Quantifying the Dynamics of Livestock Distribution by Unmanned Aerial Vehicles (UAVs): A Case Study of Yak Grazing at the Household Scale

Managed grazing is the most extensive land use worldwide. Information about the spatio-temporal distribution of livestock is critical for grassland ecosystem management. However, no direct and cost-effective method exists to monitor livestock distribution under natural conditions. We proposed a practical method that uses unmanned aerial vehicles (UAVs), and tested it at a typical household pasture on the Qinghai-Tibetan Plateau. We monitored and analyzed the hourly spatial distribution of each yak (Bos mutus). We found that (1) yak information extracted by our independently developed software was sufficiently accurate (P > 0.05); (2) yak density (frequency/area/period) decreased with increasing distance from campsites in the early growing season, while the pattern reversed in the late growing season; (3) dispersion index (DI, m²/yak) of the yak herd exhibited a tendency to decrease in the morning and then to increase in the afternoon within a day; from June to September DI decreased in both the morning and afternoon, but was similar at noon. The monitoring method we developed in this study characterized the spatial distribution of the whole yak herd dynamically with high frequency, resolution, and efficiency. We conclude that this method is suitable for long-term monitoring of animal behavior, and for studying relationship between the distribution of pastoral livestock and resource availability, which will be beneficial for grassland sustainable management.     

西宁地区引种大豆生长发育特性研究

８ａ引种试验结果表明,大豆７９６４５选系在西宁生态条件下生育期平均１１６ｄ。出苗６０ｄ左右茎叶生长速度最快,７０ｄ前后开始结英,８０ｄ左右植株鲜重和干重增长速度最快,９０ｄ左右营养生长量、单株荚果数和物质生产积量均达一生最高值,１００ｄ左右苹果大小基本定型。此后生长急剧减缓渐趋成熟。最高产量达２８９５．１ｋｇ／ｈｍ＾２。