.5cm/y and 0.032m3/y per tree, respectively. The maximum diameter mean annual increments (MAI) are achieved at 80 years and for the volume at 140 year, with growth rates of 0.45cm/y and 0.018m3/y per tree, respectively. The generated information is useful for the sustainable management of Cativo forests. Rev. Biol. Trop. 59 (4): 1813-1831. Epub 2011 December 01.
The knowledge of tree age is important for understanding tree growth and forest dynamics. It may be estimated by ‘direct’ methods involving growth ring counts, or by ‘indirect’ methods involving field measurements of growth rates. Direct methods are considered more accurate, but it is not clear if they are appropriate for all species, notably from the humid tropics. In this paper we assess the occurrence of annual growth rings and their utility for age estimation in three tropical tree species, Acrocarpus fraxinifolius, Dalbergia latifolia (Fabaceae) and Syzygium cumini (Myrtaceae), growing in traditional shade coffee plantations of the southern Western Ghats, India. These species previously were described as having “indistinct or absent” growth rings. We used anatomical studies, field measurements and computational methods to characterise growth rings and assess similarities between directly and indirectly estimated tree ages. Our study revealed that annual growth rings were characterised by different sets of anatomical features per species and were most distinct in the fast-growing deciduous A. fraxinifolius. Growth rates measured in the field showed annual periodicity in all three species, and reflected annual rainfall-drought cycles in D. latifolia and S. cumini. Direct age estimates were most similar to indirect estimates in D. latifolia, and least so in S. cumini. The results of direct age estimation by counting rings are consistent with them being annual in nature in tropical species with distinct and reliable annual growth ring formation. However, for species with poorly defined growth rings, indirect age estimation methods might be more useful.
Availability of quantitative information on growth increment, biomass accumulation and growth dynamics of fragmented and degraded forest ecosystems is a common challenge in restoration work. Ecological models of forest dynamics have the potential to provide a structure through which data, observations and assumptions can be combined and explored. The utility of such models, however, is often limited by lack of validation. In this paper we used growth data for 143,200 tree measurements, in 121 plots spanning up to 70 years of forest monitoring from uneven-aged mixed species callitris forests of Australia to test the Ecosystem Dynamics Simulator (EDS). These are among the least known and most degraded forest communities in Australia and are known habitat for threatened and rare fauna species including brush-tailed rock wallaby (Petrogale penicillata), glossy black-cockatoo (Calyptorhynchus lathami), grey falcon (Falco hypoleucos), golden-tailed gecko (Strophurus taenicauda) and others. We determined growth parameters for 26 woody species and applied these to the EDS to validate projected stand structure and growth. The model projections explained 93.9% (diameter at breast height (dbh)), 88.9% (basal area), 90.5% (stem density) and 88.6% (aboveground biomass) of the observed variation. To our knowledge, this is one of the most accurate validations of forest dynamics simulation achieved to date. Diameter growth rates for most species were <0.3 cm yr−1 and reproduced well by the EDS, for all the species in the callitris forest communities. These growth rates indicate that exceptionally long periods will be required to restore the degraded or cleared forests to a mature state. Results can guide restoration and sustainable management of callitris forest ecosystems by providing projected measurable forest attributes to meet multiple goals, including harvesting of forest resources, carbon storage and conservation of biodiversity.
One of the key problems confronting ecological forecasting is the validation of computer models. Here we report successful validation of a forest dynamics model Ecosystem Dynamics Simulator (EDS), adapted from the JABOWA-II forest succession model. This model and many variants derived from it have successfully simulated growth dynamics of uneven-aged mixed forests under changing environment with a moderate amount of input data. But rarely are adequate time-series data available for quantitative model validation. This study tested the performance of EDS in projecting the tree density, tree diameter at breast height (dbh), tree height, basal area and aboveground biomass of uneven-aged, mixed species sclerophyll forests in St. Mary state forests of eastern Australia. The test data were collected between 1951 and 2005. Every tree was uniquely numbered, tagged and measured in consecutive re-measurements. Projected growth attributes were compared with those observed in an independent validation dataset. The model produced satisfactory projections of tree density (91.7%), dbh (92.3%), total tree height (82.8%), basal area (89.3%) and aboveground biomass (87.6%) compared to the observed attributes. These results suggest that the EDS model can provide reasonable capability in projecting growth dynamics of uneven-aged, mixed species sclerophyll forests.
Subtropical forests are usually composed of many tree species. Knowledge of the age and radial growth variation of the dominant
tree species is useful for understanding forest dynamics and community structure and function. The aims of this study are
to explore whether there are identifiable annual growth rings in the main tree species and to examine the growth characteristics
within and among the species in Mount Gutian subtropical forest of China. The results showed that four out of eight tree species
from which samples were collected had visible and cross-datable rings. There were no stable relationships between the age
and diameter for these subtropical trees. Significant differences existed in radial growth rate within and among the four
species, suggesting a high spatial heterogeneity in the mixed-species subtropical forest. The common pattern in age distribution
of multiple species suggests a stand-wide disturbance occurring around the 1960s. It is interesting to note that the growth
rate at the same age intervals was different for trees younger than 40 years of age and older than 40 years of age, suggesting
a change in climate or forest structure in the two time periods. The results obtained from this study help understand the
growth dynamics in other subtropical forests having these tree species.
La Soufrière of Guadeloupe is a dangerous volcano characterized over the last decade by moderate seismic and fumarolic unrest. In the last 15,000 years it has experienced phreatic and magmatic eruptions and unusually numerous flank collapse events sometimes associated with a magmatic eruption. We propose a new age of 1530 A.D. and a new eruptive scenario for the last magmatic eruption on the basis of a novel statistical analysis of radiocarbon age dates, and new field and geochemical data. This eruption is the only magmatic eruption likely to have occurred in Guadeloupe during the last 1400 years. The eruption mainly involved an andesitic magma which, in the first phase of the eruption, partially mixed with a slightly more differentiated magma stored in a small and shallow magma chamber. Ascent of magma to the surface generated a partial collapse of the hydrothermally altered edifice that increased the magma discharge and led to a sub-plinian phase with scoria fallout and column-collapse pyroclastic flows followed by near-vent pyroclastic scoria fountains. The eruption ended with growth of a lava dome. Our revised interpretation of the last magmatic eruption of La Soufrière constitutes the most likely key to a future magmatic eruption scenario for this volcano which displays strong evidence of unrest since 1992.
In rocky, heterogeneous environments that support old-growth forests, the relationship between tree size and age is weaker than it is for trees growing in productive and homogeneous habitats. To assist in the management and conservation of ancient forests on rocky land of low productivity, it would be useful if the relationships among age, environmental heterogeneity, and morphological variability could be understood and used to develop predictive models of longevity so that extensive core sampling of trees would not be required. Here we sampled 296 mature Thuja occidentalis L. growing on limestone cliffs along the Niagara Escarpment, southern Ontario, Canada. We measured a variety of site conditions and morphological traits, including age, which varied from 51 to 1316 years. We then used redundancy analysis and multiple regression to model the relationships among age, morphology, growth rate, and environment, resulting in quantitative models predicting tree age from four subsets of variables. We subsequently tested the models on 60 additional trees not used to build the models and found that they predicted up to 78% of the variation in actual tree age. This approach could be adopted for use in other forest types to predict the age of trees without using tree-ring analysis.
Because old trees contain centuries of environmental history, investigators are increasingly turning to dendrochronology to create context for current environmental change. While a suite of char-acteristics to identify old trees has been developed, most of these characteristics are for conifers or trees growing in low-density forests. Given that the diverse Eastern Deciduous Forest (EDF) is dominated by a species-rich, angiosperm-dominated woody flora, old-growth forests are scarce in the EDF, and research permits in natural areas often limit the number of trees that can be sampled, having a suite of characteristics that identify old trees for a wider range of species increases the likelihood of efficiently creating longer depths of ecological history. The common indicators of old (> 250 year old) EDF an-giosperms are presented to aid in the recovery and preservation of these living sources of information. Six common external characteristics of old angiosperm trees include: (1) smooth or "balding" bark; (2) low stem taper; (3) high stem sinuosity; (4) crowns comprised of few, large-diameter, twisting limbs; (5) low crown volume; and (6) a low ratio of leaf area to trunk volume. The existence of old trees in the landscape can also be related to life-history traits or land-use histories. Both professionals and lay folk can be trained to identify these traits and environmental conditions. While these characteristics and settings generally signal the potential for old trees, there is no guarantee that they represent old ages. However, these characteristics should aid in the discovery of old trees throughout the EDF.
Abstract Spatial heterogeneity in the intensity of past disturbances has directly influenced the structure and composition of present-day forests around the world. In south-eastern Australia infrequent, high-intensity wildfires are a major part of the historical disturbance regime. While these fires are often assumed to produce even-aged stands, spatial heterogeneity in fire intensity due to highly variable topography may lead to more complex forest age structures. Our study describes the influence of disturbance on the age structure and dynamics of a mosaic of tall, open eucalypt forest, cool temperate rainforest and mixed species forest surrounding Bellel Creek in the Central Highlands of Victoria using dendrochronological techniques. We were particularly interested in the impacts of the 1939 Black Friday fire and its effects on forest age structure and subsequent stand development patterns. Within our study site tall open forest displayed two distinct age cohorts: (i) trees that established immediately after the 1939 fire and accounted for the majority of individuals in the forest, and (ii) scattered groups of older trees estimated to be approximately 200–250 years old. Cool temperate rainforest and mixed forest were also dominated by the post-1939 fire age cohort. However, a greater proportion of trees in these forest types survived the 1939 fire relative to the tall open forest. The impact of the 1939 fire on the growth of surviving trees was highly variable but generally short-lived. In most cases growth decreased after the 1939 fire, but generally returned to prefire levels within 1–3 years. Non-fire disturbances were limited to small-scale branch- and tree-fall events, although the extreme snowstorm of 1977 appears to have caused extensive damage to rainforest communities. Our study demonstrates the opportunities for dendroecological studies to reconstruct historical dynamics and disturbance patterns in Australian forests and provides important insights into variation in landscape-scale fire impacts and their effect on subsequent forest development patterns.
As part of an assessment of sustainability for the strip clear-cutting system (or Palcazú Forest Management System), we determined whether commercial tree species regenerating in two strips (30 m × 150 m) clear-cut in the Peruvian Amazon in 1989 would reach commercial size (≥30 cm diameter at breast height (dbh)) 40 years after the initial cutting, the expected harvesting cycle. We projected the growth of six common commercial species (Eschweilera bracteosa, Guarea cinnamomea, Micropholis guyanensis, Pouteria guianensis, Qualea paraensis, and Cedrelinga catenaeformis) and two pioneer species (Alchornea triplinervia and Miconia phaeophylla) using bootstrapping techniques (the Lieberman model), based on 2-year diameter increments (2004–2006) and mortality rates obtained from 1630 trees growing in secondary forest sites including the regenerating strips. These demographic data were further used to project the growth of all trees ≥6.5 cm dbh of commercial (sawnwood value) species from each strip, and from a deferment-cut treatment applied to half of one of the strips. Three models were used for growth projections: (1) using all diameter increments to simulate average growing conditions, (2) using diameter increments of trees exposed to high light to simulate growing conditions under intensive forest management with low mortality rates and (3) using diameter increments of the fastest growing individuals. Roundwood volume was calculated using allometric equations for emergent, canopy, and subcanopy species.
The Cativo (Prioria copaifera) forms very homogeneous forests called cativales in the flooded plains of some rivers from Costa Rica to Colombia. For over 70 years Cativo has been the main base of the timber industry in the Colombian Darien area. Because of high productivity and high-dominance of Cativo trees, they represent one of the most prone tropical forests for sustainable forest management. The objective of this research is to model diameter and timber volume growth and growth rates (absolute, mean and relative) of Cativo as a function of age, using tree ring data derived from dendrochronologycal techniques. We evaluated the annual nature of the tree rings by radiocarbon analysis and crossdating techniques. Besides, the diameter and volume growth was modeled using von Bertalanffy's model. As of our results, we estimated the life span of Cativo in 614 years as the time required to reach 99% of the asymptotic diameter. By the mean value we have found that the mean rate of diameter growth is 0.31cm/y. The species requires 90 years to reach 40cm in diameter, the regulated cut diameter in Colombia. We find that Cativo reaches maximum current annual increment (ICA) in diameter at 40 years and in volume at 90 years with rates of 0.5cm/y and 0.032m3/y per tree, respectively. The maximum diameter mean annual increments (MAI) are achieved at 80 years and for the volume at 140 year, with growth rates of 0.45cm/y and 0.018m3/y per tree, respectively. The generated information is useful for the sustainable management of Cativò forests.
There is great concern about the effect of climate change in arid and subarid areas of the tropics. Climate change combined with other anthropogenic activities such as deforestation, fires and over-grazing can accelerate their degradation and, consequently, the increases in losses of biological and economic productivity. Climate models, both local and global, predict that rainfall in the arid Peninsula of La Guajira in the Colombian Caribbean would be reduced and temperature would be increased as a result of climate change. However, as there are only suitable climate records since 1972, it is not possible to verify if, indeed, this is happening. To try to verify the hypothesis of reducing rainfall and rising temperatures we developed a growth ring chronology of Capparis odoratissima in the Middle Peninsula of La Guajira with 17 trees and 45 series which attain 48 years back. We use standard dendrochronological methods that showed statistically significant linear relationship with local climatic variables such as air temperature, sea surface temperature (SST), annual precipitation and wind speed; we also reach to successful relationship of the chronology with global climatic variables as the indices SOI and MEI of the ENSO phenomenon. The transfer functions estimated with the time series (1955 and 2003) do not showed statistically significant trends, indicating that during this period of time the annual precipitation or temperatures have not changed. The annual nature of C. odoratissima growth rings, the possibility of cross-dated among the samples of this species, and the high correlation with local and global climatic variables indicate a high potential of this species for dendrochronological studies in this part of the American continent.
To improve our understanding of the ecology of tropical forest trees, it is essential to obtain information on tree growth over periods of decades to centuries. Using tree-ring analysis such data can be derived as this technique allows reconstructing the growth history over the entire lifespan of a tree. This PhD thesis reports on the use of tree-ring analysis for reconstructing long-term growth patterns of Bolivian forest trees. A large number of discs was collected from five tree species, and tree rings were identified and measured. First, I evaluated whether those trees that are currently large have had faster rates of diameter growth when they were small compared to present-day small trees. This ‘juvenile selection effect’ would imply that fast-growers have a higher probability to reach the forest canopy and become reproductive. For three out of five species, I could indeed detect a juvenile selection effect. Thus, for these three species fast growth of small trees may be essential to reach the canopy. The above finding has consequences for growth models that are often used to simulate tropical timber yield. If fast-growing trees have a higher chance to reach the size at which they can be harvested, it is important to include these higher growth rates in such models. I found that this was indeed the case: simulated timber yield was higher when this juvenile selection effect was taken into account. Nevertheless, even with the higher growth rates, the recuperation of timber volume during one logging cycle remained low. Only 20-33% of the timber volume harvested at the first harvest could be obtained at second harvest after 20 years. Reaching the forest canopy for tropical trees implies large investments in height. Such investments may imply that less carbohydrates are invested in diameter growth and stem volume. I collected stem discs at various heights of juvenile trees to reconstruct height, diameter and volume growth. I found that individual trees differed very strongly in growth rates (height, stem volume, diameter). These growth rates were related: the faster height growers grew relatively little in stem volume, and vice versa. This suggests that juvenile trees in favourable (light) conditions invest relatively more in stability and crown development than in height growth Tree-ring analysis allows evaluating whether diameter growth rates have increased or decreased over time. For four out of five species I found that growth rates of small trees increased over the last two centuries. This pattern is consistent with what would be expected due to CO2-fertilization, but other causes cannot be ruled out. I then checked for indications of changes in forest dynamics over time. To this end, I calculated the frequency of releases (periods of fast growth) and autocorrelation strength. No indications for a change in forest dynamics were found. In this thesis I showed that tree-ring analysis can strongly contribute to improving our understanding of long-term ecological processes in tropical forests. This knowledge is much needed in assessing the response of tropical forests to the predicted climate changes in the future.
In fire-prone regions, assessing stand age of obligate-seeding species provides an estimate of time since last fire. If a relationship exists between tree age and diameter, measuring the stem diameter of trees is a simple field method for determining age-class distribution within a stand. In this study, we examined whether age of the obligate seeder Allocasuarina littoralis could be estimated from diameter by using dendrochronological applications. Analysis of radial samples established that A. littoralis puts down annual growth rings. The relationship between the number of growth rings and stem diameter was tested for both male and female stems by using regression analysis. For female plants, this relationship varied significantly between sites. In contrast, male stems provided a strong relationship between age (as a function of the number of growth rings) and diameter, regardless of site. A regression model estimating age from stem diameter, based on male trees only, was subsequently developed and tested with data collected from trees of known age. Predicted estimates from stem diameter were within 3.76 years of the true age. Field measures of stem diameters can therefore provide a tool for estimating the fire history, especially time since last fire, in areas where stands of this species occur.
Estimation of tree growth is based on sparse observations of tree diameter, ring widths, or increments read from a dendrometer. From annual measurements on a few trees (e.g., increment cores) or sporadic measurements from many trees (e.g., diameter censuses on mapped plots), relationships with resources, tree size, and climate are extrapolated to whole stands. There has been no way to formally integrate different types of data and problems of estimation that result from (1) multiple sources of observation error, which frequently result in impossible estimates of negative growth, (2) the fact that data are typically sparse (a few trees or a few years), whereas inference is needed broadly (many trees over many years), (3) the fact that some unknown fraction of the variance is shared across the population, and (4) the fact that growth rates of trees within competing stands are not independent. We develop a hierarchical Bayes state space model for tree growth that addresses all of these challenges, allowing for formal inference that is consistent with the available data and the assumption that growth is nonnegative. Prediction follows directly, incorporating the full uncertainty from inference with scenarios for "filling the gaps" for past growth rates and for future conditions affecting growth. An example involving multiple species and multiple stands with tree-ring data and up to 14 years of tree census data illustrates how different levels of information at the tree and stand level contribute to inference and prediction.
Crown class and diameter of 1862 yellow birch (Betula alleghaniensis Britton) >1.5 cm have been monitored at 10-year intervals since 1927. Nominal stand age was 25 years in 1927. Survival and growth of yellow birch in 25- to 85-year-old stands were influenced by antecedent crown class and disturbance. Mortality was negatively correlated with antecedent diameter growth and to a lesser extent crown class. Mortality of suppressed trees was 2x to 4x higher than for trees in the upper canopy. Mortality of trees growing <1 cm DBH per decade was 8x higher than for trees growing greater than or equal to 2 cm DBH per decade. Mortality and diameter growth were independent of tree diameter when antecedent diameter growth and crown class effects were removed. The decline of yellow birch diameter growth between stand ages 35 and 55 years was linked to vertical stratification. Diameter growth increased following a period of defoliation and drought between stand ages 55 and 65 years, presumably because of increased oak mortality during this period. Simultaneously, persistence in the upper canopy increased and crown class regression decreased. After a 10-year lag, crown class ascension of intermediate trees increased. Yellow birch ingrowth and ascension of suppressed trees into the intermediate crown class peaked after a 20-year lag. Cutting practices that mimic defoliation-initiated mortality should increase yellow birch density in southern New England.
Crown classes and diameters of 704 northern red oaks on medium quality sites were measured at 10-yr intervals between 1927-1987. Nominal age of northern red oaks at the beginning of the study was 25 yr. Mortality rates between ages 25-55 and between ages 55-85 decreased with each increase in crown class (i.e., mortality of dominant is less than codominant is less than intermediate is less than suppressed). Ascension rates into higher crown classes increased with each increase in crown class between ages 25-55 and between ages 55-85. Mortality rates of dominant, codominant, and intermediate trees were higher between ages 55-85 than between ages 25-55. The cause of the increased mortality was likely periodic episodes of defoliation which began after age 55. Within several diameter classes at age 25, survival through age 55 and the proportion found in upper canopy at age 55 increased with crown class. Mortality rates between ages 25-55 were lower for the largest northern red oak in a sprout clump than for lesser sprouts and for those trees which were not part of a sprout clump. There was no significant difference in canopy position transition rates between ages 55-85 for the largest red oaks in a sprout clump and those trees which were not part of a sprout clump. However, mortality rates between ages 55-85 of lesser trees in a sprout clump were significantly higher than for either the largest sprout in a clump or for those trees which were not part of a sprout clump. Survival of suppressed and intermediate 25-yr-old red oak was negatively related to the number of oaks in dominant and codominant crown classes. Crown class can be a powerful tool for determining the future status of maturing northern red oaks in southern New England. For. Sci. 40(2): 221-237.
Tree ring chronologies from 24 mixed-conifer stands were used to reconstruct the long-term history of western spruce budworm (Choristoneura occidentalis) in northern New Mexico. Temporal and spatial patterns of budworm infestations (within-stand occurrences) and outbreaks (more-or-less synchronous infestations across many stands) were investigated to identify local-scale to regional-scale forest disturbance patterns. Nine regional-scale outbreaks were identified from 1690 to 1989. One ancient stand of Douglas-fir trees (Pseudotsuga menziesii) exceeding 700 yr in age revealed that budworms and overstory trees can coexist for extraordinary lengths of time. Using spectral analysis we found that the regional outbreak record contained important cyclical components with periods varying from @?20 to 33 yr. The statistically significant (P
With a view toward understanding species-specific differences in juvenile tree mortality and the community-level implications of these differences, we characterized juvenile survivorship of 10 dominant tree species of oak transition-northern hardwood forests using species-specific mathematical models. The mortality models predict a sapling's probability of dying as a function of its recent growth history. These models and species-specific growth functions (published elsewhere), characterize a species' shade tolerance. Combined growth and mortality models express a sapling's probability of mortality as a function of light availability. We describe the statistical bases and the field methods used to calibrate the mortality models. We examined inter- and intraspecific variation in juvenile mortality across three sites: Great Mountain Forest (low pH, nutrient poor soils) in northwestern Connecticut, a calcareous bedrock region (neutral pH, nutrient rich soils) also in northwestern Connecticut, and a site in central-western Michigan (low pH, nutrient poor soils). Interspecific differences in juvenile mortality have profound effects on community dynamics and composition; the importance of these effects is demonstrated through a spatially explicit simulator of forest dynamics (SORTIE). The 10 species we examined occupy a continuum of survivorship levels at 1% of full sun. There was surprisingly little intraspecific variation in mortality functions for sugar maple, American beech, eastern hemlock, and white ash between the Great Mountain and Michigan sites. However, there was a striking increase in survivorship for sugar maple in the calcareous site. Differences in survivorship among the sites are correlated with soil pH and presumably nutrient availability. Growth rates in high-light and low-light survivorship are inversely correlated across species; as level of shade tolerance increases, a species grows more slowly in high light and exhibits increased survivorship under low light. Our results indicate that interspecific differences in sapling mortality are critical components of forest community dynamics.
Stem radial growth patterns were used to reconstruct the history of suppression and release during canopy recruitment of Fagus grandifolia Ehrh. (beech) in three old-growth northern hardwood forests. Overall, eighty percent of the cores showed periods of suppression prior to recruitment. The average number of periods of suppression in the 3 stands ranged from 1.9-2.4, and the average total length of suppression ranged from 45-52 years. At recruitment, trees averaged 66-80 years old with diameters of 5.1-7.4 cm at 1 m height. In comparison with Acer saccharum Marsh. (sugar maple) in the same stands, beech trees reached final release after fewer and shorter total length of suppression, and at much smaller sizes. Calculations using average height growth rates for suppressed and released saplings of both species suggest that beech saplings achieve half of their height at final release while suppressed, while growth of sugar maple saplings during suppression accounts for only 15% of their height at final release. The frequency and duration of periods of release in beech indicate that canopy gaps were short-lived relative to the time required for canopy recruitment in this shade-tolerant species, and that saplings responded to gaps created by the deaths of nearby canopy trees before replacing the canopy tree directly overhead.
A study was made to determine the rate and extent of border-tree crown expansion into openings cut to obtain reproduction in sawtimber stands of Appalachian hardwoods. Measurements were made on poletimber- and sawtimber-sized trees of red oak and yellow-poplar. A regression was developed for each species, based on the independent variables of tree d.b.h. and the number of years since cutting. Red oak crowns extended farther and grew faster laterally than yellow-poplar crowns. However, the rate of crown encroachment into openings was surprisingly slow for both species.
The temporal and spatial dynamics of tree populations in coastal forests of southeastern Long Island, New York, were reconstructed from analyses of (1) historical accounts, maps, and aerial photos, (2) field evidence of forest history (3) age and height class distributions along the moisture gradient, and (4) fossil-pollen content of bordering salt-marsh deposits. Tide-gauge records of sea level provided independent evidence for long-term change in the physical environment (rise in sea level) that caused populations to migrate up the continental shelf. Field evidence for fire and historically documented land-use change demonstrated the important role of disturbance in the dynamics of tree populations. Spatial and temporal patterns in forest, were determined by information on disturbance frequency, dispersal, generation times, and rates of change in the physical environment. Mature cohorts occupied lower elevations than did their progeny because during the period from germination to seed production, suitable soil-moisture conditions shifted upslope in response to sea-level rise. Establishment of new regeneration depended on disturbances that opened the forest canopy and/or prepared seed beds. Frequent fire, land clearance and abandonment, and tree blowdowns insured opportunities for seedling establishment at higher elevations as conditions became unsuitable for regeneration on low-elevation sites. The resultant pattern of range shifts was stepwise, with waves of regeneration following disturbances and subsequent reduced seedling establishment as soil moisture continued to increase. The vegetation dynamics could be explained solely on the basis of life histories of plant species and environmental change; @'emergent properties@' and @'successional stages@' in a deterministic sense were not apparent. An understanding of successional change required information on both the spatial and temporal dimensions of vegetation pattern because composition change over time resulted from range shifts in response to environmental transition.
1 Stand reconstruction methods which involved the dating of live and dead trees were used to demonstrate the major flaws inherent in the common approach of using static stand structure to infer stand dynamics. To illustrate the problems with this approach we tested two hypotheses on conifer forest succession: (i) that the empty middle age classes in static stand age-class distributions are the result of a period in stand development in which recruitment was prevented, and (ii) that understorey trees have replaced canopy trees. 2 Reconstructions of age-class distributions at 20-year intervals into the past for five stands ranging in age from 58 to 222 years revealed a short postfire period of high recruitment of both Pinus contorta and Picea engelmannii followed by low and sporadic recruitment for the rest of the life of the stands. The initial postfire cohort also had a lower mortality rate than the subsequent cohorts. This pattern of low recruitment and high mortality for the understorey cohort resulting in the disappearance of these cohorts over time explains the false impression of a period of prevented recruitment in the middle age class of the static stand age distribution. 3 Height-date curves for individual standing live and dead trees, obtained by sectioning trees at 1-m intervals and ageing the disks, showed little, if any, canopy replacement by trees which were once in the understorey. Again, the combination of low recruitment and high mortality precludes any trees in the subsequent (understorey) cohorts from surviving and growing into the canopy. 4 This study of the dynamics of Pinus contorta - Picea engelmannii forest points out that forests must be viewed as a collection of species populations of stacked cohorts and that succession (dynamics) can be understood by studying the recruitment and mortality rates of these cohorts.
Forests in the eastern and northwestern United States often develop in even-aged patterns, with certain species predictably forming the upper canopy and others relegated to lower strata. The vertical sorting (or stratification) by species and broad ranges of diameters has sometimes led foresters and ecologists to assume these stands are all-aged. For this reason the stands have often been selectively logged and thereby degraded unintentionally. If manipulated as even-aged or in age classes, these mixtures can often be as economically and ecologically advantageous to manage as pure stands are.
The purpose of this study is to see if it is possible to determine the course of forest succession over several hundred years by the dissection and close scrutiny of live and dead plant material. The study area was a one-tenth-acre (0.04-ha) square plot in a forest that had never been cut, located near Ashuelot in southwestern New Hampshire. Within it stem-location and growth-rate data were collected from three different classes of stems: 1) living trees, 2), dead unburied stems and stem fragments, and 3), woody remnants buried in the forest floor. The vegetational history of the plot was reconstructed from before 1665 to 1967. During this time, autogenic succession did not contribute significantly to compositional changes, whereas disturbance was an important mediator of such changes. Furthermore, changes in forest structure were often manifestations of species behavior: each tree species had a distinctive stem-distribution pattern in relation to microtopography, mode of germination, and growth. The approach seemed to provide a useful means to obtain evidence about forest change through time that may help prediction and illuminate ecological theory. Limits and modifications of the procedure are discussed.
Age and size data on over 2200 trees were used to reconstruct developmental patterns and regeneration dynamics of four successional and two climax stands of subalpine forests in the Colorado Front Range. The dominant tree species of these forests are Engelmann spruce (Picea engelmannii), subalpine fir (Abies lasiocarpa), limber pine (Pinus flexilis), and lodgepole pine (Pinus contorta). Due to relatively weak relationships between age and size for all four species, patterns of stand development could not have been reliably inferred from size data alone. Following wildfire on the most xeric sites, limber pine is the principal pioneer species and dominates seedling establishment for 50 to 100 or more years. At most sites, however, Engelmann spruce and subalpine fir eventually establish and gradually replace limber pine. On less xeric sites, depending on availability of seed, either Engelmann spruce of lodgepole pine, alone or together, may act as pioneer species. Establishment of subalpine fire may be coincident or may be several decades later. Eventually it and Engelmann spruce replace lodgepole pine as the canopy dominants. The age structures of the stands investigated are consistent with the view that variation in establishment is a least as important as mortality in shaping age frequency distributions in successional stands. in climax Engelmann spruce - subalpine fire stands both species have all-aged populations; the typically greater abundance of young subalpine fir appears to be compensated by the much greater longevity of Engelmann spruce.
The need for information regarding tree age and growth in tropical forests. Pages 3–6 in Age and growth rates of tropical trees: new directions for research
- P S Ashton
Ashton, P. S. 1981. The need for information regarding tree age and growth in tropical forests. Pages 3–6 in F. H. Bor-mann and G. P. Berlyn, editors. Age and growth rates of tropical trees: new directions for research. Yale University School of Forestry and Environmental Studies, Bulletin Number 94, New Haven, Connecticut, USA
A study of virgin forest near Sandakan North Borneo. Pages 67-87inA
- D I Nicholson
Nicholson, D. I. 1965. A study of virgin forest nearSandakan, North Borneo. Pages 67–87 in A. J. G. H. Kostermans and F. R. Fosberg, editors. Proceedings of the symposium on ecological research in humid tropics vegetation, UNESCO. Science Cooperation Office for Southeast Asia, Bangkok, Thailand
Spa-tiotemporal growth dynamics and disturbances in a sub-alpine spruce forest in the Alps: a dendroecological recon-struction Life history diversity of canopy and emergent trees in a neotropical rainforest
- P Cherubini
- P Piussi
- F H Schweingruber
Cherubini, P., P. Piussi, and F. H. Schweingruber. 1996. Spa-tiotemporal growth dynamics and disturbances in a sub-alpine spruce forest in the Alps: a dendroecological recon-struction. Canadian Journal of Forest Research 26:991– 1001. r1732 PATRICK J. BAKER Ecological Applications Vol. 13, No. 6 Clark, D. A., and D. B. Clark. 1992. Life history diversity of canopy and emergent trees in a neotropical rainforest
Philippine dipterocarp forests
- W H Brown
- D M Mathews
Brown, W. H., and D. M. Mathews. 1914. Philippine dip-terocarp forests. Philippine Journal of Science 9:413–516
Age and growth rates of tropical trees: new directions for research
- F H Bormann
- G P Berlyn
Bormann, F. H., and G. P. Berlyn, editors. 1981. Age and growth rates of tropical trees: new directions for research. Yale University School of Forestry and Environmental Studies, Bulletin Number 94, New Haven, Connecticut, USA
Silvics of North America. Agriculture Handbook Number 654
- R M Burns
- . H Honkala
The practice of silviculture. Eighth edition. John Wiley and Sons, New York, New York, USA.
- D. M. Smith
Development of habitat structure through succession in an Amazonian floodplain. Pages 28–46 in S. S. Bell, E. D. McCoy, and H. R. Mushinsky, editors. Habitat structure: the physical arrangement of objects in space. Chapman and Hall, New York, New York, USA.
- J. Terborgh
- K. Petren
The management of natural tropical high-forests with special reference to Uganda. Imperial Forestry Institute, University of Oxford, Institute Paper 34, Oxford, UK.
- H. C. Dawkins
Forest stand dynamics. Update edition. John Wiley and Sons, New York, New York, USA.
- C. D. Oliver
- B. C. Larson
The need for information regarding tree age and growth in tropical forests. Pages 3-6inF
- P S Ashton
Crown characteristics of tropical trees. Pages 591-615inP
- P S Ashton