中文摘要：

运用Granier热消散探针连续监测荷木的树干液流,于2009年的湿季（8月）和干季（11月）选择天气晴朗的3d测定叶片水势,同步连续监测林冠上方光合有效辐射、土壤含水量、气温和空气相对湿度。结果表明：干湿季下荷木树干液流存在显著差异,此外,土壤水势和液流有较好的相关性,且干季时的相关性更好;荷木的叶面积/边材面积比值平均为（0.416±0.033）m2·cm-2,并与树高呈指数函数下降关系;随着11月土壤水势下降,荷木的整树水力导度和午间叶片水势也有所下降,但不明显;对叶片水势和整树蒸腾进行回归分析,二者之间呈二次多项式关系（P〈0.01）,叶片水势并非无限制下降;结果还表明,大气水汽压亏缺（D）和叶片水势呈负相关,这是否空气温度和相对湿度或共同作用影响叶片水势,需要进一步研究。

英文摘要：

The stem sap flow of Schima superba was monitored continuously by using Granier＇s thermal dissipation probe,and the leaf water potential of the plant was measured during three sunny days （from predawn to sunset） in wet season （August） and dry season （November）,2009.The photosynthetically active radiation above canopy,soil moisture content,air temperature,and air relative humidity were monitored simultaneously.There was a significant difference in the sap flux density on the trunk between wet and dry seasons.Besides,the sap flux density and soil water potential were highly correlated,and the correlation was much better in dry season.The ratio of leaf area to sapwood area was 0.416±0.033 m2·cm-2,and decreased exponentially with tree height.With the decline of soil water potential in November,the whole-tree hydraulic conductance and midday leaf water potential decreased,but not obviously.The regression analysis showed that there existed a quadratic polynomial relation between the whole-tree transpiration and leaf water potential （P0.01）,and the leaf water potential was not declined unlimitedly.The vapor pressure deficit within the surrounding air had a negative correlation with leaf water potential,but whether the air temperature and relative humidity co-affect the leaf water potential needed to be further studied.