Soil organic carbon plays an important role in the stability and fertility of soil and is influenced by different management practice. We quantified active and passive carbon pools from total soil organic carbon (TOC) in seven different land use systems of northeast India. TOC was highest (2.75%) in natural forest and lowest in grassland (1.31%) and it decreased with increasing depth in different pools of lability. Very Labile Carbon (VLC) fraction ranged from 36.11 to 42.74% of TOC across different land use system. Active carbon (AC) pool was highest in Wet Rice Cultivation (61.64%) and lowest (58.71%) in natural forest. Higher AC pools (VLC and less labile) in most land use systems barring natural forests suggest that the land use systems in the region are vulnerable to land use change and must adopt suitable management practice to harness carbon sequestration.

The eastern Himalayan region of Northeast India is well known for its traditional home gardens, which are considered to play important roles in the maintenance of livelihoods of indigenous communities and conservation of biological diversity. This study determines the plant diversity in home gardens and their importance in conservation of plant genetic resources (PGR) through utilization. We studied 90 home gardens in detail located in six villages. Different aspects of the home gardens and plant species were observed directly and through discussion with the farmers. A total of 333 plant species (133 trees, 92 shrubs, and 108 herbs) belonging to 128 plant families with an average of 78 species per home garden were recorded. The size of home gardens ranged between 0.10 and 0.60 ha and showed significant (P<0.001) positive correlation between the garden size and plant species diversity. The species diversity index for trees, shrubs, and herbs was 4.76, 4.39, and 4.58, respectively. The species similarity within each life form was high with 50% for trees, 38% for shrubs, and 49% for herbs. Plant species in the home gardens could be grouped into 11 major use categories with the majority of plants in the medicinal or multiple use category. These home gardens are reservoirs of PGR and play a vital role in sustaining the livelihood of local inhabitants. They are also functioning as domestication and conservation centers of many crop relatives.

No abstract

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.

No abstract