高山林线生态交错带（简称高山林线）的森林动态被誉为气候变化的天然监测器，是全球变化研究的重要内容。高山森林动态评价指标中，树木的径向生长对气候变化响应敏感、迅速，在全球变暖的背景下已经成为森林生态学的研究热点。前人在大量关注温度垂直梯度上森林动态规律的同时，越来越多地发现升温所引发的干旱胁迫对高山森林生长调控的重要作用。在我国专门针对干旱和高山森林动态的系统研究非常少，空间尺度上不同干旱梯度对高山林线森林径向生长和气候响应的作用机理仍不明确。.本项目利用滇西北-川西地区降水量随纬度升高而递减的特点，在纬度梯度上设置高山林线样地，研究林线建群树种在不同干旱胁迫和竞争梯度上各龄级的径向生长规律和对主要气候指标的响应模式，阐明建群树种径向生长的主要气候、生态控制因子和作用机理。为预测气候变化背景下该地区的高山森林动态和未来森林管理策略提供科学依据。

Forest dynamics of Alpine Treeline Ecotone, often referred as the bio-indicator of climatic change, is an important subject in global change study. Various indices have been developed monitoring forest dynamics, among them radial growth has received more and more attentions for its high sensitivity and fast responding to climatic change. While most alpine forest studies focused on growth patterns along altitudinal temperature gradients, increasing publications have reported significant effects of warming induced drought stress in controlling radial growth pattern. So far very few study was conducted about radial growth along topographic moisture gradients in China, and drought effects on alpine forests still remains unclear. .To study the radial growth and climatic response patterns of dominant trees species along drought, competition and age gradients, we plan to set alpine treeline plots along North Yunnan and West Sichuan provinces, where annual precipitation amount exhibiting significant longitudinal gradients. In each plot, tree rings of all age levels are sampled in 2 subplots with contrasting competition levels. All samples are processed, ring-widths are measured and combined into BAI (Basal Area Increment) chronologies, then compared with meteorological data. The expected results may provide insights of growth trends and evidences of dominant climatic and ecological controlling factors, both are important references for predicting alpine forest dynamics and forest management policy in this region.