Floristic diversity and tree biomass studies at Jathika Namal Uyana, Anuradhapura; A tropical dry forest in Sri Lanka

Abstract

The Jathika Namal Uyana is a strict nature reserve at Anuradhapura district, located in north central province of Sri Lanka. It represent tropical dry forest type of Sri Lanka. This study aims to assess the floristic diversity and carbon stock of this forest. The study area covers an extent of 105 ha. A total of 30 sampling plots were randomly selected at a size of 20 m × 20 m with three replicates. A total of 735 trees, 2019 saplings and 1438 seedlings were enumerated. A total species of 42 woody trees and 13 lianas were identified from 20 families. Based on the important value index (IVI), the forest was dominated by Mesua ferrea (43.53%) next to Dimocarpus longan (16.73%) and Pterospermum suberifolium (12.78%). Mean density of trees, saplings and seedlings were 1,500, 1,484 and 1,057 ha -1 , respectively. Mean values of Shannon Wiener index for trees, saplings and seedlings were 1.52±0.0499, 1.96±0.034 and 1.42±0.076, respectively. Mean value of evenness for trees, saplings and seedlings were 0.77±0.02, 0.86±0.02 and 0.87±0.01, respectively and the above results revealed that the forest was in dense and medium floristic diversity with equally distributed species. Mean value of species richness for trees, saplings and seedlings were 6.6±0.41, 6.1±0.33 and 9.7±0.32, respectively and this result revealed that the seedlings richness were high in the forest. Mean value of canopy cover was 76.77% and this result showed that the forest was distributed with dense canopy. Mean value of total tree biomass and carbon stock was 366.35 and 172.18 tha -1 , respectively. Mean value of soil carbon, soil pH and soil CEC were 3.4 %, 5.5 and 140.21 (Cmol (+) kg -1 ), respectively.