长期模拟增雨对荒漠植物形态特征及空间分布格局的影响

Effects of long-term rainfall addition on the morphological characteristics and point pattern of desert plants

研究降雨变化对荒漠优势植物形态特征、空间点格局及空间关联性的影响有助于预测荒漠生态系统对全球气候变化的响应.以乌兰布和沙漠典型荒漠植物唐古特白刺和油蒿为研究对象,进行了连续10年的模拟增雨试验,运用Programita软件,采用Ripley K函数和Monte Carlo随机模拟方法,对长期模拟增雨条件下两种植物形态特征、空间格局及空间关联性进行研究.结果表明:不同增雨处理下唐古特白刺和油蒿植株的数量、高度、平均冠幅和基径均存在显著差异,增雨处理的唐古特白刺和油蒿植株数量、高度、平均冠幅和基径均显著大于对照,并随着增雨量的增大而增大.当增雨量小于72 mm时,白刺枝条具有明显的聚集分布趋势;当增雨量大于72 mm后,随着增雨量的增大,白刺枝条表现出聚集强度明显降低的趋势.油蒿植株随着增雨量的增加空间分布格局表现为随机分布-聚集分布-随机分布.就空间关联性而言,对照处理下唐古特白刺枝条与油蒿之间表现为负关联,随着增雨量的增加两者呈现无关联或正关联,当增雨量达到144 mm时,空间关联由负关联向正关联转变.未来降雨增加条件下,土壤水分明显改善,两种荒漠植物对水分的竞争减弱,更有利于白刺和油蒿的共存生长.

Studying the effects of rainfall change on morphological characteristics,spatial pattern and spatial correlation of desert dominant plants could help to predict the response of desert ecosystem to global climate change.We conducted a 10-year simulated rainfall addition experiment and examined the morphological characteristics,spatial pattern and spatial correlation of typical desert plant species,Nitraria tangutorum and Artemisia ordosica,under long-term simulated rainfall enhancement conditions in Ulanbuh desert,using Programita software,Ripley’s K function,and Monte Carlo method.The results showed that there were significant differences in the number,height,average crown and base diameter of the desert plants under different treatments.The number,height,average crown and base diameter of N.tangutorum and A.ordosica were significantly larger than CK,all of which increased with the amount of rainfall.When the amount of rainfall addition was less than 72 mm,the branch of N.tangutorum showed cluster distribution.When it was larger than 72 mm,it showed a tendency to decrease the aggregation intensity with rainfall increasing.The spatial distribution of A.ordosica population was characterized by random distribution-cluster distribution-random distribution pattern with rainfall increasing.In terms of spatial association,branch of N.tangutorum and A.ordosica showed negative correlation under control,but no correlation or positive correlation with rainfall increasing.When the amount of rainfall increased to 144 mm,the spatial association between two species changed from negative to positive.Under the scenario of increasing rainfall,soil moisture was improved,which would lead to a positive correlation between species and be more conducive to the coexistence and growth of N.tangutorum and A.ordosica.