基于树干液流和土壤-叶片水势梯度分析荷木干湿季整树水分利用特征

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.

Whole-tree water use characteristics of Schima superba in wet and dry seasons based on sap flow and soil-leaf water potential gradient analysis

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...