摘 要 ：为了解荷木人工林水分利用特征及与环境因子的关系，利用Granier热消散探针于2007年12月(干季)和2008年9月(湿季)对荷木(Schima superba)人工林的15株样树树干液流进行测定并结合环境因子，计算林段总蒸腾(Jd)和冠层气孔导度(gs)。结果表明：边材面积(As)越大的径级对林段总蒸腾量的贡献越大。Jd干湿季差异显著，9月和12月平均分别为21.1 g H2O s-1和7.03 g H2O s-1，显示了明显的季节变化。环境因子与Jd呈极显著相关性，相关系数依次为：光合有效辐射(PAR)>水汽压亏缺(VPD)>空气相对湿度>气温。gs在9月和12月的最大值分别为30.8 mmol m-2s-1和19.7 mmol m-2s-1；gs与PAR呈线性正相关；当PAR >1000 μmol m-2s-1且VPD>2 kPa时，gs与VPD呈线性负相关；偏相关分析表明土壤含水量与gs没有显著的相关性，显示所研究时间内土壤水分状况对荷木人工林蒸腾没有显著影响。
Abstract:In order to understand water use characteristics of Schima superba plantation and their relationships with environmental factors, Granier’s thermal dissipation probes were applied to measure sap flow density of 15 trees in a typical plantation stand, in which environmental factors including photosynthetically active radiation (PAR), air relative humidity, air temperature and soil moisture were recorded synchronously. Stand transpiration (Jd) and canopy stomatal conductance (gs) were then calculated based on sap flow density, sapwood area, environmental humidity and temperature from December 2007 (dry season) and September 2008 (wet season). The results showed that trees with larger sapwood areas had greater contribution of stand transpiration. Jd was found to be significantly different during wet and dry seasons, which had an average of 21.1 g H2O s-1 in September but only 7.03 g H2O s-1 in December, indicating a dramatic seasonal variation of it. In the meantime, Jd was found to be significantly correlated with environmental factors, in which PAR had the largest correlation coefficient and followed by vapor pressure deficit (VPD), air relative humidity and air temperature in sequence. On the other hand, the maximum gs were calculated to be 30.8 mmol m-2s-1 and 19.7 mmol m-2s-1 in September and December, respectively. It had positive linear relationship with PAR but negative one with VPD when PAR was larger than 1000 μmol m-2s-1 and VPD was over 2 kPa. However, gs did not present any statistically significant relation with soil moisture either in July or December, indicating that soil moisture was not the major environmental factor influencing stand transpiration of S. superba during our study periods.