Multiple plant diversity components drive consumer communities across ecosystems

Abstract

Humans modify ecosystems and biodiversity worldwide, with negative consequences for ecosystem functioning. Promoting plant diversity is increasingly suggested as a mitigation strategy. However, our mechanistic understanding of how plant diversity affects the diversity of heterotrophic consumer communities remains limited. Here, we disentangle the relative importance of key components of plant diversity as drivers of herbivore, predator, and parasitoid species richness in experimental forests and grasslands. We find that plant species richness effects on consumer species richness are consistently positive and mediated by elevated structural and functional diversity of the plant communities. The importance of these diversity components differs across trophic levels and ecosystems, cautioning against ignoring the fundamental ecological complexity of biodiversity effects. Importantly, plant diversity effects on higher trophic-level species richness are in many cases mediated by modifications of consumer abundances. In light of recently reported drastic declines in insect abundances, our study identifies important pathways connecting plant diversity and consumer diversity across ecosystems.

Tree species identity determines wood decomposition via microclimatic effects

“…Due to equal tree density across plots, the proportion of beech trees within a plot decreases with increasing tree species richness, and therefore, its effect on soil microbial properties is expected to get weaker. While the exact mechanism behind the canceling result of spruce remains unclear, it also provides further support for the observation that other biodiversity facets—such as functional trait identity and diversity—may be crucial to understand relationships between tree diversity and soil ecosystem functions in general (Cesarz et al, ; Craven et al, ; Schuldt et al, ). More specifically, recent studies have shown that certain plant traits are especially relevant for wood decomposition, suggesting that the identity of trees can be of particular significance (Fujii et al, ; Jewell et al, ; Joly et al, ).…”

“…Biodiversity-ecosystem functioning research has shown that not only species richness per se but also other facets of biodiversity, such as trait identity and diversity reflecting functional differences among species, have to be considered to understand biodiversity effects and to reveal the underlying mechanisms (Craven et al, 2018;Ebeling et al, 2014;Eisenhauer et al, 2016;Scherer-Lorenzen, Bonilla, & Potvin, 2007;Schuldt et al, 2019). A high diversity of functional traits is likely to increase resource use efficiency through niche partitioning and resource use complementarity (Hillebrand, Bennett, & Cadotte, 2008).…”

Multiple components of plant diversity loss determine herbivore phylogenetic diversity in a subtropical forest experiment

“…species richness being promoted by factors that increase abundance, as more individuals can support viable populations of more species; see e.g. Storch et al, ) play an important role in structuring host plant–consumer relationships at our study site (see also Schuldt et al, ). Direct pathways between tree diversity and lepidopteran abundance were generally stronger than the direct pathways between tree diversity and lepidopteran diversity tested in our alternative path model approach.…”

“…We sequentially removed non‐significant pathways if their removal resulted in increased model fit (lower AIC) (Scherber et al, ). Indirect effects via abundance were recently shown to play an important role in modifying arthropod species richness (Schuldt et al, ) and might operate by influencing local population persistence or host choice behaviour of a larger number of species (Scheirs & De Bruyn, ; Storch, Bohdalková, & Okie, ). In addition, we tested two alternative model variants: first, we recalculated the models in the same way as described above, but assuming that lepidopteran diversity influenced lepidopteran abundance (i.e.…”

Climate and food resources shape species richness and trophic interactions of cavity‐nesting Hymenoptera

“…While the availability of resources has repeatedly been found to be positively correlated with species richness for endothermic taxa (Buckley, Hurlbert, & Jetz, 2012;Ferger, Schleuning, Hemp, Howell, & Böhning-Gaese, 2014), its relevance for ectotherms is more variable and depends on consumer groups, tropic level and habitat type (Schuldt et al, 2019). Furthermore, climate impacts ectotherms by limiting resource acquisition at low temperatures.…”