Transpiration from a Cryptomeria japonica plantation, part 1: aerodynamic control of transpiration

Abstract

Abstract:To our knowledge, no one has examined the canopy conductance of a Cryptomeria japonica plantation, although such forests are very common in Japan. We plan to examine the canopy conductance of a Cryptomeria japonica plantation (canopy height 8 m) based on 1-year sap-flow data using the simplified Penman-Monteith equation. This study examines the effect of the aerodynamic control of transpiration before calculating canopy conductance using the simplified Penman-Monteith equation, because the equation assumes that the effect of aerodynamic control is negligible. To examine the effect of aerodynamic control, we examined the dependency of the relationship between the vapour pressure deficit (VPD) and transpiration on wind speed, when solar radiation, air temperature, and soil water content do not limit transpiration greatly. The relationship between VPD and the heat pulse velocity measured 11 m above the ground was dependent on wind speed only when the wind speed was <0Ð7 m s 1 . This suggests that the effect of aerodynamic control was negligible when the wind speed was ½0Ð7 m s 1 , but that the effect was not negligible when the wind speed was <0Ð7 m s 1 . Therefore, we should use data from when the wind speed was ½0Ð7 m s 1 for calculating canopy conductance G c , based on the simplified Penman-Monteith equation. Although this criterion is site specific, the methods used to develop it are applicable to other sites.

Analysis of suspended sediment yields after low impact forest harvesting

“…Weirs were constructed in both watersheds, and water levels at these weirs were measured beginning in 1993. Cryptomeria japonica and some Chamaecyparis obtusa, common plantation trees in Japan (Komatsu et al, 2005), were planted at a density of c. 4400 ha 1 in both watersheds in 1929. Major thinning has taken place twice.…”

Contemporary Role of Catchment Water Balance Data for Forest Evapotranspiration Research.

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A modified Jarvis-Stewart model for predicting stand-scale transpiration of an Australian native forest

“…Measuring tree water use is an important step in determining the water balance of woody landscapes (Komatsu et al 2006a;Wullschleger and Hanson 2006;Rollenbeck and Dieter 2007;Simonin et al 2007) and determining landscape water balances is important to forestry and mining industries and to water and landscape management agencies. Whilst estimating tree water use can be undertaken using sapflow technologies (O'Grady et al 1999(O'Grady et al , 2006, such measurements are made at the scale of individual trees, usually over relatively short time frames (days and weeks) and typically only during the growing season (Wullschleger et al 1998;Lundblad and Lindroth 2002).…”