科尔沁沙质草地禾本科植物主要功能类型对连续放牧的反应

Responses to continual grazing of major functional types of Gramineae in Horqin sandy grassland,Inner Mongolia

为了正确评价连续放牧对禾本科牧草的影响,在科尔沁典型沙质草地,设置不同放牧强度的4块样区,连续放牧4年后对各样区植被中禾本科植物的盖度和高度进行了样方调查,分析了3个禾本科植物功能类型。结果表明:1)禾本科植物的平均盖度对重牧比较敏感,而在中牧区、低牧区和对照区差异较小;2)3个功能类型植物的高度随放牧强度的增加,呈有规律的降低。而且多年生牧草的高度对放牧强度最敏感,一年生优质牧草次之,一年生劣性牧草最不敏感;3)多年生牧草在各样区的相对盖度随放牧强度的增加,逐渐减少,在重牧区仅为0.69%;一年生优质牧草在各样区的相对盖度表现为中牧区>低牧区>重牧区>封育对照区,说明放牧干扰有提高此相对盖度的影响;一年生劣性牧草在各样区的相对盖度随放牧强度的增加,逐渐增大。

Four field plots with different grazing intensities,namely,heavy grazing (6 sheep/hm^2,HG),moderate grazing (4 sheep/hm^2,MG),light grazing (2 sheep/hm^2,LG) and a control (0 sheep/hm^2,CK) were set up on typical Horqin sandy grassland.After four years of continual grazing,the main Gramineae plants were assessed.The average height and coverage of three functional groups,namely,perennial grasses (PG),annual high-quality grasses (AHG),and annual low-quality grasses (ALG) were analyzed.There was little difference between average coverage of Gramineae plants in plots MG,LG and CK,but was markedly lower in HG,indicating greater sensitivity to the disturbance of heavy grazing.With increasing grazing intensity,PG relative coverage gradually decreased,and was only 0.69% with HG.Relative coverage of AHG showed the following differences:MG>LG>HG>CK,indicating grazing disturbance had an enhancing effect.Relative coverage of ALG gradually increased with increase of grazing intensity.Heights of the three functional types of Gramineae all decreased with increase in grazing intensity.Sensitivity of height to grazing intensity for the three types showed the following differences:PG>AHG>ALG.