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

为了阐明阿索地区半自然草地植被类型和植物区系组成的多样化过程，我们研究了放牧和微环境对景观和取食地植物区系多样性的影响。主要研究结果如下：1.在景观水平上对芒草和日本竹草地进行了研究。通过焚烧去除植物死亡部分和割草或放牧去除植物叶片，降低了高秆草的优势度，导致植物区系组成多样化。2.分别对苦竹型和结缕草型草地的植物区系多样性进行了研究。植物区系组成受放牧和非生物环境空间异质性的影响。例如，频繁的动物访问扰乱了植物群落，并为耐践踏的物种提供了合适的栖息地，其结果是改变了植物区系组成。3.利用数字电影分析、下颌运动传感、心率传感和全球定位系统（GPS）等新的测量技术对动物行为的分析方法进行了研究。将动物的定位数据与放牧行为的二进制数据结合起来分析，可以了解植被放牧频率的时空分布。植被结构，即，冠层高度、垂直植物种类组成等，在半自然草地中，不同的利用和维护方式对不同生态层次的植被产生了一定的干扰，从而促进了草地生态系统的多样性。

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.