Where there is sucient water storage in the soil the water potential …Wx† in shoots of Norway spruce [Picea abies (L.) Karst.] is strongly governed by the vapour pressure de®cit of the atmosphere, while the mean minimum values of Wx usually do not drop below ÿ1:5 MPa under meteorological conditions in Estonia. If the base water potential …Wb† is above ÿ0:62 MPa, the principal factor causing wa...

1. The water regime in soil commonly approaches equilibrium of water potential with the insects living there. 2. Even under these conditions, non-equilibrium processes have a significant effect on water movement through the cuticle of soil insects. 3. Measurements of water potential on either side of the cuticle of Costelytra zealandica larvae showed that equilibrium is not reached while the in...

ECOPHYS, an individual-based process model for poplar, requires a three-dimensional soil water redistribution model to simulate soil water dynamics, plant uptake, and root growth. SOILPSI is a potential-driven water redistribution model based on the RHIZOS rhizosphere simulator. It expands on RHIZOS by calculating water flux based on water potential, and has a macropore flow mode to allow rapid...

Aim: Soil water is essential for the physiological processes of plant growth and fitness. Owing to the difficulty of assessing wide variations in soil water reserves, plant distribution models usually estimate available water for plants through such climatic proxies as precipitation data (P) or climatic water balance (P minus potential evapotranspiration). We evaluated the ability of simple cli...

We investigated hydraulic constraints on water uptake by velvet mesquite (Prosopis velutina Woot.) at a site with sandy-loam soil and at a site with loamy-clay soil in southeastern Arizona, USA. We predicted that trees on sandy-loam soil have less negative xylem and soil water potentials during drought and a lower resistance to xylem cavitation, and reach E(crit) (the maximum steady-state trans...

Two types of Soil Vegetation Atmosphere Transfer (SVAT) modeling approaches can be applied to monitor root-zone soil moisture in agricultural landscapes. Water and Energy Balance (WEB) SVAT modeling is based on forcing a prognostic root-zone water balance model with observed rainfall and predicted evapotranspiration. In contrast, thermal Remote Sensing (RS) observations of surface radiometric t...

In arid ecosystems, variation in precipitation causes broad-scale spatial heterogeneity in soil moisture, but differences in soil texture, development, and plant cover can also create substantial local soil moisture heterogeneity. The boundary between inland desert sand dunes and adjacent desert habitats exhibits abrupt changes in soil and vegetation characteristics that may be associated with ...

A process model of the soil-tree-atmosphere continuum, which treats the plant physiology, eco-physiology and vegetation structures in detail, needs to describe the dynamics of the water flow within this continuum. The concept of a soil-plant-atmosphere continuum (SPAC) (Philip, 1966) was first described by Huber (1924). In such a continuum, the removal of water lowers the water potential in the...

Water conservation is a priority in San Antonio, Austin, Dallas, and other major Texas cities that routinely face water shortages and drought. Soil management is fundamental to water conservation efforts. Incorporation of composted biosolids (CB) in low quality soils can enhance water conservation and provide organic carbon and nutrients that improve growth of vegetation and limit sediment loss...