scholarly journals Holocene plant diversity dynamics shows a distinct biogeographical pattern in temperate Europe

2020 ◽  
Author(s):  
Jan Roleček ◽  
Vojtěch Abraham ◽  
Ondřej Vild ◽  
Helena Svitavská Svobodová ◽  
Eva Jamrichová ◽  
...  
Keyword(s):  
Plant Diversity ◽  
Late Holocene ◽  
Time Window ◽  
Fossil Pollen ◽  
Pollen Record ◽  
Diversity Patterns ◽  
The Holocene ◽  
Modern Pollen ◽  
Biogeographical Region ◽  
Temperate Europe

AbstractAimsReconstruction of the Holocene diversity changes in a biogeographically complex region. Description of major diversity patterns, testing their predictors, and their interpretation in the palaeoecological and biogeographical context. Testing the assumption that pollen record is informative with respect to plant diversity in our study area.MethodsFossil pollen extracted from 18 high-quality profiles was used as a proxy of past plant diversity. Pollen counts of tree taxa were corrected by pollen productivity, and pollen assemblages were resampled to 100 grains per sample and 150 grains per 500-years time window. SiZer analysis was used to test and visualize multi-scale diversity patterns. Linear modelling was used to identify the best predictors. SiZer maps and pollen composition were analysed using non-metric multidimensional scaling. K-means clustering and indicator species analysis were used to interpret ordination results.ResultsMean Holocene plant diversity is significantly predicted by latitude, while its temporal pattern followed the biogeographical region and elevation. Major differences were found between the Mesic and Montane Hercynia (lower diversity, increasing only in the Late Holocene) and Pannonia, the Carpathians and Warm Hercynia (higher diversity, increasing from the Early or Middle Holocene on). Low diversity in the Middle and Late Holocene is associated with the prevalence of woody and acidophilic taxa. High diversity is associated with numerous grassland and minerotrophic wetland taxa, crops and weeds. Fossil-modern pollen diversity and modern pollen-plant diversity show significant positive relationships.ConclusionsPlant diversity and its changes during the Holocene are geographically structured across temperate Europe. Main causes appear to be differences in past dynamics of the landscape openness and vegetation composition, driven mainly by changes in climate and human impact and their different timing. Fossil pollen, if appropriately treated, is a useful proxy of past plant diversity.

scholarly journals Holocene Environmental Change in the Frobisher Bay Area, Baffin Island, N.W.T.: Deglaciation, Emergence, and the Sequence of Vegetation and Climate

2007 ◽  
Vol 39 (2) ◽  
pp. 151-162 ◽  
Author(s):  
J. D. Jacobs ◽  
W. N. Mode ◽  
C. A. Squires ◽  
G. H. Miller
Keyword(s):  
Late Holocene ◽  
Late Glacial ◽  
Pollen Record ◽  
Baffin Island ◽  
Bay Area ◽  
Modern Pollen ◽  
Moist Environment ◽  
Organic Fractions ◽  
Late Glacial And Holocene ◽  
Inland Ice

ABSTRACT The late-glacial and Holocene paleoenvironmental sequence for the Frobisher Bay area is outlined using glacial, sea level, and palynological evidence. A rapid retreat of ice from the late Foxe glacial maximum in the lower part of the bay after 11,000 BP was followed by a series of stillstands or minor readvances between ca. 8500 and 7000 BP and possibly later, before the final disappearance of the inland ice centred near Amadjuak Lake. Lithostratigraphy of three buried organic sections which together represent deposition occurring over the period from 5500 to 400 BP indicates a change from a relatively warm, moist environment before 5500 BP to neoglacial conditions, with the coldest phases centred around 5000, 2700, 1200 BP and probably sometime after 400 radiocarbon years BP. As evidenced by peat growth and pollen data, milder, wetter conditions prevailed from 4500 to 3000 BP and again from ca. 2600 to 1800 BP. Peat growth and soil organic fractions point to lesser mild intervals ca. 900 BP and 400 BP, but these are not apparent in the pollen assemblage. The pollen record does not extend to the last four centuries; however, lichenometric studies of neoglacial moraines by DOWDESWELL (1984) show that the maximum late Holocene advance of glaciers in the area occurred within the last century. Modern pollen samples indicate that the present vegetation of the inner Frobisher Bay area is comparable to that of the milder intervals of the late Holocene.

scholarly journals Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai–Tibetan Plateau, China

2016 ◽  
Vol 12 (2) ◽  
pp. 415-427 ◽  
Author(s):  
Enlou Zhang ◽  
Yongbo Wang ◽  
Weiwei Sun ◽  
Ji Shen
Keyword(s):  
Late Holocene ◽  
Southern Oscillation ◽  
Summer Precipitation ◽  
Forest Understory ◽  
Pollen Record ◽  
The Holocene ◽  
Asian Winter Monsoon ◽  
Holocene Climatic Optimum ◽  
Southeastern Margin ◽  
Climatic Optimum

Abstract. We present the results of pollen analyses from a 1105 cm long sediment core from Wuxu Lake in southwestern China, which depict the variations of the East Asian winter monsoon (EAWM) and the Indian summer monsoon (ISM) during the last 12.3 ka. During the period of 12.3 to 11.3 cal ka BP, the dominance of Betula forest and open alpine shrub and meadow around Wuxu Lake indicates a climate with relatively cold winters and dry summers, corresponding to the Younger Dryas event. Between 11.3 and 10.4 cal ka BP, further expansion of Betula forest and the retreat of alpine shrubs and meadows reflect a greater seasonality with cold winters and gradually increasing summer precipitation. From 10.4 to 4.9 cal ka BP, the dense forest understory, together with the gradual decrease in Betula forest and increase in Tsuga forest, suggest that the winters became warmer and summer precipitation was at a maximum, corresponding to the Holocene climatic optimum. Between 4.9 and 2.6 cal ka BP, Tsuga forest and alpine shrubs and meadows expanded significantly, reflecting relatively warm winters and decreased summer precipitation. Since 2.6 cal ka BP, reforestation around Wuxu Lake indicates a renewed humid period in the late Holocene; however, the vegetation in the catchment may also have been affected by grazing activity during this period. The results of our study are generally consistent with previous findings; however, the timing and duration of the Holocene climatic optimum from different records are inconsistent, reflecting real contrast in local rainfall response to the ISM. Overall, the EAWM is broadly in-phase with the ISM on the orbital timescale, and both monsoons exhibit a trend of decreasing strength from the early to late Holocene, reflecting the interplay of solar insolation receipt between the winter and summer seasons and El Niño–Southern Oscillation strength in the tropical Pacific.

scholarly journals Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai-Tibetan Plateau, China

2015 ◽  
Vol 11 (5) ◽  
pp. 4751-4786
Author(s):  
E. Zhang ◽  
Y. Wang ◽  
W. Sun ◽  
J. Shen
Keyword(s):  
Late Holocene ◽  
Southern Oscillation ◽  
Summer Precipitation ◽  
Forest Understory ◽  
Pollen Record ◽  
The Holocene ◽  
Asian Winter Monsoon ◽  
Holocene Climatic Optimum ◽  
Southeastern Margin ◽  
Climatic Optimum

Abstract. We present the results of pollen analyses from a 1105-cm-long sediment core from Wuxu Lake in southwestern China, which depict the variations of the East Asian winter monsoon (EAWM) and the Indian summer monsoon (ISM) during the last 12.3 ka. During the period of 12.3 to 11.3 cal ka BP, the dominance of Betula forest and open alpine shrub and meadow around Wuxu Lake indicates a climate with relatively cold winters and dry summers, corresponding to the Younger Dryas event. Between 11.3 and 10.4 cal ka BP, further expansion of Betula forest and the retreat of alpine shrubs and meadows reflect a greater seasonality with cold winters and gradually increasing summer precipitation. From 10.4 to 4.9 cal ka BP, the dense forest understory, together with the gradual decrease in Betula forest and increase in Tsuga forest, suggest that the winters became warmer and summer precipitation was at a maximum, corresponding to the Holocene climatic optimum. Between 4.9 and 2.6 cal ka BP, Tsuga forest and alpine shrubs and meadows expanded significantly, reflecting relatively warm winters and decreased summer precipitation. Since 2.6 cal ka BP, reforestation around Wuxu Lake indicates a renewed strengthening of the ISM in the late Holocene; however, the vegetation in the catchment may also have been affected by grazing activity during this period. The results of our study are generally consistent with previous findings; however, the timing and duration of the Holocene climatic optimum from different records are inconsistent, reflecting real contrast in local rainfall response to the ISM. Overall, the EAWM is broadly in-phase with the ISM on the orbital timescale, and both monsoons exhibit a trend of decreasing strength from the early to late Holocene, reflecting the interplay of solar insolation receipt between the winter and summer seasons and El Niño Southern Oscillation strength in the tropical Pacific.

scholarly journals Thresholds of potential concern as benchmarks in the management of African savannahs

2007 ◽  
Vol 362 (1478) ◽  
pp. 309-319 ◽  
Author(s):  
L Gillson ◽  
K.I Duffin
Keyword(s):  
Vegetation Cover ◽  
Vegetation Change ◽  
Quadratic Equation ◽  
Woody Vegetation ◽  
Fossil Pollen ◽  
Pollen Record ◽  
Pollen Data ◽  
Modern Pollen ◽  
Management Objectives ◽  
Arboreal Pollen

In the Kruger National Park (KNP), South Africa, ecosystem managers use a series of monitoring endpoints, known as thresholds of potential concern (TPCs), to define the upper and the lower levels of accepted variation in ecosystems. For woody vegetation, the current TPC suggests that woody cover should not drop by more than 80% of its ‘highest ever’ value. In this paper, we explore the utility of palaeoecological data in informing TPCs. We use calibrated fossil pollen data to explore variability in vegetation at two sites over the past 5000 years, to provide a long-term record of changes in woody vegetation cover and a context for interpreting more recent vegetation change. The fossil pollen data are calibrated using studies of modern pollen and vegetation from KNP; arboreal pollen percentage was simulated using pollen–landscape modelling software for savannah landscapes of varying woody vegetation cover, and the relationship between vegetation and pollen data was quantified using nonlinear regression. This quadratic equation was then applied to fossil pollen data in order to estimate woody vegetation cover from arboreal pollen percentages. Our results suggest that the TPCs have not been exceeded during the period represented in the pollen record, because estimated woody vegetation cover has remained above 20% of its highest ever value. By comparing the fossil pollen data with TPCs, our study demonstrates how palaeoecological data can be presented in a form that is directly relevant to management objectives.

scholarly journals Analysis of Fossil Pollen Record from the Late Holocene in the Turkish Highland (Middle Taurus,Turkey)

2017 ◽  
Vol 26 ◽  
pp. 91
Author(s):  
İpek Özalp ◽  
Hülya Caner ◽  
Nurgül Karlıoğlu Kılıç ◽  
Meral Avcı
Keyword(s):  
Late Holocene ◽  
Fossil Pollen ◽  
Pollen Record

scholarly journals Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP)

2020 ◽  
Vol 47 (3) ◽  
pp. 599
Author(s):  
Gonzalo D. Sottile ◽  
Marcos E. Echeverría ◽  
Marcela S. Tonello ◽  
María A. Marcos ◽  
Florencia P. Bamonte ◽  
...  
Keyword(s):  
Plant Diversity ◽  
Forest Ecosystems ◽  
Environmental Variability ◽  
Geographical Location ◽  
Pollen Record ◽  
The Holocene ◽  
Steppe Communities ◽  
Climatic Evolution ◽  
Cyclic Changes ◽  
Vegetation And Climate

Paleoecological studies in Patagonia provide information about vegetation and climate changes occurred during the Holocene. The climatic evolution of this region offers a unique opportunity to study the environmental variability as well as the ecosystem variations. The dynamic of the forest ecosystems is modulated by the occurrence of disturbances. Fires are one of the most important disturbances in temperate forest ecosystems, and its study allows contrasting independently about the changes experienced by ecosystems. In addition, in Patagonia, environmental and postglacial vegetation changes have been determined by variations in the temperature and westerlies winds. In order to reconstruct changes experienced by the forest ecosystem and patterns of plant diversity during the Holocene, in relation to Postglacial dynamics, natural and anthropic disturbances in the Lake Argentino, pollen and charcoal were studied in a sedimentary sequence at Península Avellaneda. Pollen assemblages suggest non-cyclic changes in plant diversity during the Holocene. The highly diverse cold grass-shrub communities dominated the area up to the Early Holocene, when they were displaced upland by less diverse forest and steppes. Also, The Early and Midd-Holocene was characterized by opposite variations of hydric balance between Andean and extra-andean plant communities present between 48° and 50° S, whereas fire activity occurs synchronously between forest (Andean) and steppe communities (Extra-andean). Late Holocene is characterized by different proxy signals depending on the geographical location of the paleoecological records. To conclude, this work provides a better understanding of the fossil pollen record by its comparison with modern surface pollen samples along an altitudinal vegetation gradient.

scholarly journals Pollen-based temperature and precipitation inferences for the montane forest of Mt. Kilimanjaro during the last Glacial and the Holocene

2014 ◽  
Vol 10 (1) ◽  
pp. 195-234 ◽  
Author(s):  
L. Schüler ◽  
A. Hemp ◽  
H. Behling
Keyword(s):  
East Africa ◽  
Transfer Functions ◽  
Montane Forest ◽  
Weighted Averaging ◽  
Pollen Record ◽  
Climate Variables ◽  
The Holocene ◽  
Modern Pollen ◽  
Temperature And Precipitation ◽  
Pollen Rain

Abstract. The relationship between modern pollen-rain taxa and measured climate variables was explored along the elevational gradient of the southern slope of Mt. Kilimanjaro, Tanzania. Pollen assemblages in 28 pollen traps positioned on 14 montane forest vegetation plots were identified and their relationship with climate variables was examined using multivariate statistical methods. Canonical correspondence analysis revealed that the mean annual temperature, mean annual precipitation and minimum temperature each account for significant fractions of the variation in pollen taxa. A training set of 107 modern pollen taxa was used to derive temperature and precipitation transfer functions based on pollen subsets using weighted-averaging-partial-least-squares (WA-PLS) techniques. The transfer functions were then applied to a fossil pollen record from the montane forest of Mt. Kilimanjaro and the climate parameter estimates for the Late Glacial and the Holocene on Mt. Kilimanjaro were inferred. Our results present the first quantitatively reconstructed temperature and precipitation estimates for Mt Kilimanjaro and give highly interesting insights into the past 45 000 yr of climate dynamics in tropical East Africa. The climate reconstructions are consistent with the interpretation of pollen data in terms of vegetation and climate history of afro-montane forest in East Africa. Minimum temperatures above the frostline as well as increased precipitation turn out to be crucial for the development and expansion of montane forest during the Holocene. In contrast, consistently low minimum temperatures as well as about 25% drier climate conditions prevailed during the pre LGM, which kept the montane vegetation composition in a stable state. In prospective studies, the quantitative climate reconstruction will be improved by additional modern pollen rain data, especially from lower elevations with submontane dry forests and colline savanna vegetation in order to extend the reference climate gradient.

Vegetation responses to late Holocene climate changes in an Andean forest

2017 ◽  
Vol 89 (1) ◽  
pp. 60-74 ◽  
Author(s):  
Jacob D. Schiferl ◽  
Mark B. Bush ◽  
Miles R. Silman ◽  
Dunia H. Urrego
Keyword(s):  
Late Holocene ◽  
Global Scale ◽  
Ice Age ◽  
Cloud Base ◽  
Fossil Pollen ◽  
Pollen Record ◽  
Human Occupation ◽  
Holocene Climate ◽  
Vegetation Responses ◽  
The Stability

AbstractA paleoecological record from Lake Palotoa (1370 m elevation) in the Andean foothills of Peru spans the last 3800 years. Lake Palotoa lies near the modern cloud base in a location sensitive to changes in atmospheric moisture. In many areas, these forests have been destroyed, but Lake Palotoa shows no sign of human occupation today or in the past. The modern forest surrounding the lake is dominated by the Andean palm, Dictyocaryum lamarckianum, which is also the most abundant taxon in the fossil pollen record. Fossil pollen data show the vegetation assemblages have not experienced strong compositional changes in the late Holocene. Global-scale climatic events such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) are identified within the record, though the vegetation responses are subtle. Hedyosmum and Sloanea pollen percentages increase near the onset of the MCA and may reflect decreased seasonality. The LIA coincides with increased Hedyosmum pollen percentages, and increases in Clethra and Begonia, two elements that tend to occupy forests now found at higher elevations. Our findings demonstrate the stability of montane forest systems to natural Holocene climate change.

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