施肥和刈割对青藏高原东部高寒草甸群落生物量补偿效应的影响

Effects of fertilization and mowing on community biomass compensation in eastern alpine meadow of Tibetan Plateau

通过对青藏高原东部高寒草甸植物群落在4个施肥处理及7个刈割水平下的群落生物量、物种丰富度和补偿指数的比较,分析了该类草甸群落主要特征对施肥及刈割强度差异的响应。结果表明:施肥显著增加了群落生物量,并降低物种丰富度,而刈割处理虽然增加了物种丰富度,但对群落生物量无显著影响;随着施肥量的增加,高寒草甸由莎草科和杂草类物种占优势的群落构成逐渐向禾本科物种占优势的群落构成转变;施肥可提高群落的补偿能力,在不同施肥梯度中,刈割后植物群落补偿能力也不相同;随着施肥量的增加,增加刈割强度,减少刈割次数,发生超补偿的机率增大;可见,施肥是主效应,刈割对群落主要特征的影响随营养水平的不同而发生变化。

A comparative study was made on the community biomass, species richness, and compensation index in eastern alpine meadow of Tibetan Plateau under four levels of fertilization and seven levels of mowing, aimed to understand the responses of the community to different intensities of fertilization and mowing. Fertilization increased the aboveground biomass and reduced the species richness, while mowing increased the species richness but had little effects on the aboveground biomass. With increasing fertilization, the dominance of Cyperaceae and forb species gradually shifted to grass species. Fertilization also promoted the community compensation ability, but the ability after mowing differed along the fertilization gradient. In addition, the probability of overcompensation increased with increasing mowing intensity and decreasing mowing number along the fertilization gradient. Therefore, fertilization was the main factor for community compensation, and the mowing effect on the community characters depended on fertilization level.