Abstract:

Aims The mechanism of herbivore foraging effect on plant diversity and ecosystem functions of grasslands is the core issue of grazing ecology research. This study is aimed to examine 1) how species respond to different grazing intensity in grassland, and how plant diversity responds to different grazing intensity within different organization scales and whether there are cascade effects across multiple organization scales? 2) How herbivore foraging affects plant diversity.Methods Based on a six-year grazing experiment in Sonid Right Banner, Xilingol, the study attempted to explain the relationships between plant diversity and herbivore foraging from two perspectives, i.e. plant diversity index and herbivore preference index.Important findings Results showed that there were four modes for desert grassland plant in response to herbivore: grazing-hidden species, grazing-sensitive species, grazing-non inductive species and absolute dominant species. At the community scale, species diversity index decreased with an increased grazing intensity. Compared with no grazing, heavy grazing and moderate grazing treatments decreased community plant diversity, and the same principle is applicable to the functional group diversity. Further analysis found that differences of grazing species diversity within a functional group were mainly caused by shrubs and semi-shrubs. Compared to plots without grazing, the herbivore preference degree on the whole species was lower for moderate grazing plots than heavy grazing ones. The foraging preference order on the plant functional groups was annual and biennial forbs (AB), perennial forbs (PF), shrubs and semi-shrubs (SS) and perennial grasses (PG). The preferred species were mainly distributed in AB and PF. The diversity index of plant and preference index of herbivore were basically significant and negatively correlated (p < 0.05).

Key words: plant diversity, preference species, herbivore, desert grassland, organization scale