降水频率和强度改变对青藏高原高寒湿地土壤真菌群落的影响

Effects of changes in precipitation frequency and intensity on soil fungal communities in alpine wetlands on the Qinghai-Tibet Plateau

近年来降水模式从高频低强度逐步向低频高强度转变已成为青藏高原高寒湿地气候变化的重要特征,了解降水模式变化对真菌群落的影响对于深入理解高寒湿地对气候变化的响应与适应机制具有重要意义.以若尔盖降水模式变化长期野外控制实验平台为依托,基于ITS基因高通量测序技术和FunGuild数据库,分析不同降水模式变化强度下土壤真菌群落多样性、组成和功能特征,构建真菌共现网络.研究发现,土壤真菌群落多样性在中度降水模式变化下达到峰值,这同土壤pH与真菌多样性之间显著负相关有关(r=-0.80--0.57).降水模式变化下,真菌门水平上的优势群落相对丰度发生改变,子囊菌门(Ascomycota)和担子菌门(Basidiomycota)表现出相反的变化趋势.从群落功能上来看,降水模式变化对腐生营养型真菌群落的分布产生了重要影响.重度降水模式变化下真菌群落网络结构松散,复杂性降低,而中度降水模式变化促进了真菌群落网络规模的扩大和复杂性的提高,该结果支持了“中度干扰假说”.本研究从新的角度揭示了湿地微生物对气候变化的响应与适应机制,可丰富对复杂气候变化事件生态效应的理解.(图5表2参52)

The transition of precipitation regime from high-frequency and low-intensity to low-frequency and high-intensity has become a prominent characteristic of climate change in alpine wetlands.Understanding variation in fungal communities under changing precipitation regimes is crucial for predicting the response and adaptation of ecosystems to future climate change.Based on a multi-year field control experimental platform for changes of the precipitation regime in Zoige County,this study utilized high-throughput sequencing of the internal transcribed spacer(ITS)gene and the FunGuild database to analyze the characteristics of soil fungal community diversity,composition,and functional groups under different intensities of changes in precipitation regimes,and constructed a fungal co-occurrence network.This study found that the diversity of soil fungal communities peaked under moderate changes in precipitation regimes,which was related to the significant negative correlation between soil pH and fungal diversity indices(r=-0.80--0.57).Changes in the precipitation regime altered the relative abundance of the dominant fungal communities at the phylum level,with Ascomycota and Basidiomycota showing opposite trends.Functionally,changes in precipitation regimes significantly affected the distribution of saprotrophic fungal communities.Under the severely changes in precipitation regime,the fungal community network structure became loose and its complexity decreased;whereas,moderately changes in precipitation regime facilitated the expansion and increased complexity of the fungal community network,supporting the“intermediate disturbance hypothesis.”This study reveals the response and adaptation mechanisms of wetland microorganisms to climate change from a new perspective,enriching our understanding of the ecological effects of complex climate change events.