Zhu Zhong-Long, Jia Zhong-Kui, Ma Lu-Yi, Wang Xiao-Ling, Duan Jie
Ministry of Education Key Laboratory for Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China.
Ying Yong Sheng Tai Xue Bao. 2012 Sep;23(9):2390-6.
From September 26 to November 5, 2011, the sap flow of Yulania wufengensis trees including cold-resistance type (HK) and non cold-resistance type (HF), Y. 'Sunspire' (HY), and Yulania x soulangeana (EQ) which were introduced into Beijing four years before was monitored by Flow-32 stem heat balance sensor, and, in combining with the environmental factors monitored synchronically, the changes of the sap flow before dormancy and the environmental factors were analyzed, with the responses of the sap flow to the environmental factors investigated at the scales of 0.5 h and 1 day. The sap flow of the Yulanias trees before dormancy displayed an obvious trend of declining day by day. The environmental factors affecting the sap flow could be divided into two categories, i. e., meteorological index (MI) and soil index (SI). The sap flow of the Yulanias trees had a synchronous variation rhythm with MI, and declined in parallel to SI. The combined effect of MI and SI on the diurnal changes of the sap flow was 69% - 73%. At both 0.5 h and 1 day scales, the sap flow showed significantly correlations with total radiation (Rs), air vapor pressure deficit (D), air relative humidity (RH), air temperature (Ta), and wind speed (w). The sap flow showed no significant correlations with soil temperature (Ts) and soil water content (SWC) at 0. 5 h scale, but had significant correlations with Ts, SWC, and day length (Z) at 1 day scale (the correlation efficient was about 0.8). Only Rs, Z, and D were included into the model at 1 day scale, but almost all environmental factors (except SWC and Ts) were included in the model at 0.5 h scale. Except for HF type, the regression coefficients of the model for the Yulanias trees at 1 day scale (0.92-0.96) were larger than those at 0.5 h scale (0.77-0.87), and the correlations between the dynamic changes of sap flow and the environmental factor were consistent, which was in accord with the fact that the HF could not overwinter in Beijing but the others could.
2011年9月26日至11月5日，采用Flow-32茎热平衡传感器对4年前引种到北京的耐寒型（HK）和不耐寒型（HF）的五峰玉兰、‘阳光’玉兰（HY）以及二乔玉兰（EQ）植株的液流进行了监测，并结合同步监测的环境因子，分析了休眠前液流变化与环境因子的关系，探讨了0.5小时和1天尺度下液流对环境因子的响应。玉兰植株休眠前的液流呈现出明显的逐日下降趋势。影响液流的环境因子可分为气象指标（MI）和土壤指标（SI）两类。玉兰植株的液流与气象指标有同步变化节律，与土壤指标呈平行下降趋势。气象指标和土壤指标对液流日变化的综合影响为69% - 73%。在0.5小时和1天尺度下，液流均与总辐射（Rs）、空气水汽压差（D）、空气相对湿度（RH）、气温（Ta）和风速（w）显著相关。在0.5小时尺度下，液流与土壤温度（Ts）和土壤含水量（SWC）无显著相关性，但在1天尺度下与Ts、SWC和日长（Z）显著相关（相关系数约为0.8）。在1天尺度下，模型仅纳入Rs、Z和D，但在0.5小时尺度下几乎纳入了所有环境因子（除SWC和Ts）。除HF型外，玉兰植株在1天尺度下模型的回归系数（0.92 - 0.96）大于0.5小时尺度下的回归系数（0.77 - 0.87），液流动态变化与环境因子的相关性一致，这与HF型在北京不能越冬而其他类型能越冬的事实相符。
