在川西高原松潘县二道海林区的东南坡、西北坡和扎日寺林区的东坡用零信号法建立4条云、冷杉树轮年表,通过年轮-气候响应分析、多因素方差分析等方法研究不同坡向树木生长对快速升温的响应差异.结果表明:快速升温(1980年)后,东坡紫果云杉生长显著加速(0.011 a^-1),而西北坡紫果云杉生长则显著降低(-0.006 a^-1),东南坡紫果云杉和西北坡岷江冷杉生长降低,但不显著.随着快速升温,不同坡向云、冷杉径向生长与气候因子的关系均出现显著变化.快速升温后,生长季温度对东坡紫果云杉径向生长的促进作用显著增加,对东南坡和西北坡紫果云杉径向生长的抑制作用也显著增加,但生长季温度对西北坡岷江冷杉径向生长的影响在升温前后变化不明显.5月降水量对东坡紫果云杉径向生长由升温前的抑制作用变为升温后的显著促进作用,而对东南坡和西北坡紫果云杉径向生长的抑制作用显著增加,5月降水量对西北坡岷江冷杉径向生长的影响在升温前后变化不明显.树轮与帕尔默干旱指数响应分析表明,快速升温后,不同坡向的土壤湿度变化是造成树轮响应差异的重要原因.多因素方差分析表明,坡向与温度、降水的综合作用是影响紫果云杉径向生长的重要因素.因此,在模拟预测树木生长对气候变暖的响应动态时,应考虑不同坡向与温度、降水的综合作用.
By using an empirical ' signal-free' standardization approach, we constructed four Picea purpurea and Abies faxoniana tree-ring chronologies at southeast and northwest slope aspects of Erdaohai and east slope aspect of Zharisi, Songpan, west Sichuan, China. The response analysis and multivariate analysis of variance between tree rings and climatic variables were conducted to explore the divergent responses of tree growth at different slope aspects to the recent warming climate. Results showed that tree growth of P. purpurea at east slope aspect was obviously accelerated (0.011 a^-l) since rapid warming in 1980, whereas those at northwest slope aspect was significantly reduced ( -0.006 a^-1 ). Tree growth of P. purpurea at southeast slope aspect and A. faxoniana at northwest slope aspect decreased in significantly. With the rapid warming, growth-climate relationships of P. purpurea and A. faxoniana at different slope aspects changed significantly. After rapid warming in 1980, the promoting effects of growing season temperature (GST) on P. purpurea growth at east slope increased significantly, while the inhibitory effects of GST on its growth at southeast and northwest slopes also increased significantly. However, the effects of GST on A. faxoniana growth at northwest slope did not change significantly before and after rapid warming. The effects of precipitation in May (PM) on P. purpurea growth at east slope was changed from inhibition before rapid warming to significant promotion alter rapid warming, while the inhibitory effects of PM on P. purpurea growth at southeast and northwest slopes increased significantly. For A. faxoniana at northwest slope, however, it did not change obviously before and after rapid warming. The response analysis between tree growth and the Palmer drought severity index (PDSI) showed that soil moisture variations at different slope aspects were an important reason of tree-ring growth response difference since rapid warming. In addition, the results of multivariat