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选择广西公净水库,开展集水区范围内2种主要木本植物巨尾桉(Eucalyptus grandis×E.urophylla)和马尾松(Pinus massoniana)群落蒸腾速率(Tr)、叶面积指数(LAI)和相关环境因子的现场观测,结果表明:马尾松蒸腾速率的季节变化为0.14~0.69μmol·m-2·s-1,<2年龄巨尾桉为1.65~3.76μmol·m~(-2)·s~(-1),>4年龄巨尾桉为1.05~2.04μmol·m-2·s-1,<2年龄巨尾桉和>4年龄巨尾桉年均蒸腾速率均高于马尾松,分别是马尾松的6倍和3.4倍。2种植物蒸腾速率均是夏季最高,冬季最低,夏季蒸腾速率约是冬季的2倍。相关分析结果显示,2种植物蒸腾速率均与叶面积指数、土壤含水率和林下空气温度呈极显著正相关(P<0.01),但各影响因素并不是独立作用于蒸腾速率的。通径分析结果表明,林下空气温度和土壤含水率对马尾松蒸腾速率起主导作用,是主要决策变量;叶面积指数和土壤含水率分别是<2年龄和>4年龄巨尾桉蒸腾作用的主要决策变量。
The Gongzhuan Reservoir in Guangxi was selected to study the transpiration rate (Tr), leaf area index (LAI), and leaf area index of two major woody plants, Eucalyptus grandis × E.urophylla and Pinus massoniana, The results showed that the seasonal variation of transpiration rate of Pinus massoniana was 0.14-0.69μmol · m-2 · s-1, while that of <2-year-old E. grandis was 1.65-3.76μmol · m -2 The average transpiration rate of E. grandis <2 years old> Eucalyptus grandis × E. grandis × 1.04 ~ 2.04μmol · m-2 · s-1 in s -1 and> 4 years old was higher than that in Masson pine , Respectively 6 times and 3.4 times that of masson pine. The transpiration rates of the two plants were the highest in summer and the lowest in winter, respectively. The transpiration rate in summer was about twice that in winter. Correlation analysis showed that there was a significant positive correlation (P <0.01) between the transpiration rate of two plants and leaf area index, soil moisture content and air temperature below the forest, but the influencing factors did not act independently on the transpiration rate. The results of path analysis showed that the air temperature and soil water content in the forest dominated the transpiration rate of Pinus massoniana and were the main decision variables. The leaf area index and soil water content were the transpiration rates of <2 years and> 4 years old, respectively The main decision variables.