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2011年9月26日—11月5日,利用热平衡技术连续测算了引种北京4年的红花玉兰[抗寒型(HK)和非抗寒型(HF)]、黄玉兰(HY)和二乔玉兰(EQ)的树干液流,结合同步观测的环境因子数据,分析休眠前玉兰的树干液流和综合环境因子的变化,以及在0.5h尺度和日尺度下液流对各环境因子的响应.结果表明:休眠前,玉兰的树干液流呈明显的逐日下降趋势.影响玉兰树干液流的7个环境因子可分为气象因子(MI)和土壤因子(SI)两类.树干液流与MI具有同步的单峰节律性变化规律,与SI呈同步降低趋势.MI和SI对树干液流的共同影响程度为69.8%～73.2%.0.5h尺度和日尺度下,玉兰树干液流与总辐射(Rs)、空气水汽压亏缺(D)、相对湿度(RH)、气温(Ta)和风速(w)极显著相关;在0.5h尺度下与土壤温度(Ts)和土壤含水量(SWC)的相关性不显著,在日尺度下与Ts、SWC和昼长(Z)极显著相关,相关系数在0.8左右.日尺度下进入各回归模型的环境因子有Rs、Z和D,而0.5h尺度下除SWC和Ts外其余环境因子均进入模型,且日尺度逐步回归决定系数(0.92～0.96)大于0.5h尺度(0.77～0.87)(除HF外).除HF外,其余玉兰的液流变化规律与各单一环境因子间的相关程度一致,这与HF无法正常越冬而其余玉兰在北京顺利越冬的实际情况相一致.
From September 26, 2011 to November 5, 2011, the heat balance technology was used to continuously measure the effects of four years of introduction of Magnolia biondii [cold type (HK) and non-cold type (HF)], yellow magnolia (HY) The stem sap flow of Magnolia grandiflora (EQ) and the data of environmental factors observed simultaneously were used to analyze the changes of sap flow and comprehensive environmental factors in Magnolia grandis before dormancy, and the responses of the flow to various environmental factors at 0.5 h scale and daily scale. The results showed that: before dormancy, the sap flow of Magnolia had a clear downward trend day by day.The seven environmental factors affecting the flow of Magnoliaceae sap could be divided into two categories: meteorological factor (MI) and soil factor (SI) With synchronized monomodal rhythmic variation, decreasing in synchronism with SI.MMI and SI have a common impact on the sap flow of 69.8% ~ 73.2% .0.5h scale and day scale, Magnolia sap flow and total radiation (Rs), air vapor pressure deficit (D), relative humidity (RH), temperature (Ta) and wind speed (w) were significantly correlated with soil temperature (Ts) and soil moisture (SWC) The correlation coefficient was significant at the day scale, and was significantly correlated with Ts, SWC and day length (Z) The environmental factors of regression model were Rs, Z and D, while the other environmental factors except SWC and Ts at 0.5h scale entered into the model, and the step-by-step regression coefficient (0.92-0.96) was larger than 0.5h scale (0.77-0.87) (Except for HF) .In addition to HF, the changes of the flow pattern of Magnoliae Magnolia were consistent with those of single environmental factors, which was consistent with the fact that HF could not overwinter and other Magnolia successfully passed through Beijing in winter.