基于小波分析的我国森林草原火灾周期震荡研究
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摘要
火灾是森林草原生态的重要干扰因子,研究火灾发生的子因素有助于分析森林草原火灾发生规律和预测火灾发展趋势。运用软件Matlab 2009a对我国森林草原火灾统计资料进行小波分析,Daubechies 10作为小波基进行小波分解与重构,讨论多种火灾影响因素下不同时间尺度的子序列对森林草原火灾的影响。结果表明:1993—2003年森林火灾面积呈小幅上升趋势,2004—2016年森林火灾面积呈小幅下降趋势; 1994—2004年草原火灾面积呈上升趋势,2005—2016年草原火灾面积呈稳定下降趋势,预计未来我国森林、草原火灾发生面积将继续呈小幅减少趋势。森林与草原火灾发生次数总体呈下降趋势,但森林火灾发生次数仍处于小波谷中,预计未来我国草原火灾发生次数保持稳定降低的趋势,森林火灾发生次数虽然会在较低水平波动,但较2016年森林火灾发生频率可能会更高,所以未来森林火灾的发生还将处在一个相对较活跃的状态。
Fire is an important disturbance factor in forest and grassland ecology. The study of the subfactors of fire occurrence can help analyze the law of occurrence of forest and grassland fires and predict the trend of fire development.The software Matlab 2009 a was used to carry out the wavelet analysis of statistical data of China's forest and grassland fires. Daubechies 10 was used as a wavelet base to decompose and reconstruct the wavelets. The effects of subsequences of different time scales on forest and grassland fires under various fire influence factors were discussed. The results showed that,on the time scale of 2-5 years,forest and grassland fires were quite different,and their periodicity was not obvious. Grassland fires occurred frequently in about 3-5 years,indicating that human factors were the main causes of grassland fires except for a few other factors. On the time scale of more than 10 years,the fluctuation of fuels and vegetation had slight effect on the number of forest and grassland fires in recent years. Although the longterm climate could have a greater impact,the number of forest and grassland fires has remained at a relatively low level,and the areas of forest fires showed a slight increase trend in 1993-2003,and the areas of forest fires showed a slight decline trend in 2004-2016. The areas of grassland fires showed an increase trend in 1994-2004,and the areas of grassland fires showed a steady decline trend in 2005-2016. It was expected that the areas of forest and grassland fires in China would continue to decrease slightly in the future. The occurrence times of forest and grassland fires generally showed decline trends,but the occurrence times of forest fires were still in the wavelet trough,expecting that the occurrence times of grassland fires would continue to decrease steadily. Although the occurrence times of forest fires would fluctuate at a relatively low level,the frequency of fire may be higher than that in 2016,so the occurrence of forest fires would also be in a relatively active state in the future.
Fire is an important disturbance factor in forest and grassland ecology. The study of the subfactors of fire occurrence can help analyze the law of occurrence of forest and grassland fires and predict the trend of fire development.The software Matlab 2009 a was used to carry out the wavelet analysis of statistical data of China's forest and grassland fires. Daubechies 10 was used as a wavelet base to decompose and reconstruct the wavelets. The effects of subsequences of different time scales on forest and grassland fires under various fire influence factors were discussed. The results showed that,on the time scale of 2-5 years,forest and grassland fires were quite different,and their periodicity was not obvious. Grassland fires occurred frequently in about 3-5 years,indicating that human factors were the main causes of grassland fires except for a few other factors. On the time scale of more than 10 years,the fluctuation of fuels and vegetation had slight effect on the number of forest and grassland fires in recent years. Although the longterm climate could have a greater impact,the number of forest and grassland fires has remained at a relatively low level,and the areas of forest fires showed a slight increase trend in 1993-2003,and the areas of forest fires showed a slight decline trend in 2004-2016. The areas of grassland fires showed an increase trend in 1994-2004,and the areas of grassland fires showed a steady decline trend in 2005-2016. It was expected that the areas of forest and grassland fires in China would continue to decrease slightly in the future. The occurrence times of forest and grassland fires generally showed decline trends,but the occurrence times of forest fires were still in the wavelet trough,expecting that the occurrence times of grassland fires would continue to decrease steadily. Although the occurrence times of forest fires would fluctuate at a relatively low level,the frequency of fire may be higher than that in 2016,so the occurrence of forest fires would also be in a relatively active state in the future.
引文
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[17]田晓瑞,舒立福,赵凤君,等.中国主要生态地理区的林火动态特征分析[J].林业科学,2015,51(9):71-77.DOI:10.11707/j.1001-7488.20150910.TIAN X R,SHU L F,ZHAO F J,et al.Dynamic characteristics of forest fires in the main ecological geographic districts of China[J].Scientia Silvae Sinicae,2015,51(9):71-77.
[18]田晓瑞,舒立福,赵凤君,等.气候变化对中国森林火险的影响[J].林业科学,2017,53(7):159-169.DOI:10.11707/j.1001-7488.20170716.TIAN X R,SHU L F,ZHAO F J,et al.Impacts of climate change on forest fire danger in China[J].Scientia Silvae Sinicae,2017,53(7):159-169.
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[2]虞湘宾,董涛.一种离散小波变换的快速分解和重构算法[J].东南大学学报(自然科学版),2002,32(4):564-568.DOI:10.3321/j.issn:1001-0505.2002.04.005.YU X B,DONG T.Fast decomposition and reconstruction algorithm on discrete wavelet transform[J].Journal of Southeast University(Natural Science Edition),2002,32(4):564-568.
[3]徐博尧,杨刚,李欣欣.小波变换的时频分析及其在实际中的应用[J].中国传媒大学学报(自然科学版),2011,18(2):79-83,59.DOI:10.3969/j.issn.1673-4793.2011.02.013.XU B Y,YANG G,LI X X.Wavelet transform for timefrequency analysis and its application[J].Journal of Communication University of China Science and Technology,2011,18(2):79-83,59.
[4]田晓瑞,刘晓东,舒立福,等.中国森林火灾周期振荡的小波分析[J].火灾科学,2007,16(1):55-59.DOI:10.3969/j.issn.1004-5309.2007.01.011.TIAN X R,LIU X D,SHU L F,et al.The wavelet analysis of periodicity variation of forest fires in China[J].Fire Safety Science,2007,16(1):55-59.
[5]田晓瑞,李红,舒立福,等.黑龙江省森林火灾年际变化的小波分析[J].自然灾害学报,2007,16(2):118-121.DOI:10.3969/j.issn.1004-4574.2007.02.021.TIAN X R,LI H,SHU L F,et al.Wavelet analysis of annual variation of forest fire in Heilongjiang Province[J].Journal of Natural Disasters,2007,16(2):118-121.
[6]国家统计局.中国统计年鉴[M].北京:中国统计出版社,1993-2016.
[7]陈铁,何琼.小波变换及其在时频分析中的应用[J].中国水运(学术版),2006,6(5):58-59.CHEN T,HE Q.Wavelets transformations andits in time frequency analysis application[J].China Water Transport(Academic Version),2006,6(5):58-59.
[8]李舜酩,郭海东,李殿荣.振动信号处理方法综述[J].仪器仪表学报,2013,34(8):1907-1915.DOI:10.3969/j.issn.0254-3087.2013.08.031.LI S M,GUO H D,LI D R.Review of vibration signal processing methods[J].Chinese Journal of Scientific Instrument,2013,34(8):1907-1915.
[9]姚树人,韩焕金.中国森林防火现状及其对策的研究[J].森林防火,2002(4):14-16.DOI:10.3969/j.issn.1002-2511.2002.04.006.YAO S R,HAN H J.A study on present conditions and countermeasures of forest fire prevention in China[J].Forest Fire Prevention,2002(4):14-16.
[10]苏立娟,何友均,陈绍志.1950-2010年中国森林火灾时空特征及风险分析[J].林业科学,2015,51(1):88-96.DOI:10.11707/j.1001-7488.20150110.SU L J,HE Y J,CHEN S Z.Temporal and spatial characteristics and risk analysis of forest fires in China from 1950 to 2010[J].ScientiaSilvae Sinicae,2015,51(1):88-96.
[11]张思玉.我国森林火灾特点的动态分析[J].森林防火,2013(2):15-19.DOI:10.3969/j.issn.1002-2511.2013.02.006.ZHANG S Y.Dynamic analysis on the characteristics of forest fires in China[J].Forest Fire Prevention,2013(2):15-19.
[12]赵凤君,舒立福.气候异常对森林火灾发生的影响研究[J].森林防火,2007(1):21-23.DOI:10.3969/j.issn.1002-2511.2007.01.009.ZHAO F J,SHU L F.Climate anomaly and its influence on occurring forest fire under global warming[J].Forest Fire Prevention,2007(1):21-23.
[13]田晓瑞,王明玉,舒立福.全球变化背景下的我国林火发生趋势及预防对策[J].森林防火,2003(3):32-34.DOI:10.3969/j.issn.1002-2511.2003.03.012.TIAN X R,WANG M Y,SHU L F.The developing trend and prevention countermeasure about forest fire of our country under the background of global change[J].Forest Fire Prevention,2003(3):32-34.
[14]VACCHIANO G,FODERI C,BERRETTI R,et al.Modeling anthropogenic and natural fire ignitions in an inner-alpine valley[J].Natural Hazards and Earth System Sciences,2018,18(3):935-948.DOI:10.5194/nhess-18-935-2018.
[15]李兴华,任丽媛,刘秀荣.气候变化对内蒙古草原火灾的影响[J].干旱区资源与环境,2014,28(4):129-133.DOI:10.13448/j.cnki.jalre.2014.04.013.LI X H,REN L Y,LIU X R.Impact of climate change on the grassland fires in Inner Mongolia[J].Journal of Arid Land Resources and Environment,2014,28(4):129-133.
[16]刘兴朋,张继权,周道玮,等.中国草原火灾风险动态分布特征及管理对策研究[J].中国草地学报,2006,28(6):77-82.DOI:10.3969/j.issn.1673-5021.2006.06.016.LIU X P,ZHANG J Q,ZHOU D W,et al.Study on grassland fire risk dynamic distribution characteristic and management policy[J].Chinese Journal of Grassland,2006,28(6):77-82.
[17]田晓瑞,舒立福,赵凤君,等.中国主要生态地理区的林火动态特征分析[J].林业科学,2015,51(9):71-77.DOI:10.11707/j.1001-7488.20150910.TIAN X R,SHU L F,ZHAO F J,et al.Dynamic characteristics of forest fires in the main ecological geographic districts of China[J].Scientia Silvae Sinicae,2015,51(9):71-77.
[18]田晓瑞,舒立福,赵凤君,等.气候变化对中国森林火险的影响[J].林业科学,2017,53(7):159-169.DOI:10.11707/j.1001-7488.20170716.TIAN X R,SHU L F,ZHAO F J,et al.Impacts of climate change on forest fire danger in China[J].Scientia Silvae Sinicae,2017,53(7):159-169.
[19]LUNT I D.Effects of long-term vegetation management on remnant grassy forests and anthropogenic native grasslands in south-eastern Australia[J].Biological Conservation,1997,81(3):287-297.DOI:10.1016/s0006-3207(96)00159-0.