Behavioural effect of grazing yak (Bos grunniens) on material circulation in east Tibetan Plateau, Qinghai Province, China

点击翻译按钮获取中文摘要

Investigation was carried out in northern and southern sites of in Tibetan Plateau, Qinghai Province, China. Northern one was a model grazing rangeland area and southern one was suspected that the degradation and desertification of grazing rangeland were going on. The purpose of this research was to obtain the fundamental data for preventing the rangelands from deterioration and desertification through investigating behaviour of yak and material circulation in rangeland ecosystem and for finally establishing sustainable grazing system of yak in the rangelands of Qinghai-Tibetan Plateau.Trial was carried out totally seven times, 3 times in Yushu Prefecture, Yushu State and 4 times in Mengyuan Prefecture, Haibei State during 4 years from 2003 to 2006. Consecutive three day recording of behavioural observation and amount of feces excreted for 3 yak cows, grazing tracking with GPS apparatus, grazing behaviour and plant species grazed, vegetation of grazing rangelands, and samples of feces, plants and soils were collected and the chemical compositions were analyzed.Average rumination time of yak in cold season was shorter, material circulation estimated by chemical composition of feces was smaller and approximately a half in southern site than in northern one. Yaks in southern site grazed even the plant species known as avoided. From these results, it is suggested that deterioration of rangeland by overgrazing might have been in progress in southern site.Even in northern site where rangeland was rotationally grazed in warm and cold seasons and was recognized the ecosystem being in good condition, it was indicated that warm season paddock was degraded and yak could not intake nutrition enough for fertilization.From these results, it is considered that alternative grazing systems should be investigated for maintaining floral diversity and preventing grazing rangeland from deterioration and desertification in Qinghai-Tibetan Plateau.