关键词: 连香树, 土壤理化性质, 气候, 海拔

Abstract: Employing Granier's probes, this paper measured the sap flow of 14 sample trees in an Acacia mangium forest on the Heshan hilly lands of Guangdong Province, and recorded the photosynthetic active radiation (PAR), air relative humidity (RH), and air temperature (T) above the forest canopy. The wholetree transpiration (E), stand transpiration (E_t), and mean canopy stomatal conductance (g_c) were calculated, and the relationships between tree morphological characters and whole-tree water use as well as the responses of g_c to PAR and vapor pressure deficit (D) were analyzed. The results showed that the whole-tree transpiration had logarithmical positive correlations with tree diameter at breast height (DBH) (P＜0.0001), sapwood area (P＜0.0001) and canopy size (P=0.0007), and an exponential positive correlation with tree height (P=0.014). The maximum g_c (g_cmax) changed with PAR hyperbolically (P＜0.0001), and with D logarithmically (P＜0.0001). The sap flow measurement system used in this study was reliable and accurate in estimating the transpiration of whole-tree and stand and the canopy stomatal conductance, being an effective tool in studying the relationships between forest water use and environmental factors.

Key words: Cercidiphyllum japonicum, Chemical and physical characteristics in soil, Climate, Elevation