气候变化背景下云南省林火演变特征及规律研究

Research on the evolution characteristics and laws of forest fires in Yunnan Province under the background of climate change

全球气候变暖背景下,森林火灾频发,探究气候变化与森林火灾的关系有利于开展森林火灾防控工作。选择云南省1980-2020年的森林火灾次数、过火面积和极端气候事件年份,分析森林火灾发生规律、极端气候年份之间及其与普通年份林火发生情况的组间差异;并选择聚类分析法划分森林火灾形势等级,以及应用马尔科夫链研究各等级转移规律和预测2023-2027年各年不同等级发生的概率。结果表明:云南省林火演变特征表现为火灾次数与过火面积变化相关系数为0.931;火灾次数时间序列断点分别为1989年、2012年;1980-1989年厄尔尼诺年与拉尼娜年的火灾次数存在显著差异(Sig.<0.05),但过火面积无显著差异(Sig.>0.05);1990-2012年火灾次数与过火面积均存在显著差异(Sig.<0.05);其他情况无显著差异(Sig.>0.05);K-聚类划分森林火灾形势为Ⅰ级(轻度)、Ⅱ级(一般)、Ⅲ级(中度)、Ⅳ级(高度)、Ⅴ级(极高度)5个等级,Ⅰ、Ⅱ级相互转移的概率约占全部转移事件的78%,Ⅰ~Ⅲ级相互转移的概率高于90%。2023-2027年云南省森林火灾形势等级为Ⅰ~Ⅴ级的概率分别在0.683~0.702、0.251~0.253、0.036~0.048、0.003~0.006和0.007~0.012,云南省未来5年森林火灾形势总体平稳,发生Ⅰ~Ⅱ级的概率高于93%,Ⅳ~Ⅴ级的概率低于2%。该结论可为气候变化下森林火灾管理及防控提供理论支撑。

Under the background of global warming, forest fires occur frequently. It is conducive to forest fire prevention and control. The frequency of forest fires, burned area and extreme weather events from 1980 to 2020 in Yunnan Province were selected to analyze the occurrence law of forest fires, the differences between extreme weather years and between groups of forest fires and ordinary years. The forest fire situation was classified by cluster analysis, and the transfer law of each grade and predict the probability of different grades in 2023-2027 was used by Markov chain. The results show that the correlation coefficient between fire number and fire area is 0.931. The breakpoints of the time series of fire number are 1989 and 2012.There was a significant difference in fire number between El Nino and La Nina years from 1980 to 1989(Sig. <0.05), but there was no significant difference in fires area(Sig. >0.05).There was a significant difference in fire number and fires area between 1990 and 2012(Sig. <0.05). There was no significant difference in other cases(Sig. >0.05). The forest fire situation was divided into five levels as level Ⅰ(mild), level Ⅱ(general),level Ⅲ(moderate), level Ⅳ (height) and level Ⅴ(extreme height) by K-cluster. The probability of level Ⅰ~Ⅱ mutual transfer accounts about 78% of all transfer events, and I~Ⅲ mutual transfer is higher than 90%. From 2023 to 2027, the probability of forest fire situation grade Ⅰ~Ⅴ in Yunnan Province is between0.683~0.702, 0.251~0.253, 0.036~0.048, 0.003~0.006 and 0.007~0.012 respectively. The forest fire situation in Yunnan Province will be generally stable in the next five years. The probability of grade Ⅰ~Ⅱ is higher than 93%, and grade Ⅳ~Ⅴ is lower than 2%.This conclusion can provide theoretical support for forest fire management and prevention under climate change.