Response of velvet mesquite to groundwater decline
1992; Elsevier BV; Volume: 23; Issue: 1 Linguagem: Inglês
10.1016/s0140-1963(18)30540-8
ISSN1095-922X
AutoresJuliet C. Stromberg, James A. Tress, Scott D. Wilkins, Sheldon D. Clark,
Tópico(s)Tree-ring climate responses
ResumoMesquite (Prosopis velutina) bosques are groundwater-dependent riparian woodlands that were once widespread in the American Southwest. Groundwater withdrawal from the aquifer below an ephemeral creek in the Sonoran Desert of Arizona created the opportunity to quantify relationships between groundwater depths and bosque traits. Temporal and spatial variation in plant water potential, leaflet size, leaflet number, canopy height, and live and dead vegetation volume all indicate that the bosque requires a shallow aquifer and that bosque traits change continuously with groundwater depth. The bosque had high water potentials, large leaflets (>7 cm2), tall stature (> 12 m), and large vegetation volume (>2 m3/m2) only where the water table was <5 m below the surface. Trees became increasingly stressed as groundwater declined to 15–18 m. Summer rains and seasonal surface flow temporarily reduced water stress and increased leaflet size for some trees, but did not offset effects of groundwater decline. Trees in areas of greatest groundwater decline (18–30 m) were under sublethal stress, as evidenced by low stem water potentials (<–4 MPa), reduced leaflet size ( 45%). These deepest groundwater levels are in the range of those documented to be lethal to mesquite in other bosque systems.
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