Regional Biomes Research Articles

Regional Biomes outperform broader spatial units in capturing biodiversity responses to land‐use change

Biogeographic context, such as biome type, has a critical influence on ecological resilience, as climatic and environmental conditions impact how communities respond to anthropogenic threats. For example, land‐use change causes a greater loss of biodiversity in tropical biomes compared to temperate biomes. Furthermore, the nature of threats impacting ecosystems varies geographically. Therefore, monitoring the state of biodiversity at a high spatial resolution is crucial to capture variation in threat–responses caused by biogeographical context. However such fine‐scale ecological data collection could be prohibitively resource intensive. In this study, we aim to find the spatial scale that could best capture variation in community‐level threat responses whilst keeping data collection requirements feasible. Using a database of biodiversity records with extensive global coverage, we modelled species richness and total abundance (the responses) across land‐use types (reflecting threats), considering three different spatial scales: biomes, biogeographical realms, and regional biomes (the interaction between realm and biome). We then modelled data from three highly sampled biomes to ask how responses to threat differ between regional biomes and taxonomic group. We found strong support for regional biomes in explaining variation in species richness and total abundance compared to biomes or realms alone. Our biome case studies demonstrate that there is variation in magnitude and direction of threat responses across both regional biomes and taxonomic group, although the interpretation is limited by sampling bias in the literature. All groups in tropical forest showed a consistently negative response, whilst many taxon‐regional biome groups showed no clear response to threat in temperate forest and tropical grassland. Our results provide the first empirical evidence that the taxon‐regional biome unit has potential as a reasonable spatial unit for monitoring how ecological communities respond to threats and designing effective conservation interventions to bend the curve on biodiversity loss.

Human adaptation to diverse biomes over the past 3 million years

To investigate the role of vegetation and ecosystem diversity on hominin adaptation and migration, we identify past human habitat preferences over time using a transient 3-million-year earth system-biome model simulation and an extensive hominin fossil and archaeological database. Our analysis shows that early African hominins predominantly lived in open environments such as grassland and dry shrubland. Migrating into Eurasia, hominins adapted to a broader range of biomes over time. By linking the location and age of hominin sites with corresponding simulated regional biomes, we also find that our ancestors actively selected for spatially diverse environments. The quantitative results lead to a new diversity hypothesis: Homo species, in particular Homo sapiens, were specially equipped to adapt to landscape mosaics.

Disparate continental scale patterns in floral host breadth of Australian colletid bees (Colletidae: Hymenoptera)

Plant-bee networks are rarely, if ever, studied quantitatively at continental scales, yet these have the potential to inform how biota and ecosystems are assembled beyond narrower regional biomes. The short-tongued bee family Colletidae comprises the major component of bee diversity in Australia, with three key subfamilies: the Neopasiphaeinae, Hylaeinae, and Euryglossinae. We use museum data (> 27,000 records) to record binary interactions between these bees (from each of these subfamilies, resolved to subgenera) and plants (resolved to genera). The resulting networks were analysed using bipartite graphs and associated indices of network structure. The three bee subfamilies showed markedly different network structures with their floral hosts. Euryglossinae had strong interactions with Myrtaceae and an otherwise relatively narrow host breadth, Neopasiphaeinae had little signal of host specialisation above genera and a very broad host breadth, and Hylaeinae appeared intermediate in network structure. Furthermore, Euryglossinae is more speciose within Australia (404 species, or ~ 25% of described Australian bee fauna) than Hylaeinae and Neopasiphaeinae, but these differences do not correspond to the stem ages of the three subfamilies, suggesting that time-since-origin does not explain bee species diversity or floral host breadth. Patterns of host breadth persist after rarefaction analyses that correct for differing numbers of observation records. We suggest that visitation networks could be influenced by evolutionary constraints to expansion of floral host breadth, but it is also possible that many bee-plant interactions are shaped by bees exploiting floral traits that are driven by non-bee fauna operating at large biogeographical scales.

Assessment and Constraint of Mesozooplankton in CMIP6 Earth System Models

AbstractAlthough zooplankton play a substantial role in the biological carbon pump and serve as a crucial link between primary producers and higher trophic level consumers, the skillful representation of zooplankton is not often a focus of ocean biogeochemical models. Systematic evaluations of zooplankton in models could improve their representation, but so far, ocean biogeochemical skill assessment of Earth system model (ESM) ensembles have not included zooplankton. Here we use a recently developed global, observationally based map of mesozooplankton biomass to assess the skill of mesozooplankton in six CMIP6 ESMs. We also employ a biome‐based assessment of the ability of these models to reproduce the observed relationship between mesozooplankton biomass and surface chlorophyll. The combined analysis found that most models were able to reasonably simulate the large regional variations in mesozooplankton biomass at the global scale. Additionally, three of the ESMs simulated a mesozooplankton‐chlorophyll relationship within the observational bounds, which we used as an emergent constraint on future mesozooplankton projections. We highlight where differences in model structure and parameters may give rise to varied mesozooplankton distributions under historic and future conditions, and the resultant wide ensemble spread in projected changes in mesozooplankton biomass. Despite differences, the strength of the mesozooplankton‐chlorophyll relationships across all models was related to the projected changes in mesozooplankton biomass globally and in regional biomes. These results suggest that improved observations of mesozooplankton and their relationship to chlorophyll will better constrain projections of climate change impacts on these important animals.

Assembly dynamics of East Asian subtropical evergreen broadleaved forests: New insights from the dominant Fagaceae trees.

The dominant species of a biome can be regarded as its genuine indicator. Evergreen broadleaved forests (EBLFs) in subtropical East Asia harbor high levels of species biodiversity and endemism and are vital to regional carbon storage and cycling. However, the historical assembly of this unique biome is still controversial. Fagaceae is the most essential family in East Asian subtropical EBLFs and its dominant species are vital for the existence of this biome. Here, we used the dominant Fagaceae species to shed light on the dynamic process of East Asian subtropical EBLFs over time. Our results indicate high precipitation in summer and low temperature in winter are the most influential climatic factors for the distribution of East Asian subtropical EBLFs. Modern East Asian subtropical EBLFs did not begin to appear until 23 Ma, subsequently experienced a long-lasting development in the Miocene and markedly deteriorated at about 4 Ma, driven jointly by orogenesis and paleoclimate. We also document that there is a lag time between when one clade invaded the region and when its members become dominant species within the region. This study may improve our ability to predict and mitigate the threats to biodiversity of East Asian subtropical EBLFs and points to a new path for future studies involving multidisciplinary methods to explore the assembly of regional biomes.

A novel biome concept and classification system based on bioclimate and vegetation – a Neotropical assay

The knowledge of biomes as large-scale ecosystem units has benefited from advances in the ecological and evolutionary sciences. Despite this, a universal biome classification system that also allows a standardized nomenclature has not yet been achieved. We propose a comprehensive and hierarchical classification method and nomenclature to define biomes based on a set of bioclimatic variables and their corresponding vegetation structure and ecological functionality. This method uses three hierarchical biome levels: Zonal biome (Macrobiome), Biome and Regional biome. Biome nomenclature incorporates both bioclimatic and vegetation characterization (i.e. formation). Bioclimate characterization basically includes precipitation rate and thermicity. The description of plant formations encompasses vegetation structure, physiognomy and foliage phenology. Since the available systems tend to underestimate the complexity and diversity of tropical ecosystems, we have tested our approach in the biogeographical area of the Neotropics. Our proposal includes a bioclimatic characterization of the main 16 Neotropical plant formations identified. This method provides a framework that (1) enables biome distribution and changes to be projected from bioclimatic data; (2) allows all biomes to be named according to a globally standardized scheme; and (3) integrates various ecological biome approaches with the contributions of the European and North American vegetation classification systems. Taxonomic reference: Jørgensen et al. (2014). Dedication: This work is dedicated to the memory of and in homage to Prof. Dr. Salvador Rivas-Martínez.

Forest biomes of Southern Africa

ABSTRACT The forests of South Africa and the neighbouring countries, including Lesotho, eSwatini, Namibia, Botswana, Zimbabwe, and Mozambique (south of the Zambezi River), were mapped and classified according to the global system of biomes. The new four-tier hierarchical biome system suggested in this paper includes zonobiome, global biome, continental biome (all recognised earlier), and regional biome – a novel biome category. The existing spatial coverages of the forests were revised and considerably improved, both in terms of forest-patch coverage and mapping precision. Southern Africa is home to three zonal forest types, namely Subtropical Forests (Zonobiome I), Tropical Dry Forest (TDF; Zonobiome II) and Afrotemperate Forests (Zonobiome X). These three biomes are characterised by unique bioclimatic envelopes. Five, two, and eight regional biomes, respectively, have been recognised within these zonal biomes. Recognition of the Zonobiome I and the global biome Tropical Dry Forests in southern Africa is novel and expands our knowledge of the biome structure of African biotic communities. The system of the azonal regional biomes is also new and comprehensively covers the variability of the azonal helobiomes (riparian woodlands and swamp forests), mangroves, and azonal coastal forests. In total, 11 azonal regional biomes have been recognised in the study area. The forest biomes in southern Africa were captured in our electronic map in the form of more than 60 000 polygons, covering 42 416 km2 (1.27% of the study area). No less than 83% of these forests occur in the territory of southern Mozambique. Abbreviations: for the abbreviation of the biome units, see Table 1; CE: centre of endemism; IOCB: Indian Ocean Coastal Belt; MBSA: the area of the Map of Biomes of Southern Africa; VegMap2006 and VegMap2018: Vegetation Map of South Africa, Lesotho and Swaziland (as released in respective years); for the meaning of the codes of the biome units see Table 1, and for the meaning of the abbreviations of climatic characteristics see Appendix S1

Agricultural vulnerability to climate change in the Rio das Contas Basin, Brazil

Climate change threats agriculture, mainly in developing countries. Understanding the vulnerability of farmers is very important to counteract the negative impacts. Therefore, this paper aims to analyze the degree of vulnerability to climate change of farmers of the Rio das Contas Basin, Brazil, based on their degree of sensibility, exposure, and adaptive capacity. Variations in exposure and vulnerability indexes between regional biomes were calculated. The sensibility index was higher than 50% in all municipalities. The exposure index was over 60% in most municipalities. A value of the adaptive capacity index, sufficient to reduce vulnerability, was not observed in any municipality. The vulnerability index was higher than 66% in more than half of the municipalities. Exposure and vulnerability indexes varied with the biome. The vulnerability is the result of high exposure and sensibility combined with low adaptive capacity. This suggests the need for investment to minimize these effects and mitigation activities to counter the negative impacts of future climate variability.

Medicinal Plants of Arid and Semiarid Biomes of Russia

The article analyzes a set of medicinal-plant species in arid and semiarid biomes of Russia. The species diversity of medicinal plants in general, as well as those used to treat diseases of various classes, is determined. A statistical analysis of the relationships between the number of species of medicinal plants in regional biomes and climatic indices is carried out; the corresponding thematic schematic maps are constructed and analyzed. It is shown that the number of medicinal-plant species is related to the total biome species number. This, in turn, is determined by the geographic location, which determines the average annual temperature and precipitation in the regions. The closest established relationship was between the number of medicinal-plant species and the average annual air temperatures. A relatively high relationship was found between the species number and the average annual precipitation. In the analysis of the relationship between the number of medicinal-plant species used to treat certain classes of diseases and the climatic factors, the picture turned out to be similar.

Niche-neutral theoretic approach to mechanisms underlying the biodiversity and biogeography of human microbiomes.

The human microbiome consists of five major regional biomes distributed in or on our five body sites including skin, oral, lung, gut, and reproductive tract. Its biogeography (the spatial and temporal distribution of its biodiversity) has far‐reaching implications to our health and diseases. Nevertheless, we currently have very limited understanding on the mechanisms shaping the biogeography, since it is often rather difficult to determine the relative importance of drift, dispersal, speciation, and selection, the four processes (mechanisms) determining the patterns of microbial biogeography and community dynamics according to a recent synthesis in community ecology and biogeography. To disentangle these mechanisms, I utilize multisite neutral (MSN) model and niche‐neutral hybrid (NNH) model to analyze large number of truly multisite microbiome samples covering all five major human microbiome habitats, including 699 metacommunities and 5,420 local communities. Approximately 89% of metacommunities and 92% local communities exhibit patterns indistinguishable from neutral, and 20% indistinguishable from niche‐neutral hybrid model, indicating the relative significance of stochastic neutral forces versus deterministic niche selection in shaping the biogeography of human microbiome. These findings cast supporting evidence to van der Gast's revision to classic Bass‐Becking doctrine of microbial biogeography: “Some things are everywhere and some things are not. Sometimes the environment selects and sometimes it doesn't,” offering the first educated guess for “some” and “sometimes” in the revised doctrine. Furthermore, the logistic/Cox regression models describing the relationships among community neutrality, niche differentiation, and key community/species characteristics (including community diversity, community/species dominance, speciation, and migration rates) were constructed to quantitatively describe the niche‐neutral continuum and the influences of community/species properties on the continuum.

Global Carbon Cycle and Climate Feedbacks in the NASA GISS ModelE2.1

AbstractWe present results from the NASA GISS ModelE2.1‐G‐CC Earth System Model with coupled climate‐carbon cycle simulations that were submitted to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) Coupled Climate‐Carbon Cycle MIP (C4MIP). Atmospheric CO2 concentration and carbon budgets for the land and ocean in the historical simulations were generally consistent with observations. Low simulated atmospheric CO2 concentrations during 1850–1950 were due to excess uptake from prescribed land cover change, which erroneously replaced arid shrublands with higher biomass crops, and assumed high 2004 LAI values in vegetated lands throughout the historical simulation. At the end of the historical period, slightly higher simulated CO2 than observed resulted from the land being an insufficient net carbon sink, despite the net effect of CO2 fertilization and warming‐induced increases to leaf photosynthetic capacity. The global ocean carbon uptake agreed well with the observations with the largest discrepancies in the low latitudes. Future climate projection at 2091–2100 agreed with CMIP5 models in the northward shift, of temperate deciduous forest climate and expansion across Eurasia along 60°N latitude, and dramatic regional biome shifts from drying and warming in continental Europe. Carbon feedback parameters were largely similar to the CMIP5 model ensemble. For our model, the variation of land feedback parameters within the uncertainty arises from the fertilization feedback being less sensitive due to lack of increased vegetation growth, and the comparably more negative ocean carbon‐climate feedback is due to the large slowdown of the Atlantic overturning circulation.

ECOSYSTEM AND BIOTIC DIVERSITY OF THE CASPIAN REGION

The aim is development of methodological approaches for an estimation of a biodiversity (species and ecosystems) and the cartographic representation of the regularities of its distribution on the basis of ecosystmes (biomes) concept in biogeography, and integrated ecology-geographical approach to the interpretation of the data. Material and methods. A series of natural maps of the Electronic Atlas of the Caspian Sea includes small-scale vegetation map of the Caspian region, which represents the spatial organization of vegetation with the organizing role of environmental and geographical factors. The created cartographic model can be the basis for an estimation of the ecosystem diversity of the region. The materials for the map were publications and cartographic models, original materials on the study of vegetation cover of the Caspian regions and available data on biodiversity estimation. The analysis of materials is carried out in accordance with the classification system of phytocoenomers and phytocoenochore VB. Sochava; we used ecology-morphological classification and ecology-geographical approach in the preparation of the map legend. Results. The botanical and geographical features of the Caspian region are shown. The characteristic of coenotic diversity of plain deserts of the region within the subzone units is given. Typical altitudinal belt spectra and the formation compositions of high-altitude belts for mountain areas are shown. Using biome as a basic unit of biodiversity accounting, it is possible to proceed to quantifying biodiversity at species and coenotic levels. An example of biodiversity estimation for the regional Caspian desert-steppe biome is given. Conclusion. The cartographic model of bioclimatically determined vegetation types (climatypes) of the Caspian region is a good basis for further estimation of biodiversity (at species and ecosystem levels) based on the concept of regional biomes.

Assessment of the Distribution of Rare Bird Species in Regional Arid Biomes of Russia as the Basis for Their Protection

The biodiversity of rare, endangered, and recovering bird species has been assessed for the arid and semiarid regional biomes of Russia (the Red Book of the Russian Federation and the IUCN Red List of Threatened Species (Krasnaya kniga..., 2001; IUCN, 2018)). It is shown that 104 protected species of the 118 species that live in the entire territory of Russia inhabit arid and semiarid territories. The paper identifies a group of rare species that are not or are poorly provided with protection at the level of reserves within the arid and semiarid regional biomes of Russia. The results of the study can be used to assess the regional biodiversity of rare and endangered bird species and to develop effective measures to increase the level of their protection.

Assessing and Interpreting the Within-Body Biogeography of Human Microbiome Diversity.

A human body hosts a relatively independent microbiome including five major regional biomes (i.e., airway, oral, gut, skin, and urogenital). Each of them may possess different regional characteristics with important implications to our health and diseases (i.e., so-termed microbiome associated diseases). Nevertheless, these regional microbiomes are connected with each other through diffusions and migrations. Here, we investigate the within-body (intra-individual) distribution feature of microbiome diversity via diversity area relationship (DAR) modeling, which, to the best of our knowledge, has not been systematically studied previously. We utilized the Hill numbers for measuring alpha and beta-diversities and built 1,200 within-body DAR models with to date the most comprehensive human microbiome datasets of 18 sites from the human microbiome project (HMP) cohort. We established the intra-DAR profile (z-q pattern: the diversity scaling parameter z of the power law (PL) at diversity order q = 0–3), intra-PDO (pair-wise diversity overlap) profile (g-q), and intra-MAD (maximal accrual diversity) profile (Dmax-q) for the within-body biogeography of the human microbiome. These profiles constitute the “maps” of the within-body biogeography, and offer important insights on the within-body distribution of the human microbiome. Furthermore, we investigated the heterogeneity among individuals in their biogeography parameters and found that there is not an “average Joe” that can represent majority of individuals in a cohort or population. For example, we found that most individuals in the HMP cohort have relatively lower maximal accrual diversity (MAD) or in the “long tail” of the so-termed power law distribution. In the meantime, there are a small number of individuals in the cohort who possess disproportionally higher MAD values. These findings may have important implications for personalized medicine of the human microbiome associated diseases in practice, besides their theoretical significance in microbiome research such as establishing the baseline for the conservation of human microbiome.

Effect of Arid Conditions on the Distribution of Poisonous Plants in the Regional Biomes of Russia

An ecological and geographical analysis of the distribution of poisonous plants in the regional biomes of Russia and the effect of arid conditions on it are presented. On the territory of Russia, 82 of the most toxic species of vascular plants (belonging to 34 families) were identified; of them, 55 were poisonous species of the genus Aconitum. Cartographic analysis demonstrated that the smallest number of poisonous plant species (excluding species of the genus Aconitum) is confined to the plain biomes of the forest-tundra and tundra, and the largest number of such species grows in lowland steppe biomes. In the lowland desert biome and in some mountain biomes, the number of poisonous plant species is also significant but is slightly lower than in the steppe biomes. The maximal number of species of the genus Aconitum was detected in the mountainous Far Eastern biomes. Correlation analysis of the relationship between the number of plant species and climatic factors revealed the maximal correlation between the total number of poisonous plant species (excluding species of the genus Aconitum) with the average annual air temperature.

A case of early Wisconsinan “over-chill”: New radiocarbon evidence for early extirpation of western camel (Camelops hesternus) in eastern Beringia

There are comparatively few fossils that document the presence of the Pleistocene western camel (Camelops hesternus) in the unglaciated regions of Alaska and Yukon, northwestern North America (eastern Beringia). It has been previously reported on the basis of stratigraphic and radiocarbon data that this species was present within this region from the Sangamonian interglaciation (Marine Isotope Stage (MIS) 5) through the Last Glacial Maximum (LGM, MIS 2). However, the continued presence of western camel through the LGM is at odds with its ecological preferences as inferred from more southerly parts of the continent. Here we report 43 new radiocarbon dates on 34 western camel fossils from Alaska and Yukon, including specimens that have been dated previously. To minimize exogenous carbon contamination, we utilized either ultrafiltered collagen or single amino acid (hydroxyproline) methodologies in conducting the analyses. All samples, including previously reported specimens with finite ages, yielded ages that were either non-finite or close to the effective limit of radiocarbon dating. These results indicate that dates implying local presence of western camels in Alaska and Yukon during full-glacial conditions of MIS 2 are erroneous by as much as several tens of millennia, probably because of carbon contamination from glue or varnish used in fossil preparation and conservation. The revised radiocarbon chronology, together with other evidence, indicates that western camels were only able to occupy eastern Beringia only during Pleistocene interglaciations such as MIS 5, when forests and shrublands became the dominant regional biomes. The subsequent transition to cold, arid full-glacial conditions during the early Wisconsinan glaciation (MIS 4) around 75 000 years ago created unfavorable environmental conditions, eliminated browse, and led to their local extirpation in eastern Beringia. After their complete population loss in the Arctic and Subarctic, the range of western camels was restricted to the temperate mid-continent, where they eventually went extinct ∼13 000 years ago.

BIODIVERSITY OF OROBIOMES IN THE NORTH CAUCASUS ON THE BIOME MAP OF RUSSIA

The aim is to introduce the concept of biogeographical map "Biomes of Russia" (m 1:.7.500000), scientific and methodological principles of the development of its content, the selection of indicators to characterize the biodiversity of the regional biomes and mark its place and role in the development of biogeography as well as biogeographical mapping and in terms of practical application as in education, in the sustainable development of the regions and for solving the problems in the field of nature and environmental protection. Materials and methods. Map is based on the classification of terrestrial ecosystems (biomes) and eco-geographical approach to their subordination on different levels of organization of the biotic cover. Results. We have displayed on the map the differentiation of the country on the composition of ecosystems and their biodiversity at the regional level. Biomes at the regional level are central to the study and are mapping units. Legend includes 35 lowland biomes and 31 orobiomes (in the mountains). A characteristic has been made up for each biome, which includes indicators of moisture and heat supply, the number of species of vascular plants, mosses and lichens, terrestrial vertebrates (mammals, birds, reptiles and amphibians). To illustrate this, there is the characteristic of the 3 orobiomes of the North Caucasus. Conclusion. Using biomes as supporting biodiversity accounting units enables the integrated analysis of botanical and zoogeographic information about biota, as well as the dual study of biotic and abiotic components of the ecosystem. The current state of biomes is defined by two interrelated processes of transformation and modification of ecosystems and the reduction or loss of biological diversity. Map of regional biomes can serve as a basis for further research on the biome biodiversity on species and ecosystem levels; as the inventory of the biota and the creation of databases on species and cenotic diversity of biomes; for the development and justification of environmental protection measures.

Spatial and topographic trends in forest expansion and biomass change, from regional to local scales.

Natural forest growth and expansion are important carbon sequestration processes globally. Climate change is likely to increase forest growth in some regions via CO2 fertilization, increased temperatures, and altered precipitation; however, altered disturbance regimes and climate stress (e.g. drought) will act to reduce carbon stocks in forests as well. Observations of asynchrony in forest change is useful in determining current trends in forest carbon stocks, both in terms of forest density (e.g. Mg ha(-1) ) and spatially (extent and location). Monitoring change in natural (unmanaged) areas is particularly useful, as while afforestation and recovery from historic land use are currently large carbon sinks, the long-term viability of those sinks depends on climate change and disturbance dynamics at their particular location. We utilize a large, unmanaged biome (>135 000 km(2) ) which spans a broad latitudinal gradient to explore how variation in location affects forest density and spatial patterning: the forests of the North American temperate rainforests in Alaska, which store >2.8 Pg C in biomass and soil, equivalent to >8% of the C in contiguous US forests. We demonstrate that the regional biome is shifting; gains exceed losses and are located in different spatio-topographic contexts. Forest gains are concentrated on northerly aspects, lower elevations, and higher latitudes, especially in sheltered areas, whereas loss is skewed toward southerly aspects and lower latitudes. Repeat plot-scale biomass data (n = 759) indicate that within-forest biomass gains outpace losses (live trees >12.7 cm diameter, 986 Gg yr(-1) ) on gentler slopes and in higher latitudes. This work demonstrates that while temperate rainforest dynamics occur at fine spatial scales (<1000 m(2) ), the net result of thousands of individual events is regionally patterned change. Correlations between the disturbance/establishment imbalance and biomass accumulation suggest the potential for relatively rapid biome shifts and biomass changes.

Response of vegetation growth and productivity to spring climate indicators in the conterminous United States derived from satellite remote sensing data fusion

Spring temperatures strongly influence plant phenology, including budburst, canopy development, and crop planting period. Recent spring warming coincides with earlier and longer non-frozen season trends, and generally earlier spring canopy onset and vegetation productivity increases over the conterminous US (CONUS). However, earlier spring onset increases frost damage risk, with potential negative impacts to productivity. Frost sensitivity and vulnerability is heterogeneous over the CONUS domain, while the occurrence, intensity and regional impact of frost events are difficult to monitor from sparse weather stations. To enhance regional frost risk monitoring capabilities, we developed spring frost day (SFD) and spring frost damage day (SFDD) metrics spanning a long-term (>30 year) record by integrating a satellite microwave remote sensing record of daily landscape freeze-thaw (FT) status and optical-IR sensor based phenology record of start of season (SOS) and day of peak (DOP) canopy cover.We find a decreasing regional SFD trend (−1.6 days decade−1; p<0.1) coincident with spring warming, while the SFDD is generally increasing (1.5 days decade−1; p<0.1). Spring warming is reducing frost occurrence, but an earlier SOS trend is paradoxically increasing vegetation frost damage risk. The ecological significance of the SFD and SFDD changes were evaluated using satellite derived vegetation gross primary production (GPP) and vegetation greenness (EVI2) anomalies. Higher SFD and SFDD levels coincide with reduced vegetation growth in spring, but only the SFDD shows significant (p<0.1) correlation with EVI2 summer growth anomalies. Apparent vegetation sensitivity to the SFDD varies across regional biomes and elevation zones, while an increasing SFDD trend indicates potentially larger negative impacts on regional vegetation growth with continued warming.

Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia)

This paper presents a new decadal-resolution fossil pollen record from Lake Kotokel (52°47′N, 108°07′E, 458m a.s.l.) and provides a reconstruction of the Last Glacial Maximum (LGM) vegetation and environments in the study area during this interval of globally harsh climate. Lake Kotokel is situated close to the eastern shoreline of Lake Baikal, in the boreal forest zone of southern Siberia. The analysed 190cm long section 6 of the bottom core KTK10 (KTK10/6) consists of compact, undisturbed, greenish-grey to dark-grey, slightly laminated silty clay indicating continuous lacustrine sedimentation throughout the LGM period ca. 26.8–19.1cal.kaBP. The age model is supported by 11 calibrated AMS dates. The results of pollen analysis and pollen-based biome reconstruction show that steppe and tundra vegetation composed of grasses and various herbs dominated ca. 26.8–19.1cal.kaBP. Occurrence of conifer tracheids and stomata throughout the record, together with small quantities of boreal conifer and broadleaf tree and shrub taxa pollen, suggests the presence of single trees or small forest stands in the lake vicinity, most likely in the river valleys. Application of the biomisation method and the resulting numerical scores of the most characteristic biomes (steppe, tundra and cold deciduous forest) show minor fluctuations, signifying stability of the regional vegetation cover during the analysed LGM interval. In contrast to the regional biomes, the local environmental indicators demonstrate greater sensitivity of the lake system to decadal- and century-scale climate variability. The highest pollen percentages of Ranunculaceae, representing littoral/meadow vegetation communities, are registered ca. 23.8–23.4cal.kaBP. This and an increase in coarse-grained sand particles together with slightly increased total inorganic carbon (TIC) values representing calcite in the KTK10/6 sediment provide evidence of a much shorter than present distance between the coring site and the shoreline and a reduced lake area, in line with a drier-than-present LGM climate. A general stability of the grassland vegetation in the study region ca. 26.8–19.1cal.kaBP and relatively constant total organic carbon (TOC) values support the hypothesis that this productive vegetation could stably serve as a perennial food resource for large populations of herbivores, thus providing favourable environments for the local hunter–gatherers inhabiting the Lake Baikal region during the LGM interval.