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Spatial and temporal dynamics of shifting cultivation in Manipur, Northeast India based on time-series satellite data

Thong, Pentile, Sahoo, Uttam Kumar, Pebam, Rocky, Thangjam, Uttam
Remote sensing applications 2019 v.14 pp. 126-137
Landsat, fallow, forests, landscapes, population density, population dynamics, remote sensing, shifting cultivation, temporal variation, time series analysis, India
The extent and dynamics in shifting cultivation (locally called ‘jhum’) landscapes in North-East India (NEI) particularly in hilly areas of Manipur has not been studied in the past. This study is an attempt to understand the spatial and temporal dynamics of shifting cultivation in Manipur, NEI using Landsat time-series from 1999 to 2017. Effort was also made to explore if any relationship exist between the extent of jhum and population density in the study areas. Based on secondary data, we hypothesized that with the increase in population there is an increase in the number of jhum plots while the size of the jhum plots decreases. The different cropping stage and abandoned jhum patch of each year’s imagery were mapped and post-classified to determine the crop-fallow rotation cycle. The results revealed a decreasing trend in the jhum area over the past 19 years with a major part occupied by current jhum patches, covering 67.00% (1047.36 km2) and 70.47% (844.17 km2) of the total jhum area in Ukhrul and Chandel respectively. On an average, 44–55 km2 of forest was annually slashed for shifting cultivation with jhum size ranging from 1 ha to 2 ha in Ukhrul and 5–7.5 ha in Chandel. During the study period, an average of 39.88% area in Ukhrul and 41.05% area in Chandel was under current jhum, from which 19.64% land was continued for 2nd year cropping in Ukhrul while 17.20% land was continued for 2nd year cropping in Chandel. It was also observed that 10–14 years jhum cycles were most prevalent in Ukhrul (69.3% of total jhum affected area) while 9–12 years jhum cycles were most prevalent in Chandel (53.07% of total affected jhum area). With the existing 2 years cropping period, it may be inferred that the most prevalent fallow periods in Ukhrul and Chandel are 8–12 years and 7–10 years respectively. Increase in population over the years have nevertheless not only resulted in the reduction of jhum field size and total jhum extent but also the number of jhum plots except for Kamjong and Kasom Khullen blocks in Ukhrul. These findings were in partial agreement with our hypothesis that increase in population decreases the jhum field size without significant increase in the number of jhum plots.