| Abstract: |
To enhance the contribution of forest land to local livelihoods and environmental functions, the Government of Viet Nam formulated Forest Development Strategies 2006–2020. Longterm timber plantations were planned to be developed on production forest land across the country, combined with forest protection efforts, especially within watersheds to improve watershed services. In this chapter, we present the impact on hydrological functions of three forest-intensification scenarios in Ho Ho sub-watershed, Northcentral Viet Nam. The scenarios represent government planning as well as local expectations. The Generic River model was used to assess the impact on river flow of various forest scenarios.
Compared to scenarios with higher tree-canopy density, the conversion of degraded forests into short-term acacia plantations would lead to higher river flow and higher surface runoff with accompanying risk of severe soil erosion because most of the forest area is sloping land. In contrast, expansion of long-term timber plantations in the forest-restoration scenario would result in less river flow compared to an expansion of acacia plantations and less surface run-off with higher groundwater storage. The lowest surface run-off was found in the forest-restoration scenario. Owing to the projected unfavourable impact on river flow of higher tree-canopy cover and density, we recommend that local authorities carry out a trade-off analysis between environmental benefits that forest-intensification strategies can provide—such as carbon sequestration and biodiversity protection—and water provision. We also highlight the need to develop innovative forest-plantation models that can minimize soil loss, especially on sloping land, for example, by adopting agroforestry, which optimises the spatial and temporal aspects of systems. Finally, we emphasize the urgency in accomodating additional ecosystem services other than only water provision in the current Payment for Forest Ecosystem Services decree, to encourge smallholder forest owners to participate in forest-protection and -restoration efforts. |
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