摘要
研究马占相思树干的夜间水分补充现象有助于提高总蒸腾量、冠层气孔导度估算的准确度,同时可以深化对冠层蒸腾与树干液流所代表的日蒸腾之间时滞现象的认识。在广东鹤山马占相思林,采用热扩散探针法测定液流密度,同步测定主要的环境因子,从不同的时间尺度分析其树干夜间水分补充现象。结果表明:与白天相比较,夜间马占相思液流密度较小;夜间液流密度的变化幅度旱季比雨季大,树干夜间水分补充的主要时间段是前半夜;年内各个月份夜间水分补充量之间没有显著差异,它与环境因子之间相关关系不显著,但与胸径、树高、冠幅的回归曲线拟合较好;干季夜间补充的水分对总蒸腾量的贡献与白天蒸腾量、总的蒸腾量、水蒸气压亏缺(VPD)、光合有效辐射(PAR)以及大气温度(T)显著相关;湿季夜间补充的水分对总蒸腾量的贡献与白天蒸腾量、总蒸腾量显著相关。
To research the nighttime water recharge in Acacia mangium trunk is helpful to improve the preciseness of canopy transpiration- and stomatal conductance estimation, and to further understand the time lag between canopy transpiration and stem sap flow. In this study, the wholetree sap flow in A. mangium forest was measured by Granier＇ s thermal dissipation probe for over two years in Heshan Mountain of Guangdong Province, and the environmental factors, including relative humidity （ RH）, rainfall, vapor pressure deficit （ VPD）, photosynthetically active radiation （PAR）, and air temperature （T） were recorded simultaneously. The nighttime water recharge of A. mangium trunk was analyzed on daily scale and monthly scale, and the results indicated that the sap flow density was smaller at nighttime than at daytime, and the range of nighttime sap flow density was wider in dry season than in wet season. The major duration of water recharging was from sunset to midnight. No significant differences were observed among inter-annual nighttime water recharges. Nighttime water recharge had no significant correlation with environmental factors, but correlated well with the diameter in the breast, height, and crown width of A. mangium. In dry season, the contribution of nighttime water recharge to total transpiration had significant correlations with daytime transpiration, total transpiration, VPD, PAR and T; while in wet season, it was significantly correlated with daytime transpiration and total transpiration.
出处
《生态学杂志》
CAS
CSCD
北大核心
2007年第4期476-482,共7页
Chinese Journal of Ecology
基金
中国科学院知识创新工程重要方向项目(KSCX2-SW-133)
国家自然科学基金资助项目(30428022
30270239)
