Restoration of rain forest beneath pine plantations: A relay floristic model with special application to tropical South Asia

In the wet forest regions of southwest Sri Lanka and the Western Ghats, India, Pinus caribaea was a common tree species for reforestation on public lands that were originally cleared of native forest for agriculture but subsequently succeeded to fire tolerant grasses and ferns. Much of this reforestation occurred during the 1970s and 1980s. The ecological literature suggests that in many temperate broadleaf forest regions pine is an important component of early succession on old fields, beneath which second growth hardwood can establish and eventually dominate. More recent studies have demonstrated the establishment of native rain forest regeneration beneath a variety of exotic tree plantations. We review nearly twenty-five years of research on this topic for South Asia through a series of studies done in southwest Sri Lanka. Results demonstrate that native species recruitment of both pioneers and site generalist late-successional trees grow well beneath exotic pine plantations. Diversity and density increase from plantation interior to edge. Protection from groundstory fire is the single most important component of promoting regeneration recruitment beneath pine. Establishing late-successional site and dispersal restricted species requires planting beneath pine rather than reliance on natural establishment. Best establishment and growth occur in openings where rows of canopy pine have been removed. Species considered for planting comprise the major late-successional canopy tree species of the forest in the genera Dipterocarpus, Shorea (Dipterocarpaceae) and Mesua (Clusiaceae). Native species that produce non-timber forest products (NTFP) need to be planted with best results in canopy openings. The most valuable NTFP's comprise a sugar palm (Caryota urens), rattan (Calamus spp.) and a medicinal liana (Coscinium fenestratum). Financial analyses reveal that pine plantations that are enrichment planted and cultivated with rain forest timber and non-timber species can provide superior economic benefits as compared to land cultivated singly for tea. (C) 2014 Elsevier B.V. All rights reserved.