光照，施肥及刈割对垂穗披碱草生长的影响

以甘南高寒草甸常见牧草垂穗披碱草（Elymus nutans）为研究对象，比较不同光照、肥力条件下，垂穗披碱草对刈割的生长和补偿反应。研究发现，光照和肥力存在交互作用。施肥、中度光照下，未刈割单株垂穗披碱草地上生物量最大，为3．239g。施肥、中度光照下，比较刈割植株地上生物量补偿发现：晚期刈割单株地上生物量的补偿大于早期刈割；刈割强度无显著影响；刈割两次单株地上生物量的补偿最大。施肥、中度光照、晚期、轻度、一次刈割时，单株垂穗披碱草地上生物量累积最大，为4．500g。全光照、未施肥条件下，刈割对单株地上生物量的补偿无影响。就补偿机制而言，植株地上生物量的增加以地下生物量为代价。

The impacts of shading, fertilization and cutting on growth of Elymus nutans

A study was conducted with Elymus nutans, a common species in alpine meadow in Gannan, to assess the effects of shading and fertilization on its growth and compensatory responses to simulated grazing. Results show that light and fertilization interacted in no-cutting treatments: aboveground biomass was greatest (3.239g per plant) at 43.5% light in a fertilized environment. For plants at 43.5% light in a fertilized environment, the compensation index for aboveground biomass was greater after late cutting than early cutting; cutting intensity had no effect, but compensation was the greatest after cutting twice. Aboveground biomass was greatest (4.500g per plant) at 43.5% light in a fertilized environment after a single early mild cutting. Cutting did not affect compensation in natural light environment without fertilizer. For the compensation principle, increased aboveground biomass was associated with decreased belowground biomass.