中国东南部不同海拔亚热带森林中马尾松径向生长对气候的响应

Elevational Heterogeneity in Radial Growth-climate Association of Pinus massoniana in Southeastern China

摘要:

为了解我国东南部亚热带森林不同海拔树木生长对气候响应的差异，建立了福建省武夷山脉东麓2个样点的4个马尾松（Pinus massoniana）轮宽年表，对树木径向生长与气候因子进行了bootstrapped相关分析和线性混合模型（LME）拟合。结果表明，在高海拔地区马尾松径向生长对气候因子年际波动敏感性较强，主要表现为与生长季前冬季光温条件以及生长季内7月降水的正相关，生长-气候关系在不同样点间表现出较强的一致性。线性混合模型可以较好地拟合高海拔树木生长变化，当使用前1年12月平均日最高温、当年1月日照时长和当年7月降雨量3个气候变量进行拟合时，模型解释量达到0.5，其中前1年12月最高温和当年1月日照时数在模型中起到主导作用，累积相对贡献率约占80%，说明生长季前冬季的光热条件是限制高海拔马尾松径向生长最主要的气候因子。因此，我国亚热带地区高海拔的树木径向生长可能对未来气候变化有更强的敏感性，相关森林管理政策的制定需要将此纳入考虑；同时我国亚热带地区高海拔森林中的树木有被用于树轮气候重建的潜力。

Abstract:

To achieve a better understanding about the elevation heterogeneity in tree growth-climate association in southeastern China, four tree-ring width chronologies of Pinus massoniana from eastern foot of Wuyi Mountains in Fujian were established, and the relationship between radial growth and climate factors along elevation were investigated by bootstrapped correlation analysis and linear mixed effect model (LME). The results showed that radial growth of trees at higher elevation had higher sensitivity to climate and higher consistency between sites, mainly reflected as the positive correlations with the winter-spring temperature/sunshine conditions and precipitation in July. Moreover, the linear mixed effect model using three monthly climate factors, such as monthly mean daily maximum temperature in last December, monthly total sunshine hours in current January, and monthly total precipitation in current July, can explain 50% of total variance of radial growth at higher elevation, and the both fronts play a leading role in the model with cumulative relative contribution rate of 80%. So, it was suggested that the pre-growing season temperature/sunshine condition are the main factor regulating tree radial growth at high elevation, and that these trees might have higher sensitivity to future climate changes and forest management policies should take this into account. Moreover, the results showed that the trees at high elevation in subtropical forest had the potential to be used for tree ring-climate reconstruction.