Abstract
Abstract. Increasing incidences of fire from land conversion and residue burning in tropics is the major concern in global warming. Spatial and temporal monitoring of trends of fire incidences is, therefore, significant in order to determine contribution of carbon emissions from slash and burn agriculture. In this study, we analyzed time-series Terra / Aqua MODIS satellite hotspot products from 2001 to 2013 to derive intra- and inter-annual trends in fire incidences in Nagaland state, located in the Indo-Burma biodiversity hotspot. Time-series regression was applied to MODIS fire products at variable spatial scales in GIS. Significance of change in fire frequency at each grid level was tested using t statistic. Spatial clustering of higher or lower fire incidences across study area was determined using Getis-OrdGi statistic. Maximum fire incidences were encountered in moist mixed deciduous forests (46%) followed by secondary moist bamboo brakes (30%). In most parts of the study area fire incidences peaked during March while in warmer parts (e.g. Mon district dominated by indigenous people) fire activity starts as early as during November and peaks in January. Regression trend analysis captured noticeable areas with statistically significant positive (e.g. Mokokchung, Wokha, Mon, Tuensang and Kiphire districts) and negative (e.g. Kohima and north-western part of Mokokchung district) inter-annual fire frequency trends based on area-based aggregation of fire occurrences at different grid sizes. Localization of spatial clusters of high fire incidences was observed in Mokokchung, Wokha, Mon,Tuensang and Kiphire districts.
Highlights
Fire is widely used in tropical land conversion and regrowth removal (Malingreau and Tucker, 1988, Eva and Lambin, 2000; Aragãoand et al, 2008)
Most of fire pixels were encountered in Moist mixed deciduous forests (46%) followed by Secondary moist bamboo brakes (30%), Sub-tropical wet hill forest (11%) and less than 10 % combined in Subtropical pine and Wet temperate forests
Study of cultural use of fire in GIS has served as an indicator for understanding several aspects of doi:10.5194/isprsannals-II-8-53-2014
Summary
Fire is widely used in tropical land conversion and regrowth removal (Malingreau and Tucker, 1988, Eva and Lambin, 2000; Aragãoand et al, 2008). Fire is a dominant manmade disturbance in slash and burn agriculture or “Jhum” areas in north-eastern region of India. Jhum represents a mixed cropping system with a fallow period of 3-10 years, traditionally practiced by the upland communities of north-east India. It accounts for largest spatial extent of biomass burning during the annual dry season (Badarinath et al, 2009). The pattern of shifting cultivation has changed following decrease in fallow period (Ramakrishnan, 2001), increase in the area under settled agriculture and lengthening of dry season, which in turn has increased likelihood of spatial and temporal variations in fire frequency or rather increase in fire frequeny in the region. The use of fire has recently exacerbated due to increase in shifting cultivation in the moist deciduous forests (SFR, 2009)
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