大青山米老排树干径向生长变化及其对环境因子的响应

【目的】研究南亚热带大青山林区乡土珍贵树种米老排径向生长日变化特征及对环境因子的响应,为理解米老排生长-气候响应的生理机制、森林培育和保护等提供基础数据。【方法】利用点状树木径向生长变化记录仪对米老排径向生长变化进行连续观测,采用气象站同步测量辐射总量、土壤含水量、相对空气湿度、空气温度等环境因子数据。通过径向生长与环境因子的相关分析,研究米老排生长季第一个高峰期(5月)的不同分化等级径向生长日变化规律、不同天气条件下生长变化及径向生长-环境因子相互关系。【结果】1)不同分化等级米老排5月份的径向生长日变化量优势木(17.08μm)>平均木(13.94μm)>被压木(-1.81μm),差异极显著(P<0.01),且不同阶段的起始时间、阶段时长、变化量也有所不同。2)不同天气条件下,三种分化等级米老排径向日净生长量和日变化幅度均表现为雨天>晴天>阴天,受雨水影响,雨天条件下径向变化量远超其自身生长量;同种天气条件下,径向日净生长量优势木最大,日变化幅度则表现为平均木最大。3)不同分化等级米老排径向生长与相对空气湿度、降雨量呈极显著正相关关系,与气温、总辐射呈极显著负相关关系,而20 cm土壤含水率无显著性相关,且各影响因子均存在不同时间滞后效应。【结论】不同分化等级米老排由于林木生长状况的差异,导致其受到环境因子影响程度的不同,进而使得其径向生长变化量产生差异。

The stem radial growth of Mytilaria laosensis and its response to environmental factors in Daqing mountain

【Objective】To study the characteristics of stem radial diurnal variation of Mytilaria laosensis in south subtropical area of China and understand its response to environmental factors,aiming at providing basic data for understanding physiological mechanism of stem radial growth response to environmental factors and its forest cultivation and protection.【Method】An point dendrometer was used to continuously monitored the stem radial variation of M.laosensis,and the environmental factors such as total radiation,soil water content,relative air humidity and air temperature were measured simultaneously.Through the correlation analysis of the radial growth and environmental factors,the diurnal variation of radial growth for M.laosensis in different differentiation classes,the growth change under different weather conditions and the relationship between radial growth and environmental factors for the first peak of M.laosensis over growing season were studied.【Result】1)There was significant difference(P<0.01)in the stem radial diurnal variation of M.laosensis in different differentiation classes in May,and it could be ordered as dominant tree(17.08μm)>intermediate tree(13.94μm)>suppressed tree(-1.81μm).The starting time,duration and variation of different stages were also different.2)Under different weather conditions,the radial daily net growth and daily variation of the three different classes were all showed as rainy days>sunny days>cloudy days.Affected by rain,the radial variation in rainy days was much larger than its own growth.Under the same weather conditions,the dominant tree had the largest radial daily net growth,while the intermediate tree had the maximum daily variation.3)The radial growth was positively correlated with relative air humidity and rainfall,and negatively correlated with air temperature and total radiation,while there was no significant correlation with soil moisture content of 20 cm,and each influence factor had different time lag effect.【Conclusion】Due to the differences of forest growth,the different differentiation classes of M.laosensis had different responses to environmental factors,which in turn made a difference in the amount of radial growth.