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Uruguay Study: Trees Cut Water Yield 35%
7 Sep
Summary
- Forests reduced water yield by 35% in a 20-year Uruguay study.
- Pine plantations accessed and transpired more water than grasses.
- Water reductions were noticeable several years after tree establishment.
Across Uruguay, the conversion of grasslands to managed forests, particularly eucalyptus and pine plantations, has altered landscape hydrology. A comprehensive 20-year paired-watershed study initiated in 2000 in northern Uruguay offers definitive long-term measurements of this effect.
Researchers monitored two neighboring watersheds, one remaining pasture and the other afforested with loblolly pine in July 2003. By June 2020, the forested watershed demonstrated substantially less water output.
After planting, the cumulative water yield from the pine watershed decreased by 35% over 17 years. This reduction became evident several years post-establishment, gradually becoming significant as the pine plantation matured.
The study links this decline to pine trees' deeper root systems accessing more soil water, which is then lost through transpiration, thus diminishing streamflow.
This research, published in 2024, underscores the impact of afforestation on water availability, noting that factors like forest density and landscape configuration also play a role. The findings from La Corona estancia provide a clear, long-term view of the hydrological consequences of land-use change.
