降水对荒漠草原地上生物量稳定性的影响

Effects of precipitation on the stability of aboveground biomass in desert steppe

基于2019-2021年的野外降水控制试验,研究了增水(+50%)、自然降水量(CK)和减水(-50%)不同降水量对荒漠草原地上生物量稳定性的影响。结果表明:蒙古冰草通过对不同降水量的适应性决定了其在群落中的优势地位,达乌里胡枝子抗旱性能最佳,极端干旱导致猪毛蒿和短花针茅优势地位显著下降,多年生禾本科植物对降水量响应更敏感;增水显著提高了群落、多年生豆科植物、一、二年生植物或多年生杂草、达乌里胡枝子和猪毛蒿地上生物量稳定性(P<0.001),极端干旱处理显著降低了多年生禾本科植物、蒙古冰草和短花针茅地上生物量的稳定性(P<0.001),群落稳定性依赖不同功能群间的补偿作用来维持;群落地上生物量稳定性的响应机制决定了荒漠草原对极端干旱的反应,异步性和群落抵抗力,并非物种丰富度,通过降低干旱条件下地上生物量的时间变异性,以及不同响应功能群间的补偿作用来促进和维持荒漠草原生态系统的稳定性。

Based on the field precipitation control experiment from 2019 to 2021,this research studied the effects of different precipitation levels;Namely,simulated increased(+50%)precipitation,natural precipitation(CK)and precipitation reduction(-50%)on the stability of above-ground biomass in desert grasslands.This field study was conducted at Dashuikeng Grassland Research Station,Yanchi County(106°58'E,37°24'N,average elevation,1560 m),Ningxia Hui Autonomous Region,China.It was found that:1)Agropyron mongolicum determined its dominant position in the community through its adaptability to different rainfall regimes.Lespedeza davurica had the best drought resistance performance.Extreme drought led to a significant decline in the dominance status of Artemisia scoparia and Stipa breviflora,which are perennial species.Poaceous plants were more sensitive to rainfall.2)Precipitation enhancement significantly improved the stability of the aboveground biomass of communities,perennial legumes,some annual plants or perennial weeds,and L.davurica and A.scoparia(P<0.001).Extreme drought treatment significantly reduced the stability of the aboveground biomass of perennial grasses,A.mongolicum and S.breviflora(P<0.001),but a compensation effect among different response functional groups maintained community stability.3)The response mechanism of compensation between species to maintain the stability of the above-ground biomass determined the response of the desert steppe to extreme drought.By reducing the temporal variability of above-ground biomass under drought conditions,these responses,including compensation among functional groups,promote and maintain the stability of the desert grassland ecosystem.