混牧林牧草群落利用及动态分析

通过连续３a的观测得出：芝东山区林下牧草９０％以上种类为多年生宿根植物，有着比牢固的营养生态位，生产能力。物种多样性等指标由于受上层林冠的控制常于处于一种动态的变化之中，由于各种类型林分下牧草种类不同，其生物可利用能含量亦呈不同状态，总体趋势为阔叶林下＞针叶林下＞林间旷地。每３．８７hm^2林地内一个标准牛单位连续３a牧压下，单位面积（m^2）牧草生物产量及平均高度测定指标均呈下降趋势，表现最为明显的是每平方米牧草生物产量，呈放牧第一年快速下降（５０％），第二，第三年后趋于平缓，而牧草物种多样性，均匀度却呈增加或不规律。３a的观测结果表明，林下放牧未引起上层要林分蓄 积增长量减少（２．０m高度以下林分除外）混牧后其直接经济效益产出约为原效益的２倍。

Utilization and Tendencies Analyzing of the Fodder Grass Group in the Grazing Forest

The result continuously observing and surveying for three years indicated that more than 90 percent of grass in Liaoning eastern mountainous area was Perennial plants of root whose niche was strong. The productivity and variety of species often changed because of upper trees controlling. The quantity of plants tend to broad- leaf > needle > wilderness in forest because of different grass species in every type forest. In the condition of continuously: grazing for three years, output and average height of grass tend to decrease. The reduction of output of grass was the most obvious. It reduced quickly in the first year(50%). and the next and the third year reduced slowly. However, variety and balance of grass manifest an increasing or irregular tendency. The results showed that it did not reduce upper forest reserve that grazing in the forest (not include forest less than 2. 0 meter height). the economic efficiency was double after grazing.