松嫩羊草草原火烧后地上生产力的变化

Change Process of Production of Sheepgrass Grassland by Different Burning Time in Songnen Plain

松嫩羊草草甸草原不同时间火烧后，对羊草种群地上初级生产力产生不同影响，伴随出现不同的次级生产力变化格局。早春火烧提高羊草种群地上生产力，８月份产量增加１４．６％，晚春火烧导致羊草种群地上生产力下降，８月份产量降低１５．５％，与未烧相比差异显著。火烧后，叶茎比率提高，尤其是晚春火烧处理，叶茎比率最高。火烧后，蝗虫数量增多，但晚烧地７月份蝗虫数量多，早烧地８月份蝗虫数量多，未烧地基本保持稳定，三者之间差异显著。由于蝗虫取食羊草叶片，造成损失，导致收获样方法实测产量和实际合成产量有较大差别，实测样方产量不能说明不同时间火烧对产量的影响。

Different burning time of sheepgrass grassland(Aneurolepidium chinense)in Songnen plain(Iog.44°45,lat.123°45')make different effect on aboveground primary preduction of sheepgrass population,corresponding with different change pattern of second production,mainly grasshopper.Early springburning(5 April)increased abeveground primary preduction 14.6% of sheepgrass population and laterspring burning(15 May)decreased the preduction 15.4% of that.After burning,the weight ratio of leaf Vs stem increased,and the number of grasshopper increased,but,in July in early spring burned plot,thenumber of grasshopper is more than that in later burned plot,however,in August,that is reversesignificancely.