大兴安岭兴安落叶松径向生长对气候响应的时空变化

根据兴安落叶松在大兴安岭山脉的分布特征,沿纬度设置了9个采样点,分析了兴安落叶松径向生长对气候因子响应的空间差异和时间动态。结果表明:总体上所有采样点的兴安落叶松径向生长与夏季(6—8月)标准化降水蒸散指数(SPEI)及降水量、2月SPEI及降水量呈正相关,与3月温度呈负相关。在空间上,南部年均温较高区域的兴安落叶松径向生长与2月SPEI呈显著正相关,在北部年均温较低的区域与3月温度呈显著负相关。在时间上,兴安落叶松生长-气候关系不稳定。随着温度升高,在年均温较高区域,夏季SPEI和降水量对树木生长的正效应以及夏季温度的负响应显著增强;在年均温较低区域,树木生长与3月温度负响应增强更明显。这表明气候变化改变了树木生长-气候关系,而且存在明显空间差异。在未来气候暖干化的背景下,大兴安岭兴安落叶松径向生长会受到抑制,在年均温较高且降水量较少的南部地区会因夏季水分亏缺和冬季干旱而衰退,温度较低的北部地区则可能因冬季干旱和冬季变暖而使生长受到抑制。

Spatial and temporal variations of the responses of radial growth of Larix gmelinii to climate in the Daxing'anling Mountains of Northeast China

Following the distribution characteristics of Larix gmelinii in Daxing'anling Mountains, nine sampling sites along a latitude gradient were set up to analyze the spatial difference and temporal dynamic in the responses of radial growth of L. gmelinii to climate. Overall, the radial growth of L. gmelinii was positively correlated with the standardized precipitation evapotranspiration index (SPEI) in summer (June to August), summer precipitation, February SPEI, and February preci-pitation, but was negatively correlated with the March temperature. Spatially, in the southern area of the region with higher annual average temperature, the radial growth of L. gmelinii had a significant positive correlation with February SPEI. In the northern area with lower annual average tempera-ture, the radial growth of L. gmelinii was negatively correlated with the temperature in March. Temporally, the growth-climate relationship for L. gmelinii was unstable. In the area with higher annual average temperature, the positive effects of SPEI and precipitation, as well as the negative effects of temperature in summer on growth significantly enhanced with climate warming. In the area with lower annual average temperature, the negative response of growth to March temperature enhanced more obviously. Such a result indicated that climate change would alter growth-climate relationship, with great spatial variations. Our results suggested that radial growth of L. gmelinii would be limited in the future climate of warm and dry in the Daxing'anling Mountains. The growth of L. gmelinii might obviously decline in south due to summer water deficit and winter drought, and might be inhibited in north because of warm and dry winter.