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Soil and water impacts of reforesting severely degraded grasslands in Leyte, the Philippines

Researcher: J. Zhang
Current affiliation: VU University

Supervisors:

Collaborators:

Duration: 2012-2015
Funding: China Scholarship Council (CSC) and Australian Centre for International Agriculture Research (ACIAR) project no. ASEM/2010/050 to J. Herbohn

Key research questions / background

Large areas of the Philippine island of Leyte have been subject to frequent burning and so turned into largely unproductive fire-climax grasslands. Previous research has shown that such areas can produce extremely high amounts of overland flow. This has negatively affected the hydrological regime, with strongly enhanced runoff response to rainfall during the wet season and decreased availability of water in the dry season. The island has now undergone significant reforestation and there are claims of improved hydrological conditions occurring ca. 15-20 years after tree planting. Since both naturally regenerating and planted forests typically use (much) more water than the degraded vegetation they replace, the implication of these claims is that infiltration of rainfall after forestation has improved to such an extent that it more than compensates the higher water use of the trees. This research aims to quantify the effect of different tree species (Acacia, Gmelina and Swietenia) on soil physical characteristics in comparison with those beneath natural regrowth on different geological substrates. Further, hillslope and catchment runoff response to rainfall will be studied under different land-cover types using stable isotope and chemical end member analytical techniques to elucidate runoff contributions from different sources.

Related background publications

Last modified: Wed Dec 30 12:46:28 CET 2015