Multiple Spatial-scale Analysis On The Distribution Patterns Of Forest Burned Areas Under Climate Change In Jiangxi Province

Forest fire area is one of the important indicators to measure forest fire status.It is of great significance to master its distribution pattern for assessing ecological effects of forest fire and formulating post fire vegetation restoration strategies.A single spatial scale is difficult to reflect the spatial distribution characteristics of forest burned area and its future trend.Based on the MODIS Global Fire Atlas dataset(2003–2015),this study:(1)explored the spatial variability,correlation,and scale effects of forest burned area in Jiangxi province at three spatial scales(city,county,and township levels)using the variation coefficient,spatial autocorrelation statistics and scale variance analysis approaches;(2)characterized relative influences and marginal effects of climate,vegetation,topography and human variables on fire patterns at three spatial scales using the boosted regression trees(BRT)modelling approach;(3)projected fire patterns for 2050 based on two general circulation models(GFDL-CM3 and GISS-E2-R)for two representative concentration pathways(RCP 2.6 and 8.5)scenarios.The main results were as follows:1)The changes of forest burned area were obviously different in Jiangxi province in each year between 2003 and 2015,which showed a trend of rising first and then declining.Among them,the burned area value was the largest in 2008,and the spatial variability was the smallest,but showed obvious aggregation characteristics across Jiangxi province;the burned value was the smallest in 2015,and the spatial variability was the largest,but the spatial aggregation characteristics was not significant.The fire hot spots were mainly distributed at the southwest,central and east of Ganzhou city,the northwest and east of Ji ’an city and the central and southern region of Fuzhou city.The cold spots were distributed at Nanchang and Yichun and other parts of central and northern Jiangxi province.2)The distribution pattern of burned area at different spatial scales was different.With the decrease of spatial scale,the degree of spatial autocorrelation of forest burned area increased,and the contribution to the distribution pattern of forest burned area increased.Large scale(city-scale)level can reflect the overall distribution characteristics of burned area.However,the level of small scale(township-scale)can highlight the variability and autocorrelation characteristics of burned.3)The factor contribution rate of forest burned area pattern is different in different spatial scales.The climate factor has the greatest influence on burned area,followed by human activity factor.And with the decrease of spatial scale,the contribution rate of human activity factors decreased.The contribution rate of topographical factors to burned area in Jiangxi Province was the smallest in different spatial scales.The marginal effect of forest fire factors on different spatial scales is basically the same.4)In the future(2050),the burned area would increase at the three spatial scales.In the scenario of high concentration of greenhouse gas emissions(RCP8.5),the burned area would larger than that in the scenario of low concentration of greenhouse gas emissions(RCP2.6).The burned area in GISS-E2-R climate model would larger than that in GFDL-CM3 climate model.By 2050,the central and southern Jiangxi province would still be the hot spot of forest fire occurrence,and the forest fire occurrence area in the northern part of Jiangxi will obviously increase compared with the current climate situation.