作 者 ：彭剑峰,勾晓华,陈发虎,刘普幸,张永,方克艳
期 刊 ：生态学报 2007年 27卷 8期 页码：3268~3276
Keywords:Picea crassifolia, elevational gradient, tree-rings, climatic response,
摘 要 ：利用位于同一坡面的青海云杉树芯样本，建立了4个海拔高度的树轮宽度指数年表。分析结果表明年表序列特征值大都因海拔而不同，各年表序列对气候因子的相关性在不同高度也表现出一定的差异：树木生长都与前一年10月份月均温显著正相关，与前一年8月份和当年5、6月份月均温显著负相关；与前一年9、10月份和当年5月份的降水量都呈显著正相关，但都随海拔升高呈波状变化。树轮宽度指数与不同时段的温度和温暖指数都呈负相关，表明5～9月是该地区青海云杉生长较为活跃的季节。响应函数分析结果表明该地区低海拔生长的青海云杉受温度和降水的影响都比高海拔生长的更显著，显然不同于以前研究的森林上下限树木的生长模式。4 a表主成分中的第一主分量贡献率为81.071%，表明同一坡面影响树木生长的大环境因子是一致的。第一主分量与气候因子的相关分析同样显示出前一年生长季末和当年生长季初的水热组合是树木生长的主要限制因子，区域模拟也进一步证明了这一点。并认清了同一坡面青海云杉树轮记录的共性和差异，为今后树轮采样和研究提供一定的理论依据。
Abstract:Based on tree-ring samples of Picea crassifolia at four different elevations along a north-facing slope in the Anymaqin Mountains, northeastern Tibetan Plateau, we developed four ring-width chronologies. Statistical results showed that characteristics of chronologies are different with the increasing elevation, and the correlations of chronologies in the common interval decreased with the increasing elevation. Meanwhile, correlations between the chronologies of different elevation and the two climatic parameters (temperature and precipitaton) exhibited distinct difference: tree-rings were significantly and positively correlated with the October mean monthly temperature of precious year, and also were significantly but negatively correlated with prior August and current May and June mean monthly temperatures, respectively. All the correlations were fluctuating with the increasing elevation. Tree-rings were significantly and positively correlated with the September and October precipitation of precious years, but were decreasing along the increasing elevation. Tree-rings were also significantly and positively correlated with the May precipitation of current years, and the correlations were increasing along the increase of the elevation. Furthermore, tree-rings were also negatively correlated with temperatures of different time interval and the warming index, proving that the optimal growing season of Picea crassifolia is May-September. The results of response function analyses showed that the influence of temperature and precipitation explained most of the growth variance at the low-elevation site, but much less at the high-elevation site. The results were greatly different from previous studies that tree-rings were significantly and positively correlated with temperature at the upper forest limit, whereas were significantly correlated with precipitation at the lower forest limit. Principal component (PC) analysis was used to indicate regional variations in radial growth patterns. Of the four chronologies，the first PC explains 81.071% of their total variance. According to the response function analyses, the first PC of the four chronologies showed that moisture and temperature of the last stage of prior year growing season and the initial stage of current year growing season are the most important limiting factors of tree growth. This conclusion was further proved by regional model simulation results. Overall, our results indicated the similarities and discrepancies of Picea crassifolia ring-width chronologies on the same slope, and provided some background information for future dendrochronological studies in this area.