Assessment of tree diversity in distinctive deciduous forests of Suruli falls, Southern Western Ghats

A quantitative inventory was conducted in two distinctive tropical deciduous forests at Suruli falls forest of southern Western Ghats. Two one-hectare plots were established and all trees >10cm DBH measured. Species richness, density, family importance value (FIV) and importance value index (IVI) were calculated and the results varied among the two sites. A total of 777 stems and 52 species were documented in both the sites and moist deciduous forest (MDF) had maximum number species richness and density than dry deciduous forest (DDF). The basal area was higher in MDF (502 stems/ha and 16.52 m2/ha) than in DDF (275 stems/ha and 7.23 m2/ha). However, Shannon and evenness indices showed a negative trend (DDF- 2.62, 0.41 and MDF- 2.37, 0.27). Diameter class-wise distribution of trees showed reverse ‘J shaped’ curve in both the forest types. Pterocarpus marsupium was the mono-dominant species holding one-third of the IVI (113), 27% of the stem density and 30% of the total basal area. DDF site is suspected to recurrence of annual fire. Anogeissus latifolia and Strychnos potatorum were the fire-tolerant species only found in lower diameter class. The maximum species shared contiguous distribution in the deciduous forests. The observed variations in the tree community between the two deciduous forest sites are possibly due to variations in altitude, rainfall, temperature, past disturbance, fire and edaphic characteristics.