Effects of Climatic Factors on Tree-ring Maximum Latewood Density of Picea schrenkiana in Xinjiang, China

气候因子对新疆雪岭云杉树轮最大晚材密度的影响（英文）

Based on two tree-ring maximum latewood density （MXD） chronologies of Picea schrenkiana from the Manas River Basin, Xinjiang, the response characteristics of MXD to climate variation was discussed. Correlation analysis between MXD chronologies and instrumental records from Shihezi meteorological station showed that each chronology was significantly and positively correlated with the maximum monthly average temperature in July-August, and especially, the regional chronology （RC） was the most highly correlated variable （r=0.54, P〈0.001）. Afterwards, the maximum average temperature in July-August was reconstructed using RC. Comparison among reconstructed temperature, observed values, and the drought index （Is） confirmed that precipitation would affect MXD when the absolute value of Is is greater than 1.5σ （｜Is｜ 〉 2.5 during 1953-2008） or near to 1.5a over a 2-3 year period. The response characteristics are related to the semiarid climate of the study area. In dry years, lack of precipitation would limit the thickening of latewood cell walls and, as a result, impact MXD. Therefore, compared with relatively humid regions, the response of tree-ring MXD to air temperature similarly would be influenced by extreme moisture conditions in semiarid areas, and MXD, as a temperature proxy, should be used prudently on a limited scale.

基于新疆玛纳斯河流域2个雪岭云杉树轮最大晚材密度（MXD）年表,探讨了半干旱区MXD对气候变化的响应特征。研究结果显示,2个样点MXD年表及其区域平均年表（RC）均与7～8月平均最高气温之间呈极显著正相关关系。其中,RC与7～8月平均最高气温相关最高（r=0.54,P〈0.001）,并利用RC重建了7～8月份平均最高气温。重建值、观测值以及干旱指数（Is）之间的对比分析揭示,当干旱指数绝对值大于1.5σ（｜Is｜〉2.5,1953～2008年）或连续2～3年干旱指数绝对值接近1.5σ时,水分条件将会对MXD产生影响。这一气候响应特征与研究区半干旱气候有关,在干旱年份,水分匮缺会限制晚材细胞壁的加厚,从而影响MXD。因此,与相对湿润地区相比,半干旱地区树轮MXD对气温响应的同时也会受到极端降水状况的影响,作为气温代用指标需谨慎而有限度的使用。