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Free keywords:
Diffuse-porous
Granier sensor
Soil moisture
Drought
Weibull function
Canopy conductance
Deciduous forests
Water-balance
Pine forests
Scots pine
Transpiration
Flow
Xylem
Stands
Mature
Abstract:
Sap flux density (SFD) was measured continuously during 1999 with the heat dissipation method in natural Fagus crenata Blume ( Japanese beech) forests growing at 900 m on the northern slope of the Kagura Peak of the Naeba Mountains near the Sea of Japan. Radial variations in xylem daily SFD ( SFDday) on three trees were investigated during the growing season. The radial pattern of SFDday that reached a maximum just behind of the cambium layer and then decreased exponentially was described by applying the Weibull function based on sensor measurements at 20 mm intervals. SFDday ratio of 20 - 40 mm depth ( the value of 0 - 20 mm depth was 100%) increased by 10 - 32% because of soil drying. The peak value of the Weibull function shifted to 2 - 10% interior by those changes in the relative xylem depth. The variation of the radial pattern of SFDday under different environmental conditions was expressible as the shift of the peak position of the Weibull function. [References: 36]
