Changes In Terrestrial Vegetation Research Articles

Holocene climate and vegetation change in the Main Ethiopian Rift Valley, inferred from the composition (C/N and δ 13C) of lacustrine organic matter

In order to track changes in the relative abundance of C 3 and C 4 plants in savanna vegetation, C/N and δ 13C values were measured on bulk organic material in an 8840 14C-year record from Lake Tilo, Ethiopia. Between 8840 and 2500 BP, high C/N ratios suggest that input to the lake was predominantly from terrestrial plants. The corresponding δ 13C values thus provide a proxy for changes in catchment vegetation that are supported by pollen data. δ 13C values in the early Holocene are relatively low, reflecting the dominance of C 3 vegetation (woody plants) and a more humid climate. δ 13C shows no response to a known regional arid interval at 7800 yr BP, suggesting that woody vegetation was able to survive relatively prolonged dry periods. A gradual, rather than sharp, δ 13C response to the end of the early Holocene humid interval at ∼4500 yr BP further supports this. Higher δ 13C values at ∼2800–2300 and ∼1000 yr BP correspond to increases in sedge pollen, thought to be growing in freshwater springs, exposed as lake-level fell. The C/N and δ 13C composition of bulk organic material complements the pollen evidence and may be useful in other lakes in savanna regions as indicators of terrestrial vegetation change.

Biomarker signature in tropical wetland: lignin phenol vegetation index (LPVI) and its implications for reconstructing the paleoenvironment

Organic matter of a peat core (3.60 m, 7428 years BP) collected from Rawa Danau, west Java, Indonesia, was analyzed to evaluate the early diagenetic fates of lignin in a tropical wetland and to reconstruct past vegetation and climate changes. Vertical profiles of (Ad/Al)v, (Ad/Al)s, and λ 8 show that the lignin composition is well preserved in a sub-aqueous environment under reducing conditions. The sedimentary terrigenous plant material at Rawa Danau is comprised predominantly of angiosperm wood. For this kind of tropical, diverse, and dynamic ecosystem, a new vegetation change index called lignin phenol vegetation index (LPVI): LPVI is defined using the lignin phenol composition. This index can sensitively detect terrestrial vegetation changes as well as environmental conditions forcing such changes. The LPVI of the Rawa Danau peat core provides better resolution than other lignin parameters used previously, and reveals four major vegetation change events since the mid–late Holocene. In comparison to other geochemical data (i.e. elemental carbon, isotopes, and hydrocarbons), the LPVI is more sensitive and is able to trace even minor vegetation and climate changes and thus could improve biogeochemical interpretations of peat records.

Evidence for rapid climate change in the Mesozoic-Palaeogene greenhouse world.

The best-documented example of rapid climate change that characterized the so-called 'greenhouse world' took place at the time of the Palaeocene-Eocene boundary: introduction of isotopically light carbon into the ocean-atmosphere system, accompanied by global warming of 5-8 degrees C across a range of latitudes, took place over a few thousand years. Dissociation, release and oxidation of gas hydrates from continental-margin sites and the consequent rapid global warming from the input of greenhouses gases are generally credited with causing the abrupt negative excursions in carbon- and oxygen-isotope ratios. The isotopic anomalies, as recorded in foraminifera, propagated downwards from the shallowest levels of the ocean, implying that considerable quantities of methane survived upward transit through the water column to oxidize in the atmosphere. In the Mesozoic Era, a number of similar events have been recognized, of which those at the Triassic-Jurassic boundary, in the early Toarcian (Jurassic) and in the early Aptian (Cretaceous) currently carry the best documentation for dramatic rises in temperature. In these three examples, and in other less well-documented cases, the lack of a definitive time-scale for the intervals in question hinders calculation of the rate of environmental change. However, comparison with the Palaeocene-Eocene thermal maximum (PETM) suggests that these older examples could have been similarly rapid. In both the early Toarcian and early Aptian cases, the negative carbon-isotope excursion precedes global excess carbon burial across a range of marine environments, a phenomenon that defines these intervals as oceanic anoxic events (OAEs). Osmium-isotope ratios ((187)Os/(188)Os) for both the early Toarcian OAE and the PETM show an excursion to more radiogenic values, demonstrating an increase in weathering and erosion of continental crust consonant with elevated temperatures. The more highly buffered strontium-isotope system ((87)Sr/(86)Sr) also shows relatively more radiogenic signatures during the early Toarcian OAE, but the early Aptian and Cenomanian-Turonian OAEs show the reverse effect, implying that increased rates of sea-floor spreading and hydrothermal activity dominated over continental weathering in governing sea-water chemistry. The Cretaceous climatic optimum (late Cenomanian to mid Turonian) also shows evidence for abrupt cooling episodes characterized by episodic invasion of boreal faunas into temperate and subtropical regions and changes in terrestrial vegetation; drawdown of CO(2) related to massive marine carbon burial (OAE) may be implicated here. The absence of a pronounced negative carbon-isotope excursion preceding the Cenomanian-Turonian OAE indicates that methane release is not necessarily connected to global deposition of marine organic carbon, but relative thermal maxima are common to all OAEs. 'Cold snaps' have also been identified from the Mesozoic record but their duration, causes and effects are poorly documented.

The climatic impacts of land surface change and carbon management, and the implications for climate-change mitigation policy

Strategies to mitigate anthropogenic climate change recognize that carbon sequestration in the terrestrial biosphere can reduce the build-up of carbon dioxide in the Earth’s atmosphere. However, climate mitigation policies do not generally incorporate the effects of these changes in the land surface on the surface albedo, the fluxes of sensible and latent heat to the atmosphere, and the distribution of energy within the climate system. Changes in these components of the surface energy budget can affect the local, regional, and global climate. Given the goal of mitigating climate change, it is important to consider all of the effects of changes in terrestrial vegetation and to work toward a better understanding of the full climate system. Acknowledging the importance of land surface change as a component of climate change makes it more challenging to create a system of credits and debits wherein emission or sequestration of carbon in the biosphere is equated with emission of carbon from fossil fuels. Recognition of the complexity of human-caused changes in climate does not, however, weaken the importance of actions that would seek to minimize our disturbance of the Earth’s environmental system and that would reduce societal and ecological vulnerability to environmental change and variability.

A 180,000-year pollen record from Owens Lake, CA: terrestrial vegetation change on orbital scales

Pollen from the upper 90 m of core OL-92 from Owens Lake is a climatically sensitive record of vegetation change that indicates shifts in the plant associations representing warm and cold desertscrub, pinyon–juniper woodland, and pine–fir forest during the past 180,000 years. These changes are synchronized with glacial–interglacial cycles. During glacial and stadial climates, juniper woodland expanded downslope and replaced warm desert shrubs while upper montane and subalpine forests in the arid Inyo Mountains also expanded, and those in the Sierra Nevada were displaced by the ice cap and periglacial conditions. Conversely, during interglacial and interstadial climates, warm desert plants expanded their range in the lowlands, juniper and sagebrush retreated upslope, and montane and subalpine forests expanded in the Sierra Nevada. The reconstructed vegetation history demonstrates a regional climatic response, and the congruence of the pollen sequence with marine and ice cap oxygen isotope stratigraphies suggests a link between regional vegetation and global climate change at orbital scales.

Relation between interannual variations in satellite measures of northern forest greenness and climate between 1982 and 1999

This paper analyzes the relation between satellite‐based measures of vegetation greenness and climate by land cover type at a regional scale (2° × 2° grid boxes) between 1982 and 1999. We use the normalized difference vegetation index (NDVI) from the Global Inventory Monitoring and Modeling Studies (GIMMS) data set to quantify climate‐induced changes in terrestrial vegetation. Climatic conditions are represented with monthly data for land surface air temperature and precipitation. The relation between NDVI and the climate variables is represented using a quadratic specification, which is consistent with the notion of a physiological optimum. The effects of spatial heterogeneity and unobserved variables are estimated with specifications and statistical techniques that allow coefficients to vary among grid boxes. Using this methodology, we are able to estimate statistically meaningful relations between NDVI and climate during spring, summer, and autumn for forests between 40°N and 70°N in North America and Eurasia. Of the variables examined, changes in temperature account for the largest fraction of the change in NDVI between the early 1980s and the late 1990s. Changes in stratospheric aerosol optical depth and precipitation have a smaller effect, while artifacts associated with variations in solar zenith angle are negligible. These results indicate that temperature changes between the early 1980s and the late 1990s are responsible for much of the observed increase in satellite measures of northern forest greenness.

The climatic impacts of land surface change and carbon management, and the implications for climate-change mitigation policy

Strategies to mitigate anthropogenic climate change recognize that carbon sequestration in the terrestrial biosphere can reduce the build-up of carbon dioxide in the Earth's atmosphere. However, climate mitigation policies do not generally incorporate the effects of these changes in the land surface on the surface albedo, the fluxes of sensible and latent heat to the atmosphere, and the distribution of energy within the climate system. Changes in these components of the surface energy budget can affect the local, regional, and global climate. Given the goal of mitigating climate change, it is important to consider all of the effects of changes in terrestrial vegetation and to work toward a better understanding of the full climate system. Acknowledging the importance of land surface change as a component of climate change makes it more challenging to create a system of credits and debits wherein emission or sequestration of carbon in the biosphere is equated with emission of carbon from fossil fuels. Recognition of the complexity of human-caused changes in climate does not, however, weaken the importance of actions that would seek to minimize our disturbance of the Earth's environmental system and that would reduce societal and ecological vulnerability to environmental change and variability. © 2003 Elsevier Science Ltd. All rights reserved.

A high resolution late Holocene palaeo environmental record from the central Adriatic Sea

A multi-proxy study of a Holocene sediment core (RF 93-30) from the western flank of the central Adriatic, in 77 m of water, reveals a sequence of changes in terrestrial vegetation, terrigenous sediment input and benthic fauna, as well as evidence for variations in sea surface temperature spanning most of the last 7000 yr. The chronology of sedimentation is based on several lines of evidence, including AMS 14C dates of foraminifera extracted from the core, palaeomagnetic secular variation, pollen indicators and dated tephra. The temporal resolution increases towards the surface and, for some of the properties measured, is sub-decadal for the last few centuries. The main changes recorded in vegetation, sedimentation and benthic foraminiferal assemblages appear to be directly related to human activity in the sediment source area, which includes the Po valley and the eastern flanks of the central and northern Appenines. The most striking episodes of deforestation and expanding human impact begin around 3600 BP (Late Bronze Age) and 700 BP (Medieval) and each leads to an acceleration in mass sedimentation and an increase in the proportion of terrigenous material, reflecting the response of surface processes to widespread forest clearance and cultivation. Although human impact appears to be the proximal cause of these changes, climatic effects may also have been important. During these periods, signs of stress are detectable in the benthic foram morphotype assemblages. Between these two periods of increased terrigeneous sedimentation there is smaller peak in sedimentation rate around 2400BP which is not associated with evidence for deforestation, shifts in the balance between terrigenous and authigenic sedimentation, or changes in benthic foraminifera. The mineral magnetic record provides a sensitive indicator of changing sediment sources: during forested periods of reduced terrigenous input it is dominated by authigenic bacterial magnetite, whereas during periods of increased erosion, anti-ferromagetic minerals (haematite and/or goethite) become more important, as well as both paramagnetic minerals and super-paramagnetic magnetite. Analysis of the alkenone, U 37 k′, record provides an indication of possible changes in sea surface temperature during the period, but it is premature to place too much reliance on these inferred changes until the indirect effects of past changes in the depth of the halocline and in circulation have been more fully evaluated. The combination of methods used and the results obtained illustrate the potential value of such high resolution near-shore marine sedimentary sequences for recording wide-scale human impact, documenting the effects of this on marine sedimentation and fauna and, potentially, disentangling evidence for human activities from that for past changes in climate.

Importance of structure in the longer‐term dynamics of landscapes

When one is attempting to simulate the dynamic response of the vegetation over short timescales (days to as long as years), it is efficacious to ignore the change in the vertical and the horizontal structure of natural vegetation. At longer timescales, for example, the timescales associated with monitoring and predicting interannual variation in the vegetation, structural dynamics can strongly alter the process‐based predictions of such features as ecosystem productivity. There are ecosystem models that have the capability of simulating structural change, and these models have been tested to some degree using large‐scale remotely sensed information. This paper reviews types of ecological modeling approaches used for evaluations of terrestrial vegetation change at large‐area and longer‐than‐annual timescale. It then provides examples of results from models that simulate structural change. Finally, examples of ecosystem dynamics that change with spatial scale are presented.

GIS Models of Past Vegetation: An Example from Northern England, 10,000–5000 BP

Archaeological interpretations of past societies, particularly those of past hunter-gatherer groups, have traditionally drawn heavily on evidence for past environments and environmental changes. Ironically however our understanding of these environments is typically far from ideal, particularly at the scale most relevant to broad settlement patterns. Limitations lie not just in the lack of evidence, but also the nature of the evidence that we have for past environments. Most notably, descriptions of environments and environmental change tend to be either very simplistic at the large scale, or detailed, but limited to small scale local landscapes. It is thus difficult to find regional reconstructions to relate to interpretations or models of population and settlement (particularly important when considering mobile populations). The models described here have been developed in order to improve understanding of large scale spatial changes in terrestrial vegetation. The limitations and potentials for developing models of vegetation patterns are considered, and one such model (constructed using GIS techniques) of changes in the distribution of woodland types in northern England from the Early Holocene is described.

124,000-year periodicity in terrestrial vegetation change during the late Pliocene epoch

The late Pliocene (∼3–2.6 million years ago) is an interval of exceptional interest for understanding the Earth's climate system. It was a time of progressive global cooling, resulting in the growth of large terrestrial ice sheets and the initiation of extensive Northern Hemisphere glaciation1,12. The build up of the ice sheets was cyclical and apparently paced by the orbitally driven oscillations in incoming solar radiation (Milankovitch cycles) at periods of approximately 41 kyr (obliquity) and 23–19 kyr (precession). Here we present a high-resolution continental record of late Pliocene climate change, detailing the response of terrestrial vegetation to this interval of dramatic global environmental change. The annually laminated sequence of lake sediments from Pula maar, in Hungary, represents approximately 320 kyr of accumulation between ∼3.0 and 2.6 million years ago. Spectral analyses of the record indicate terrestrial responses to incoming solar radiation at obliquity and precession periodicities, but the strongest response appears at a period of ∼124 kyr. Calculations indicate that variations in insolation forcing at this periodicity were negligible at this time. The Pula record thus demonstrates that internally driven nonlinear responses of the climate system, at a period of ∼124 kyr, were at least as important as external forcing at the orbital frequencies of precession and obliquity in driving late Pliocene large-scale environmental change.

Changes in carbon and nitrogen cycling during tree-line retreat recorded in the isotopic content of lacustrine organic matter, western Taimyr Peninsula, Russia

Bulk organic and cellulose stable carbon isotope and bulk organic nitrogen isotope profiles from the sediments of a small tundra lake on the western Taimyr Peninsula, Russia, show changes that are correlated with climate cooling and treeline retreat at c. 4000 14C years BP. Increased soil organic matter decomposition, combined with a moist climate, probably provided a 13C-depleted source of CO2(aq) to lake phytoplankton thriving under favourable conditions during the forest interval. Increased concentration of CO2(aq) and re-utilization of respired CO2(aq) from organic matter settling through the water column may have also contributed to the relatively low δ13C values in the lower part of the lake sediment record. Bulk organic and cellulose carbon are more enriched in 13C after the boreal forest retreated probably because CO2 from the atmosphere became the dominant source of carbon to the lake as soil organic decomposition rates declined, the lake became more oligotrophic, and the climate became colder and drier. Reduced concentration of CO2(aq) may have also led to 13C-enrichment. Interpretation of the bulk organic δ15N record is somewhat more speculative but changes in drainage basin terrestrial vegetation, soil decomposition and hydrology also appear to have strongly influenced the lake water nitrogen cycling. Although considerably more effort is required to assess modern carbon and nitrogen isotope systematics, these promising results suggest that lake sediment organic matter δ13C, δ15N and cellulose δ13C combine to form useful tracers of past nutrient cycling in boreal tree-line watersheds.

Lake evolution in a semi-arid montane environment: response to catchment change and hydroclimatic variation

Pollen, geochemical and sedimentological data from Sidi Ali, a montane Moroccan lake, provide a 7000 yr record of changes in climate, catchment vegetation and soil erosion intensity. Diatoms, non-silicious algae, macrophyte fossils and ostracods from the same core record the dynamics of the lake ecosystem. Oxygen isotope and trace-element ratios of benthic ostracods appear to be relatively insensitive to climatic variation in this open lake with low water-residence time, but diatom plankton / periphyton (P/L) ratios show lake-level variations that are probably climate controlled. At least two superimposed processes are recorded, but at different timescales: catchment vegetation and soils show long-term changes due to climate and human impact, whereas P/L ratios suggest century-scale oscillations in lake depth. The timing of changes in algal and macrophyte productivity and carbon cycling within the lake broadly corresponds to changes in terrestrial vegetation, suggesting either that lake nutrient status is linked to catchment vegetation and soils, or that both were influenced by climate. The lack of a sensitive and independent (non-biological) climate proxy makes it more difficult to assess the lake''s ecological response to short-term climate variation. Overall, the lake''s evolution has been influenced both by catchment-mediated nutrient flux and by changes in water balance, thus having characteristics in common with both temperate and arid zone lakes.

δ13C analyses of individual lignin phenols in Quaternary lake sediments: A novel proxy for deciphering past terrestrial vegetation changes

This study of the sediments from Sacred Lake, Mount Kenya, demonstrates that δ 13 C analyses of individual lignin phenols can be used to assess past changes in the proportion of C 3 and C 4 plants within different plant groups in the lake catchment. Vegetation changes resulting from climatic and atmospheric changes since the last glacial maximum can be deduced from specific lignin phenols. Lignin, a major biopolymer in vascular plants, differs from n-alkyl lipids in (1) its higher specificity and more quantitative representation of vascular-plant input and (2) its major transport mechanism into the sediments by fluvial runoff, as opposed to the greater importance of eolian transport for leaf waxes and pollen. Lignin δ 13 C data support the hypothesis that atmospheric CO 2 concentration is an important factor controlling the vegetation in tropical mountain ecosystems, and provide additional insights into past changes in vegetation structure. Specifically, the δ 13 C values of p -coumaric acid indicate the persistence of C 4 grasses during the late glacial, when the lake level was lower than today, suggesting that aridity also played a role in controlling the abundance of C 4 plants.

Estimating changes in terrestrial vegetation and carbon storage: Using palaeoecological data and models

Climatic changes that accompanied the transition from the last glacial to the present interglacial conditions over the past 18,000 14C years impacted both terrestrial ecosystem structure (vegetation distribution) and function (carbon dynamics), which in turn influenced the climate through biogeophysical mechanisms. Palaeoecological records provide not only past records of vegetation patterns at various spatial and temporal scales, but also a means of evaluating the associated change in past terrestrial carbon storage. After a brief review of the role of palaeoecological data and biosphere models in evaluating the potential impacts of past climate change on terrestrial ecosystems, we synthesize the methods for reconstructing the vegetation patterns from palaeoecological data and the way to integrate it with biosphere models to reconstruct the long-term terrestrial carbon dynamics since the Last Glacial Maximum (LGM). The main results obtained at both the global and regional scales suggest that colder, more arid and low atmospheric CO2 climatic conditions at the LGM may have favored the extensions of steppe and grassland dominated by C4 plants, to the detriment of forested ecosystems. However, the warmer and wetter climatic conditions during the Holocene favored extensions of temperate deciduous forests in mid-latitudes and reduced the tundra and taiga forests at high latitudes. Carbon storage in terrestrial vegetation was relatively low during the full-glacial time and increased considerably to a maximum during the mid-Holocene. Most of the recent estimates converge to an increase of about 30% global carbon storage from the LGM to the present. There still is a significant gap in our understanding of ice-age terrestrial carbon budget. The difference between the marine and terrestrial estimations is about 150–430PgC (1Pg=1015g). It results from the uncertainties in reconstruction of terrestrial vegetation and carbon storage as well as the uncertainties in the interpretation of marine Δ∂13C changes. Further progress in understanding the dynamic processes of global vegetation and carbon cycle will require both the development of global palaeoecological database and the development of biosphere models.

Setting Restoration Goals for an Acid and Metal-Contaminated Lake: A Paleolimnological Study of Daisy Lake (Sudbury, Canada)

ABSTRACT Many lakes in the Sudbury region of Ontario have been affected by acidic and metal inputs as a result of local smelting operations. Several initiatives are now underway to restore some of these systems. Long-term limnological data are rarely available, therefore lake managers must use proxy methods to set reasonable targets for lakes undergoing mitigation. Daisy Lake is presently an acidic (pH 4.7), metal-contaminated lake (Ni=370 μg L−1; Al=350 μg L−1), that has been selected for mitigation efforts. We used fossil pollen analysis to reconstruct past changes in terrestrial vegetation, and paleolimnological techniques (primarily diatoms and chrysophytes) to identify pre-disturbance conditions and to reconstruct past changes in water quality variables in Daisy Lake. Our data indicate that, if Daisy Lake and its watershed are limed to restore the lake to a state that approximates the pre-disturbance natural pH, the lake water pH has to be about 1.5 pH units higher than its present level.

Differentiating Climatic and Successional Influences on Long‐Term Development of a Marsh

Comparison of long—term records of local wetland vegetation dynamics with regional, climate—forced terrestrial vegetation changes can be used to differentiate the rates and effects of autogenic successional processes and allogenic environmental change on wetland vegetation dynamics. We studied Holocene plant macrofossil and pollen sequences from Portage Marsh, a shallow, 18—ha marsh in northeastern Indiana. Between 10 000 and 5700 yr BP the basin was occupied by a shallow, open lake, while upland vegetation consisted of mesic forests of Pinus, Quercus, Ulmus, and Carya. At 5700 yr BP the open lake was replaced rapidly by a shallow marsh, while simultaneously Quercus savanna developed on the surrounding uplands. The marsh was characterized by periodic drawdowns, and the uplands by periodic fires. Species composition of the marsh underwent further changes between 3000 and 2000 yr BP. Upland pollen spectra at Portage Marsh and other sites in the region shifted towards more mesic vegetation during that period. The consistency and temporal correspondence between the changes in upland vegetation and marsh vegetation indicate that the major vegetational changes in the marsh during the Holocene resulted from hydrologic changes forced by regional climate change. Progressive shallowing of the basin by autogenic accumulation of organic sediment constrained vegetational responses to climate change but did not serve as the direct mechanism of change.

Modelling of time-dependent biome shifts under global climate changes

The study of biosphere response to climate changes due to anthropogenic emission of greenhouse gases is a very important scientific and practical problem. The core of its solution -modelling and long-term forecast of global terrestrial vegetation changes -is considered in this paper. There are a few approaches to modelling long-term vegetation dynamics; their principles are discussed in brief. A model approach based on bioclimatic schemes has been chosen for further considerations. A model based on Holdridge's bioclimatic scheme was designed for simulation of time-dependent biome shifts. A procedure of time delays was designed to take into account inertia of vegetation response to climate change. It was based on expert estimates of biome replacements. Computer experiments have been designed to investigate the consequences of time-dependent climate changes for the vegetation of Russia. The results showed the importance of the temporal factor for long-term forecasts. The obtained assessments demonstrated complex non-linear dynamics of vegetation even under the simplest climatic scenario. Further prospects of suggested model were discussed.

Global climate models and ‘dynamic’ vegetation changes

AbstractModels of global change must come to incorporate changes in terrestrial vegetation. Here we choose a 1‐ year meshing (coupling) period to link a global climate model to a well‐known biophysical representation of the continental surface by means of eleven vegetation functional types. This coupled model is used to answer two questions: Can a ‘standard’ GCM ‘cope' with sudden switches in continental characteristics?’ and Does the climate ‘care’ about the changing underlying vegetation? We find affirmative answers to both questions. Our results also suggest that those content to generate vegetation post facto from climate output have incomplete results.

Late quaternary pollen transport processes, western North Atlantic: Data from box models, cross-margin and N-S transects

Surface pollen assemblages in coastal and neritic sediments of the western North Atlantic compare well with eastern North American vegetation zones, and late Quaternary pollen in marginal marine sediments clearly correlate with changes in terrestrial vegetation and paleoclimates. In contrast, offshore assemblages are strongly affected by differential adaptation of pollen to long distance transport by wind and water. Marine pollen transport processes were studied by measuring air and water inputs to a coast-shelf box model, and by study of surface samples from cross-margin transects in three different climatic and oceanographic regions at approximately 38°, 45° and 55°N latitude. The box model shows that aerial transport is the main process by which pollen moves across the continental margin off Nova Scotia. Two clear seabed distribution patterns were found: Betula, Quercus, and herb pollen decrease rapidly offshore in abundance (grains per cubic centimetre) and in relative abundance (percentage); Pinus and Picea have abundance peaks on the continental margin, but percentages increase further offshore. Distributions of the main pollen and spore taxa were compared for late Wisconsinan glacial (oxygen isotopic stage 2, 12–28 ka), terminal Pleistocene (10–12 ka) and Holocene sediments at 5 continental margin and 3 deep-sea sites. The largest changes were found in percentages of Pinus, Picea, and herb pollen during the late Wisconsinan glacial and terminal Pleistocene intervals at subpolar latitudes. These data can be related to shifts in paleo-vegetation, -winds and -hydrology that accompany global climate change.