EFFECTS OF WATER DEFICIT ON URBAN FOREST GROWTH IN A DRYLAND SOUTH AMERICAN REGION.

C. F. MARTINEZ; F. A. ROIG; J. BRUNO CAVAGNARO; M. A. CANTÓN; A. M. DI BLASI

PHYTON - INTERNATIONAL JOURNAL OF EXPERIMENTAL BOTANY BA ARGENTINA

FUNDACION ROMULO RAGGIO

Lugar: Buenos Aires; Año: 2012 vol. 82

0031-9457

Urban forests located in dryland regions of Argentina are sustained by groundwater and meltwater irrigation, since the most commonly planted trees species have high water requirements and are exposed to shortages. This study assesses the effect of water deficit on diverse growth variables in saplings of Acacia visco (native tree species) and Morus alba (exotic tree species), two common trees in the urban forests of Mendoza?s Metropolitan Area. The saplings were exposed to different levels of water deficit under controlled nursery conditions during three growing seasons. There were three watering treatments:  replacement of 100% transpired water (control group or T1), replacement of 66% transpired water (moderate water deficit group or T2) and replacement of 33% transpired water (severe water deficit group or T3). Data indicated that the impact of water stress was more significant in the exotic tree-species, Morus alba. The growth variables height, stem diameter, leaf area, and annual tree-ring width showed no significant difference between T1 and T2 in Acacia visco. In T3 growth was affected in both species. This indicated that a reduction of 33% of water resulted in reduced tree growth, compared to T1. However, the Morus alba trees showed a low tolerance to any water deficit, while Acacia visco had more tolerance under moderate water stress conditions, which even promoted growth. These results reflect the importance of selecting tree species with lower water consumption (i.e. in terms of their suitability with limited water resources) in sustainable urban forests in cities located in dryland environments.