Urban sacred grove forests are potential carbon stores: A case study from Sikkim Himalaya

Abstract

Urban forests function as lungs in the cities and help in providing a healthy environment to people by reducing warming and improving air & water quality. Information on the carbon storage and capture capacity of the urban forests especially sacred forests in India is limited. We estimated and examined the different carbon pools and sequestration potentials of two urban sacred forests i.e. Deorali Chorten monastery sacred forest (DMS) and Enchey monastery sacred forest (EMS) and tested its performance against a rural natural forest (STF). Carbon in trees was estimated allometrically from five plots of 31.6 × 31.6 m2 in each of the study sites using the Forest Survey of India's volume equations, wood density, and tree height. Thirty soil samples collected from three soil depths (0–15, 15–30, and 30–45 cm) from each of the study sites were colorimetrically estimated for soil carbon. Litter biomass collected from ten quadrats of 1 × 1m2 from each of the study sites was used for the estimation of litter carbon. Ecosystem carbon sequestration was calculated from the carbon stock values of each of the study sites by dividing by the corresponding age of sites. Tree carbon density varies significantly (p<0.001) across sites, and aboveground biomass exhibited a positive significant relationship with tree density (p<0.05), and basal area (p<0.01). Pattern of carbon stock and sequestration is EMS (156.04 Mg C ha−1; 2.5 Mg C ha−1y−1) ; DMS (155.39 Mg C ha−1; 3.42 Mg C ha−1y−1) ; STF (76.58 Mg C ha−1; 5.27 Mg C ha−1y−1).Topsoil has the highest carbon stock with a peak value in EMS (118.70 Mg C ha−1) followed by STF (107.84 Mg C ha−1), and DMS (97.64 Mg C ha−1). The Present study revealed that old forests have higher carbon storage but reduced sequestration potential. Urban forests allocate more carbon in vegetation than in soil, and warming and a shift in precipitation pattern due to climate change may decrease soil carbon and fertility. Hence, proper management of urban forests by replacing old trees with new ones can effectively mitigate the ill effects of global warming in the cities by regulating the climate through CO2 sequestration.