Global patterns and determinants of vascular plant diversity
03 Apr 2007-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 104, Iss: 14, pp 5925-5930
TL;DR: This work investigates the global-scale species-richness pattern of vascular plants and examines its environmental and potential historical determinants, highlighting that different hypotheses about the causes of diversity gradients are not mutually exclusive, but likely act synergistically with water–energy dynamics playing a dominant role.
Abstract: Plants, with an estimated 300,000 species, provide crucial primary production and ecosystem structure. To date, our quantitative understanding of diversity gradients of megadiverse clades such as plants has been hampered by the paucity of distribution data. Here, we investigate the global-scale species-richness pattern of vascular plants and examine its environmental and potential his- torical determinants. Across 1,032 geographic regions worldwide, potential evapotranspiration, the number of wet days per year, and measurements of topographical and habitat heterogeneity emerge as core predictors of species richness. After accounting for environmental effects, the residual differences across the major floristic kingdoms are minor, with the exception of the uniquely diverse Cape Region, highlighting the important role of historical contingencies. Notably, the South African Cape region contains more than twice as many species as expected by the global environmental model, confirming its uniquely evolved flora. A combined multipredictor model explains 70% of the global variation in species richness and fully accounts for the enigmatic latitudinal gradient in species richness. The models illustrate the geographic interplay of different environmental predictors of species richness. Our findings highlight that different hypotheses about the causes of diversity gradients are not mutually exclusive, but likely act synergistically with water- energy dynamics playing a dominant role. The presented geostatistical approach is likely to prove instrumental for identifying richness patterns of the many other taxa without single-species distribution data that still escape our understanding. biodiversity historical contingency latitudinal gradient macroecology species richness
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American Museum of Natural History1, University of Tartu2, University of Colombo3, Royal Netherlands Academy of Arts and Sciences4, University of Florida5, University of Palermo6, Goethe University Frankfurt7, Hobart Corporation8, Nakhon Phanom University9, University of Bamenda10, University of Gothenburg11, Naturalis12, Swedish University of Agricultural Sciences13, Royal Botanic Gardens14, Universiti Malaysia Sabah15, United States Department of Agriculture16, Forest Research Institute Malaysia17, Humboldt State University18, Chinese Academy of Sciences19, Landcare Research20, University of Western Australia21, Estonian University of Life Sciences22, University of Southern Queensland23, Botanic Garden Meise24, Manchester Metropolitan University25, James Cook University26
TL;DR: Diversity of most fungal groups peaked in tropical ecosystems, but ectomycorrhizal fungi and several fungal classes were most diverse in temperate or boreal ecosystems, and manyfungal groups exhibited distinct preferences for specific edaphic conditions (such as pH, calcium, or phosphorus).
Abstract: Fungi play major roles in ecosystem processes, but the determinants of fungal diversity and biogeographic patterns remain poorly understood. Using DNA metabarcoding data from hundreds of globally distributed soil samples, we demonstrate that fungal richness is decoupled from plant diversity. The plant-to-fungus richness ratio declines exponentially toward the poles. Climatic factors, followed by edaphic and spatial variables, constitute the best predictors of fungal richness and community composition at the global scale. Fungi show similar latitudinal diversity gradients to other organisms, with several notable exceptions. These findings advance our understanding of global fungal diversity patterns and permit integration of fungi into a general macroecological framework.
2,346 citations
Cites background or methods from "Global patterns and determinants of..."
...Alternatively, lower fungal richness could be related to the disproportionately strong shifts in biomes during the Pleistocene, which impoverished the African flora (18)....
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...To determine the relationship between plant and fungal richness, we relied on co-kriging values from the global vascular plant species richness data set (18), which covered 96....
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TL;DR: This work provides the first quantitative support for the generality of positive heterogeneity-richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identifies specific needs for future comparative heterogeneity- richness research.
Abstract: Environmental heterogeneity is regarded as one of the most important factors governing species richness gradients. An increase in available niche space, provision of refuges and opportunities for isolation and divergent adaptation are thought to enhance species coexistence, persistence and diversification. However, the extent and generality of positive heterogeneity–richness relationships are still debated. Apart from widespread evidence supporting positive relationships, negative and hump-shaped relationships have also been reported. In a meta-analysis of 1148 data points from 192 studies worldwide, we examine the strength and direction of the relationship between spatial environmental heterogeneity and species richness of terrestrial plants and animals. We find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness. The use of equal-area study units, spatial grain and spatial extent emerge as key factors influencing the strength of heterogeneity–richness relationships, highlighting the pervasive influence of spatial scale in heterogeneity–richness studies. We provide the first quantitative support for the generality of positive heterogeneity–richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identify specific needs for future comparative heterogeneity–richness research.
1,161 citations
Cites background or result from "Global patterns and determinants of..."
...We expected a positive effect of ambient energy, measured as mean PET, as previous studies have found topographic EH to be much more important for mammal and plant species richness in high than in low energy regions (Kerr & Packer 1997; Kreft & Jetz 2007)....
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...…energy, water availability and productivity, area, biotic interactions and environmental heterogeneity, and factors related to historical processes such as phylogenetic niche conservatism and geological or climatic history (Currie 1991; Hawkins et al. 2003; Kreft & Jetz 2007; Field et al. 2009)....
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...(2) The effect of EH is stronger in regions with higher energy availability, where energy is not a limiting factor of species richness (Kerr & Packer 1997; Kreft & Jetz 2007)....
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Cornell University1, University of Missouri2, California State University, Fresno3, University of Leeds4, University of Massachusetts Amherst5, University of Melbourne6, North-West University7, University of Waikato8, Butler University9, Swedish University of Agricultural Sciences10, Helmholtz Centre for Environmental Research - UFZ11, Royal Institute of Technology12, Charles University in Prague13, Stellenbosch University14, Academy of Sciences of the Czech Republic15, University of Queensland16
TL;DR: It is found that the majority of urban bird and plant species are native in the world's cities, with the most common being Columba livia and Poa annua and few plants and birds are cosmopolitan.
Abstract: Urbanization contributes to the loss of the world's biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the world's cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.
1,100 citations
TL;DR: Two major patterns emerged: coastal species showed maximum diversity in the Western Pacific, whereas oceanic groups consistently peaked across broad mid-latitudinal bands in all oceans, and changes in ocean temperature, in conjunction with other human impacts, may ultimately rearrange the global distribution of life in the ocean.
Abstract: Using large-scale data sets, these authors present a new assessment of global marine species diversity and its correlation with environmental and spatial parameters.
1,073 citations
TL;DR: This work quantifies geographic patterns of endemism-scaled richness (“endemism richness”) of vascular plants across 90 terrestrial biogeographic regions, including islands, worldwide and evaluates their congruence with terrestrial vertebrates.
Abstract: Endemism and species richness are highly relevant to the global prioritization of conservation efforts in which oceanic islands have remained relatively neglected. When compared to mainland areas, oceanic islands in general are known for their high percentage of endemic species but only moderate levels of species richness, prompting the question of their relative conservation value. Here we quantify geographic patterns of endemism-scaled richness (“endemism richness”) of vascular plants across 90 terrestrial biogeographic regions, including islands, worldwide and evaluate their congruence with terrestrial vertebrates. Endemism richness of plants and vertebrates is strongly related, and values on islands exceed those of mainland regions by a factor of 9.5 and 8.1 for plants and vertebrates, respectively. Comparisons of different measures of past and future human impact and land cover change further reveal marked differences between mainland and island regions. While island and mainland regions suffered equally from past habitat loss, we find the human impact index, a measure of current threat, to be significantly higher on islands. Projected land-cover changes for the year 2100 indicate that land-use-driven changes on islands might strongly increase in the future. Given their conservation risks, smaller land areas, and high levels of endemism richness, islands may offer particularly high returns for species conservation efforts and therefore warrant a high priority in global biodiversity conservation in this century.
930 citations
Cites background from "Global patterns and determinants of..."
...The high values of tropical montane areas might be partly because of steep elevational and climatic gradients resulting in high species turnover (41, 46, 47)....
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References
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TL;DR: A ‘silver bullet’ strategy on the part of conservation planners, focusing on ‘biodiversity hotspots’ where exceptional concentrations of endemic species are undergoing exceptional loss of habitat, is proposed.
Abstract: Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.
24,867 citations
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26 May 1995TL;DR: In this article, the authors present a hierarchical dynamic puzzle to understand the relationship between habitat diversity and species diversity and the evolution of the relationships between habitats diversity and diversity in evolutionary time.
Abstract: Preface 1 The road ahead 2 Patterns in space 3 Temporal patterns 4 Dimensionless patterns 5 Speciation 6 Extinction 7 Evolution of the relationship between habitat diversity and species diversity 8 Species-area curves in ecological time 9 Species-area curves in evolutionary time 10 Paleobiological patterns 11 Other patterns with dynamic roots 12 Energy flow and diversity 13 A hierarchical dynamic puzzle References Index
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TL;DR: The steps of model selection are outlined and several ways that it is now being implemented are highlighted, so that researchers in ecology and evolution will find a valuable alternative to traditional null hypothesis testing, especially when more than one hypothesis is plausible.
Abstract: Recently, researchers in several areas of ecology and evolution have begun to change the way in which they analyze data and make biological inferences. Rather than the traditional null hypothesis testing approach, they have adopted an approach called model selection, in which several competing hypotheses are simultaneously confronted with data. Model selection can be used to identify a single best model, thus lending support to one particular hypothesis, or it can be used to make inferences based on weighted support from a complete set of competing models. Model selection is widely accepted and well developed in certain fields, most notably in molecular systematics and mark-recapture analysis. However, it is now gaining support in several other areas, from molecular evolution to landscape ecology. Here, we outline the steps of model selection and highlight several ways that it is now being implemented. By adopting this approach, researchers in ecology and evolution will find a valuable alternative to traditional null hypothesis testing, especially when more than one hypothesis is plausible.
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