[Seasonal variation of Cyclobalanopsis glauca whole-tree transpiration in karst region].
By using Granier's sap-flow method, the variations of sap flux density and whole-tree transpiration of Cyclobalanopsis glauca (syn. Quercus glauca) on a hilly slope in the karst region of South China were studied, with their driving factors analyzed. The sap flux density (Js) of C. glauca varied randomly with the diameter of breast height of individual trees, and its maximum occurred at 13:30-14:30. In a seasonal course, the daily Js was the maximum (56.00 g H2O x m(-2) x s(-1)) in summer, and the minimum (35.86 g H2O x m(-2) x s(-1)) in spring. The daily whole-tree transpiration had a greater change with weather condition, representing a power functional relationship with vapor pressure deficit (VPD) and photosynthesically active radiation (PAR) (R = 0.97, P < 0.01). The average daily whole-tree transpiration tended to be high in summer and low in winter and spring, and decreased with the decrease of soil moisture content in autumn (drought season). However, comparing with that of the tree species in other regions, the daily whole-tree transpiration amount of C. glauca in study region was still higher, even though the weather was dry and the soil was thin. It was presumed that in the dry season in karst region, the water supply for C. glauca could be mainly depended on the water-rich epikarst.
Huang
Yu-Qing
YQ
Guangxi Institute of Botany, Guilin 541006, Guangxi, China. hyqcoco@gxib.cn
Zhang
Zhong-Feng
ZF
He
Cheng-Xin
CX
Zhao
Ping
P
Yuan
Wei-Yuan
WY
Jiao
Ji-Fei
JF
You
Ye-Min
YM
D002681:China; D017753:Ecosystem; D029962:Fagaceae / Q000378:metabolism / Q000502:physiology*; D018526:Plant Transpiration; D012621:Seasons; D012987:Soil / Q000032:analysis*; D014867:Water / Q000032:analysis; D014887:Weather
D012987:Soil; D014867:Water