Several Andean countries have planned to restore forest cover in degraded land to enhance the provision of multiple ecosystem services in response to international commitments such as the Bonn Challenge. Hydrological services, e.g. water supply, hydrological regulation and erosion mitigation, are particularly important to sustain the life of more than fifty million Andean people. To help improve decision-making on forestation in the Andes, we reviewed the available literature concerning the impacts of forestation on water supply, hydrological regulation, mitigation of erosion and landslides, hydrological processes such as infiltration, evapotranspiration and runoff in forest stands. Results show that forestation has had clear impacts on degraded soils, through reducing water erosion of soils and risk of moderate floods, increasing soil infiltration rate by 8 and topsoil organic matter (SOM). 20 years of tree plantation was sufficient to recover infiltration rate and sediment yield close to the levels of native forests whereas SOM, soil water storage and surface runoff of native forests could not be recovered by forestation in the time scales examined. At high elevations, exotic tree plantations on Andean grasslands had the most detrimental consequences since these grasslands showed an excellent capacity for hydrological regulation and erosion mitigation but also a water yield up to 40% higher than tree plantations.

Type of Case
Printed publication (book, sourcebook, journal article…)

Publisher
Forest Ecology and Management, Volume 433, Pages 569-584

Region
Americas

Biome
All

Forest Type
Planted forest

Primary Designated Function
Protection of soil and water