辽宁西部人工林油松径向生长对气候要素的响应

Response of radial growth of planted Pinus tabuliformis in western Liaoning to climatic factors

全球气候变化对森林生态系统产生广泛影响,特别是对气候响应敏感的农牧交错带。辽西丘陵位于我国农牧交错带东北部,为探究辽西丘陵人工林油松与气候要素的关系,基于树木年代学方法,利用树轮宽度年表,对温度、降水、scPDSI及生长期要素进行相关分析,探究气象因子对树木径向生长的影响情况。结果表明:油松标准化年表与上年7月、9月及当年5月的气温呈负相关,相关系数分别为−0.457、−0.426、−0.471(p<0.05),与当年5月的降水量呈正相关,相关系数为0.52(p<0.05);年表与逐月scPDSI显著正相关,并表现出相近的周期变化,表明水分胁迫是研究区油松生长的关键限制因子;在不同阈值温度下,辽西人工林油松径向生长与生长期活动积温和持续天数呈负相关,由高温引起的水分蒸发是影响其径向生长的关键因子。最低温11℃阈值下对树木生长期影响大,年表与其初日位序、积温、持续天数的相关系数分别达到0.663、−0.619、−0.732(p<0.01);通过V-S模型模拟出辽西油松的生长对春季的9.0℃和秋季的9.5℃较敏感,生长期为4—10月,生长速率的变化受温度和土壤湿度变化的影响。因此在进行人工油松林区经营抚育时,可适当考虑造林树种对不同气候因子响应的敏感期,注意水热合理配置,以提高林区生态林的营林质量。

Background,aim,and scope Western Liaoning is located in the northeastern part of the agro-pastoral ecotone where a region influenced by global climate change in China.The relationships between radial growth of planted Chinese pine(Pinus tabuliformis)and climate factors were analyzed by using tree-ring width index and meteorological data in western Liaoning.This study is of great significance for the management and maintenance of the planted P.tabuliformis forest under the context of continuous warming.Materials and methods The treering chronology was developed form cores of planted Chinese pine for western Liaoning.The correlations between the chronology and temperature,precipitation,scPDSI and threshold temperatures were calculated during the period from 1983 to 2012,and the variations of tree-ring width were verified by V-S model simulation.Results The standardized chronology of P.tabuliformis showed a negative correlation with the temperature in previous July,September and current May,with a correlation coefficient of−0.457,−0.426 and−0.471(p<0.05),and a positive correlation with the precipitation in current May,with a correlation coefficient of 0.52(p<0.05).The chronology was positively correlated with scPDSI on the monthly scale.Radial growth of P.tabuliformis was negatively correlated with accumulated temperature and duration of different threshold temperatures during the current growth period.The minimum temperature of 11℃had a great influence on pines.The correlation coefficients between tree-ring index and its initial date sequence,accumulated temperature and duration were 0.663,−0.619 and−0.732(p<0.01),respectively.The V-S model results showed that P.tabuliformis was sensitive to 9℃in spring and 9.5℃in autumn.The current growth season occurred from April to October,and the variability of growth rate was affected by both temperature and soil moisture.Discussion Drought stress was the main factor limiting the response of P.tabuliformis growth to climate.This response pattern was confirmed by positive correlations of the tree-ring chronology with moisture condition including precipitation and scPDSI,and negative correlations with temperature condition including accumulated temperature and duration.The results of the V-S model demonstrated the similar growth-climate relationship.Conclusions The radial growth of planted P.tabuliformis in western Liaoning was dominated by moisture stress during the growth season.Longer growth period and more accumulated temperature caused by increasing temperatures in spring and autumn could enhance the risk of radial growth of Chinese pine planted in study area.Recommendations and perspectives The response pattern of P.tabuliformis to different climate factors should be considered in the management and nurturing of planted Chinese pine forest in western Liaoning,and the reasonable allocation of water and heat should be paid more attention to improve the quality of ecological effect.