蚂蚁扰动对青海湖北岸高寒草甸草原群落结构影响

蚂蚁的筑丘活动是草地生态系统中不可忽视的生物干扰因子。本文针对青海湖北岸高 寒草甸草原，调查了不同大小的蚁丘及其周围对照草地的土壤理化性质和植被状况。结果表明： 蚂蚁筑丘活动显著地降低了土壤容重和土壤湿度，增加土壤温度，但对土壤pH 值的影响较小。 蚂蚁扰动改变了群落组成，增加了大部分禾本科和豆科物种的重要值而降低了杂类草的重要值。 以莎草科的矮嵩草（Kobresia humilis）和禾本科的异针茅（Stipa aliena Keng）、赖草（Leymus secalinus）、溚草（Koeleria cristata）等为主的群落逐步演替为以禾本科的异针茅和赖草为主的 群落。植物群落的盖度降低但其地上、地下生物量增加；植物群落丰富度指数降低但均匀度指 数增加。

Ants' hill-building activities on the plant community structure in alpine meadow grassland in the northern Qinghai Lake, China

As one of the most important biotic disturbance factors in terrestrial ecosystems, ants mound-building and feeding activities have profound effects on grassland ecosystems which cannot be ignored. We investigated plant height, coverage, and abundance for each species and calculated Species richness, Gleason index, Shannon-Wienerindex, Simpsonindex, and Pielou index for small ant hills (SAH), big ant hills (BAH), and the control plots in the northern shore of Qinghai Lake, China. We also calculated relative coverage, relative frequency, relative height,relative abundance, relative biomass and important values. Additionally, soil bulk density, pH values, soil moisture and soil temperature were also recorded. Our results indicated that: (1) ants'' hill-building activities significantly decreased soil bulk density and soil moisture, profoundly increased soil temperature, while have minor effects on pH values. (2) Ant hills altered community composition, increased important values of most of grasses and leguminosae, while decreased important values of weeds. (3) Ant hills decreased community coverage, Species richness, and Gleason index, increased biomass, Simpson index, and Pielou index, and altered plant height, plant coverage, and plant biomass. Ants'' hill-building activities make the community dominated by Kobresia humilis, Stipa aliena Keng, Leymus secalinus, Koeleria cristata gradually successes into the Stipa aliena Keng and Leymus secalinus community.