中文摘要：

以青藏高原东北部高寒矮嵩草草甸为研究对象，通过3年的野外控制实验，研究了刈割（留茬高度1，3cm及不刈割）、施肥（施和不施尿素＋磷酸二铵）和浇水（浇、不浇）处理对群落补偿生长的影响及其补偿机制．研究结果显示：随着刈割强度的增大，群落逐渐向以低矮植物为优势的方向转变，高大禾本科植物的重要值减少，矮生阔叶类杂草逐渐占据优势地位，物种多样性在各刈割处理间差异不显著．群落密度在中度刈割条件下最高，在不刈割和重度刈割处理间差异不显著．地上生物量的超补偿仅发生在中度刈割＋施肥条件下，在不施肥处理中则为低补偿．群落盖度在中度刈割下较低，不刈割与重度刈割处理间差异不显著．浇水处理能显著增加群落密度，但对物种多样性、群落盖度及地上生物量影响均不显著．上述结果说明，重度刈割处理显著降低了生产性禾本科植物的重要值，而施肥能显著提高这些植物在群落中的优势度，并增加群落密度．盖度和地上生物量．中度刈割后，群落在密度和地上生物量方面表现出的超补偿机制与施肥的正效应共同作用，提高了群落的补偿能力．

英文摘要：

A 3-years field-manipulative experiment was conducted to study the impact of clipping （stubbled 1 cm, 3 cm and unclipped）, fertilizing （fertilized and unfertilized Urea＋DAP） and watering （watered and unwatered） treatment upon the compensatory growth and mechanisms of the community in the Kobresia humilis meadow in Haibei research station. The results showed that, with increasing clipping intensity, the community structure turned to be more flourished with shorter species, the importance value of gramineae species decreased, dwarf broadleaf weeds gradually held the dominant position, and the difference in species diversity during the clipping treatment was not significant. The community density was the highest on the condition of moderate clipping, while there was no difference between heavy clipping and no clipping. Only when moderate clipping and fertilizing treatments were applied the over-compensation of aboveground biomass occured, compared to under-compensation with no fertilizing. The coverage of the community was lower under moderate clipping intensity, while there was no difference between heavy clipping and no clipping. Watering greatly increased the community density but had no significant effects on the species diversity, coverage and the aboveground biomass of the community. These results suggested that heavy clipping treatment can significantly reduce the importance value of the gramineae species and fertilizing can significantly increase their dominance in the community and increase the density, coverage and aboveground biomass of the community. The over-compensation mechanism of the community density and aboveground biomass after moderate clipping can enhance the compensatory capability of the community together with the positive effects of fertilizing.