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Lanzhou University (2020)

The Growth Response of Picea Wilsonii Mast. to Climate Change and Intraspecific Competition in Semi-arid Area

卢康隆

Titre : The Growth Response of Picea Wilsonii Mast. to Climate Change and Intraspecific Competition in Semi-arid Area

Auteur : 卢康隆;

Grade : Master’s Theses 2020

Université : Lanzhou University

Résumé
The impact of climate change on tree growth has always been the focus of attention around the world.However,there is currently a lack of studies on the response of tree growth to increased drought and increased atmospheric carbon dioxide concentration on a long-term scale,and the role of competition in regulating tree growth in response to climate variability is also ignored.In this study,in Xinglong Mountain,a semi-arid region of northwestern China,9 Picea wilsonii Mast.standard plots were investigated,and 274 tree cores were collected.Based on the dendroecology method,the above problems were discussed by using the mixed-effect models,regression analysis,correlation analysis and variance analysis.Results found the basal area increment of trees decreased by 28%(from 7.59 to 5.43 cm2 year-1)as the intrinsic water use efficiency increased 32%(from 98.61 to 130.28μmol mol-1).Despite both Ca and drought positively affected intrinsic water use efficiency,they did not promote tree growth.Meanwhile,values of intercellular[CO2]increased 14%(from 158.83 to180.89 ppm)while the ratio of intercellular[CO2]to Ca decreased 7%(from 0.50 to0.46).In relatively wet years(precipitation>average),there was no significant difference in climate sensitivity between different competition classes.However,trees suffering from highly competitive stress were more sensitive to climate variability in all years,and particularly in the subset of years that was relatively drought(precipitation

Mots clés : tree rings; carbon isotopes; drought; carbon dioxide concentrations; climate-growth relationship; competition;

Présentation (CNKI)

Page publiée le 17 octobre 2020