高寒草地沙化过程土壤碳氮储量变化及其驱动机制  

Changes in soil carbon and nitrogen storage during desertification of alpine grasslands and the driving mechanisms

作　　者：宗宁[1] 缪雨珏 ZONG Ning;MIAO Yujue(Key Laboratory of Ecosystem Network Observation and Modelling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京100101 [2]中国科学院大学,北京100049

出　　处：《生态学报》2024年第15期6642-6651,共10页Acta Ecologica Sinica

基　　金：国家重点研发项目(2023YFF1304304);西藏自治区科技计划项目(XZ202101ZD0007G);西藏自治区自然科学基金项目(XZ202201ZR0026G);中国科学院西部青年学者项目(2021年)。

摘　　要：沙化问题是影响草原地区生产与牧民生活的重要环境问题。草原作为重要碳库和养分库,沙化过程可能会对其土壤碳、氮库产生重要影响。为探讨沙化过程对高寒草地土壤碳、氮储量的影响,采用空间序列代替时间演替的方法研究了藏北高原高寒草地沙化过程中驱动土壤碳、氮储量变化的因素。研究发现:(1)轻度、中度和重度沙化阶段土壤总碳、全氮储量无变化,而极重度沙化阶段碳氮流失严重(分别下降69%和55%,P<0.05)。(2)群落地上生物量随沙化程度加重逐渐降低,重度和极重度沙化草地根系生物量显著下降(分别下降47%和99%,P<0.05)。土壤容重、砾石含量随沙化程度加重呈逐渐增加趋势,而总碳、全氮含量和含水量逐渐下降,说明沙化过程导致土壤粗粒化和贫瘠化。(3)进一步分析发现,影响土壤总碳储量的因子中排前三位依次是土壤砾石含量、土壤含水量和植物地上生物量,影响土壤氮储量的因子依次是土壤砾石含量、含水量和土壤微生物丰度。综合这些研究结果,沙化过程植物群落生产力的改变对土壤碳、氮影响较小,主要受土壤砾石含量与含水量等因子驱动。沙化过程中土壤碳、氮储量存在转化阈值(重度到极重度沙化阶段),故潜在沙化高寒草地的早期防护有利于土壤碳汇的维持。Grassland desertification is an important issue in grassland areas.Desertification process not only results in the appearance of wind-sand landscapes on the surface,but also causes a significant reduction in vegetation cover and soil production potential.Grassland as an important carbon and nutrient reservoir,desertification process may also have important impacts on the changes of soil carbon and nitrogen pools.To investigate the influence of soil carbon and nitrogen storage during alpine grassland desertification,this study used spatial sequences instead of temporal succession to investigate the variations of soil carbon and nitrogen storage in different depths and the variation patterns of productivity and soil physicochemical properties during alpine grassland desertification in the northern Xizang plateau.The results showed that:(1)The lightly,moderately and severely deserted grasslands showed no change in soil total carbon and total nitrogen storage,while extremely severely deserted grasslands led to sharp carbon and nitrogen loss(69% and 55% decrease,respectively,P<0.05).(2)Above-ground biomass of the community gradually decreased with the aggravation of the degree of desertification,and the root biomass of severe and extremely severe desertification grassland decreased significantly(47% and 99%,respectively,P<0.05).Soil bulk density and gravel content showed gradual increases with the increase of desertification,while total carbon,total nitrogen content and water content gradually decreased,indicating that the desertification process led to coarse-grained and infertile soils.(3)The Shannon diversity index and Chao1 richness index of soil bacteria showed increasing trends with increasing desertification gradient,with significant differences in the severe heavy and heavy desertification gradients,while these two indices of soil fungi did not show significant differences along with the desertification gradient.(4)We used structural equation modeling to explore the factors that drove changes in soil total car

关 键 词：沙化草地 西藏高原 理化性质 驱动因子 

分 类 号：S812.2[农业科学—草业科学]