Analysis Of The Temporal And Spatial Distribution And Risk Zoning Of Forest Fires In Yunnan ProvinceBased On MODIS Data

To comprehensively evaluate the situation of forest fires in China,master the laws of occurrence and development of forest fires,and discuss the drivers of forest fires,this paper takes Yunnan Province as an example,based on GIS technology,using MODIS data(MODIS14 thermal anomaly)to study the temporal and spatial distribution of forest fires in Yunnan Province from 2001 to 2008,and analyze the influencing factors of promoting forest fires.Through the preprocessing of the obtained image data and the extraction and superposition of forest fire information,a forest fire database and a graphic library are established,and the laws of forest ifire change are intuitively reflected on the map.At the same time,the topographic factors of Yunnan Province and meteorological factors in the corresponding time periods were extracted and divided according to certain criteria.A quantitative relationship was established between the established database of forest fires and various factors,and data overlay analysis was performed according to the purpose of research to analyze the distribution of forest fires in Yunnan Province at different times and in different spaees and the impact of different factors on forest fires.The results show that:(1)The numerical value of the fire field area of forest fires in Yunnan Province varies greatly each year,and there is instability,indicating that the annual occurrence of forest fires is random and there is no certain trend on the annual scale.In March and April,it was the prone period of Yunnan’s fire.The most forest fire occurred in these two months,accounting for 82%of all fires in the fire prevention period.Judging from the whole province of Yunnan,the area and frequency of fires in forest fires have significant regional characteristics.The fires are mainly distributed in the southwest of Yunnan Province,followed by the southeast and northwest regions.(2)Terrain have a significant impact on the occurrence of forest fires,slope and elevation have a significant impact on the occurrence of forest fires among terrain factors,and the impact of slope orientation on forest fires is minimal.Forest lires are distributed on all slopes,but mainly on gentle slopes,slopes and steep slopes.The area of forest fires on these three slopes takes up 88%of all fire areas.Forest fires mainly occur in areas with an elevation of less than 2,000 meters,occupying 86%of all fires.The impact of slope direction on forest fires is relatively small.The number and area of forest fires distributed on shady slopes and sunny slopes are approximately equal.(3)In meteorological factors,the average monthly precipitation is inversely proportional to the occurrence of forest fires while the temperature is proportional to the occurrence of forest fires,the law of the changes of forest fires over time in Yunnan Province is basically consistent with the rules of climate change over time.(4)From the overall view of the forest fire hazard zoning in Yunnan,forest fires are more likely to occur in the south than north,and the fire risk of forest fires from south to north is gradually reduced.In the northern part of Yunnan,forest fires are more likely to occur in the northwest than northeast,and forest fires in the northeast are the lowest.