Abstract
AbstractAimRecent studies in southern Africa identified past biome stability as an important predictor of biodiversity. We aimed to assess the extent to which past biome stability predicts present global biodiversity patterns, and the extent to which projected climatic changes may lead to eventual biome changes in areas with constant past biome.LocationGlobal.TaxonSpermatophyta; terrestrial vertebrates.MethodsBiome constancy was assessed and mapped using results from 89 dynamic global vegetation model simulations, driven by outputs of palaeoclimate experiments spanning the past 140 ka. We tested the hypothesis that terrestrial vertebrate diversity is predicted by biome constancy. We also simulated potential future vegetation, and hence potential future biome patterns, and quantified and mapped the extent of projected eventual future biome change in areas of past constant biome.ResultsApproximately 11% of global ice‐free land had a constant biome since 140 ka. Apart from areas of constant Desert, many areas with constant biome support high species diversity. All terrestrial vertebrate groups show a strong positive relationship between biome constancy and vertebrate diversity in areas of greater diversity, but no relationship in less diverse areas. Climatic change projected by 2100 commits 46%–66% of global ice‐free land, and 34%–52% of areas of past constant biome (excluding areas of constant Desert) to eventual biome change.Main conclusionsPast biome stability strongly predicts vertebrate diversity in areas of higher diversity. Future climatic changes will lead to biome changes in many areas of past constant biome, with profound implications for biodiversity conservation. Some projected biome changes will result in substantial reductions in biospheric carbon sequestration and other ecosystem services.
Highlights
Global biodiversity patterns have long fascinated biogeographers, leading to the proposal of a range of hypotheses as to the factors underlying their origins (Gaston, 2000)
Using global biome patterns inferred from simulations made using the LPJ-GUESS dynamic global vegetation model, we show that a substantial fraction of areas that are simulated to have supported the same biome throughout the last glacial-interglacial cycle are projected to experience biome change as a consequence of 21st century climatic changes
The origins of these areas of high species diversity remain a subject of debate, and it is unlikely that any one factor fully accounts for the overall global pattern of such areas of diversity concentration, an increasing body of recent evidence supports the role of historical factors (Brown et al, 2020; Colville et al, 2020; Huntley et al, 2016)
Summary
Global biodiversity patterns have long fascinated biogeographers, leading to the proposal of a range of hypotheses as to the factors underlying their origins (Gaston, 2000). The historical factors examined were the degrees of climatic and of biome stability over the past 140,000 years, that is, the period since the penultimate glacial maximum, spanning the last glacial–interglacial cycle, and including last glacial millennial climatic fluctuations These factors were contrasted with aspects of the present environment, including topographic diversity, as well as those associated with ecological opportunity, namely rainfall seasonality and productivity. Biome stability was the strongest predictor of present regional diversity patterns, whereas ecological productivity had only a marginal influence These results parallel those of a study of endemic birds of southern Africa that concluded the degree of biome persistence over the past 140,000 years more strongly predicted present patterns of endemic species-richness than did the degree of climatic stability (Huntley et al, 2016)
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