Invertebrate herbivory accelerates shift towards forbs caused by warming in a sedge‐dominated alpine meadow

Abstract

Invertebrate herbivory is suggested to modulate community shifts caused by climate warming in grasslands. However, experimental evidence is lacking, especially in high elevation areas. We examined the interactive effect of experimental warming and the grassland caterpillar Gynaephora alpherakjj, a typical invertebrate herbivorous insect with sedge preference, on the structure of plant community in a sedge-dominated alpine meadow in the Tibetan Plateau. We manipulated both herbivore and temperature in a full factorial field experiment using passive warming chambers over one plant-growing season. Results show that simulated warming significantly increased the aboveground plant biomass (APB) of forbs and total APB, while the presence of caterpillars significantly decreased sedge APB and total APB. The increase in consumption of sedges by caterpillars under warmed conditions can largely be ascribed to the increase in feeding time of caterpillars. Importantly, the presence of caterpillars significantly decreased the APB ratio of sedges to forbs in the warmed but not in the unwarmed chambers. These results suggest that with a warming climate, invertebrate herbivory could accelerate community shifts from sedge dominance to forb dominance in only one plant-growing season in the Tibetan alpine meadow. This shift would reduce the biomass of high-quality forage and further threaten animal husbandry in this area. Considering the harm of G. alpherakjj to grasslands, its population should be controlled more strictly under the global warming scenario.