贺兰山东坡高山林线青海云杉(Picea crassifolia)径向生长对气候因子的响应

RESPONSE OF TREE RADIAL GROWTH OF PICEA CRASSIFOLIA AT ALPINE TIMBERLINE TO CLIMATE FACTORS IN EASTERN SLOPE OF HELAN MOUNTAIN

基于建立的贺兰山东坡高山林线青海云杉树轮宽度年表,分析了青海云杉径向生长与该区气温、降水和帕尔默干旱指数(PDSI)等主要气候因子之间的关系.结果显示研究区青海云杉径向生长与5月的降水呈显著正相关(P<0.05),与1、3、6月的气温呈显著负相关(P<0.05),而与除当年9月外的所选各月PDSI均呈显著正相关(P<0.05).分析表明,贺兰山林线附近树木径向生长对气候因子具有一致的响应关系,山地相对较低的气温条件对树木生长限制作用不明显,而干旱是限制林线树木径向生长的主要因子.

relationships between tree radial growth of Picea crassifolia and climatic variables such as temperature, precipitation and PDSI were analyzed from established standard ring-width index series of Picea crassifolia at alpine timberline on the eastern slope of Helan Mountains. In the study area, tree radial growth was significantly positively correlated with precipitation in May （P〈0.05） and PDSI in every month selected except September （P〈0.05）, and significantly negatively correlated with temperature in January, March and June （P 〈0.05）. Analysis showed that tree radial growth was sensitive and consistent to climate near timberline. Not low temperature but drought was the major limiting factor to tree radial growth at alpine timberline.