تحلیل زمانی - مکانی رخدادهای مخاطره آتش‌سوزی‌های طبیعی در استان لرستان با استفاده از محصولات سنجنده مادیس

مخاطره آتش‌سوزی‌های عرصه‌های طبیعی در دوره گرم سال، یکی از مهم‌ترین مخاطرات اقلیمی استان لرستان است. هدف اساسی نوشتار پیش رو تحلیل روند سری زمانی رخدادهای آتش‌سوزی عرصه‌های طبیعی و آشکارسازی الگوی زمانی مکانی کانون‌های آتش‌سوزی در ارتباط با نوع پوشش اراضی است. در این راستا از داده‌های محصول آتش سنجنده مادیس و نیز محصول پوشش اراضی و پوشش گیاهی سنجنده مادیس طی دوره آماری 2000 تا 2020 استفاده شد. از تحلیل ماتریس اطّلاعات متقاطع و ماتریس همبستگی فضایی، برای آشکارسازی ارتباط بین رخدادهای آتش‌سوزی و پوشش اراضی استفاده شد. نتایج نشان داد که بیش از 70% کلّ فراوانی رخدادهای آتش‌سوزی عرصه‌های منابع طبیعی (آتش‌سوزی‌های با کد 2) استان لرستان، مربوط به ماه ژوئن و سپس جولای است. نتایج حاصل از تحلیل ماتریس اطّلاعات متقاطع بیانگر آن بود که سه کاربری مراتع با تاج پوشش متوسّط، اراضی جنگلی کم تراکم و زمین های کشاورزی دیم، 75% از تعداد رخدادهای آتش‌سوزی را به خود اختصاص داده‌اند. بیش از 70% از فراوانی سالانه رخدادهای آتش‌سوزی در دو طبقه پوشش اراضی مراتع و اراضی جنگلی، در دو ماه ژوئن و جولای (خرداد و تیر) بوده است که با تراکم پوشش گیاهی دو ماه قبل در این طبقات (آپریل و می) همبستگی معنی‌داری داشته است؛ در حالی‌ که فراوانی رخدادهای آتش‌سوزی زمین های کشاورزی دیم، به طور کلّی در ماه‌های آگوست و سپتامبر متمرکز بوده است و همبستگی معنی‌داری با پوشش گیاهی هیچ ماهی نشان نداده است. به‌طور کاربردی می‌توان گفت که با توجّه به اینکه وجود تراکم پوشش گیاهی در دو ماه آپریل و می در مراتع و اشکوب جنگلی استان، یکی از مهم‌ترین فاکتورهای محرّک آتش سوزی های طبیعی در دو ماه بعد، یعنی ژوئن و جولای است؛ بنابراین با تمرکز مدیریت طی یک دوره زمانی 62 روزه؛ یعنی 25 اردیبهشت تا 25 تیر در عرصه دو پوشش اراضی مراتع و اشکوب جنگلی، می‌توان 55% از رخدادهای آتش‌سوزی را کنترل کرد.

Spatiotemporal Analysis of Wildfire Hazards in Lorestan Province applying MODIS Products

The risk of fires in natural areas is one of the most important climatic hazards in Lorestan Province. The current study aims to analyze the temporal series trend of wildfire events in natural areas and to reveal the spatialtemporal pattern of wildfire related to the type of land cover. In this regard, the data of MODIS fire product as well as land cover and vegetation product of MODIS during the 20002020 were used. Crosstabulation matrix analysis and spatial correlation matrix were used to reveal the relationship between wildfire events and land cover. The findings showed that more than 70% of the total frequency of wildfire in natural resources (wildfire code 2) in Lorestan Province is related to June and then July. The results of crosstabulation matrix analysis revealed that 3 uses of rangelands with medium canopy, low density forest lands and rainfed agricultural lands accounted for 0.75 of wildfires. More than 70% of the annual frequency of fire events in the two forest land cover classes was in June and July (June and July), which is significantly correlated with the density of vegetation in these classes two months ago (April and May). While the frequency of fires in rainfed agricultural lands was generally concentrated in August and September, it did not show a significant correlation with vegetation of any month. Practically, it can be said that the presence of vegetation density during April and May in the forest floors is one of the most important factors related to wildfire in following two months, June and July. Therefore, focusing on management over a 62day period, from May 15 to July 16, 55% of fire incidents can be controlled in the area of ​​pastures and forest floors.Extended Abstract1IntroductionIn recent years, increasing the extreme temperature events such as hot waves, has been one of the major manifestations of climate change in Iran. This events occurred in the forest and rangelands of the country, such as the forests of Zagros and Lorestan province, in the form of wildfire incidents. Fires of natural or human origin directly or indirectly have destructive and harmful effects on human communities. In fact, if such an event happened, it would have a great impact on the environment, settlements and their inhabitants due to the concentration of population around the villages. Natural environment of forests and pastures are always exposed to natural damage and degradation. Among the destructive factors, fire is known as one of the main causes of destruction of natural ecosystems, which causes a lot of damage to these areas annually. In Lorestan Province, the occurrence of fires in natural areas has caused a lot of damage to the forest and rangeland cover of the province during the last three decades. The Province, which covers more than 40% of the area of ​​Zagros oak forests, faces numerous occurrences of fires in natural areas annually due to various reasons such as topographic diversity, limitations and lack of environmental facilities, diversity of pastures, human factors such as oak charcoal, agricultural waste fires, and deliberate fires caused by tourism as well as tribal conflicts. Recognizing the relationship between the spatial distribution of fires in natural areas and their relationship with land cover makes it possible to determine the temporal and spatial pattern of spatial distribution of fires in Lorestan province to a large extent leading to propose fire control programs.2Materials and MethodsIn this study, the data of MODIS sensor active fire product (MOD14) for the statistical period of 20002020 were taken from MODIS sensor databases in order to reveal the time series trend of natural area fire incidents. The monthly and annual frequency of these fire incidents in Lorestan province were extracted and analyzed. However, in addition to the active fire product of MODIS sensor, respectively, from the other two products of this sensor, namely the product of land cover classes of this sensor. (MCD12Q1), as well as the monthly vegetation product of the same sensor with a spatial resolution of 1 km was used as MOD13A3 in order to investigate the relationship between temporal and spatial distribution events of natural area fires in relation to land cover classes and vegetation. Accordingly, for this research during the statistical period of 20002020, a total of 42 images of land cover crop, 504 monthly crop of fire incidents and 504 monthly crop vegetation crop were used. Finally, using spatial correlation matrix analysis, as well as crossinformation analysis matrix, temporal and spatial correlation was obtained between the monthly frequency of fire events and the monthly vegetation of the province, and in addition, with the help of crossdata analysis matrix, the relationship between frequency Fire events were obtained in different land use classes.3Results and DiscussionIn this study, it was observed that the temporal and spatial distribution of fires are significantly related to the land cover classes of the province. The two categories of forest land cover and rangeland land have the highest frequency of fire incidents (55% of the total registered fires). This result was also observed in the study that examined the spatial distribution pattern of fire events in Lorestan province. The findings from his research showed that the highest incidence of fire was observed in forest use with medium canopy (36%) and rangeland with medium canopy (25%). Another important result of the study was that more than 75% of fire incidents in June and July (June and early August) are concentrated in these two land covers (forests and medium to poor pastures). Rainfed arable land was another land cover that accounted for 19% of the frequency of fire incidents, but the pattern of temporal distribution of fire events in this land cover, in contrast to the forest cover and medium to poor pastures, in August and September (MidAugust to late September) has been concentrated. On the other hand, the results of the correlation matrix analysis between the monthly frequency of fire events with the monthly vegetation index showed that in the field of natural resources, the frequency of fire events has a significant correlation with the amount of vegetation in April and May. In other words, the higher the density of vegetation in the two months of April and May in the two floors of forest lands and medium to poor pastures, the higher the frequency of fires two months later, June and July. However, the frequency of fires recorded in rainfed land cover classes did not show a significant correlation with vegetation density for any month.4ConclusionPractically, it can be said that vegetation density in the two months of April and May in the pastures and forest floors of the province is one of the most important factors in the vegetation in the next two months, June and July. Focusing on the management during a period of 62 days, ie from May 15 to July 16 in the field of pastures and forest floors, can control 55% of fire incidents. On the other hand, citing Article 20 of the Clean Air Law, it prevented farmers from burning agricultural residues on agricultural lands, thus controlling a large number of natural resource fire incidents in the province.