大兴安岭南段山杨不同龄组径向生长对极端干旱的响应

Response of Radial Growth to Extreme Drought in Different Age Groups of Populus davidiana in Southern Great Xing’an Mountains

【目的】通过对大兴安岭南段山杨不同龄组应对极端干旱能力的探讨,为今后山杨生长及森林群落结构动态变化提供数据基础。【方法】对大兴安岭南段3个20 m×20 m山杨样地树芯进行取样测定,划分为4个年龄组,分别为中龄林组(20~30 a);近熟林组(31~40 a);成熟林组(41~60 a);过熟林组(≥61 a);建立不同龄组年表,对1983—2013年的平均温度、降水和帕尔默干旱指数(PDSI)与年表进行相关性分析,揭示不同龄组山杨径向生长对气候的响应规律,并分析了不同龄组在极端干旱气候条件下的抵抗力(Rt)、恢复力(Rc)和弹性(Rs)。【结果】不同龄组山杨年表与平均温度大多数呈负相关,与9月份的平均温度达到显著负相关水平,近熟林组、成熟林组对平均温度的响应程度高于其它龄组;成熟林组对降水的响应程度高于其它龄组;成熟林组的年表与上一年11月份至当年10月份PDSI的相关性最高,其次是近熟林、中龄林组,过熟林组最低。不同龄组山杨年轮指数与PDSI的响应比平均气温和平均降水的响应程度更高。弹性力分析中,成熟林组的抵抗力、高于其它龄组。但是成熟林组的恢复力、弹性低于其它龄组。【结论】成熟林组对气候的响应最为敏感;成熟林组的抵抗力最高,近熟林组的恢复力最高,中龄林组的弹性最高。

【Objective】In order to provide data basis for Populus davidiana growth and forest community structure dynamic change in the future,the ability of Populus davidiana to cope with extreme drought in different age groups of the Southern Great Xing’an Mountains was discussed.【Method】Three 20 m×20 m Populus davidiana tree cores were sampled and measured in the Southern Great Xing’an Mountains,They were divided into four age groups,namely the Middle forest group(20-30 a);Near mature forest group(31-40 a);Mature forest group(41-60 a);Over mature forest group(≥61 a);Establish a chronology of different age groups.The correlation analysis between the mean temperature,precipitation and Palmer Drought Severity Index(PDSI)from 1983 to 2013 and the chronology was carried out.The resistance(Rt),recovery(Rc)and resilience(Rs)of different age groups under extreme drought conditions were analyzed.【Result】Populus davidiana chronology of different age groups was negatively correlated with average temperature and significantly negatively correlated with the average temperature in September.The response degree of near mature forest group and mature forest group to average temperature was higher than that of other age groups.The response degree of mature forest group to precipitation is higher than that of other age groups.The chronology of the mature forest group had the highest correlation with PDSI from November to October of the previous year,followed by the near mature forest group and the middle forest group,and the over mature forest group had thelowest correlation.The response of Populus davidiana ring index and PDSI in different age groups was higher than that of average temperature and average precipitation.In resilience analysis,the Rt of mature forest group was higher than that of other age groups.However,the Rc and Rs of mature forest group were lower than those of other age groups.【Conclusion】Mature forest groups are the most sensitive to climate response.The mature forest group had the highest Rt,the near mature forest group had the highest Rc,and the middle age forest group had the highest Rs.