RESTORATION SUCCESS EVALUATION OF A THINNED AND ENRICHED PINE PLANTATION IN SRI LANKA

Abstract

Enrichment of monoculture plantations with broad-leaved species convert poorly managed exotic plantations into mixed species woodlands with enhanced ecosystem services. However, the effect of enrichment planting on the recruitment of plant diversity is poorly understood. This study aims to investigate the effect of enrichment planting in an eleven-year-old restored Pine (Pinus caribaea Morelet) plantation (RP) and a 25–30-year-old unrestored Pine plantation (UP) in Hantana, Sri Lanka. All naturally regenerated woody species were tagged, identified, and counted. The height and the diameter at breast height were measured. Nearly four times more woody species emerged from RP than UP. However, majority of species in both RP and UP were represented by the exotic invasive tree species Alstonia macrophylla Wall. ex G. Don. The mean density of seedlings of woody species was higher in RP than UP. The Shannon-Wiener diversity index was higher in RP than UP for all different life stages. Endemics were only recorded in RP. Since improved plantation structure and higher diversity was recorded in RP than UP, thinning followed by enrichment planting can be used to restore monoculture Pine plantation into mixed species plantations.