Water relations in native trees, northeastern Mexico.

摘要: Native trees and shrubs that grow in the semiarid regions of northeastern Mexico are important feed resources for range ruminants white-tiled deer. They also provide high quality fuelwood timber fencing construction. Since water stress is most limiting factor this region, present work was focused to study how seasonal leaf potentials ( ) native tree species related soil availability evaporative demand components. Studied were: Cordia boissieri (Boraginaceae), Condalia hookeri (Rhamnaceae) Diospyros texana (Ebenaceae) Bumelia celastrina (Sapotaceae). Determinations four were at 10 days intervals between July November 30, 2007 by using a Scholander pressure bomb. monitored five different plants per 06:00 h p, predawn) 14:00 md, midday). Air temperature, relative humidity, vapor deficit, precipitation content registered throughout. data subjected oneway ANOVA correlation analysis. During wettest period (Sep-10) p ranged from -0.72 (C. boissieri) -1.30 MPa (B. celastrina), contrast, during driest (Nov-30), m varied -2.90 celastrina) -6.10 (D. texana). Diurnal values negatively correlated with air temperature positive relationship found humidity. The ability cope drought depends on pattern uptake extent control loss through transpirational flux. Introduction main type vegetation Mexico, known as Tamaulipan thornscrub, distinguished wide taxonomic groups exhibiting differences growth patterns, life spans, textures, dynamics, phenological development (Reid et al., 1990; McMurtry 1996). This shrubland, which covers about 200,000 km 2 including southern Texas (Udvardy, 1975), characterized an average annual 805 mm yearly potential evapotranspiration 2,200 mm. Vegetation has been utilized forage source domestic livestock wildlife, fuelwood, construction, medicine, agroforestry reforestation practices disturbed Corresponding author: E-mail: humberto@fcf.uanl.mx