鼢鼠土丘演替对植物功能群与生产力的影响

利用空间序列代替时间序列的方法, 就高寒草甸鼢鼠土丘演替对植物功能群(生活型功能群和适口性功能群)及生产力的影响进行了研究。结果表明,鼠丘的演替对生活型功能群的影响表现为: 一年生 (或二年生)植物的物种多样性随着演替的进程而减少; 多年生禾草的物种多样性随演替的进程而增加; 莎草类和多年生杂类草的物种多样性均随演替的进程表现出单峰曲线格局。一年生植物的生产力随着演替时间的增加而下降, 多年生禾草和莎草类的生产力则在演替后期达到最大, 多年生杂类草生产力的峰值则出现在演替的中期阶段。 对牧草适口性功能群的影响为: 随着演替年限的增加, 有毒牧草和良等牧草功能群的物种多样性呈现出先增 (2~6年间) 后降 (6年以后) 的变化趋势; 而劣等、中等和优等牧草功能群的物种多样性均随着演替年限的延长而大幅度增加。有毒牧草和良等牧草的生产力亦呈现出先升后降的变化趋势; 劣等牧草的生产力随演替年限的增加而减少; 中等牧草和优等牧草的生物量均随演替年限的延长而急剧增加。由此可见, 鼢鼠土丘的演替使植物群落功能群多样性和草地生产力水平均有程度不同的提高。

Effects of zokor-mound succession on plant functional group and productivity

Using a spatial sequence instead of a temporal sequence approach,the species diversity and productivity of different plant functional groups, including life form groups and palatability groups, were investigated along a successional gradients of zokor-mond in alpine meadows on the Qinghai-Tibetan Plateau. Plant functional groups of both life forms and palatability, as well as productivity were strongly affected by the succession on zokor-mounds. For life form groups, with an increase of successional gradients, the diversity of annuals significantly decreased, perennial grasses significantly increased, while sedges and perennial forbs showed a unimodal tendency. The situation of successional effects on productivity for life forms was similar to that of species diversity. For palatability groups, the diversity of poisonous and fine species peaked in the intermediate stage, while the diversity of inferior, medium and excellent species increased considerably along the successional gradients. The peak productivity of poisonous and fine species was also manifested during the intermediate stage. The productivity of inferior species decreased significantly, while that of medium and excellent species increased dramatically along the successional gradients. These results indicate that the succession on zokor-mounds benefits both the plant functional group diversity and grassland productivity.