Abstract
BackgroundShifting cultivation (locally known as “jhum”) is a major driver of deforestation and loss of ecosystem services in rainforests. For developing any effective conservation of biodiversity and carbon service program, an in-depth understanding to the recovery of vegetation and carbon after abandonment of jhum is essential. We estimated species richness, abundance and composition of trees, shrubs and herbs, carbon distribution in aboveground and belowground components along a chronosequence of jhum fallow in northeast India, and elucidated the factors affecting the recovery processes of jhum fallows.MethodsSpecies composition and other plant community attributes, carbon storage in different pools were studied in 5 jhum fallows (< 5, 5–10, 11–15, 16–20, 21–25 years old) and an old-growth forest. The data were subjected to linear mixed effect modeling using R-package “nlme” for identifying the important factors contributing to the recovery of vegetation and carbon.ResultsSpecies composition varied significantly (P < 0.05) between jhum fallows and old-growth forest. Tree density varied from 28 stems ha−1 in 5 years old jhum fallow to 163 stems ha−1 in old-growth forest. Both biomass carbon in all components and soil organic carbon were significantly (P = 0.01) lower in jhum fallows than in the old-growth forest except living non-woody biomass component. The recovery of aboveground biomass carbon was faster during early successive years than the mid-successive jhum fallows. Total ecosystem carbon and soil organic carbon stock in the oldest jhum fallow was 33% and 62% of those in the old-growth forest, respectively. The fallow age was found to be the most important explanatory factor in the recovery process of vegetation and carbon stock in re-growing fallows.ConclusionThe shifting cultivation fallows gradually recovered both vegetation and carbon and are potential repository sites for biodiversity conservation, which may take much longer time to reach up to old-growth forest in northeast India.
Highlights
IntroductionShifting cultivation ( known as slash-and-burn agriculture) has been the subject of much debate over the past decades
Shifting cultivation has been the subject of much debate over the past decades
The species richness of both shrub and herb species was highest in young jhum fallows (< 5 years old) and their number showed a trend of gradual decrease with increased age of jhum fallows
Summary
Shifting cultivation ( known as slash-and-burn agriculture) has been the subject of much debate over the past decades. The economic security provided by shifting cultivation and its cultural importance provided to indigenous tribes over other sedentary agriculture partly explains its persistence over the years despite the fact it is blamed as the major cause of forest loss, turning it into targets of policy interventions (Griffiths 2008; Fox et al 2014; Erni 2009) Though such policies and policy-oriented research program have pushed a transformation of lives and livelihoods of many people, such economic oriented objectives are critical drivers of deforestation (Ickowitz 2006). Abundance and composition of trees, shrubs and herbs, carbon distribution in aboveground and belowground components along a chronosequence of jhum fallow in northeast India, and elucidated the factors affecting the recovery processes of jhum fallows
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