Cryptogam spores and other non-pollen microfossils as sources of palaeoecological information: Case-studies from Spain
Abstract and Figures
Four examples from Mediterranean Spain are used to show that records of non-pollen palynomorphs (algal and fungal spores and cysts, charophytes and other microfossils of unknown biological origin) are worthwhile in addition to pollen analysis for studies of palaeoecological reconstruction. In the lacustrine sequence of Cañada de la Cruz, the stratigraphy of palaeolimnological indicators is compatible with climatic control of vegetation stages at the response scales of decades to centuries. The sequence of Navarrés provides evidence of millennial-scale change in the trophic conditions of a peat-forming basin, which parallels local and vegetation changes since the last glacial to the Holocene under the influence of fire events, climate change and human activity. The sequence of Villaverde shows out-of-phase relationships of vegetational and limnological developments. The sequence of San Rafael offers an example of synchronous variation of xerophytic pollen and microfossils indicative of temporary marsh desiccation, in concordance with regional evidence of aridification since the mid-Holocene.
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... Additionally, some authors postulate that the presence of this algae indicates M.S. Raigemborn, S. Lizzoli, D. Moyano-Paz et al. Cretaceous Research 150 (2023) 105587 warm climatic areas with summer drought periods (local seasonal drying) (Scott, 1992;Carri on and Navarro 2002). Bryophytes and lycopsids of the upper section inhabited moist places, as along river banks and around swamp/ponds, probably associated with Liliales (see Fig. 8). ...
The Maastrichtian dinosaur-bearing Chorrillo Formation in southern Patagonia (⁓50° S, Austral-Magallanes Basin, Argentina) is a pedogenically modified fluvial succession, which records sediment deposition at mid-high paleolatitudes in the Southern Hemisphere. In order to reconstruct the paleoenvironment and paleoclimates for the Chorrillo Formation, we performed a paleopedological study (abiotic components) of the unit within a well-defined sedimentological-paleontological context, and considering new paleobotanical data of the unit. Using detailed macro and micromorphological features and clay mineralogy of the paleosols, we show that the Chorrillo Formation paleosols are overall smectite-rich soils with vertic and redoximorphic features (i.e., moderately developed hydromorphic Vertisol-, calcic Vertisol-, poorly developed hydromorphic Vertisol-, Histosol-, and argillic Vertisol-like paleosols). The small-scale or high-frequency stacking of such paleosols indicates that they developed under different hydrologic conditions, and subtle differences in grain-size (parent material) and topographic relief on a distal floodplain. Conversely, the large-scale or small-frequency vertical stacking of different paleosols is linked to avulsion processes. Paleobotanical remains through the Chorrillo succession demonstrates different ecological requirements for the inhabited part of the fluvial floodplain. Abiotic and biotic climate proxies suggest that these paleosols formed under a broadly temperate-warm and seasonally humid climate. Overall, these combined data record environmental and climatic conditions during the uppermost Cretaceous, and preserve a record of Maastrichtian terrestrial conditions in the Southern Hemisphere.
... Identification of pollen and plant spores followed standard keys (Moore et al., 1991;Beug, 2015). NPP identifications were carried out as in van Geel, 1978;van Geel and van der Hammen, 1978;van Geel et al., 1983;Jankovská and Komárek 2000;Komárek and Jankovská 2001;Carrión and Navarro, 2002;Fugassa et al., 2006;Montoya et al., 2012;Barthelmes et al., 2012;Prager et al., 2012;Kołaczek et al., 2013;Dietre et al., 2014;López-Vila et al., 2014;Shumilovskikh et al., 2016;Schlütz and Shumilovskikh, 2017;and Roche et al., 2020. NPP types were assigned to an existing code according to Miola (2012). ...
The aim of the present paper is to discuss the application of phytolith (microbiomorphic) and non-pollen palynomorph (NPP) analyses to the geoarchaeological study of a Medieval – Early Modern Time period
farmyard in Graft, a settlement located in the polder region of North Holland, the Netherlands. The authors have assessed the potential of the methods chosen for studying this type of archaeological site during rescue excavations, when archaeologists often have a limited number of samples or methods for
geoarchaeological analysis. The studies conducted have proved the informative value and effectiveness of microbiomorphic and NPP analyses in rescue excavations, especially when applied in combination, thus providing controlling and complementary information for each analysis. The data obtained have provided an important insight into the archaeological interpretation of the cultural layer within the farmyard. In addition, more information was gained on the local palaeoenvironmental dynamics and the phases of economic activity at the farmyard during the 13th–17th centuries CE.
... The presence of anthropogenic-nitrophilous herbs, such as Asteracea, Asteroideae and Cichorioideae, together with coprophilous and saprophytic fungi (mainly Sordariaceae, Sporomiella and Coniochaeta) are indicative of nitrate-rich environments deriving from livestock pressure and/or animal husbandry. The presence of Glomus (HdV-207) and Pseudoschizaea circula imply the existence of erosive processes occurring at the site: the first is associated with dry or desiccated areas, root activity and/or crop rotation (Anderson et al. 1984;López-Sáez et al. 2000;van Geel et al. 1989); the latter is related to seasonal droughts and/or rapid sedimentation processes (Carrión and Navarro 2002;Pantaleón-Cano et al. 1996;Scott 1992). Sample HdV-207, which was collected from the "black level", namely, the event layer Ey, reflects the prevailing conditions during the Roman period. ...
... The presence of anthropogenic-nitrophilous herbs, such as Asteracea, Asteroideae and Cichorioideae, together with coprophilous and saprophytic fungi (mainly Sordariaceae, Sporomiella and Coniochaeta) are indicative of nitrate-rich environments deriving from livestock pressure and/or animal husbandry. The presence of Glomus (HdV-207) and Pseudoschizaea circula imply the existence of erosive processes occurring at the site: the first is associated with dry or desiccated areas, root activity and/or crop rotation (Anderson et al. 1984;López-Sáez et al. 2000;van Geel et al. 1989); the latter is related to seasonal droughts and/or rapid sedimentation processes (Carrión and Navarro 2002;Pantaleón-Cano et al. 1996;Scott 1992). Sample HdV-207, which was collected from the "black level", namely, the event layer Ey, reflects the prevailing conditions during the Roman period. ...
Over the past decades, substantial progress has been made in tsunami research. Be that as it may, little is still known about tsunami deposits and their related depositional mechanisms in coastal areas in historical and archaeological contexts. In particular, the Phoenician, Greek and Roman trade and military networks along the Mediterranean and Atlantic coasts, with their cities, harbours and additional facilities, are susceptible to serving as archives for extreme wave events. The ruins of the Roman city of Baelo Claudia, located on the Bay of Bolonia Bay (southern Spain), offer a unique environment for studying historical tsunamis in the Gulf of Cadiz. Baelo Claudia suffered at least two earthquakes in Roman times, namely, in the first and fourth centuries CE. The latter, associated with a tsunami, led to the city’s destruction and subsequent decline. Accordingly, three tsunami deposits in Baelo Claudia, dated to ca. 4000 cal BP (2000 BCE), ca. 400 CE and 1755 CE, the last corresponding to the Lisbon tsunami, are described here. The multi-disciplinary research conducted on the sedimentary, archaeological and palaeontological records has revealed event deposits, together with major landscape changes in the environs of the bay after tsunami landfall. Furthermore, the significant archaeoseismic damage detected in recently excavated buildings has been dated to the end of the fourth-century CE. The results presented here serve to supplement the earthquake and tsunami record of coastal Iberia.
The study was conducted in the southern part of the lower Strymon valley, in northern Greece, and revealed up to 25 m of fluvio-lacustrine sediments deposited over the last seven millennia. This sedi-mentary record represents a significant opportunity for high-resolution palaeoenvironmental studies of the period from 6 to 3 ka cal BP linked to land use and climate change. The results of geophysical investigations , multi-proxy sedimentological (grain size, magnetic susceptibility, loss-on-ignition), pollen and NPP analyses, based on high-precision radiocarbon dating enabled reconstruction of past landscapes as well as a comprehensive discussion of anthropogenic responses and their impact on the vegetation cover, especially during periods with well-known Holocene Rapid Climate Change events (5.6, 4.2 and 3.2 ka cal BP). During the 7e5.7 ka cal BP corresponding to the Late and Final Neolithic, wet conditions created an extended lake surrounded by the densely wooded Strymon watershed, followed by a shift to a shallower lake environment that lasted until ca. 4.5 ka cal BP. The continuous presence of anthropogenic taxa suggests the persistence of human activities even in the absence of formally recognized sites, suggesting the relocation of settlements. The first signs of human disturbance of the landscape at regional scale occurred toward 5.2 ka cal BP (onset of the Early Bronze Age). The so-called « 4.2 ka BP event », which coincided with the end of the Early Bronze Age and the transition to the Middle Bronze Age, is divided into three distinct periods (4.35e4.1, 4.1e3.95 and 3.95e3.75 ka cal BP). The first corresponds to gradual aridification before a period with severe dry conditions that marks a tipping point toward wetland contraction. From this period on, diversification, and multiplication of anthropogenic species including Olea, Juglans and Castanea reflect a global trend toward cultural landscapes. The later periods are characterized by dramatic climatic change around 3.2e3 ka cal BP, at the end of Late Bronze Age, and increasing impacts of agro-pastoral activities and forest clearing starting at the beginning of Antiquity, around 2.8 ka cal BP (Thracian period). After the 4.2 ka cal BP event and we suggest that climatic adversity may have acted as a stimulus to innovation and relocation rather than retarding societal Quaternary Science Reviews 313 (2023) 108130 development in the region. To conclude, environmental factors in the lower Strymon valley were not sufficient on their own to trigger a social crisis similar to that mentioned in the Middle East.
The aim of this study was to reconstruct the vegetation changes, fire history and local landscape dynamics of central Croatia (the western part of southeastern Europe) from 9800 cal yr BP to the beginning of the Common Era. Pollen, non-pollen palynomorphs and charcoal were analyzed for the first time in the aforementioned area by modern palynological methods. Three different assemblage (sub)zones were identified: "Pinus-Fagus-Quercetum mixtum" (Preboreal), "Fagus-Corylus" (Boreal) and "Alnus-Fagus" (Atlantic, Subboreal and older Subatlantic). Additionally, the oldest observation (~9800 cal yr BP) of beech pollen for continental Croatia was confirmed by radi-ocarbon dating. Our results indicated a possibly milder climate with less extreme temperatures and higher precipitation during the Preboreal chronozone, alongside intensive flooding, a transition from a mosaic of wetland/wet grassland communities to alder carr during the Boreal, and an unusually long multi-thousand-year period, the annual presence of alder on the mire itself. An increase in the number of secondary anthropogenic indicators can be tracked from the 6th century BC to the beginning of the Common Era. Although regional vegetation changes are insufficiently clear, our results fill a gap in the interpretation of vegetation/palaeoenvironmental changes before the Common Era in in this part of Europe.
The paper presents results of detailed investigation of freshwater microalgae from the Upper Miocene deposits from Jozefina (Krakow-Silesia Upland, central Poland). During the studies 28 microphytoplankton species of the genera Sigmopollis, Geiselodinium, Botryococcus, Ovoidites, Cycloovoidites, Stigmozygodites, Diagonalites, Tetraporina, Spintetrapidites, Closteritetrapidites, Planctonites,Cystidiopsis, Zygodites, and Pseudoschizaea were identified. One new species, Closteritetrapidites pacltovae sp. nov. has been proposed. Most of the recorded algae preferred meso-to eutrophic, stagnant or slowly flowing shallow waters. The presence of resting cells – e.g. zygospores of Zygnemataceae (Mougeotia, Spirogyra, and Zygnema) and desmids (Closterium), suggests that the water body (bodies) might periodically dried out. The occurrence of Pseudoschizaea is characteristic forwarm climate, possibly with seasonal moisture fluctuations. Occurrence of determined species in various localities (listed in synonyms) suggests that these algae were widespread in the past.
This paper presents new results on a quali-quantitative analysis of the heterocysts of the Rivularia type as a key bioindicator informative on local eutrophic conditions. The Rivularia type is usually reported in palynological analyses due to the thick, multilayered envelope that ensures the preservation of heterocysts in sediments. Samples come from two continuous terrestrial cores (N-S3: 77 samples, C-S1: 20 samples) drilled in the area surrounding the Bronze Age site of the Terramara S. Rosa di Poviglio (Po Plain; N Italy) and spanning at least over the last 15 ka years. Concentrations and percentages of the Rivularia type, combined with pollen curves of wet environments, describe local variability and rapid changes in ecological conditions over the millennia of deposition. Given the abundance and diversity of heterocysts of the Rivularia type in the studied samples, this paper attempts to group these cells based on morphology (ellipsoidal or elongated) and the state of preservation of the sheaths (presence or absence). Actually, it is difficult to confirm a relationship between heterocyst morphologies and the presence of different cyanobacteria species. Increasingly accurate identification of heterocysts from biostratigraphical archives may improve the data available on these bioindicators for achieving more detailed decoding of wetland (and terrestrial) transformations. Since the Bronze Age and at the most recent levels, the Rivularia type may be a good indicator of the local presence of agriculture and livestock, which lead to trophic and water changes in the soil.
An Upper Cretaceous paleolake near Jamsavli in the Mandla Lobe of central India has provided a unique opportunity to understand paleoecological conditions during Deccan volcanism. The sedimentary deposits of this paleolake are dominated by freshwater aquatic and semiaquatic flora, such as algae Pediastrum, Lecaniella, dinocysts (Pierceites deccanensis), diatoms (Aulacoseira), aquatic ferns of Salviniaceae (Azolla), Marsileaceae (Crybelosporites), and pollen grains of Sparganiaceae/Typhaceae (Sparganiaceaepollenites). Such paleolakes, representing a few hundred years of lake history with only aquatic and semiaquatic biota, have rarely been documented from the Deccan volcanic province.
An overview of aquatic and semiaquatic flora from the infratrappean and intertrappean beds associated with the Deccan volcanic province across the Cretaceous-Paleogene shows that the floral communities include algal remains of Botryococcaceae, Chlorophyceae, Chlorellaceae, Cyanophyceae, Hydrodictyaceae, Oedogoniaceae, Ulotrichaceae, Zygnemataceae, dinocysts, and diatoms. Bryophytes are scarce, whereas aquatic ferns of Salviniaceae (Azolla) and Marsileaceae (Marsilea and Regnellidium) are the dominating groups in the intertrappean deposits. Aquatic and semiaquatic angiosperms show less taxonomic diversity and are represented by only five families, namely Nymphaeaceae, Typhaceae, Liliaceae, Acanthaceae, and Pontederiaceae. The ubiquitous presence of macrophytes and microfloral fossil remains of Zygnemataceae (Oedogonium), Salviniaceae (Azolla), Marsileaceae (Crybelosporites and Gabonisporis), and palms, along with paleosol, indicate frost-free, warm, humid tropical to subtropical climates with intermittent dry and wet semi-arid conditions across the Late Cretaceous–early Paleocene.
SUMMARY.
Vegetation Analysis, Pollen Analysis, and Pollen Morphology have been considered together to study the present-day and past Holocene vegetation in the Carvalhal region and surrounding landscape.
In part IV - Pollen Morphology of Portuguese Ericales - we propose a new terminology for describing tetrads of Ericales. Later, 14 pollen types (out of the 18 species recognized in the Portuguese Flora) were established and characterized. Finally, a dichotomous key was prepared, permitting detailed identification of the
Ericales pollen in the cores studied. The importance of this result in palaeoecological research is exceptional, for it permitted the identification of three heathland types, preponderant elements of the past vegetation of NW Alentejo.
Preliminary vegetation analysis was done on the upland (dry-land) vegetation of the NW Alentejo dune district. The Braun-Blanquet approach was used, but no definitive syntaxonomic hierarchical classification was considered. A provisional classification scheme is proposed, based on the informal "community" and "variant".
16 vegetation communities and 12 variants are described from the littoral unstable dunes and from the inland old dune region:
Communities occurring on the littoral unstable dunes (AMMOPHILETEA)
1. the Elymus farctus - Otanthus maritimus community, an AMMOPHILION high beach prairie on predunes or incipient dunes.
2. the Artemisia crithmifolia - Ammophila arenaria community, a AMMOPHILION first dune prairie.
3. the Artemisia crithmifolia - Helichrysum italicum community, a AMMOPHILION community on the exposed flanks of the second dunes;
4. the Helychrysum italicum - Pancratium maritimum community, a AMMOPHILION "compression" community between the AMMOPHILION and the COREMION vegetation on overlapping dune systems.
5. the Helichrysum italicum - Ononis ramosissima community, a COREMION community on the exposed flanks of the third dunes (occurring also in the first dune depressions).
6. the Juniperus phoenicea - Corema album community, a COREMION scrub on the protected flanks of the third dunes.
Communities occurring on the inland old dunes:
7. the Halimium halimifolium - Cistus salvifolius community, a STAURACANTHO GENISTOIDES - HALIMIETALIA COMMUTATI degraded shrubland on regosols and eroded podzols.
8. the Santolina impressa - Stauracanthus genistoides community, a STAURACANTHO GENISTOIDES - HALIMIETALIA COMMUTATI degraded "charneca".
9. the Thymus capitellatus - Corynephorus canescens community, a TUBERARIETEA GUTTATAE developed prairie on long-term fallows.
10. the Vulpia alopecurus - Bromus rigidus community, a TUBERARIETEA GUTTATAE weed community on fallows.
11. the Arctotheca calendula - Hordeum murinum ssp. leporinum community, a CHENOPODIETALIA ruderal (nitrophilous) prairie.
12. the Erica scoparia - Halimium lasianthum community, a CALLUNO - ULICETALIA high heathland in old dune depressions.
13. the Calluna vulgaris - Ulex parviflorus community, a CALLUNO - ULICETALIA low heathland on (degraded?) podzols.
14. the Cistus psilosepalus - Scirpus holoschoenus community, a CALLUNO - ULICETALIA dawrfshrubland vegetation on the margins of the wetlands.
15. the Scirpus pseudosetaceus - Eleocharis multicaulis community, an ISOETONANO-JUNCETEA low prairie on small dune depressions, with temporary wet soils.
16. the Anagallis monelli - Scirpus holoschoenus community, a AMMOPHILETEA prairie on the coastal lagoon margins, subjected to seasonal flooding.
Following the unedited results of QUEIROZ (manuscr.) a concise description of the main vegetation units of the NW Alentejo wetlands is provided. This scheme is valuable for dealing with the palaeoecological reconstruction of past wetland vegetation of the basins.
Palaeoecological studies included pollen analysis of three cores - Lagoa Travessa I (LT.I), Lagoa Travessa II (LT.II), and Figueira de Baixo (FIG). In addition to pollen, non-pollinic microfossils were systematically counted in the FIG profile.
Special emphasis was directed to the pollen identification procedure itself: We systematically used 1000 x oil immersion observation of different aspects of the pollen grains, which could be rotated by locally pressing a needle on the coverglass, This time-consuming method proved quite useful for recording a rich pollen flora in the diagrams and for solving difficult pollen identification problems (frequent in the case of the Ericales, Quercus, or Umbelliferae, among others...).
The three diagrams are only partly synchronous. With the help of a set of 18 C14 dates, a "regional pollen-zone correlation scheme" was reconstructed. It includes 8 regional pollen zones and several subzones. These zonation units are not all homogeneous in character. They correspond to chronozones, regional or site
assemblage pollen zones, or a hybrid between both. Main palaeoecological results are summarized in part III and are only referred here briefly:
Palaeovegetation units: Prior to the description of the diagrams, zone by zone, or before any interpretation of past vegetation history, eco-stratigraphical pollen groups were identified and a first scheme of palaeovegetation units was erected accordingly. Main palaeovegetation units identified in the NW Alentejo are:
In the dry-lands:
- Maritime pinewoods; especially abundant in the Early Holocene, gradually declining after 6000 BP.
- A Quercus faginea marcescent forest. Extensive formations before 3000 PB, drastically declining afterwards and relictual nowadays.
- An Erica scoparia heathland (UCI-A), preclimacic, mesomediterranean humid/subhumid. Extensive during zone CAR-D (roughly from 4000 to 2000 BP), now relictual.
- A more xeric heathland type (UCI-B) related to our present-day Calluna vulgaris - Ulex parviflorus community (Erica umbellata variant). The UCI-B heathland expands after man's clearance of forests and preclimacic heathlands (through cutting, fire) and is favoured by the expansion of degraded podzols.
- A "charneca" vegetation (COR-B) (disturbance shrubland dominated by Cistaceae and spiny Leguminosae). COR-B charneca expands under strong human impact on the vegetation and subsequent deep podzol erosion.
In the littoral dunes:
- A COR-A scrub, a Corema - Juniperus formation, which we relate to our present-day COREMION Juniperus phoenicea - Corema album community. Especially abundant in the Carvalhal coastal dry-lands from 6000 to 4000 BP.
In the freshwater wet-lands:
- A Alnus/Salix riparian forest; edaphic climax on the fluvial wetlands. Extensive formations before 3000 BP, residual nowadays.
- An Erica erigena wet heathland (from the ERICETO SPHAGNETALIA). Edaphic climax on (oligohaline?) coastal freshwater lagoons.
- A Myrica gale wet scrub (replacement community on the wet peat marshes). Especially expanding on eutrophic conditions, enhanced by strong upland and lowland human impact (mainly after the Bronze Age).
- A MOLINIETALIA related fen vegetation (another replacement community). The MOL fen expands under strong zoo-anthropogenic pressure in the wetlands, most probably on grazed wet marshes and moors.
In the littoral lowlands:
- An estuarine vegetation especially characterizing the very high salt-marshes of the storm flooding zone. This PAV/CHE palaeovegetation is especially evident in the Carvalhal Palaeoestuary from around 5 700 to 4000 BP.
Two main themes conduct our interpretation on vegetation history and evolution: Littoral palaeoecology and Human impact.
Littoral palaeoecology: Main palaeovegetation events related to the littoral history are ascribed to littoral transgressions and regressions in strict palaeoecological terms. These are pollen-zone episodes characterized respectively by an increased or decreased marine influence in the ecosystems. Littoral transgressions are generally defined by the simultaneous 1) expansion and/or inland ingression of the salt-marsh palaeovegetation (CHE and PAV), 2) drastic changes in the local conditions of the coastal mires (fluvio-marine clastic deposition on fluvial mires; inundation episodes in the marginal basins, occasionally with
brackish water), and 3) decline (and/or inland retreat) of freshwater riparian woods. Littoral regressions are defined by the simultaneous 1) decline and/or seaward retreat of the salt marsh palaeovegetation (CHE and PAV), 2) terrestrialization processes in the coastal mires, and 3) expansion (and/or seaward advance) of freshwater riparian woods. Four littoral transgressions and three littoral regressions have been traced.
The expansion and/or inland ingression of the littoral dune palaeovegetation occurs mainly during phases of increased proximity of the littoral zone to the LT and FIG coring sites (such as the Carvalhal Estuary Phase); their fluctuating patterns, however, do not strictly follow the transgression and regression episodes.
The palaeoecological interpretation of these patterns remains complex. In addition to the transgressions and regressions, four main phases in the evolution of the Carvalhal littoral ecosystems have been considered:
1) The Coastal Retreat Phase - Coast line migrating inland to the vicinity of the LT basin.
2) The Carvalhal Estuary Phase - Important salt-marshes developed in a "mature" estuary system north of Lagoa Travessa.
3) The Travessa III Regression Phase ("Lagoa Travessa Hiatus") - The Carvalhal palaeoestuary is de-activated and a massive coastal sand barrier is formed north of Lagoa Travessa.
4) Barbaroxa I Transgression Phase - New inland ingressions of the littoral tide zone occur, but far from Lagoa Travessa.
Human impact: Although still preliminary, palaeoecological results concerning human impact on the vegetation agree well with the archaeological evidence and with the chronology of cultural phases generally accepted for South Portugal.
Before the Bronze Age, human impact in the Carvalhal region and surrounding landscape was diffuse and sometimes difficult to distinguish from other major factors of vegetation change such as climate or littoral dynamics. Early/Middle Neolithic communities may have had a certain influence in the old dune interfluves,
clearing pinewoods and preclimacic heathlands. Late Neolithic and Calcolithic communities had a more extensive impact, affecting ecosystems in the interfluves, in the valley margins, and in the wetlands. The impact of human communities of the Southwest Bronze II culture was remarkable, affecting all types of ecosystems, and it may be related to the spread of small family-type settlements in NW Alentejo.
There must have been a certain continuity in land-use during the Second Iron Age and the Roman Republican period, when a certain emphasis may have been given to the use of upland pastures. The land use of the "Early Roman Empire" was again remarkably strong and modern in character: expansion of wetland and upland pastures, emphasis on cultivated land (mainly cereal fields), exploitation of exotic tree crops. During the "Middle Roman Empire" this rural productive landscape declined strongly and was partly abandoned, to re-expand later on during the "Late Roman Empire". The last 1600 years are either missing from the Carvalhal pollen records or correspond to disturbed peat sequences, unsuitable for interpretation.
An abundant and diversified non-pollinic microfossil assemblage (microremains of algae, fungi, invertebrata, and unknown remains) was recorded in the Figueira de Baixo profile. The highly dynamic and distinct patterns shown by these microfossil curves throughout the organic sequence are symptomatic of the importance of these assemblages for the reconstruction of local mire environments. A preliminary catalogue of types is presented in part V, following the approaches of Bas van Geel and collaborators from the Hugo de Vries Laboratory (Amsterdam).
An inventory of eleven charophyte-bearing sites located between the Tropic of Cancer and eastern Somalia is drawn. Except for two-sites_which show signs of Pleistocene humid phases, the floras are Holocene and range from 9 000 to 5 000 BP. Gyrogonite species composition and morphology compared to the ecological conditions of equivalent still living species leads to distinguishing between five types in aquatic environments. No less than fivE sites contain the charophyte species Nitellopsis obtusa, which indicates permanent, relatively deep (4-12 m), cool oligotrophic freshwater. Further, the charophytes from the area studied can be used to distinguish between perennial and temporary waterbodies and to detect saline influences. Charophytes are iignificant biomarkers for completing the reconstruction of Quaternary lacustrine envtonments.
Studies of sediment, chronology, fossil pollen and charcoal from cores from Lost Trail Pass Bog (2152 m) provide the first postglacial bog, forest, and fire history for the Bitterroot Mountains. The 6.27 m of sediment, dated by 16 radiocarbon dates and two volcanic ashes, represent lake, fen, and bog deposition spanning the last 12,000 yr. Lycopodium spores were introduced as tracers into the 81 constant-volume samples to estimate pollen and charcoal influx. Because of considerable variation between samples, pollen and charcoal estimates were averaged by pollen zones. Glacial ice withdrew leaving a lake by 12,000 yr ago and sagebrush steppe dominated the landscape for the next 400 to 500 yr. If lodgepole and whitebark pine are the diploxylon and haploxylon pine pollen in the record, then by 11,500 yr ago whitebark pine forests replaced the steppe and persisted for the next 3000 to 4000 yr under climatic conditions that were probably cooler than present. Two falls of Glacier Peak volcanic ash, separated by less than 25 yr, occurred about 11,250 BP. By 7000 yr ago, under warmer but not necessarily drier climatic conditions, Douglas-fir and lodgepole pine replaced whitebark pine and charcoal influx increased. The fall of Mazama volcanic ash was dated at about 6700 yr ago. By 5000 yr ago aquatic, fen, and bog microfossils became important. With the return to cooler climates, about 4000 yr ago, Douglas-fir was no longer common in the pine forest. Little vegetational change is indicated after 4000 years ago. However, more charcoal was deposited during the last 2000 yr than during the previous 9500 yr.
The paper reports the results of a study carried out in the Canal de Navarrés tectonic valley to establish its evolution. The study was based on field surveys and the analysis of a 25 m long core. Both exorheic and endorheic episodes occurred in the valley, giving rise to alluvial fans and thick travertine deposits which dammed the valley bottom. Sedimentological analyses confirmed the presence of high energy fluvial episodes alternating with diffuse rainwash and decantation of fine deposits. The upper levels in the studied core correspond to a lacustrine environment with peat layers. At the depth of 4.30 m, remains of ostracods, molluscs, gastropods and charophytes are present suggesting high energy conditions; from 2.20 m lower energy conditions prevail up to the end of the sequence. Absolute datings indicate that the sequence spans over a period from about 178 ka BP to less than 3 ka BP. Pollen analyses of the most superficial portions of the studied core show Pinus as the predominant tree from 15 to 5 ka BP, when it is partially replaced by Quercus with Mediterranean shrubs and deciduous trees. The presence of an Eneolithic settlement at ca. 5 ka BP seems to coincide with a period of greater erosion with eutrofication of the basin and diffusion of hydrophytes.
The results of an analysis of pollen, spores and other micro-fossils (or parts of such fossils) with a characteristic form, from a 195 cm high peat section are reported. It appeared that certain Fungi types are connected with more strongly humified layers, which were presumably formed under drier conditions. Other fungal types show a clear connection with the peat-forming vegetation. An attempt was made to identify the micro-fossils other than pollen grains, which in some cases proved to be possible. A more extensive study is required before more accurate identifications can be arrived at and the emanating interpretations can be substantiated.Attention was paid to cyclic phenomena in the Alnus curve in the diagram. According to calculations with the help of 14C datings, cycles of about 32 years occurred. Further analysis may lead to an answer to the question whether this is a matter of periodic or cyclic phenomena and may reveal the possible cause of the fluctuations.By means of the pollen diagram information was obtained concerning the influence of prehistoric man on the vegetation from about 1700 B.C. to about 300 A.D. It appears that the influence is relatively important in the period between about 700 B.C. and 100 A.D. In this period agriculture on field complexes of the ‘Celtic Field’ type was probably carried out in the neighbourhood of the Wietmarscher Moor. By the beginning of the Christian era Secale pollen appears in the section for the first time. A decrease in population density is marked during the second century of the era. The reliable part of the diagram ends at the 10 cm level which corresponds to a date of about 300 A.D.Through a further analysis of microscopic and macroscopic remains in peat bogs one may expect to gather novel data regarding various aspects of peat analysis discussed in this article.
In the Guadix Basin there is a clear inconsistency between the high erosion rates which one would expect from the general visual appearance of the landscape, and the persistence of appreciable interfluve areas untouched by erosion for 4000 years. This is accounted for by sharp variations in the slope form stability and the sensitivity of response in different areas of the basin, despite continuing incision along the drainage lines since the Pliocene. As a result, interfluve areas have developed much more slowly and overall denudation rates are lower than one might expect on the basis of the prevailing climate and appearance of the landscape. -from Authors