Transpiration is generally assumed to be insignificant at night when stomata close in response to the lack of photosynthetically active radiation. However, there is increasing evidence that the stomata of some species remain open at night, which would allow for nighttime transpiration if there were a sufficient environmental driving force. We examined nighttime water use in co-occurring species...

      Water flux in a young, 4-year old, cashew (Anacardium occidentale L.) plantation was studied over a dry season, from November 2001 to March 2002, in the forest-savannah transition zone of Ghana, West Africa. The temperature-difference method was used over this five-month period to quantify the diurnal and day-to-day whole-tree sap flow (Qt) and hence the canopy scale transpiration (Ec). M...

Plant water use is an important function reflecting vegetation physiological status and affects plant growth, productivity, crop/fruit quality. Although hyperspectral indices have recently been proposed to assess use, limited sample sizes for established models greatly astricts their wide applications. In this study, we managed gather a large volume of continuous measurements canopy spectra thr...

We investigated the radial variation of sap flow within sapwood below the live crown in relation to tree size in 10-, 32-, 54- and 91-year-old maritime pine stands (Pinus pinaster Ait.). Radial variations were determined with two thermal dissipation sensors; one measured sap flux in the outer 20 mm of the xylem (Jref), whereas the other was moved radially across the sapwood in 20-mm increments ...

Actual evapotranspiration is assessed via surface energy balance at an hourly rate. However, a robust estimation of daily evapotranspiration from hourly values is required. Outcomes of surface energy balance are frequently determined via measures of eddy covariance latent heat flux. Surface energy balance can be applied on images acquired at different times and spatial resolutions. In addition,...

Nocturnal water flux has been observed in trees under a variety of environmental conditions and can be a significant contributor to diel canopy water flux. Elevated atmospheric CO(2) (elevated [CO(2)]) can have an important effect on day-time plant water fluxes, but it is not known whether it also affects nocturnal water fluxes. We examined the effects of elevated [CO(2)] on nocturnal water flu...

[1] We quantified canopy transpiration (EC) using sap flux measurements representing the four major forest types (northern hardwoods, conifer, aspen/fir, and forested wetland) around the WLEF-TV tall tower in northern Wisconsin. In order to scale individual sap flux measurements to EC, we quantified the amount of sapwood area per unit ground area and the spatial distribution of sap flux within ...