The edaphic control of plant diversity

Abstract

Background The central thesis of plant ecology is that climate determines the global distribution of vegetation. Within a vegetation type, however, finer‐scale environmental features, such as the physical and chemical properties of soil (edaphic variation), control patterns of plant diversity and distributions. Aims Here, we review the literature to provide a mechanistic framework for the edaphic control of plant diversity. First, we review three examples where soils have known, prevalent effects on plant diversity: during soil formation, on unusual soils and in regions with high edaphic heterogeneity. Second, we synthesize how edaphic factors mediate the relative importance of the four key processes of community assembly (speciation, ecological drift, dispersal and niche selection). Third, we review the potential effects of climate change in edaphically heterogeneous regions. Finally, we outline key knowledge gaps for understanding the edaphic control of plant diversity. In our review, we emphasize floras of unusual edaphic areas (i.e., serpentine, limestone, granite), because these areas contribute disproportionately to the biodiversity hotspots of the world. Taxa Terrestrial plants. Location Global. Conclusion Edaphic variation is a key driver of biodiversity patterns and influences the relative importance of speciation, dispersal, ecological drift, niche selection and interactions among these processes. Research is still needed to gain a better understanding of the underlying mechanisms by which edaphic variation influences these community assembly processes, and unusual soils provide excellent natural systems for such tests. Furthermore, the incorporation of edaphic variation into climate change research will help to increase the predictive power of species distribution models, identify potential climate refugia and identify species with adaptations that buffer them from climate change.

Area Not Geographic Isolation Mediates Biodiversity Responses of Alpine Refugia to Climate Change

“…Site area can mediate changes in biodiversity within refugia through several mechanisms. First, larger sites are more likely to contain a greater variety of environmental conditions (Bell et al, 1993;Hulshof and Spasojevic, 2020), which may buffer environmental change. This may be the case in alpine systems where stark topography leads to differential distribution of snow on the landscape, creating strong gradients in stress exposure and resource availability and generating a complex mosaic of distinct vegetation types that differ greatly in species composition and productivity (Bowman and Fisk, 2001;Walker et al, 2001;Bowman et al, 2003;Seastedt et al, 2004;Litaor et al, 2008).…”

Sedimentary ancient DNA shows terrestrial plant richness continuously increased over the Holocene in northern Fennoscandia

“…Changes in species richness by other drivers, such as nutrient levels, species introductions, and dispersal lags, are often context-dependent and hence difficult to predict. For example, edaphic variation, including variation in nutrient content, is hypothesized to strongly influence establishment, ecological drift, and niche selection, which all affect the local species pool, and this in turn affects richness (9). Experimental approaches have shown a non-linear impact of fertilization on Arctic plant richness and their ecosystem functions (10).…”

“…Edaphic variation is hypothesized to strongly influence establishment, ecological drift, and niche selection, which all affect the local species pool, and this in turn affects species richness (Hulshof & Spasojevic, 2020). An overall greater species richness has been reported from calcareous as compared with siliceous bedrock areas in the eastern Swiss Alps (Holzinger et al , 2008).…”

Pronounced Genetic Separation Among Varieties of thePrimula cusickianaSpecies Complex, a Great Basin Endemic

“…Additionally, in conjunction with climatic niche preferences, complex varieties maguirei, domensis , and nevadensis are found on the cliffs and crevices of exclusively limestone substrates. While it’s unclear whether these habitats are tied to mineral or pH constraints, or simply reflect preferences for moisture-retentive substrates, edaphic heterogeneity is known to contribute to plant speciation and biodiversity, both globally (Hulshof and Spasojevic 2020) and within the Great Basin (e.g. de Queiroz et al 2012).…”