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.

A study was conducted to assess growth, carbon stock and sequestration potential of oil palm plantations along a chronosequence in Mizoram, Northeast India for which a total of 148 oil palms drawn from different age group plantations (1 to 11 years) were sampled for their biometric parameters and assessment of carbon stock through partial non-destructive methods. All the growth parameters of oil palm (trunk height, crown depth, total height, trunk diameter) and biomass drew from different parts of the palm showed a significant (p < 0.05) progressive growth along a chronosequence. Crown biomass was observed higher (65.00%) in younger age groups 1 -3 years, while the trunk with old frond bases biomass showed a larger percentage (67.96%) in the older oil palm aged 4 -11 years. All the linear correlations between the growth variables with age and biomass were observed significant at p < 0.01. Total above ground biomass (AGB) was highly correlated with the trunk height (r = 0.985), total height (r = 0.994) and age (r = 0.973). On an average, portioning of biomass and carbon stock was in the order: AGB > belowground biomass (BGB) > standing litter biomass > deadwood biomass > understorey biomass. AGB, BGB and deadwood biomass followed an increasing trend while understorey biomass decreased with age. An 11-year oil palm plantation accumulated 111.96 Mg ha −1 biomass with a carbon density of 49.90 Mg C ha −1 and could sequester 3.70 Mg C ha −1 year −1 in 10 years after planting in Mizoram, Northeast India. The findings showed considerable carbon storage with comparative higher values in oil palm plantations than shifting cultivation fallows. This will enable policy and decision makers in framing climate change mitigation and adaptation policies regarding the extension of oil palm plantations in Mizoram.

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Land use change activities have greatly affected the total ecosystem carbon stock (TECS) and also contribute to global change through emission of greenhouse gases. The present study assessed the change in vegetation biomass carbon stock (VBCS) and soil organic carbon stock (SOCS) following conversion in major land use sectors (agriculture, agroforestry, forest and plantation) in Mizoram, Northeast India. SOCS was the highest in agroforestry (50.85 Mg C ha −1) and the lowest in agriculture (33.99 Mg C ha −1). VBCS was the highest in plantation (131.66 Mg C ha −1) and the lowest in agriculture (7.44 Mg C ha −1). The highest positive TECS change rate was observed when agriculture was converted to plantation (6.61 Mg C ha −1 •yr −1), while negative rate of change in carbon stock was observed following the establishment of agriculture from other land use. A positive rate of change was observed in both VBCS and SOCS with TECS rate of 3.58 Mg C ha −1 •yr −1 when agriculture got converted to agroforestry. The absolute carbon stock change rates were higher in VBCS than SOCS signifying the importance to maintain tree based vegetation cover.