To examine water consumption of eucalypt plantation species and to provide guidance for plantation establishment and tending, sap flow of plantation grown Eucalyptus urophylla × Eucalyptus grandis was contin-uously measured using the thermal diffusion stem flow meter (Germany, SF-G) which allowed analyses of water use characteristics during both dry and rainy seasons. Stand meteorological conditions were determined syn-chronously to enable a correlation analysis for differences between sap flow and meteorological factors in both dry and rainy seasons. Results showed that diurnal variations of sap flow displayed typical single-peaked curves in both dry and rainy seasons. The start (07:15) and peak (11:30) times for sap flow during the rainy season were earlier than those in the dry season (07:45 and 13:00) with the peak sap flow in the rainy season being 1.3 times more than in the dry season. Time duration for relatively high levels of flow were longer in the rainy season than in the dry. In both dry and rainy seasons, variation and total stem sap flow observed during the first half of the night were significantly greater (P<0.01)than those observed after midnight. Likewise, the variation in total stem sap flow observed during the entire rainy season was significantly greater (P<0.01) than that ob-served during the dry season. The average daily (3.99 kg·d-1) and monthly (122.4 kg·month-1) fluxes during rainy season were significantly greater (P<0.05) than fluxes in the dry season (daily-2.64 kg·d-1 and monthly-80.00 kg·month-1). The main meteorological factors, such as vapor pressure deficit, photosynthetically active radiation (PAR), air humidity, and air temperature, were not correlated to seasonal sap flow of E. urophylla × E. grandis. However, flow density during the rainy season was highly significant (P<0.01) and positively cor-related (r = 0.39) with wind velocity and significantly (P<0.05) and negatively correlated (r = -0.08) with rainfall. The above results show that the rainy season is a fast growth period of E. urophylla × E. grandis, with high water consumption, also is the important period for water and fertilizer management.%为正确认识桉树的耗水规律,为桉树栽培及抚育提供指导,采用热扩散茎流计(德国,SF-G)对尾巨桉Euca-lyptus urophylla×E.grandis树干液流进行连续监测,分析其旱雨两季特征差异,并同步测定林分气象条件,分析旱雨两季树干液流与气象因子之间的相关性.结果表明:旱雨两季树干液流日变化均呈典型单峰曲线,雨季启动时间和达到峰值的时间(7:15,11:30)均早于旱季(7:45,13:00),雨季峰值是旱季的1.3倍,维持峰值的时间雨季大于旱季;夜间液流密度及变化幅度旱雨两季均是前半夜大于后半夜,且雨季夜间液流变化幅度和液流密度均大于旱季;平均日通量和平均月通量雨季(3.99 kg·d-1,122.40 kg·月-1)大于旱季(2.64 kg·d-1,80.00 kg·月-1).旱雨两季影响尾巨桉树干液流密度的主要气象因子相同,均为水汽压亏缺、 光合有效辐射、 空气湿度和大气温度,但雨季树干液流密度与风速呈极显著正相关(P<0.01),与降雨量呈显著负相关(P<0.05),而旱季与两者之间无显著相关性.
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