大兴安岭兴安落叶松和樟子松径向生长对气候变化的响应差异

Response differences of radial growth of Larix gmelinii and Pinus sylvestris var.mongolica to climate change in Daxing’an Mountains,Northeast China

大兴安岭是我国气候变化最为显著的地区之一,兴安落叶松和樟子松是该地区最为重要的树种,研究它们径向生长对气候变化的响应差异,可以为预测气候变化下我国北方森林动态提供科学依据。在大兴安岭地区选择6个样点共采集兴安落叶松树轮和樟子松树轮样芯451个,建立了12个标准年表。比较了1900年以来树木径向生长趋势,利用Pearson相关分析法分析各样点兴安落叶松和樟子松生长对气候因子的响应,运用线性混合模型探讨温度和降水对兴安落叶松和樟子松年径向生长的影响,通过滑动相关对比两个树种生长-气候关系的时间稳定性。结果表明:兴安落叶松径向生长与3月平均温度呈负相关,与上一年冬季和当年7月降水呈正相关。樟子松径向生长与当年8月温度呈正相关,与当年生长季(5—9月)降水呈正相关。冬季降雪对兴安落叶松径向生长起到重要的促进作用,夏季过多降水对樟子松径向生长起到显著的限制作用。兴安落叶松和樟子松生长对气候变化的响应存在明显差异,因此,气候变化可能会影响北方森林生态系统的树木生长、物种组成以及空间分布等。

Daxing’an Mountains is one of regions in China with the most significant climate change.Larix gmelinii and Pinus sylvestris var.mongolica are the most important species in this area.The study of their radial growth response to climate change would provide a scientific basis for predicting the dynamics of boreal forests under climate change.A total of 451 tree-ring cores of L.gmelinii and P.sylvestris var.mongolica were collected from six sites in the Daxing’an region,and 12 standard chronologies were established.We compared the tree growth trend since 1900,and analyzed their response to the climate factor in each site using Pearson correlation analysis.Effects of temperature and precipitation on the annual radial growth of L.gmelinii and P.sylvestris var.mongolica were investigated by linear mixed models.The time stability of the relationship between two species growth-climate was compared by moving correlation.The results showed that the radial growth of L.gmelinii was negatively correlated with mean temperature in March and positively correlated with precipitation in the previous winter and July of current year.The radial growth of P.sylvestris var.mongolica was positively correlated with temperature in August and precipitation in the growing season(from May to September)of current year.Snow in winter played an important role in promoting the radial growth of L.gmelinii,whereas precipitation in summer limited the radial growth of P.sylvestris var.mongolica.The responses of L.gmelinii and P.sylvestris var.mongolica to climate change were significantly different,which affected tree growth,species composition,and spatial distribution in the boreal forests.