Diversity of woody species in the Medicinal Plant Conservation Area (MPCA) of Silent Valley National Park, Kerala

Abstract

Silent Valley National Park (latitude 11°03′–11°13′ N, longitude 76°24′–76°32′ E) is a highly protected habitat situated in the Western Ghats, Palakkad district, Kerala. The area has gained importance in the history of conservation as a biodiversity-rich area which has been protected due to peoples’ intervention. The diversity of woody species (trees and lianas) of evergreen vegetation in the Medicinal Plant Conservation Area (MPCA) was studied through a quadrat sampling method. A total of 123 woody species, including 103 trees and 20 lianas, were enumerated. Three taxa were identified at generic level (Cinnamomum, Connarus and Pavetta). These 123 species belonged to 51 families and 103 genera. Among the families, Lauraceae was the most specious family represented by 13 species followed by Euphorbiaceae (12) and Rubiaceae (6). Shannon–Weiner (3.961) and Simpson indices (0.029) indicated high species diversity. A high number of species in a community is ecologically important since diversity increases as the community becomes more stable. The total stand density of the site was 2469 stems ha−1. Species density values varied from 0.83 to 151.67 stems ha−1. The highest value was shown by Dimocarpus longan (156.67 stems ha−1) followed by Cullenia exarillata (151.67 stems ha−1), Myristica beddomei (142.50 stems ha−1) and Syzygium laetum (125.83 stems ha−1). About 43% of the space and resources were shared by the top ten species, of which Cullenia exarillata, Myristica beddomei, Palaquium ellipticum and Dimocarpus longan had a major share, while the remaining 57% was shared by 113 species, as indicated by importance value index (IVI) values. Species represented by one or two individuals were considered as rare. Out of 123 woody species, 41% of the species were found to be rare in the study area. Such species require specific microhabitat conditions.