Effects of microenvironments and animal grazing on the floristic diversity of semi-natural grasslands of the Aso region

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In orader to clarify a process diversifying vegetation type and floristic composition in semi-natural grasslands of the Aso region, we studied effects of animal grazing and microenvironments on the floristic diversity at both landscape and feeding site levels. The results are as follows :1.We carried out a study at a landscape level on the grassland dominated by Miscanthus sinensis and Sasa nipponica. Removing plant dead parts by burning and defoliating vegetation by mowing or grazing reduced the dominance of tall-type grasses with the consequence that the floristic composition diversified.2.We investigated about the floristic diversity on a Pleioblastus-type pasture and a Zoysia-pasture at a feeding site level, respectively. It was suggested that the floristic compositions are affected by spatial heterogeneities of grazing and non-biotic environments. For instance, frequent visiting of animal disturbed the plant community and provided suitable habitat for the trampling-tolerant species with the consequence that floristic composition changed. We also found the several coexistent relationships between species.3.We examined the analytical methods of animal behavior using several new measuring techniques such as digital movie analysis, jaw movement sensing, heart rate sensing, and global positioning system (GPS). The spatiotemporal distributions of grazed frequency of the vegetation were understood when the positioning data of the animal was analyzed jointly with the binary data of grazing behavior. The vegetation structure, i.e., canopy height, vertical plant species composition, etc., appeared to affect both the time spent for dietary selection and bite rate of the animal.In the semi-natural grasslands, it seems that the various use and maintenance ways moderately disturb vegetation at various ecological levels and contribute the diversity of grassland ecosystems.