短花针茅荒漠草原植物群落组成对模拟降水的响应

Response of plant community composition to simulated precipitation in Stipa breviflora desert steppe

摘要:

为了阐明降水变化对荒漠草原植物群落组成的影响，在短花针茅荒漠草原进行了模拟增加降水和减少降水的试验。试验有 4 种处理，分别是减少 50% 自然降水量(P1)、自然降水量(P2)、增加 50% 自然降水量(P3)、增加 100% 自然降水量(P4)。结果表明：(1)增加 50% 降水量对土壤含水量没有显著影响，增加 100% 降水量时土壤含水量明显增加，减少 50% 降水量使土壤含水量显著降低(P ＜ 0. 05)；(2)群落物种丰富度和多样性指数没有随着降水增加而增加，但是群落内部的组成却发生了变化，多年生杂类草和一、二年生草本的比例显著增加(P＜0. 05)，而减少降水使得一、二年生草本显著减少(P＜0. 05)。试验结果有助于更好地预测植物群落组成对降水变化的响应，制定合理的草原保护措施来提高草原的生态系统稳定性，从而应对降水变化的影响。

Abstract:

In order to understand the effects of precipitation changes on plant community composition in desert steppe，an experiment was conducted to simulate increased precipitation and decreased precipitation in Stipa brevi- flora desert steppe. The experiment was divided into four treatments：50% decrease in precipitation (P1)，natural precipitation (P2)，50% increase in precipitation (P3) and 100% increase in precipitation . The results were as fol‐ lows：(1) The 50% increase in precipitation had no effect on soil water content (P＞0. 05)，but the 100% increase in precipitation significantly increased soil water content (P＜0. 05)，while the 50% decrease in precipitation signifi‐ cantly reduced soil water content；(2) The species richness and diversity index of the plant community did not in‐ crease with the increase of precipitation，but the composition of the community changed. The proportion of perennial forbs grasses and annuals and biennials increased significantly(P＜0. 05)，and the proportion of annuals and biennials decreased significantly with the decrease of precipitation. This discovery helps us to better predict the response of plant community composition to precipitation change，formulate reasonable grassland protection measures，and im‐ prove the stability of grassland ecosystem，so as to cope with the influence of global climate change.