庐山日本柳杉水分利用效率对气候变化的响应

Response of water use efficiency of Cryptomeria japonica to climate change in Lushan Mountain,Jiangxi Province of eastern China

【目的】分析气候变化背景下庐山日本柳杉水分利用效率(WUE)的变化特征以及WUE与主要气候因子之间的关系,为科学评估庐山日本柳杉的碳水耦合关系提供理论支持。【方法】本研究采用树木年轮稳定碳同位素方法计算日本柳杉WUE,并选择平均气温(T)、降水量(W)、平均风速(Ws)、太阳辐射(Rs)、干旱指数(SPEI、SPI、WI)等气候变化相关指标,分析气候变化背景下庐山日本柳杉水分利用效率及其对气候变化的响应。【结果】(1)1969-2018年,庐山日本柳杉树轮δ_(13)C值序列呈现下降趋势,变化区间为-23.09‰~-25.67‰,年平均-24.55‰;庐山日本柳杉WUE的年际值呈现上升趋势,变化区间为91.06~118.89μmol/mol,年平均102.37μmol/mol;(2)相关性分析表明:庐山日本柳杉WUE与上一年的7月、9-11月和当年的2-6月、9-11月的气温呈显著正相关系,与上年7-12月以及当年的1-12月风速均呈极显著负相关关系;而庐山日本柳杉WUE与各月太阳辐射、降水、SPEI、WI以及SPI未产生显著关系;(3)多元回归模型分析表明:庐山日本柳杉WUE主要与Ws_(1)(当年1月风速)、T_(3)(当年3月均温)、T_(9)(当年9月均温)、T_(-9)(上年9月均温)、Ws_(12)(当年12月风速)相关。【结论】T和Ws是影响庐山日本柳杉WUE变化的主要气候因子。W、Rs以及干旱指数(SPI、SPEI以及WI)对庐山日本柳杉WUE的变化未产生显著影响。

[Objective]This study aimed to theoretically support the scientific assessment of the carbohydrate-water coupling connection of Cryptomeria japonica.[Method]The water use efficiency(WUE) of Cryptomeria japonica was calculated using the tree-ring stable carbon isotope method in this study.Additionally,average temperatures (T),precipitation (W),average wind speeds (Ws),solar radiation(Rs),the drought index (SPEI,SPI,WI),and other climate change-related indicators were used to analyze the WUE of Cryptomeria japonica and its adaptation to climate change.[Result](1) From 1969 to 2018 the sequence of 13C values of Cryptomeria japonica tree rings in Lushan Mountain,Jiangxi Province of eastern China showed a downward trend;the variation range was -23.09‰ to -25.67‰,and the annua average was -24.55‰;the inter-annual value of Cryptomeria japonica WUE showed an upward trend;the variation range was 91.06 to 118.89μmol/mol,with an annual average of 102.37μmol/mol.(2) Correlation analysis revealed that the WUE of Cryptomeria japonica in Lushan Mountain was significantly correlated with the temperature in July,September to November of the previous year,February to June,and September to November of the current year,and significantly negatively correlated with the wind speed in July to December of the previous year and January to December of the current year.However,the solar radiation precipitation,SPEI,WI,and SPI of each month had no significant impact on the WUE of Cryptomeria japonica on Lushan Mountain.(3)The multiple regression model analysis showed that the WUE of Cryptomeria japonica on Lushan Mountain was mainly related to Ws_1 (wind speed in January of the curren year),T_3 (average temperature in March of the current year),T_9 (average temperature in September of the current year),T_(-9) (average temperature in September of the previous year),and Ws_(12) (wind speed in December of the current year).[Conclusion]T and Ws are the primary climatic variables affecting WUE of Cryptomeria japonica.The WUE of Cryptomeria japonica on Lushan Mountain is not significantly affected by W,Rs,or the drought indicators (SPI,SPEI and WI).