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The northeastern region of India, with an area of 255 090 km2, is predominantly hilly. Major socio-economic factors affecting sediment production in the region are; shifting cultivation, land tenure system, fast growing population, small land-holdings, deforestation and free range grazing. A multi-disciplinary long- -term study showed that 92.9 to 99.1% of rainwater can be retained in-situ, compared to 66.3% in shifting cultivation. Mean annual soil loss varied from 11.2 to 97.2 t km–2 in new land use systems as against 3621.3 t km–2 in shifting cultivation. The sediment load per litre of runoff from watersheds varied from 1250–20,300 mg suspended sediment, 5.4 to 23.6 mg NO3 – N, 2.3 to 6.5 mg P–PO4, 17.2 to 35.8 mg K2O, 0.4 to 1.8 mg Zn, 0.9 to 2.7 mg Mn, 6.5 to 12.0 mg Mg, 7.1 to 18.4 mg Fe and 4.0 to 7.2 mg SO4. The sediment transport from the catchments showed spatial and temporal variations.
Shifting cultivation, or swiddening, involves alternating cycles of cropping and fallow periods. Rather than being abandoned, the fallow swidden fields provide a source of important plant products for remote, forest-dwelling human communities. In northern Laos, the traditional length of fallow periods used to range between five and 11 years, depending on the availability of land and quality of the soil. Fallow periods are currently being shortened because of population pressures and government policies. To determine the potential impacts of shorter fallow periods, 128 swidden fallows of various ages (up to 20 years), located at altitudes between 400 and 800 m a.s.l. in northern Laos were sampled for usable plants. The impact of fallow length on plant abundance and species diversity was analysed. The number of usable plant species was found to increase with the fallow age until it was 11–12 years old, and then decline, while the abundance of usable plants increased beyond that period. We conclude that shorter fallows will result in a significantly smaller usable plant abundance and species diversity for the villagers. We propose that 11–12-year-long fallows should be considered in order to fully exploit the greater plant volume of older fallows as well as the compositional shift of species in fallows over time.
This study present species composition and potential of litter on carbon and nitrogen return in secondary mixed deciduous forest after shifting cultivation. The dominant species of trees were Haldina cordifolia, Albizia odoratissima and Lagerstroemia duperreana. The Important Value Index (IVI) values of trees were 132.91, 17.78 and 14.22, respectively. The pattern for the decomposition coefficients (k) was highest in the wet period (May–September) and lowest in the dry period (October–April). The carbon and nitrogen return patterns increased in the dry period (October– April) and decreased in the wet period (May–September). Carbon and nitrogen loss in the decomposing litter continually decreased during the decomposition process from the initial levels, with a final relatively rapid release in the wet period. Results from this study was understanding of community composition, litterfall production and litter decomposition for understanding potential of secondary mixed deciduous forest for balancing carbon for mitigating greenhouse gas effect in the local area.
The knowledge behind the culture and beliefs of indigenous community needs to be harnessed and should be used to complement the modern technologies and policies for better and sustainable use of biological resources and increase resilience of the sector associated. The main objective of the current research was to study Jhum (Traditional Shifting Cultivation System) and the cycles and culture associated with it. The study was done in northeast Himalayan region of India and phenomenological approach was used. The research reveals that Jhum is the component of traditional agro-ecosystem encompassing diverse set of knowledge and practices of indigenous and local communities embodying traditional life-styles relevant for the conservation and sustainable use of natural resources for their livelihood. The cycle associated with the system reflects the synergy of practices with the natural phenomenon and indicators. Contrary to common modern belief, Jhum is carbon sink, maintain soil health, preserve biological diversity and sustain local climate. Forest clearing during Jhum is not deforestation but forest modification allowing forest regrowth during sufficiently long fallow. Fundamentally, Jhum as a system is an integrated approach to establish agro-ecosystem in the difficult terrains of tropical hill regions that involve forest, soil, biodiversity and livestock management through their culture, tradition and rituals that coevolved with associated ecosystem. Instead of being threat to climate or environment, the system can provide deeper insight into the many different aspects of sustainable and climate resilient development; and the interrelated role of local peoples and their cultures.
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