Stemflow and soil water redistribution in intact and disturbed plants of Larrea divaricata in southren Argentina

CECCHI, G.A.; KRÖPFL, A.I.; VILLASUSO, N.M.; DISTEL, R.A.

Arid Land Research and Management

Taylos&Francis

Año: 2006 vol. 20 p. 209 - 217

1532-4982

Abstract The interception of rainfall by the shrub canopy and its redistribution via stemflow to deep soil layers represents an important source of deep-water. Therefore, reductions in stemflow trough canopy disturbance should reduce deep-water recharge. The objectives of this study were to determine (1) stemflow, (2) soil moisture beside the root crown at three depths (10-25 cm; 25-45 cm; 45-75 cm) and (3) predawn plant water potential in intact and disturbed individuals of Larrea divaricata. Disturbed individuals were sprouts (0.85 m height) coming after mechanical clearing. Stemflow was higher (p<0.01) in intact (9% precipitation) than in disturbed (4% precipitation) plants. Soil moisture besides root crown was similar or higher (p<0.05) in intact than in disturbed plants, particularly at deep soil layers. Variations of predawn water potential in intact plants of L. divaricata were mostly accounted by variations in soil water content at 45-75 cm depth, whereas variations of predawn water potential in disturbed plants were mostly accounted by variations in soil water content at 10-25 cm depth.  Our results suggest that disturbance of L. divaricata canopy by mechanical clearing reduces stemflow efficiency and the amount of water redistributed to deep soil layers. Sprouts appear to be more dependent on shallow water, which may intensify competition for water with shallow rooted grasses. Keywords: shrub water potential; deep soil moisture; mechanical clearing