CLIMATE RESILIENCE THROUGH NATURAL REGENERATION IN DEGRADED NATURAL FORESTS OF SOUTH-EASTERN HILLY REGION OF BANGLADESH

A study was conducted by using 5m × 5m sized 179 quadrates following multistage random sampling method for comparative regenerating tree species, quantitative structure, diversity, similarity and climate resilience in the degraded natural forests and plantations of Cox's Bazar North and South Forest Divisions. A total of 70 regenerating tree species were recorded representing maximum (47 species) from degraded natural forests followed by 43 species from 0.5 year 39 species from 1.5 year and 29 species from 2.5 year old plantations. Quantitative structure relating to ecological dominance indicated dominance of Acacia auriculiformis, Grewia nervosa and Lithocarpus elegans seedlings in the plantations whereas seedlings of Aporosa wallichii, Suregada multiflora and Grewia nervosa in degraded natural forests. The degraded natural forests possess higher natural regeneration potential as showed by different diversity indices. The dominancebased cluster analysis showed 2 major cluster of species under one of which multiple sub-clusters of species exists. Poor plant diversity and presence of regenerating exotic species in the plantations indicated poor climate resilience of forest ecosystem in terms of natural regeneration. Introduction Global climate change scenarios strongly alarmed that the low-lying areas of Bangladesh are likely to go under water (McCarthy et al. 2001). Moreover, climate changes impart severe impacts on the forest ecosystem, species distribution, diversity, re-vegetation potentiality of forest ecosystems and plantations etc. (Wang et al. 2015). Bangladesh, being a transition part of the Indo-Myanmar biodiversity hot spot, harbored rich biological diversity (Hossain 2001, Nishat et al. 2002). The South-Eastern region of Bangladesh covers the significant part of hill forests representing features of tropical evergreen and semi-evergreen forests. The natural forests of the region are one of the species-rich and productive government managed reserve forests, but these are becoming degraded through illegal logging, forest fire, shifting cultivation, human settlement, agriculture and horticulture expansion in the valleys, clear felling followed by commercial plantation with short rotation exotic species etc. (Ahmed 2008). Information on natural regeneration is required for sustainable forest management in terms of both economic and environmental considerations (Verma et al. 1999). The plantation preparation and maintenance activities, i.e. clear felling accelerates loss of seedlings and saplings as well as disturbs the natural condition of the forests and hence the ecosystem (Haque and Alam 1988). Patterns of natural regeneration and recruitment also answer the basic question about forest management (Hossain et al. 1999). Uncontrolled browsing, regular weeding has limiting effects on recruitment of natural regeneration (Chapman et al. 2002). Some sporadic research on regeneration composition and potential was conducted in different forests of Bangladesh by *Author for correspondence: <akhterhossain2010@gmail.com>. Institute of Forestry and Environmental Sciences Chittagong University, Chittagong-4331, Bangladesh.