Effect of altitudinal gradation on population structure, composition and diversity of non timber forest product species of Central western ghats of Karnataka

Uttar Kannada and Shivamogga districts are situated in the Central Western Ghats of Karnataka and unique in nature by having rich diversity of Non Timber Forest Products (NTFPs) plant species. This paper deals with the population structure, composition and diversity status of NTFP species and these were studied in three altitudinal zones viz., coastal zone (0-250 MSL), midghat zone (251-500 MSL) and plane zone (501-750). Population structure was worked out based on density of seedlings, saplings and adults. Sixty quadrats were laid for the floristic assessment. The vegetation of NTFP composition considered 205 species belonging to 49 families. Importance value index (IVI) recorded highest for Knema attenuata (35.49) followed by Aporosa lindliyana and Hopea ponga at coastal zone. At midghat zone the IVI recorded highest for Hope aponga (90.16) followed by Knema attenuata and Garcinia gummigutta and at plane zone the IVI of Caryo taurens was be most dominant (23.70) followed by Aporosa lindliyana and Syzygium cumini. The coastal zone was very rich in species richness as compared to rest of the altitudinal zones. The richness ranged between 64 (plane zone) to 74 (coastal zone). The diversity of NTFP species highest (3.62) in the Coastal zone followed by midghat zone (2.98) and the lowest was in the plane zone (2.95). The total tree density was highest in the coastal zone (616.25 ha^-1) while, plane zone recorded the least (608.75 ha^-1). But basal cover was maximum at midghat zone (1485.77 m² ha^-1) and minimum for plane zone (502.19 m² ha^-1). The study suggested that structure, diversity and species richness are regulated by physiographic and climatic factors along the gradient.