杉木幼树树干液流影响因子及其对杉木林蒸腾量的贡献

2012年9月至2013年8月,利用包裹式树干液流仪、插针式树干液流仪和小气象站对南京市东善桥林场的杉木幼树树干液流速率、杉木树干液流速率及环境因子进行了连续观测,研究了杉木幼树树干液流影响因子及其对杉木林蒸腾的贡献。结果表明:(1)杉木幼树液流速率的日变化具有季节差异性,均表现为单峰曲线并且日间液流速率大于夜间;(2)春、夏、秋、冬季液流速率峰值分别为:79.97,105.22,70.30,33.19g/h;(3)太阳辐射是影响杉木幼树树干液流速率的主导因子,其次是饱和水汽压差,日液流量与太阳辐射、空气温度、饱和水汽压差、各层次土壤温度呈极显著的正相关关系;(4)分别建立了液流速率、日液流量与环境因子的模型,可以较好地解释液流速率与日液流量的变化;(5)杉木幼树全年液流量对杉木林蒸腾量的贡献率为6.12%,夏季的贡献率最大。

Impact Factors of Sap Flow of Chinese Fir Sapling and Its Contribution to Transpiration of Chinese Fir Forest

Based on the 12 months observation of the sap flow rate and environmental factors by using sap flow meter and mini weather station in Dongshanqiao Forest of Nanjing City from September 2012 to August 2013, the impact factors of the sap flow of Chinese fir sapling and its contribution to transpiration of Chinese fir forest was analyzed. Results indicated that:(1) The sap flow rate of Chinese fir sapling showed seasonal differences and the change of the sap flow rate took on a single-peak curve in different seasons. Sap flow rates in daytime were higher than those during the night.(2) The crest values of the sap flow rate in spring, summer, autumn and winter was 79.97, 105.22, 70.30, 33.19 g/h, respectively.(3) The domenant environmental factor of sap flow rate was solar radiation, the next was vapor pressure deficiency. The correlation between daily sap flow and solar radiation, air temperature, vapor pressure deficiency, soil temperature at all layers showed a significant positive correlation.(4) The models to relate the sap flow rate, daily sap flow with environmental factors were established. These models could better explain the change of the sap flow rate and daily sap flow.(5) The ratio of contribution of Chinese fir saplings sap flow throughout the year to the total transpiration of Chinese fir forest was 6.12%, and the ratio of contribution in summer was the largest.