放牧干扰对松嫩平原羊草草地的影响

１９８９年在中国东北中部的松嫩平原羊草草地研究了放牧对土壤生境，植物种群，生活型，群落结构和生物担的影响，结果表明，随放牧强度增加，土壤容重和土壤ＰＨ逐渐增加，特别是重度放牧后，增加显著，但土壤水分和土壤有机质含量却随放扩强度增加而逐渐下降，重度放牧阶段，土壤水分和有机质含量比轻度放牧阶段分别下降了２２．３％和４３．２％。

Effects of Grazing Disturbance on Leymus Chinensis Grassland in Songnen Plain

A field study was conducted to address the role of grazing on edatope , plant population, life form, community structure and community biomass in a Leymus chinensis grassland in songnen plain in northeastern China in 1989. With the increase of grazing intensity, soil bulk density and soil pH increased significantly after heavily grazed, while soil moisture and soil organic matter decreased. Comparing to that in lightly grazed stage, soil .moisture and soil organic matter in heavily grazed stage reduced by 22. 3%and 43. 2% respectively. Grazing reduced relative cover values of palatable plants (e. g.Leymus chinensis and legumes), fewer legumes occurred in heavily grazed stage. Relative cover.values of unpalatable plants (e. g. Suaeda corniculata and Aeluropus littoralis var.)increased significantly. The change of life form primarily reflected a decrease in quantitative characteristics of perennial mesophytic stock plants (e. g. Leymus chinensis, Calamaigrostis epigeios) and legumes, and a increase in annual grass (Chloris vergata) and halophytes (e. g. Suaeda corniculata, Puccinellia tenuiflora). Halophytes became dominance species after overly grazed. Community biomass decreased significantly with the increase of grazing nit6nsity. Species diversity was greatest in properly grazed stage and lowest in lightly grazed stage. Because of the increase of density of halophytes in extremely grazed stage, species diversity increased significantly.