不同时间尺度环境因子对黑河下游胡杨(Populus euphratica)径向生长的影响

本研究以黑河下游额济纳旗成熟的河岸胡杨林为对象,分析不同年龄胡杨(Populus euphratica)的年轮宽度序列与不同时间尺度环境因子的关系。结果表明:①在年尺度上,气温是影响胡杨径向生长的主要因子,但不同年龄胡杨对气温的响应有所不同。②在季节尺度上,休眠季气温越高越有利于壮龄胡杨的径向生长,而生长季气温越高越不利于老龄胡杨的径向生长。③在月尺度上,前一年3月和当年9月的平均气温越高,对壮龄胡杨的径向生长越有利,而当年10月平均气温越高,对老龄胡杨的径向生长越不利;前一年7月径流量的增加对老龄胡杨的径向生长有利,而当年2月径流量的增加对壮龄胡杨径向生长有利。综上所述,在季节和年等相对较长的时间尺度上,气温是影响胡杨径向生长量的主要因素,随着时间尺度的缩小,胡杨对环境因子的响应更为细化,并且表现出一定的滞后效应。径流量作为重要的环境因子在月尺度上才突显出来,前一年7月和当年2月的径流补给对胡杨径向生长有极大的促进作用。因此,在黑河统一调度管理过程中,可通过适度调增2月和7月洪水的下泄量来满足胡杨径向生长对水分的需求。

Effects of Environmental Factors on Radial Growth of Populus euphratica at Different Time Scales in the Lower Reaches of the Heihe River

In this study, a mature riparian Populus euphratica forest in Ejina Banner in the lower reaches of the Heihe River was selected to analyze the relationship between the annual tree ring width series of P. euphratica with different ages and the environmental factors on different time scales. The results showed that: ①On the annual scale, temperature was the main factor affecting the radial growth of P. euphratica, but the response of P. euphratica with different ages to temperature was different; ②On the seasonal scale, the higher the temperature during the dormancy was, the better the radial growth of adult P. euphratica would be, however, the higher the temperature in growing season was, the worse the radial growth of old P. euphratica would be; ③On the monthly scale, the higher the average temperature in March of previous year and in September every year was, the more favorable the conditions to the radial growth of adult P. euphratica would be; the higher the average temperature in October every year, the more disadvantageous the conditions to the radial growth of old P. euphratica would be. The increase of runoff volume in February every year was beneficial to the radial growth of adult P. euphratica, while that in July of previous year was beneficial to the radial growth of old P. euphratica. In summary, on relatively long time scales, such as seasonal and annual scales, temperature was the main factor affecting the radial growth of P. euphratica. With the contraction of time scale, the response of P. euphratica to environmental factors became more detailed, and a certain hysteresis occurred. As an important environmental factor, runoff volume was prominent just on the monthly scale, the runoff recharge in July of previous year and February every year was very important for the radial growth of P. euphratica. Therefore, In the process of unified dispatching and management of the Heihe River, an appropriate flood discharge in February and July could meet the water demand of the radial growth of P. euphratica.