摘要
研究了不同放牧强度下高寒矮嵩草草甸建群种矮嵩草 (Kobresia humilis)构件种群的数量在放牧第四年 (1991年 )和停牧 1年后 (1993年 )的季节动态特性与反应。结果表明 ,随放牧强度增加 ,矮嵩草每分株中分蘖和叶片的数量增加 ,累积存活叶片数达到最大值的时间推迟。在各放牧处理下 ,分蘖数、生殖枝数和累积总叶数具有相同的季节动态过程。分蘖出生率分别在 5月中下旬和 8月下旬各有 1个高峰期 ,死亡率高峰在生长季末。叶片出生率和死亡率的周期与分蘖同步 ,叶片出生率和死亡率大小的变化也同步。矮嵩草分蘖和叶片群体的存活曲线类型分属“Deevey I”型和“阶梯”形 ,且不受放牧强度的影响。停牧 1年后 。
The seasonal dynamics and grazing responsiveness of modular populations of Kobresia humilis were studied at the fourth year (1991) of grazing under different stock intensities and after resting for 1 year(1993) in alpine meadow.The results showed that the number of tillers and leaves per ramet of modular populations of Kobresia humilis increased and the time for which the number of cumulative surviving leaves reaching its maximum was delayed with the increase of stock intensity.The seasonal dynamics of tiller,flowering tiller and total cumulative leave of the populations displayed similar variations with the change of grazing intensities.Two peaks of growth rate of tiller population were observed at the middle and last ten days of May and at the last ten days of August respectively.The peak of death rate of tiller population was at the end of season of growth.The cycle of initiation and death of leaf was nearly synchronous with that of tiller.The greatest risk of leaf death was also in concert with the highest rate birth. The pattern of survival curves was of the “Deevey type I”for tiller populations and of the “stepwise” type for leaf populations respectively.And different stock intensities had no effect on the patterns of survival curves,however, their impacts on the differences in the number of tiller and leaf populations of Kobresia humilis remained 1 year after stop grazing.
基金
中国科学院海北高寒草甸生态系统定位站基金
关键词
矮嵩草
高寒草甸
构件种群
放牧反应
种群动态
Modular population
Grazing responses
Population dynamics
Kobresia humilis
Alpine meadow
