O. P. Tripathi , H. N. Pandey , R. S. Tripathi

Abstract

The varied physiography, soil and climatic conditions are responsible for the development of sub-tropical evergreen, sub-tropical semi-evergreen, broad-leaved, sal and sub-tropical pine forests in the State of Meghalaya. The sub-tropical evergreen, semi-evergreen, and broad leaved forests are very rich in tree as well as other plant species as compared to sal and pine forests. Biotic factor, particularly human interference in the form of shifting agriculture, timber extraction and fuelwood collection, and to a lesser extent, cattle grazing have accelerated the fragmentation process of these forests, except at few places where continuous forest patch exceeds 50 km² area. Fragmentation of the forest may have serious consequences on species composition and community structure of trees in the forest communities of the state. This study shows that all of them are highly disturbed as is evident from high frequency of smallsize patches. Pine forests are most disturbed. An obvious approach to conserve plant biodiversity would be to map distribution pattern and determine concentration of biodiversity and endemic species in the forest fragments.

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Gyati Yam ¹, O. P. Tripathi ¹

Affiliations
1 Department of Forestry North Eastern Regional Institute of Science and Technology (Deemed university), Nirjuli , Itanagar, Arunachal Pradesh, IN

Abstract

Present study was conducted during 2011-2012 in subtropical forests for enumeration of floristic diversity, community characteristics and above ground biomass (AGB) analysis. Random sampling approach was adopted. Altogether 97 species were recorded from the sampled area (0.3 ha) and species richness was higher at woody (60 species) layer than other layer of forest. Majority of species showed low frequency followed by later frequency classes. Dominance distribution curve for woody species was log-normal while it was broken-stick model for shrubs and ground species. Majority of species showed clumped spatial distribution pattern. Stand density of woody species was 1607 individuals ha^-1 and basal cover was 68.07 m² ha^-1 . Density-diameter distribution of woody species differed markedly. Lower diameter individuals have contributed maximum of the total stand density however, 55% of the basal cover was added by intermediate diameter class. Diversity index was recorded highest for woody species and minimum for the shrubs/sapling layer while dominance and evenness index resulted reverse trend. Total AGB and carbon of woody species was 575.05Mg ha^-1 and 287.53Mg C ha^-1 respectively. Individuals having diameter <20cm contributed about 71% of total stand density while contribution to total AGB was only 23%. Although individuals having >50cm were low in the forest but contributed 33% of the total AGB. Distribution of AGB carbon in different population age class followed similar pattern to that of AGB distribution.

Keywords

Above Ground Biomass, Dominance, Population Structure, Species Richness, Ziro Valley.

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