Comparing Floristic Diversity between a Silviculturally Managed Arboretum and a Forest Reserve in Dambulla, Sri Lanka

摘要

Repeated slash and burn cultivation creates wasteland with thorny shrubs, which then takes a long time to become secondary forests through serial stages of succession. Assisted natural regeneration through silvicultural management is a useful restoration method to accelerate succession. This survey evaluates the effectiveness of a simple silvicultural method for the rehabilitation of degraded lands to productive forest, thereby increasing floristic wealth. Field-based comparative analyses of floristic composition were carried out at a silviculturally managed forest (Popham Arboretum) and a primary forest (Kaludiyapokuna Forest Reserve) which is located in Dambulla in Sri Lanka. Floristic analysis was used to examine the effectiveness of silvicultural techniques for successful restoration of degraded forest in the dry zone. Nine 20 m × 20 m plots in each forest were enumerated and the vegetation ≥ 10 cm girth at breast height was quantitatively analyzed. Cluster analysis resulted in five distinguishable clusters (two from Popham Arboretum and three from Kaludiyapokuna Forest Reserve). Similarity indices were generated to compare the plots within and between sites. Floristic similarity was higher in forest reserve plots compared to arboretum plots. A total of 72 plant species belonging to 60 genera and 26 families were recorded from the study sites. Of the recorded species, Grewia damine and Syzygium cumini (Importance Value Index, IVI = 24 and 23 respectively) were the ecologically co-dominant taxa at the Popham Arboretum. In contrast, Mischodon zeylanicus (IVI = 31), Schleichera oleosa (IVI = 25) and Diospyros ebenum (IVI = 21) were the abundant taxa in the forest reserve.