首页|Decline in tree-ring growth of Picea mongolica and its intra-annual eco-physiological responses to drought and CO2 enrichment in semi-arid China
Decline in tree-ring growth of Picea mongolica and its intra-annual eco-physiological responses to drought and CO2 enrichment in semi-arid China
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Episodes of drought-induced decline in tree growth and mortality are becoming more frequent as a result of climate warming and enhanced water stress in semi-arid areas.However,the ecophysiological mechanisms under-lying the impact of drought on tree growth remains unre-solved.In this study,earlywood and latewood tree-ring growth,δ13C,and δ18O chronologies of Picea mongolica from 1900 to 2013 were developed to clarify the intra-and inter-annual tree-ring growth responses to increasingly fre-quent droughts.The results indicate that annual basal area increment residuals(BAIres),which removed tree age and size effects,have significantly decreased since 1960.How-ever,the decreasing trend of earlywood BAIres was higher than that of latewood.Climate response analysis suggests that the dominant parameters for earlywood and latewood proxies(BAIres,δ13C and δ18O)were drought-related climate variables(Palmer drought severity index,temperature,rela-tive humidity,and vapor pressure deficit).The most signifi-cant period of earlywood and latewood proxies'responses to climate variables were focused on June-July and July-August,respectively.BAIres,and δ13C were significantly affected by temperature and moisture conditions,whereasδ18O was slightly affected.Decreasing stomatal conduct-ance due to drought outweighed the influence of increasing CO2 on intrinsic water use efficiency(iWUE),and ultimately led to a decline in BAIres.Compared to latewood,the faster decreasing BAIres and smaller increasing iWUE of early-wood suggested trees were more vulnerable to water stress in the early growing season.Our study provides insights into the inter-and intra-annual mechanisms of tree-ring growth in semi-arid regions under rising CO2 and climate change.
Tree growthDroughtWater-use efficiencySeasonal differencesStable isotopes
School of Geography and Tourism,Shaanxi Normal University,Xi'an 710119,People's Republic of China
The Key Laboratory of Mountain Environment Evolution and Regulation,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,People's Republic of China
CAS Key Laboratory of Forest Ecology and Management,Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang 110016,People's Republic of China
University of Chinese Academy of Sciences,Beijing 100049,People's Republic of China
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National Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNational Science Foundation of Shaanxi ProvinceFundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities
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