呼伦贝尔沙地樟子松年轮生长对气候变化的响应

以内蒙古呼伦贝尔地区沙地樟子松为样本,建立了樟子松树木年轮宽度年表,应用相关分析和响应函数分析等年轮气候学方法,研究了樟子松径向生长对气候变化的响应。结果表明,樟子松年轮宽度与4月和6—9月平均温度呈显著负相关关系(P<0.05);与各月降水量多呈正相关关系,特别是与当年5—8月的月降水量呈显著正相关关系(P<0.05);树轮年表与前一年10月至当年10月的PDSI均呈显著正相关关系(P<0.05),其中与5月份PDSI的相关性最高。响应函数分析表明,年表与当年6—7月的平均气温、上一年10月和当年5—7月份的降雨存在显著的相关性,与5—7月份PDSI存在较显著的正相关性;综合来看,呼伦贝尔沙地樟子松生长同时受降水和温度的影响,其径向生长与气候因子间的关系属于降水敏感型,为区域降水重建提供了科学基础。

Response of tree-ring width of Pinus sylvestris var. mongolica to climate change in Hulunbuir sand land, China

In order to analyze the response of tree radial growth on the climate change in the semi-arid area,the tree-ring width chronology of Pinus sylvestris var.mongolica in Hulunbuir,Inner Mongolia,including the standard chronology(STD),residual chronology(RES) and autoregressive chronology(ARS),was developed by fitting a negative exponential in this paper.According to the analysis on statistical characteristics,STD chronology showed quite well correlation between samples of different trees(correlation coefficient between trees,namely r = 0.520,P <0.01),indicating good consistency of variance characteristics of the ring-width among different trees,and thus the climate information recorded by those sampled trees can be regarded as reliable.The relationship between ring width and climate factors such as monthly mean precipitation and temperature from the previous October to current October was analyzed by correlation analysis and response function analysis during the observation period(1952—2008).The results indicate that the tree-ring width is negatively correlated to the monthly mean temperature,and the data shows a significant negative correlation from June to September in the current year(P <0.05).The mean temperature,especially the maximum temperature from June to August may constrain tree growth indirectly due to the enhanced evapotranspiration and decreased availability of soil moisture.The tree-ring width is significantly positively correlated to the monthly precipitation from May to August in the current year(P <0.05),and the highest correlation coefficient is observed between tree-ring width and the precipitation of current July(r=0.394,P<0.05).Low total annual precipitation is generally regarded as the main factor to constrain the growth of trees,indicating a clear physiological sense for the notable positive correlation between tree-ring width index and precipitation.There is no significant correlation between the tree-ring width and the precipitation from previous December to current April,but in general they were positively correlated.The tree-ring width chronology is significantly positively correlated with the Palmer Drought Severity Index(PDSI) from last October to current October during 1951—2005,which comprehensively reflects the effect of available soil moisture,precipitation and temperature,especially during May.The response function analysis showed that the chronology is significantly correlated with the average temperature from June to July,the amount of precipitation from May to July of the current year,and that of last October,and positively related to the PDSI from May to July.These results show that the tree-ring width of Pinus sylvestris var.mongolica in Hulunbuir is affected by the temperature and precipitation in the growing seasons simultaneously,but the effect of precipitation on the tree radial growth is much greater than that of temperature on the yearly scale.In general,precipitation is a direct limiting factor to the radial growth of Pinus sylvestris var.mongolica in Hulunbuir area,while the temperature is an indirect limiting factor.Namely,the radial growth of Pinus sylvestris var.mongolica is more sensitive to precipitation.This study will be helpful for the precipitation and temperature reconstruction of Hulunbuir region.