Transformation of degraded forests into semi-natural production forests in northern Thailand
This study focussed on the degraded Deciduous Dipterocarp-Oak Forests (DDF) in northern Thailand. The aim was to provide information on site and stand conditions and to propose and assess improvement treatments to transform these forests into semi-natural production forests. As a consequence of extensive exploitation and dramatic loss of forest cover, Thailand declared a nationwide logging ban in 1989. To halt ongoing forest destruction, by increasing the forest utilisation value, degraded forests have to be transformed into productive forests. The site research showed that the observed DDF on some sites originated from more productive forest types. For the first time, site productivity could be measured by stem section analyses on Vitex limoniifolia. In the research stands, stocking volume was low but the number of stems was high. Only few stems of large dimensions occurred and many of these were damaged. Regeneration seemed sufficient for transformation into semi-natural production forests. Based on the observed site productivity and stand conditions, improvement treatments were proposed and applied for this transformation. The economic feasibility of this approach was assessed: gross margins would be negative initially, however positive gross margins can be achieved in the future if timber of larger dimensions can be extracted. Taken together, the transformation of degraded DDF into semi-natural production forest as proposed and tested, proves to be a promising approach for forest protection by utilisation.
degradierte Wälder ,tropische laubabwerfende Wälder, Thailand, tropical deciduous forests, degraded, site index, improvement treatments, semi-natural production forest
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