放牧压力下夏秋矮蒿草草地潜在生产力的研究

Analysis of the potential productivity of Summer-Autumn Kobresia humilis Meadow under Grazing

放牧压力下夏秋矮嵩草草地潜在生产力是指藏系绵羊在整个夏秋放牧过程中（ｔ＝４２～１８２）的累积采食量（干物质）．采用最优控制理论分析矮嵩草草地能量动态分室模型￣［２］的潜在生产力，就是通过放牧强度随着时间的最优变化，使做为目标函数的累积采食量最大．结果指出：夏秋矮嵩草草地在常放牧压力下，采食地上生活部分（Ｖ＿１）的最优放牧强度为２５．９０ｋｊ／ｍ￣２ｄ，其最大累积采食量为：Ｊ＿（１）ｍａｘ＝３２６８．１８ＫＪ／ｍ￣２。采食地上生物量（Ｖ＿１＋Ｖ＿４＋Ｖ＿５）的最优放牧强度为２５．９４ＫＪ／ｍ￣２ｄ，其最大累积采食量为：Ｊ＿（１４５）ｍａｘ＝３６３１．２２ＫＪ／ｍ￣２．在变放牧压力下，最优放牧强度见（１８）式，其最大累积采食量为：Ｊ＿（１４５）ｍａｘ＝８７４９．０１ＫＪ／ｍ￣２．是常放牧压力下的２．５倍。

The potential productivity of he summer-autumn Kobresia humilis meadow un-der grazing was defined as the total dry matter of grass grazed by Tibetan sheep over wholeseasoi、(t = 42～182).The optimal control theory was applied to analyze the compartmentmodelling of energy dynamics in Kobresia humilis meadow and the productivity was regardedas the objective function to be maximize trough optimizatiion of the course of stocking rate. Computing of modelling system provided an inference base to support a recommendatiion un-der constant grazing,the optiimal stocking rate was 25.90 kJ/m￣2d with the maximal accumu-lated intake 3268.18 kJ/m￣2, the optimal stocking rate was 25.95KJ/m￣2 d with the maxial ac-cumulated intake 3631.22 kJ/m￣2;under variable grazing,the maximal accumulated intake was8749.01 kJ/m￣2,2 5 times higher than that under constant grazing.