Restoration of tropical rain forest success improved by selecting species for specific microhabitats

Abstract

The restoration of the Southeast Asian tropical forests is a global priority but is limited by a lack of experience and knowledge regarding tree species performance in the various micro-habitat conditions that are prevalent after disturbance. Here we study the survival, growth, susceptibility to damage and capacity to resprout of 38 Sumatran lowland tropical tree species in a restoration planting trial in several typical post-disturbance microhabitats. 3200 seedlings were planted in four two-hectare blocks in February 2013 at the Hutan Harapan Ecosystem Restoration concession in Sumatra, Indonesia, and subsequently censused every six-months for two years to assess performance and changes in microhabitat conditions. By the end of the experiment overall survival was only 41%, with damage incurred by 55% of the surviving plants. Habitat conditions (light/shade, presence/absence of bamboo and shrubs) and their interactions affected survival in complex ways. Bamboo negatively affected survival whereas shrubs had a positive effect, except where bamboo was also present. Height growth rate increased when sites were light-exposed. Individual species performances also differed across habitats. Defining a minimum threshold of 50% survival as a measure of success in different habitat types, only two species (A. pavonina and N. wallichiana) could be characterized as generalists. Eighteen other species were characterized as specialists with good performance in one-three habitat types. Our findings suggest that enhanced restoration success could be achieved through better species-site matching.