[1] Assumed representative center-of-stand measurements are typical inputs to models that scale forest transpiration to stand and regional extents. These inputs do not consider gradients in transpiration at stand boundaries or along moisture gradients and therefore potentially bias the large-scale estimates. We measured half-hourly sap flux (JS) for 173 trees in a spatially explicit cyclic samp...

The design and implementation of a new or improved irrigation or drainage system should be preceded by a study of the soil water regime (SWR) to define the need for such a system and to optimize its design. This requires estimates of appropriate parameters characterizing the long-term (multiyear) dynamics of the SWR and its relation to biomass production. Parameters that could be used for this ...

Oxygen isotope signatures of transpiration (δ E ) are powerful tracers of water movement from plant to global scale. However, a mechanistic understanding of how leaf morphological/physiological traits effect δ E is missing. A laser spectrometer was coupled to a leaf-level gas-exchange system to measure fluxes and isotopic signatures of plant transpiration under controlled conditions in seven di...

Variation in the sources of water used by tree species has important ramifications for forest water balances. The fraction of tree transpiration water derived from the unsaturated soil zone and groundwater in a riparian forest was quantified for Populus fremontii, Salix gooddingii, and Prosopis velutina across a gradient of groundwater depth and streamflow regime on the San Pedro River in south...

Rapid changes in the transpiration rate from a leaf or leafy shoot as a result of excision of that leaf or shoot have been observed in many plants bv many investigators (1, 2, 5, 7, 10, 11, 12, 13, 16). In banana plants, both photosynthesis and transpiration have been found to change rapidly following excision of the leaf (7). The mechanism underlying such rapid changes in transpiration has bee...

Stand transpiration was measured during the 2003 and 2004 growing seasons using heat dissipation sap flow sensors in a Scots pine (Pinus sylvestris L.) and a pubescent oak (Quercus pubescens Willd.) forests located in a montane area of the Eastern Pyrenees (NE Spain). The first aim of the study was to assess the differences in quantitative estimates of transpiration (Ec) and the response to eva...

The temporal aspect of a model of pupal dehydration is improved upon. The observed dependence of pupal transpiration on time is attributed to an alternation between two, essential modes, for which the deposition of a thin, pupal skin inside the puparium and its subsequent demise are thought to be responsible. For each mode of transpiration, the results of the Bursell investigation into pupal de...

Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developin...

We examined the extent of osmotic adjustment and the changes in relative water content (RWC) and transpiration rate (i.e., relative stomatal function) that occur in water-deficit-conditioned 6-year-old Thuja occidentalis L. (eastern white cedar) trees in response to a severe drought. Trees conditioned by successive cycles of mild or moderate nonlethal water stress (conditioning) and nonconditio...