围栏封育下藏北高寒湿地和高寒草原水热通量特征研究  

Water and Heat Flux Characteristics of Alpine Wetland and Alpine Steppe under Grazing Enclosure on the Northern Xizang

作　　者：王壮壮 吕雅琼 魏达 祁亚辉 王小丹[1] WANG Zhuangzhuang;LÜYaqiong;WEI Da;QI Yahui;WANG Xiaodan(Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,Sichuan,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院水利部成都山地灾害与环境研究所,四川成都610041 [2]中国科学院大学,北京100049

出　　处：《高原气象》2023年第6期1416-1428,共13页Plateau Meteorology

基　　金：青藏高原第二次综合科学考察研究项目(2019QZKK0404);国家自然科学基金项目(41975135,41971145);中国科学院战略性先导科技专项(A类)泛第三极环境变化与绿色丝绸之路建设(XDA20020401);中国科学院青年创新促进会项目(2020369)。

摘　　要：围栏封育作为直接有效的退化草地恢复治理模式,广泛应用于青藏高原退化草地恢复。围栏封育显著提升植被覆盖并改变地表与大气之间的水热交换,然而当前对其如何影响高寒生态系统水热通量的定量研究不足,缺乏对影响机制的认识。本研究以藏北腹地典型高寒湿地和高寒草原为研究对象,采用涡度相关技术开展禁牧-放牧配对观测,并基于围栏内外2019年7月至2021年6月连续两年的观测数据,探究围栏封育后的地表水热平衡变化,以提升对围栏封育改变地表水热通量机制的认知。结果显示:高寒草原和高寒湿地生态系统水热通量均表现出明显的单峰型日变化特征,且分别以感热作用(波文比为1.60)、潜热作用(波文比为0.31)为主导向大气传输能量。围栏封育降低了高寒草原地表通量值,感热通量减小5.99 W·m^(-2),潜热通量减小4.84 W·m^(-2);围栏封育提升了高寒湿地的地表通量值,感热通量增加3.04 W·m^(-2),潜热通量增加30.95 W·m^(-2),围栏封育后高寒草原感热通量和潜热通量日均值均下降,高寒湿地则增加。围栏封育对地表能量通量影响强度集中于白天,夜间较弱。高寒生态系统的31组禁牧-放牧配对数据显示,围栏封育降低高寒生态系统土壤温度,提升土壤持水能力。基于土壤温度、土壤湿度、潜热通量和感热通量视角,围栏封育对高寒生态系统存在降温潜力。Grazing enclosure has been extensively employed as a direct and effective management measure for grassland restoration on the Qinghai-Xizang Plateau.Enclosures significantly increased vegetation coverage and affected the water and heat exchange between the land surface and the atmosphere.However,there is still a lack of quantitative research on how enclosures regulates water and heat fluxes in typical alpine ecosystems.Based on continuous data observed from eddy covariance system from July 2019 to June 2021 at alpine steppe and alpine wetland of the Northern Xizang,the changes of surface energy flux after enclosure was analyzed by using the eddy covariance method.The results show that:The water and heat fluxes in alpine steppe and alpine wetland shows significant unimodal diurnal variations.The exchange of land-atmosphere in alpine steppe is mainly dominated by sensible heat(Bowen ratio:1.60)except in Summer,while wetland mainly transfers energy to the atmosphere by latent heat(Bowen ratio:0.31)whole year.Grazing enclosure decreased the surface fluxes in alpine steppe,the sensible heat flux reduced by 5.99 W·m^(-2) and the latent heat flux increased by 4.84 W·m^(-2).Grazing enclosures increased the surface fluxes in alpine wetland,the sensible and latent heat raised by 3.04 W·m^(-2) and 30.95 W·m^(-2),respectively.The daily and average sensible and latent heat fluxes decreased in alpine steppe but increased in alpine wetland.The effect of enclosure on surface energy fluxes was stronger during the day and weaker at night.The collected literature data demonstrated that fencing decreased soil temperature and increased soil water holding capacity.Given the data of soil temperature,soil moisture,latent heat flux,and sensible heat flux,our study shows the cooling potential of enclosure on alpine steppe and alpine wetland.

关 键 词：藏北高原 围栏封育 水热通量 高寒湿地 高寒草原生态系统 

分 类 号：P404[天文地球—大气科学及气象学]