中国东北样带三种针茅草原群落初级生产力对降水季节分配的响应

分析3种针茅草原群落初级生产力的年季动态,并利用积分回归模型探讨其对降水量季节性分配的响应,揭示水分有效性对植物初级生产力的影响.结果表明,制约3类针茅群落初级生产力年度变化的是水分,即前一年11月到当年8月的月降水量的年度变异是直接导致群落初级生产力年度变化的主要原因.降水的季节分配对于3类针茅群落初级生产力的形成有着不同的作用.前一年11月至当年4月降水对于植物群落的初级生产力具有正效应,从5月开始降水对植物初级生产力的促进作用有了不同程度的降低.大针茅和克氏针茅群落的季节降水量格局较为相近,但是大针茅群落与克氏针茅群落相比对降水的利用效率较高；贝加尔针茅群落则表现出更高效的降水利用率.由此可见,降水量月季分配及其对针茅群落影响程度的不同是造成3种针茅草原地带性分布的原因.

Responses of three-Stipa-communities net primary productivity along ortheast China Transect to seasonal distribution of precipitation

This paper analyzed the annual dynamics of the net primary productivity (NPP) of three Stipa communities along Northeast China Transect,and based on an integral regression model,discussed the responses of the NPP to the seasonal distribution of precipitation,aimed to reveal the effects of precipitation availability on plant NPP.The results indicated that the main factor restricting the annual dynamics of three Stipa communities NPP was the annual fluctuation of the monthly precipitation from November to next August.The precipitation from November to next April had a positive effect on the NPP,while the effect of that from May to July was decreased in different degrees.The seasonal distribution pattern of precipitation was quite similar for test Stipa communities,but S.grandis community had a higher utilization efficiency of precipitation than S.krylovii community,and S.baicalensis community had a much higher utilization efficiency of precipitation.Therefore,the seasonal distribution pattern of precipitation and its different effects on Stipa communities could be the main reasons inducing the zonal distribution of three test Stipa communities.