VIR01 Effects of invertebate and vertebrate herbivory on tallgrass prairie plant community composition and biomass, Konza Prairie LTER

The effects of herbivores and their interactions with nutrient availability on primary production and plant community composition in grassland systems is expected to vary with herbivore type. Although nutrient additions are known to affect plant species diversity and primary productivity, the role of herbivores in mediating the strength of these effects also remains unclear. Herbivores may alter plant responses to nutrient additions in several ways. First, herbivores can alter the plant community response to nutrient additions by either selectively feeding on particular groups of species (e.g. grasses versus forbs) or by generally opening up space, allowing for species turnover and immigration. Second, feeding by herbivores may reduce the production response to nutrient additions if the plants cannot compensate for tissue lost to herbivory. As the functional effects of vertebrate and invertebrate herbivores on plant community composition and production may vary, the interactive effects of vertebrate versus invertebrate herbivores with nutrient additions may also vary. Here we are experimentally assessing the independent and interactive effects of removing vertebrate and invertebrate herbivores on aboveground biomass and plant community composition in native tallgrass prairie. Further, we are examining whether the removal of vertebrate and invertebrate herbivores interacts with nutrient availability. By doing this, we address three related questions: 1) what is the relative strength of the effects of invertebrate versus vertebrate herbivory in a grassland system; 2) how does herbivory (invertebrate and/or vertebrate) affect the relative abundances of grasses and forbs, the two dominant plant functional types within the ecosystem; and 3) what are the consequences of these changes in composition for aboveground net primary productivity, an important ecosystem function?