Shanmuganathan Jayakumar

The study provides information on the tree diversity, stand structure, and regeneration pattern of the Mahananda Wildlife Sanctuary. Tree diversity and its relation to habitat have been explored using 88 plots with dimensions of 50 × 20 m. A survey of 8.8 ha of the study area was conducted during the fieldwork. Plants with a circumference of 30 cm and above were enumerated as trees, while plants with a circumference between 30–10 cm were considered juveniles (saplings and seedlings). A total of 1677 tree individuals belonging to 67 genera of 43 families were recorded. Five species - Shorea robusta, Schima wallichii, Acer oblongum, Magnolia pterocarpa and Ficus benghalensis contributed to the maximum stand density and species richness. The total stand density per hectare was recorded as 2160 individuals/ha, with a total basal area of 8.86 m²/ha. The regeneration status has been evaluated as ‘Good’, with 4336 regenerating individuals/ha recorded during the study. Diversity indices were calculated: Shannon-Weiner index was 3.607, Simpson dominance index was 0.937, Margalef index was 11.45, and evenness was 0.428.

Urban forests undoubtedly play a foremost role in mitigating the climate change impacts, also contributes to the quality of urban society thereby providing numerous environmental, ecological, psychological and socio-ecological benefits. Particularly knowing any forest's structure, function and value head from its inventory of diversity and richness. So to better understand the above mentioned and their ecosystem service, a work has been conducted in the urban forest patch of Puducherry. Keeping the importance of urban forest patch in a study to access the tree diversity, biomass and carbon stock of the urban forest patch of Puducherry, India has been undertaken. For quantitative assessment, an area of 1 hectare comprising, 25 plots of 20×20m was studied and all trees ≥ 10 cm gbh were enumerated. As a whole, 30 tree species were enumerated belonging to 17 families and 30 genera. Tree number accounted for 586 stems per hectare, the basal area was found to be 34.273 m² ha⁻¹. The total biomass and carbon stock of the patch were found to be 278.22Mgha⁻¹ and 139.11MgCha⁻¹ respectively. This baseline study will further be used to analyze its various components and its ecosystem services, inspiring for its better management.

It has been found in the last 3–4 decades that different ecosystems in the tropical regions contributed maximum trace gases (CH₄ and N₂O) to atmosphere. Terrestrial ecosystems in tropics, sub-tropics and in temperate regions are the well-known sources and sinks of important GHGs (green house gases). Nowadays, developing countries of Asia Pacific regions are contributing a maximum amount of these trace gases at the global scale. Anthropogenic activities and changing environmental conditions alter the dynamics of different ecosystems that stimulate GHGs emission in the last few years. A higher concentration of CO₂ and temperature in soil enhance microbial activity. The techniques for sampling, estimation and future prediction of fluxes of these trace gases from different types of ecosystem are still undergoing changes with the advancement in knowledge of microbiology, geology and technology. This review discusses GHG, mainly methane (CH₄) and nitrous oxide (N₂O) emission estimated from different ecosystems, advancement in estimation technology and the key controlling factors for their emission around the world.