养分添加对天山高寒草地植物多样性和地上生物量的影响

为揭示高寒草地物种多样性和地上生物量以及二者之间关系对养分添加的响应模式, 该研究以天山高寒草地为对象, 通过两年的多重养分添加实验, 研究氮(N)、磷(P)、钾(K) 3种养分单独和组合添加对天山高寒草地群落物种多样性和地上生物量的影响。结果表明: (1)养分添加使当地植物物种多样性不同程度地减少, 其中以N + P、N + K、N + P + K添加的效应最为显著, 多重养分添加导致的土壤生态位维度降低是当地物种丧失的重要原因。(2)养分添加能显著提高群落地上生物量, 其中N为第一限制养分, 解除N限制后P和K成为限制养分, N + P + K复合添加对地上生物量的提高最为显著。(3)养分添加两年后, 地上生物量与物种丰富度之间无显著回归关系且地上生物量增加主要是由于禾草类生物量增加导致, 说明地上生物量主要由少数优势种决定而非群落物种数。

Effects of nutrient addition on plant diversity and above-ground biomass in alpine grasslands of Tianshan Mountains,China

Aims The objectives were to reveal the response patterns of plant species diversity and above-ground biomass to nutrients addition and to clarify their relationships in alpine grasslands of Tianshan Mountains. Methods The nitrogen (N), phosphorus (P) and potassium (K) addition experiments were conducted in Tianshan alpine grasslands. The single factor effects and the interaction effects on plant species diversity and above-ground biomass were studied from 2019 to 2020. Important findings 1) Nutrient addition reduced plant species diversity of local community. Especially, the addition of N + P, N + K and N + P + K showed significant effects, suggesting that the decrease of soil niche dimension caused by multiple-nutrient addition was an important reason for local species loss. 2) Nutrient addition significantly increased above-ground biomass of local plant communities, with the highest above-ground biomass being found under N + P + K treatment, indicating that N was the first limiting resource, P and K became the limiting resources after N limiting was alleviated. 3) There was a negative linear regression between species diversity and above-ground biomass following two years of nutrient addition, which indicated that the dominant species but not species diversity determined above-ground biomass at our study site.