Spatial-Temporal Distribution Of Forest Fires And It's Impact In Honghe-Wenshan Prefectures And Greater Khingan Range

As a global natural disaster,forest fires will burn a large number of vegetation resources every year,which will not only cause huge economic losses to human society,but also seriously destroy the natural environment and ecological balance of human existence,and threaten the normal operation of human society.Scientific and accurate assessment and early warning of the risk of forest fires is conducive to the protection of the forest ecological environment and the smooth operation of the forest ecosystem,thus safeguarding the safety of people's lives and property.China has a vast territory,a large span between the north and the south,and factors such as topography and climate are constantly changing and different.Therefore,there are obvious differences in the natural factors or believed factors that affect the occurrence of forest fires.Because there are differences in the influencing factors of forest fires,the measures to prevent forest fires are also different.Remote sensing data,meteorological station data and topographic data of burned areas in Honghe and Wenshan prefectures of Yunnan Province and Greater Khingan Range of Heilongjiang Province in2005,2010 and 2015 were used to analyze the correlation between natural factors and forest fires with the help of Arc GIS,SPSS,Fragstats and other software,and then a BLR fire risk assessment model was established.At the same time,AHP-two-level fuzzy comprehensive evaluation method is used to evaluate the fire risks in the two areas on the basis of correlation ranking,which provides reference for the implementation of differentiated fire prevention measures.The following conclusions are drawn:(1)During the ten years from 2005 to 2015,the area of burned land in Honghe-Wenshan Prefecture increased first and then decreased,from 2.43% to 8.73% of the total area of the study area,and then decreased to 0.65%.Most of the burned areas are concentrated in the central and eastern parts of the study area.The area of burned land in Da Hinggan Ling Prefecture continued to shrink,from1.79% to 0.47% and then to 0.24% of the total area of the research area.The burning areas are mainly concentrated in the southernmost part of the study area.(2)The correlation analysis between landscape pattern and forest fire area in the study area was carried out,and the correlation ranking of different landscape indexes on forest fire spread was clarified.Among them,patch density index,landscape abundance,Shannon diversity index,patch abundance density index and patch number are negatively correlated with the spread of forest fires,while spread index is positively correlated with the spread of forest fires.(3)The factors affecting the occurrence of forest fires are different in different time periods and different regions.In 2005,the contribution of forest fires in Da Hinggan Ling Prefecture ranged from elevation and slope.At the same time,in Honghe-Wenshan Prefecture,the contributions ranged from elevation,precipitation and temperature.In 2010,the contribution of forest fires in the Da Hinggan Ling Prefecture from large to small was temperature,elevation and NDVI;At the same time,in Honghe-Wenshan Prefecture,the contributions ranged from slope,elevation,precipitation and temperature.In 2015,there was only one factor affecting the occurrence of forest fires in Da Hinggan Ling Prefecture: temperature.In Honghe-Wenshan Prefecture,the contributions from large to small are temperature,precipitation,elevation and NDVI.(4)BLR fire risk models for different years in the study area are established,and AHP-two-level fuzzy comprehensive evaluation method is used to evaluate the fire risk level in the area.By bringing random sampling points to test the results,it is found that the ability to distinguish fire points from non-fire points is approximately the same,and the limit value in AHP-two-level fuzzy comprehensive evaluation method is less than BLR fire risk model.Because the calculation process of AHP-two-level fuzzy comprehensive evaluation method is clear and the method is simple,it is more rapid and convenient to use this method to divide the fire risk when judging whether a certain area is prone to forest fires.