降水量季节分配对克氏针茅草原群落初级生产力的影响

INFLUENCE OF SEASONAL DISTRIBUTION OF PRECIPITATION ON PRIMARY PRODUCTIVITY OF STIPA KRYLOVII COMMUNITY

本文根据克氏针茅草原群落初级生产力连续１４年的定位观测资料，分析了降水量及其季节分配对群落初级生产力年度波动的影响，并应用积分回归模型，计算出１～８月各旬降水量对群落初级生产力的影响系数。结果表明：降水量的年度变化及其季节分配直接导致了克氏针茅草原群落初级生产力的年度波动；１月上旬至４月上旬及６月下旬至８月下旬的旬降水量对群落初级生产力均具有正效应，是植物对水分需求的两个关键时期。其中，１月上旬至４月上旬的正效应大于６月下旬至８月下旬。说明早期的水分条件对多年生植物的越冬、返青和生长发育极为重要；而４月中旬至６月中旬的旬降水量则相反，表现为负效应，这是植物同干旱环境长期协同进化的结果。这期间较少的降水有利于植物根系的生长和贮藏营养物质的积累，为植物进入速生期做物质和能量的准备；同时，降水量对植物群落初级生产力的影响具有放大效应。

Based on a long term(14 years) research on the primary productivity of Stipa krylovii community,the influence of seasonal distribution of precipitation on the primary productivity of the community was examined,and the influential coefficients of ten day precipitation from January to August on the primary productivity of the community were calculated using an integral regression model.The results show that annual changes and seasonal distribution of precipitation led to the fluctuation of the primary productivity of the community;positive effects of ten day precipitation from the early January to the early April and from the end of June to the end of August were found on the primary productivity,which were critical to plant growth in terms of water requirement,and the effect was greater in the first period than in the second period;the reverse pattern was found in the effect of ten day precipitation from the middle of April to the middle of June.This was mainly due to the long term coevolution of plants with their environments.Some degrees of water press may be necessary to promote the growth of roots and carbohydrate reserves.