太行山南麓栓皮栎径向生长的海拔差异及其气候响应变化

Radial growth of Quercus variabilis Blume at different altitudes and its response to climate at the southern aspect of Taihang Mountains

研究气温突变前后栓皮栎(Quercus variabilis Blume)径向生长海拔差异及其气候响应的变化,可为不同海拔栓皮栎林的养护管理提供参考数据.基于太行山南麓海拔1507 m和909 m的栓皮栎样地年轮宽度数据,结合树轮序列的差值年表(RES)与气候因子分析两个海拔栓皮栎径向生长在气温突变前后对气候响应的差异,并利用胸高断面积年增长量(BAI)分析两海拔栓皮栎生长速度的差异.结果显示,高海拔栓皮栎的BAI年增长速度[0.63 cm^(2)/(10 a)]高于低海拔[0.23 cm^(2)/(10 a)],且在温度上升作用下二者差值逐渐增大.在具有明显快速升温变化(1992年)之前,高海拔栓皮栎生长主要与当年2、7月温度显著正相关,低海拔栓皮栎生长则主要与夏季(6-8月)降水呈正相关.快速升温变化之后,高海拔栓皮栎生长与当年7月平均与最低温度由正相关转变为负相关;低海拔栓皮栎生长与当年3月最高温度和7月最低温度由正相关转变为负相关.本研究表明温度升高使两海拔栓皮栎径向生长-气候因子关系发生了改变,温度对树木生长的限制作用增强,升温促使研究区内高海拔相对低海拔区域成为栓皮栎的适生区.(图7表3参38)

The investigation of the difference in the radial growth of Quercus variabilis at different altitudes and the variation in its response to climate before and after the abrupt change in temperature could provide the basis for the conservation and management of Q.variabilis forests at different altitudes.The difference in the response of radial growth of Q.variabilis to climatic factors before and after the abrupt change in temperature was analyzed via tree-ring residual chronology(RES),based on tree-ring width data from sampling sites located at altitudes of 1507 m and 909 m in the southern aspect of Taihang Mountains in China.Basal area increment(BAI)was used to analyze the difference in Q.variabilis growth rates at the two altitudes.Results demonstrated that the difference in annual BAI growth rate of Q.variabilis between the higher(0.63 cm^(2)/10 a)and lower(0.23 cm^(2)/10 a)altitudes was amplified by the increased temperature.Before the rapid temperature rise(1992),the growth of Q.variabilis at the higher altitudes was positively correlated with temperature in February and July of the current year,while the growth of Q.variabilis at the lower altitudes was positively correlated with precipitation in summer(June to August).After the rapid temperature rise,the relationship between the tree growth and temperature in July of the current year changed from a positive correlation to a negative one at the higher altitudes;and the relationship of the highest temperature and the lowest temperature in March of the current year with tree growth changed from a positive correlation to a negative one.The relationship between the radial growth-related climate factors of Q.variabilis at the two altitudes changed with the increasing temperature,whose limiting effect on the tree growth strengthened.Owing to the temperature rise,the higher altitudes have become a more suitable area for Q.variabilis than the lower altitudes.