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

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.

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Responses of the mangrove ecosystem to Holocene environmental change in the Sundarban Biosphere Reserve, India

Acta Palaeobotanica ◽

10.2478/acpa-2019-0013 ◽

2019 ◽

Vol 59 (2) ◽

pp. 391-409

Author(s):

Arghya Kumar Hait ◽

Hermann Behling

Keyword(s):

Large Scale ◽

Sediment Cores ◽

Biosphere Reserve ◽

Mangrove Ecosystem ◽

High Rate ◽

The Holocene ◽

Modern Pollen ◽

Pollen Rain ◽

Sundarban Biosphere Reserve ◽

Rain Study

Abstract The Sundarban Mangrove Forest in the Sundarban Biosphere Reserve, located at the mouth of the Ganga–Brahmaputra Delta in India, is the most diverse mangrove ecosystem in the world. Sediment cores were taken from two widely separated islands in that reserve: Chamta (CMT) and Sudhyanyakhali (SDK). Pollen analysis and radiocarbon dating were used to study the Holocene development and dynamics of this unique ecosystem. Modern pollen rain study reveals a strong relation between modern pollen rain and the present vegetation, as well as a high rate of Phoenix palludosa pollen production.The pollen records indicate that man-grove existed at CMT from ~5960 and at SDK from ~1520 cal yr BP. Changes in relative sea level, including the frequency and intensity of inundation as well as fluctuating precipitation, have been the major factors along with geomorphic processes that control the development and dynamics of the mangrove in the area during the Holocene. The mid Holocene mangrove at CMT declined, to be progressively replaced by successive communities, and eventually reached climax stage, while the SDK site is transitional in nature. The mangrove responds rapidly to changes in environmental conditions at both locations. Because of large-scale anthropogenic interventions, it is unlikely that similar rapid responses will occur in the future.

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Elevational transects of modern pollen samples: Site-specific temperatures as a tool for palaeoclimate reconstructions in the Alps

The Holocene ◽

10.1177/0959683618810395 ◽

2018 ◽

Vol 29 (2) ◽

pp. 271-286 ◽

Cited By ~ 4

Author(s):

Giulia Furlanetto ◽

Cesare Ravazzi ◽

Federica Badino ◽

Michele Brunetti ◽

Elena Champvillair ◽

...

Keyword(s):

Transfer Functions ◽

Weighted Averaging ◽

Taxonomic Resolution ◽

Pollen Deposition ◽

High Mountain ◽

European Alps ◽

Climate Data ◽

Sample Site ◽

Modern Pollen ◽

July Temperature

The potential of quantitatively reconstructing climate from modern pollen assemblages from high mountain environments has been widely debated but seldom tested. We analysed the pollen deposition in 53 surface samples (mosses) in relation to July temperature in two elevational transects in the European Alps. Each surface-sample site was assigned climate data derived from the local-scale climate. We compared our results with a larger calibration set extracted from the European Modern Pollen Database (EMPD) and centred on the European Alps. This also was assigned local climate data. The main calibration set (234 pollen samples) had Alnus harmonized at genus level; in contrast, a second set was selected (174) that retained the taxonomic resolution of Alnus viridis, which is one of the main climate indicators in the timberline ecotone. The overall and individual pollen responses to July temperature were inferred by canonical correspondence analysis (CCA), generalized linear regression (eHOF) and weighted averaging (WA). Quantitative climate reconstructions for each sample site of the two elevational transects were obtained using transfer functions, that is, WA and WA partial least squares (WA-PLS) regressions. In each calibration set, around 30% of the pollen taxa show a relationship with July temperature through monotonic or unimodal functions. The best transfer function obtained has a good statistical performance, with a determination coefficient ( r2) of 0.74. We propose new calibration procedures formulated to include the full climate space of the modelled taxa, as well as to account for uphill pollen transport in the high mountains and for human activity.

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

10.1101/2020.08.19.257584 ◽

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.

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A modern pollen–temperature calibration data set from Korea and quantitative temperature reconstructions for the Holocene

The Holocene ◽

10.1177/0959683611400462 ◽

2011 ◽

Vol 21 (7) ◽

pp. 1125-1135 ◽

Cited By ~ 12

Author(s):

Jungjae Park

Keyword(s):

Transfer Function ◽

Correspondence Analysis ◽

East Coast ◽

Ice Age ◽

Weighted Averaging ◽

Calibration Data ◽

Data Set ◽

The Holocene ◽

Modern Pollen ◽

The Relationship

Modern surface pollen samples from the mountains along the east coast of Korea were used to derive pollen–temperature transfer functions. Detrended correspondence analysis (DCA) and detrended canonical correspondence analysis (DCCA) were performed to test the robustness of the relationship between the modern pollen assemblages and temperatures. The relationship exhibited a high correlation (DCA, r = −0.887; DCCA, r = −0.908). The performance of the best weighted averaging partial least squares (WA-PLS) transfer function was statistically good ([Formula: see text] = 0.74; RMSEP = 1.79°C). In order to quantitatively reconstruct the Holocene temperature changes, the best model was applied to five fossil pollen records produced from four coastal lagoons of the east coast and one high-altitude peat bog. Anomalies calculated from reconstructed paleotemperature data were combined to generate a synthesis temperature reconstruction for the east coast of Korea, in which the ‘Medieval Warm Period’, ‘Little Ice Age’, and ‘Migration Period’ were clearly shown. This study demonstrated the validity of the quantitative reconstruction of paleotemperature using the pollen–climate transfer function, even in heavily human-impacted areas such as the Korean Peninsula.

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Holocene vegetation, climate and human impact in steppes around Lake Sevan (Armenia) based on a multiproxy approach: Pollen, NPPs and brGDGTs

10.5194/egusphere-egu21-15206 ◽

2021 ◽

Author(s):

Mary Robles ◽

Odile Peyron ◽

Elisabetta Brugiapaglia ◽

Guillemette Ménot ◽

Lucas Dugerdil ◽

...

Keyword(s):

Human Impact ◽

Weighted Averaging ◽

Lake Sevan ◽

The Holocene ◽

Modern Pollen ◽

Climate Reconstructions ◽

Multi Method Approach ◽

The Impact ◽

Multiproxy Approach ◽

Method Approach

In the Caucasus Mountains, the role of human influences and climate changes on steppes expansion over the Holocene is still discussed because this region is poorly documented. This study investigates (1) modern pollen-vegetation relationships in Armenia and (2) changes in vegetation, human activity and climate in the Holocene record of Vanevan peat (south-eastern shore of Lake Sevan) located in Armenia. The last 9700 years are recorded in the Vanevan core. We used a multiproxy approach including XRF, Pollen, Non-Pollen Palynomorphs (NPPs) and branched glycerol dialkyl glycerol tetraethers (brGDGTs) to reconstruct changes in vegetation, human impact and climate. The combination of these proxies is innovative and aims to distinguish the impact of human activities and climate change on vegetation. Modern pollen assemblages from semi-desert/steppe regions of Armenia show an abundance of Chenopodiaceae while meadows steppes, subalpine and alpine meadows are dominated by Poaceae. The Holocene vegetation at Vanevan is characterized by steppes dominated by Poaceae, Artemisia and Chenopodiaceae. However, several arboreal taxa, such as Quercus, Betula, Carpinus betulus and Ulmus, are more developed on slopes between 8600 and 5100 cal BP. Regarding the human impact, the presence of agriculture is attested since 5200 cal BP, largely increases during the last 2000 years cal BP (high percentages of Cerealia-type pollen) and correlates with the occupation periods reported in archeological studies. Palaeoclimate changes at Vanevan are estimated from (1) water level changes (2) temperature reconstructions based on brGDGTs (3) climate reconstructions based on pollen (through a multi-method approach: Modern Analogue Technique, Weighted Averaging Partial Least Squares regression, Random Forest, and Boosted Regression Trees). Climate reconstructions based on pollen and brGDGTs are rare and the multi-method approach using pollen data is innovative in the region. The results of Vanevan give evidence of high temperatures from 7900 to 5100 cal BP and arid events at 6000, 5000-4500 and 4200 cal BP, in agreement with other regional records.

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Modern pollen–climate relationships in north Xinjiang, northwestern China: Implications for pollen-based reconstruction of Holocene climate

The Holocene ◽

10.1177/0959683616678464 ◽

2016 ◽

Vol 27 (7) ◽

pp. 951-966 ◽

Cited By ~ 8

Author(s):

Furong Li ◽

Yan Zhao ◽

Marie-José Gaillard ◽

Huan Li ◽

Jinghui Sun ◽

...

Keyword(s):

Transfer Functions ◽

Variation Partitioning ◽

Northwestern China ◽

Climate Variables ◽

Past Climate ◽

Modern Pollen ◽

Altay Mountains ◽

North Xinjiang ◽

The Individual ◽

Vegetation And Climate

Fossil pollen records are widely used to reconstruct past climate. Such reconstructions require that the relationships between pollen assemblages, vegetation, and climate are well understood. These can be studied in present circumstances given we assume that modern vegetation and climate are analogous to past ones. In this study, we analyze pollen–vegetation–climate relationships in the Jungar desert and Altay Mountains, northwestern China, a region for which careful reconstruction of past climate is needed to answer unsolved questions on past climate in an area located at the boundary between two different climate regimes (westerlies and monsoon). We use a dataset of 66 surface pollen samples from forest, meadow, steppe, and desert vegetation and six related climate variables, Tann, TJan, TJul, Pann, PJan, and PJul. Principal components analysis, redundancy analysis, Monte Carlo permutation tests, and variation partitioning are applied to quantify these relationships. We also assess pollen ratios as indices of aridity. We find that (1) Pann is the major climatic factor influencing pollen assemblages, followed by PJul, (2) the two variables are not correlated, and (3) the shared effect of (1) PJan and PJul, (2) PJan and Pann, (3) PJul and Tann, and (4) Tann, TJan, and TJul explains a larger portion of the variation in pollen data than the individual effect of each variable. Therefore, robust pollen–climate transfer functions can be developed for Pann and PJul, and several climate variables treated in combination. Artemisia/Chenopodiaceae is a strong index of aridity and Artemisia/Gramineae might be a useful index of Pann and PJul.

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Modern pollen-vegetation relationships along a steep temperature gradient in the Tropical Andes of Ecuador

Quaternary Research ◽

10.1017/qua.2019.4 ◽

2019 ◽

Vol 92 (1) ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Kimberley Hagemans ◽

Claudia-Dana Tóth ◽

Manuela Ormaza ◽

William D. Gosling ◽

Dunia H. Urrego ◽

...

Keyword(s):

Temperature Gradient ◽

Vascular Plant ◽

Montane Forest ◽

Sediment Surface ◽

Tropical Andes ◽

Modern Pollen ◽

Surface Samples ◽

Steep Temperature Gradient ◽

Pollen Rain ◽

Moss Polsters

AbstractThe characterization of modern pollen rain assemblages along environmental gradients is an essential prerequisite for reliable interpretations of fossil pollen records. In this study, we identify pollen-vegetation relationships using modern pollen rain assemblages in moss polsters (n = 13) and lake sediment surface samples (n = 11) along a steep temperature gradient of 7°C (3100–4200 m above sea level) on the western Andean Cordillera, Ecuador. The pollen rain is correlated to vascular plant abundance data recorded in vegetation relevées (n = 13). Results show that pollen spectra from both moss polsters and sediment surface samples reflect changes in species composition along the temperature gradient, despite overrepresentation of upper montane forest taxa in the latter. Estimated pollen transport distance for a lake (Laguna Llaviucu) situated in a steep upper montane forest valley is 1–2 km, while a lake (Laguna Pallcacocha) in the páramo captures pollen input from a distance of up to 10–40 km. Weinmannia spp., Podocarpus spp., and Hedyosmum sp. are indicators of local upper montane forest vegetation, while Phlegmariurus spp. and Plantago spp. are indicators for local páramo vegetation.

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Modern pollen rain within and adjacent to two giant sequoia (Sequoiadendrongiganteum) groves, Yosemite and Sequoia national parks, California

Canadian Journal of Forest Research ◽

10.1139/x90-172 ◽

1990 ◽

Vol 20 (9) ◽

pp. 1289-1305 ◽

Cited By ~ 8

Author(s):

R. Scott Anderson

Keyword(s):

National Parks ◽

Sediment Cores ◽

Pollen Dispersal ◽

Theoretical Models ◽

Pollen Record ◽

Pollen Dispersion ◽

Modern Pollen ◽

Prevailing Wind Direction ◽

Giant Sequoia ◽

Pollen Rain

Analysis of modern pollen (from polsters) and plant percentage coverage (from relevés) within and near two giant sequoia (Sequoiadendrongiganteum) groves provide data on the relationship between plant abundance and pollen dispersion. Most Sequoiadendron pollen is deposited within or near the groves, substantiating previously established theoretical models on pollen dispersion. Within the groves, Sequoiadendron is only slightly overrepresented by its pollen (R value average, 1.6). At the Tuolumne Grove, Sequoiadendron pollen averages 1.5% at stations within 450 m of the grove boundary. Pollen percentage is slightly higher (8%) for similar stations at Lost Grove. This contrasts with the more widely dispersed pollen of Pinus and Quercus, and the less widely dispersed Chrysolepis and Cornus. Patterns of pollen dispersal away from the groves are consistent with the prevailing wind direction and diurnal air mass movements. For Sequoiadendron, the relatively poor dispersal has implications for future paleoecologic studies interpreting the sedimentary pollen record from meadow sediment cores; and for understanding the exchange of genetic information between these trees that grow in stands somewhat isolated from each other.

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Vegetation Response to Holocene Climate Change in the Qinling Mountains in the Temperate–Subtropical Transition Zone of Central–East China

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.734011 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yao Zhang ◽

Qiaoyu Cui ◽

Youliang Huang ◽

Duo Wu ◽

Aifeng Zhou

Keyword(s):

Climate Change ◽

Transition Zone ◽

Early Holocene ◽

East China ◽

Mountain Range ◽

Pollen Record ◽

Qinling Mountains ◽

Vegetation Response ◽

The Holocene ◽

Temperature And Precipitation

Global warming is having a profound influence on vegetation and biodiversity patterns, especially in alpine areas and high latitudes. The Qinling Mountain range is located in the transition zone between the temperate and subtropical ecosystems of central–east China and thus the vegetation of the area is diverse. Understanding the long-term interactions between plant diversity and climate change can potentially provide a reference for future landscape management and biodiversity conservation strategies in the Qinling Mountains region. Here, we use a pollen record from the Holocene sediments of Daye Lake, on Mount Taibai in the Qingling Mountains, to study regional vegetation changes based on biomes reconstruction and diversity analysis. Temperature and precipitation records from sites close to Daye Lake are used to provide environmental background to help determine the vegetation response to climate change. The results indicate that climate change was the main factor influencing vegetation and palynological diversity in the Qinling Mountains during the Holocene. The cold and dry climate at the beginning of the early Holocene (11,700–10,700 cal yr BP) resulted in a low abundance and uneven distribution of regional vegetation types, with the dominance of coniferous forest. During the early Holocene (10,700–7,000 cal yr BP), temperate deciduous broadleaf forest expanded, palynological diversity and evenness increased, indicating that the warm and humid climate promoted vegetation growth. In the middle Holocene (7,000–3,000 cal yr BP), the climate became slightly drier but a relatively warm environment supported the continued increase in palynological diversity. After ∼3,000 cal yr BP, palynological diversity and the evenness index commenced a decreasing trend, in agreement with the decreased temperature and precipitation in the Qinling Mountains. It’s noteworthy that human activity at this time had a potential influence on the vegetation. During the past few centuries, however, palynological diversity has increased along with the global temperature, and therefore it is possible that in the short-term ongoing climatic warming will promote vegetation development and palynological diversity in the area without human interference.

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Pollen Taphonomy in a Canyon Stream

Quaternary Research ◽

10.1016/0033-5894(87)90006-8 ◽

1987 ◽

Vol 28 (3) ◽

pp. 393-406 ◽

Cited By ~ 51

Author(s):

Patricia L. Fall

Keyword(s):

Surface Soil ◽

Pollen Grains ◽

Close Correlation ◽

Soil Samples ◽

Alluvial Deposits ◽

Modern Pollen ◽

Pollen Types ◽

Pollen Rain ◽

Arid Steppe ◽

Turbulent Water

AbstractSurface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae-Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.

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