滇西北玉龙雪山不同海拔云南松(Pinus yunnanensis)径向生长对气候因子的响应

云南松(Pinus yunnanensis)是重要的造林树种,在我国西南地区广泛分布。研究不同海拔云南松径向生长对气候变化的响应,有助于了解气候变化背景下云南松的敏感性和适应性。在滇西北丽江玉龙雪山不同海拔采集了云南松树木年轮样品,采用传统的树木年轮方法制作了不同海拔云南松树轮宽度标准化年表,并分析了不同海拔云南松径向生长与气候因子的相关性。结果表明:1)低海拔样点云南松具有较快的年平均生长速率。2)不同海拔云南松对气候因子的响应模式一致,树轮宽度与当年5—6月的降水量、帕尔默干旱指数(PDSI)和相对湿度呈正相关,与同期温度呈负相关。3)不同海拔的云南松径向生长对气象因子的响应程度不一样,即低海拔样点云南松树轮宽度与当年5月份的干旱指数、相对湿度、降水量相关系数较高;而高海拔样点的云南松树轮宽度与5—6月的降水、相对湿度、干旱指数的相关系数较低。研究表明春末夏初的水分条件是玉龙雪山云南松径向生长的主要限制因子,且低海拔地区云南松生长受水分限制更为严重,区域气候变暖和干旱化趋势可能对低海拔地区云南松的生长产生持续的负面效应。研究结果可为探讨气候变化下云南松的适宜分布区、以及云南松人工林的经营和可持续管理提供参考。

Radial growth of Pinus yunnanensis at different elevations and their responses to climatic factors in the Yulong Snow Mountain, Northwest Yunnan, China

Pinus yunnanensis is an important commercial timber tree species in southwestern China. Investigation on the radial growth of P. yunnanensis at different elevations and their responses to climatic factors is essential for understanding climatic sensitivity and adaptation of this economical important species under global climate change. We collected tree increment cores of P. yunnanensis from two elevational sites in the Yulong Snow Mountain, northwest Yunnan Province, China. Two ring-width standard dendrochronologies were developed using traditional dendrochronological techniques and their growth-climate correlations were analyzed. The results showed that 1) P. yunnanensis at lower elevation site grew faster than those at higher elevation site. 2) Radial growth of P. yunnanensis correlated positively with precipitation, relative humidity, and the Palmer Drought Severity Index (PDSI), but correlated negatively with air temperatures during the early growing season from May to June. 3) The sensitivity of radial growth of P. yunnanensis to moisture availability differed between different elevations, with higher positive correlations between tree-ring chronology and precipitation, relative humidity, and PDSI at lower elevation than that of higher elevation. These results demonstrated that radial growth of P. yunnanensis in the Yulong Snow Mountain was mainly limited by moisture availability during the late spring and early summer season. Regional warming and drying climate may have negative effects on tree growth of P. yunnanensis, especially at low elevations. Our results provide important implications for understanding potential distribution shifts of P. yunnanensis under future climate changes, as well as sustainable management of pine plantations in southwest China.