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In tropical and sub-tropical regions, biomass carbon (C) losses through forest degradation are recognized as central to global terrestrial carbon cycles. Accurate estimation of forest biomass C is needed to provide information on C fluxes and balances in such systems. The objective of this study was to develop generalized biomass models using harvest data covering tropical semi-evergreen, tropical wet evergreen, sub-tropical broad leaved, and sub-tropical pine forest in North East India (NEI). Among the four biomass estimation models (BEMs) tested AGBest = 0.32(D2Hδ)0.75 × 1.34 and AGBest = 0.18D2.16 × 1.32 were found to be the first and second best models for the different forest types in NEI. The study also revealed that four commonly used generic models developed by Chambers (2001), Brown (1989), Chave (2005) and Chave (2014) overestimated biomass stocks by 300–591 kg tree−1, while our highest rated model overestimated biomass by 197 kg tree−1. We believe the BEMs we developed will be useful for practitioners involved in remote sensing, biomass estimation and in projects on climate change mitigation, and payment for ecosystem services. We recommend future studies to address country scale estimation of forest biomass covering different forest types.

The need for an alternative drug for malaria initiated intensive efforts for developing new antimalarials from indigenous plants. The information from different tribal communities of northeast India along with research papers, including books, journals and documents of different universities and institutes of northeast India was collected for information on botanical therapies and plant species used for malaria. Sixty-eight plant species belonging to 33 families are used by the people of northeast India for the treatment of malaria. Six plant species, namely, Alstonia scholaris, Coptis teeta, Crotolaria occulta, Ocimum sanctum, Polygala persicariaefolia, Vitex peduncularis, have been reported by more than one worker from different parts of northeast India. The species reported to be used for the treatment of malaria were either found around the vicinity of their habitation or in the forest area of northeast India. The most frequently used plant parts were leaves (33%), roots (31%), and bark and whole plant (12%). The present study has compiled and enlisted the antimalarial plants of northeast India, which would help future workers to find out the suitable antimalarial plants by thorough study.

Spring is vital in all hilly areas. Without question, springs have aided in the advancement of human civilization. Mountain springs supply water to rural families in the Northeast. This spring ecological study was conducted in Dhalai, Tripura, with socio-economic policy significance. The springs chosen were Jamircherra (JS) and Govindabari (GS). The seasonal features of each spring were studied. The monsoon season is used to bring the life-giving flow of perennial springs. Several water quality indicators like WT, pH, EC, TDS, Turb, TH, DO, BOD, Ca+2, Mg+2, Cl−, No3, Po4 were examined to assess the risk of spring contamination. The most common aberrant results are samples having excessive phosphate (PO42−) and turbidity levels compared to norms. The spring's water quality was tested using the weighted arithmetic index methodology. The water quality at the two springs was adequate but not great throughout the year, causing human deaths from water-borne diseases. Thus, policy implementation was emphasized to save the spring and human life. A physicochemical evaluation of both springs was used to describe a techno-legal component of Environmental regulations.

In the modern era, rapid anthropogenic activities in the vicinity of the Himalayas disturb the carbon sequestration potential resulting in climate change. For the first time, this study estimates the biomass and carbon storage potential of Northeast India’s diverse land uses through a biomass estimation model developed for this region. The mean tree density in tropical, subtropical, and temperate forests was 539, 554, and 638 trees ha−1, respectively. The mean vegetation carbon stock was the highest for temperate forests (122.09 Mg C ha−1), followed by subtropical plantations (115.45 Mg C ha−1), subtropical forests (106.01 Mg C ha−1), tropical forests (105.33 Mg C ha−1), tropical plantations (93.00 Mg C ha−1), and temperate plantations (50.10 Mg C ha−1). Among the forests, the mean soil organic carbon (SOC) stock up to 45 cm depth was the highest for tropical forests (72.54 Mg C ha−1), followed by temperate forests (63.4 Mg C ha−1) and subtropical forests (42.58 Mg C ha−1). A strong relationship between the tree basal area and biomass carbon storage was found for all land-use types. The land-use transformation from agriculture to agroforestry, and grassland to plantations increased both vegetation carbon (VC) and SOC stocks. The corresponding increase in VC and SOC was 40.80 and 43.34 Mg C ha−1, respectively, in the former, and 83.18 and 97.64 Mg C ha−1 in the latter. In general, the landscape-level estimates were drawn from site-level estimates in a given land-use type, and therefore, the corresponding values might be overestimated. Nevertheless, the results provide baseline information on carbon stock which may serve as a reference for devising appropriate land-use change policies in the region.