The framework species method: harnessing natural regeneration to restore tropical forest ecosystems.

As interest in restoring tropical forests surges, so does the need for effective methods to ensure success. The framework species method (FSM) restores forest ecosystems by densely planting open sites, close to natural forest, with woody species, indigenous to the reference ecosystem and selected for their ability to accelerate ecological succession. Criteria for selecting framework species include: (i) representative of the reference forest ecosystem, (ii) tolerant of open conditions, (iii) ability to suppress weeds, (iv) attractiveness to seed-dispersing animals and (v) easily propagated. The method is effective where forest remnants and viable populations of seed dispersers remain. The origins and elements of the FSM are discussed. We review its adoption in 12 countries. Adherence to original principles was mostly high, but some misuse of the term was evident. The need for clearer definitions was identified. We place the FSM on a scale of restoration methods, matched with degradation levels and compare its establishment costs with those of other methods. Obstacles to its wider adoption, both technical and socio-economic, are discussed, along with how these might be overcome. Finally, the FSM is more clearly defined to facilitate its use in contributing towards the goals of the UN Decade on Restoration. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.

Genetic assessment of three Fagaceae species in forest restoration trials.

Restoring isolated patches of forest ecosystems in degraded landscapes could potentially lead to genetic loss and inbreeding. Therefore, this study determined the occurrence of genetic diversity among the tree species Castanopsis tribuloides, C. calathiformis, and Lithocarpus polystachyus all of which were proven previously to be effective native tree species in the restoration of upland evergreen forests in northern Thailand when using the seed sample collection method. We tested our hypothesis as to whether the genetic diversity of a plant population that had been planted from the seeds of 4-6 adult trees would be lower and whether incidences of fixation index (Fis) would be higher among the second generation seedlings of these three Fagaceae species in isolated forest restoration trial plots. Microsatellite primers were selected from the entire genome sequence of C. tribuloides and the genetic sequences of C. tribuloides, L. polystachyus, and C. calathiformis were analyzed. Our results indicated a high degree of genetic diversity (He) in C. tribuloides (0.736) and C. calathiformis (0.481); however, a low level of genetic diversity was observed in L. polystachyus (0.281) within the restored forest. The fixation index for the second generation of L. polystachyus and C. calathiformis in the restored forest showed evidence of inbreeding. These results imply the efficiency of the seed sample collection method and verify that it does not reduce the level of genetic diversity in C. tribuloides and C. calathiformis. However, it may result in incidences of an inbreeding phenomena, suggesting the need to increase the number of adult trees used at the seed collection stage.