Effects of herbivores on grassland plant diversity

Herbivores and nutrients control grassland plant diversity via light limitation

“…Thus, climate, which predicts herbivory intensity, places an ultimate constraint on the effects of herbivores on plant diversity, but local plant diversity is determined primarily through herbivore effects on groundlevel light. These experimental data demonstrate that across a wide range of the world's grasslands, herbivores serve as an important force to maintain plant diversity in grassland ecosystems in which they increase ground-level light availability, consistent with the prediction that light limitation is a critical factor controlling grassland species diversity 9,16 , but counter to the interpretation of nutrient supply or ecosystem productivity as the dominant force constraining herbivore effects on local plant diversity [11][12][13][14][15][16][17] .…”

“…Previous work observed that herbivores have the greatest effects on diversity in high productivity ecosystems [11][12][13][14][15][16] , whereas the experimental results presented here demonstrate that in grasslands in which herbivores increase ground-level light, they rescue plant diversity regardless of nutrient addition or environmental productivity. This result is consistent with ecological theory 9,16,20 , simultaneously providing greater mechanistic understanding 20 and clarifying the apparent overall lack of response of plant diversity to herbivory 11 .…”

“…For example, in highly productive, eutrophic systems in which plant species extinction is likely to occur owing to a loss of ecological niches 8 , ecological theory predicts that herbivores can act to maintain local-scale plant diversity if they selectively consume the superior resource competitors 9 . Empirical studies in many ecosystem types find highly variable effects of herbivores on plant species diversity [11][12][13] , with the magnitude of herbivore mediation of diversity frequently observed to be greatest in regions of high ecosystem productivity [11][12][13][14][15][16][17] . Thus, ecosystem productivity and its regional climate drivers have been observed to mediate the local-scale effects of herbivores on plant diversity.…”

“…The availability of ground-level light is the commonly postulated mechanism modulating the relationships among plant diversity, herbivory and observed gradients of plant productivity. However, these patterns and predictions have primarily emerged from studies across observed gradients of productivity or reviews and meta-analyses based on an extremely limited number of single-site experiments that manipulate both nutrients and herbivory, often with different methods [11][12][13][14][15]17 . In most of these studies, ground-level light has not been measured.…”

Are dominant plant species more susceptible to leaf‐mining insects? A case study at Saihanwula Nature Reserve, China

“…Strengthened interspecific competition between dominants and subordinates influences the fate of the latter group, as weak competition permits an inferior species to persist for a longer period (Lie, 1973). Selective herbivory, predation, or parasitism generally suppresses the competitive capability of dominant species, allowing the coexistence of subordinate species and causing an increase in community diversity (Daleo, Alberti, Pascual, Canepuccia, & Iribarne, 2014; Hudson & Greenman, 1998; Iglesias et al., 2011; Ingram & Kirkpatrick, 2013; Kellogg & Bridgham, 2004; Lotze, Worm, & Sommer, 2000; Olff & Ritchie, 1998; Pierce, Luzzaro, Caccianiga, Ceriani, & Cerabolini, 2007; Roth, Whitford, & Steinberger, 2007; Santamaria, 2002; Smith et al., 2009). In contrast, nonselective herbivory, such as seed predation, may favor the dominant species and thus decrease overall diversity (Montgomery, 1980; Yu et al., 2014).…”