高寒生态脆弱区冻土碳水循环对气候变化的响应——以甘南州为例  

Response of Carbon and Water Cycles to Climate Change in the High-Frigid Ecotone: A Case Study of Gannan Zone

作　　者：刘双[1,2] 谢正辉 高骏强[1,3] 曾毓金 刘斌 李锐超 LIU Shuang;XIE Zhenghui;GAO Junqiang;ZENG Yujin;LIU Bin;LI Ruichao(State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth Science,University of Chinese Academy of Sciences,Beijing 100049,China;College of Mathematics and StutisticsNanjing University of Information Science and Technology,Nanfing 210044,Jiangsu,China)

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]南京信息工程大学数学与统计学院,江苏南京210044

出　　处：《高原气象》2018年第5期1177-1187,共11页Plateau Meteorology

基　　金：中国科学院前沿科学重点研究项目(QYZDY-SSW-DQC012);国家自然科学基金项目(41575096)

摘　　要：以位于青藏高原与黄土高原及陇南山地过渡带的甘南藏族自治州为例,基于考虑土壤冻融界面变化的陆面过程模式研究了1979-2012年冻土变化及水资源与生态系统碳通量对气候变化的响应。结果表明,甘南州气候态多年冻土面积约1. 5×104km2,季节性冻土约占2. 5×10~4km^2,多年冻土最大融化深度呈增加趋势,季节冻土最大冻结深度逐渐减少,整体上冻土正随着气温上升逐步退化;尽管降雨有所增加,而气温上升引起的蒸散发增加也可能是产流减少的原因之一,其中多年冻土区更为敏感,水热变化增减率较季节冻土区大;生态系统碳循环方面,北部主要表现为碳源,南部则表现为碳汇,升温促进植被生长,使得进入生态系统的碳呈略微增加的趋势,尽管总初级生产力(GPP)与净初级生产力(NPP)呈增长趋势,但植被碳利用效率逐步减小,表明气候变化背景下生态系统固碳能力有所退化;最后经多元回归分析可知,气候变化在多年冻土区可以解释66%的NPP变化与31%的生态系统净交换量(NEE)变化,而在季节冻土区则能解释45%的净初级生产力变化。The high-frigid ecotone is sensitive to climate change and often faced with shortage of water resources and environmental degradation,so quantitative study on its terrestrial ecological and hydrological change is helpful to better understand the impacts of climate.This work took the Gannan Zone as a case,based on a land model coupled with a scheme of the changes in soil freeze-thaw fronts,firstly partitioned the study area into climatological permafrost and seasonally frozen regions and explored the responses of frozen soil,water resource and carbon cycle to climate change from 1979 to 2012.The results show that climatological permafrost and seasonally frozen areas are about 15 000 km^2 and 25 000 km^2 respectively.The maximum thaw table depth in the permafrost region increased and the maximum frost table depth in the seasonally frozen region decreased.The precipitation was increasing but the warming air temperature made the evapotranspiration increased and reduced the total runoff so that the available water resource tailed off.The amplitude of decreasement was more obvious in the permafrost region.On the aspect of the ecosystem,the northern Gannan is a carbon source and the southern Gannan is a carbon sink.Climate warming promotes the plant growth,which is in favour of more carbon input from atmosphere.However,the carbon use efficiency decreases.Moreover,according to multiple linear regression analysis,it was found that in the permafrost region climate change can explain 66% of the change in NPP and 31% of the change in NEE,while in the seasonally frozen region only 45% of the change in NPP can be explained.

关 键 词：土壤冻融 生态水文 气候变暖 高寒生态脆弱带 

分 类 号：P435.1[天文地球—大气科学及气象学]