5. Conclusions
Our results clearly show interactive effects of large herbivores
(as ecosystem engineers) and plants on insect abundance at both
order and species levels, and indicate an advantage of using
taxonomic hierarchies as well as species richness in assessing the
effects of grazing on invertebrate communities. As our understanding of species interactions at multiple trophic levels in
grassland ecosystems (Carvell, 2002) is still weak, our study offers
new insights regarding the important cascading effects involving
three major species groups. For example, the outcome of grazing by
large herbivores on insects clearly depends on the plant diversity of
pre-grazing. In our grassland system, plant resources are highly
heterogeneous, and the responses of insect community are
significantly different across diverse plant communities and under
different managements, especially of grazing by different large
herbivore species. Better understanding the complex relationships
among plants, insects, and large herbivores will facilitate future
efforts to effectively balance the trade-offs between conservation
of plants and insects and animal production to maintain
sustainability in grasslands.
Acknowledgements
We greatly thank Bingzhong Ren and Wentao Gao for the
identification of insect species; Yuanyuan Peng, Shengping Li, and
Jushan Liu for assistances in the field and lab. This project was
supported by National Natural Science Foundation of China (Nos.
31230012 and 31400345), the State Agricultural Commonweal
Project (No. 201003019), the State Science & Technology Special
Fund (No. 2012FY111900-3), and China Postdoctoral Science
Foundation (2015M571350)