| Grassland, which has played irreplaceable role in protecting animals, development of area ecological sustainability as well as industrial and agricultural production of human society, is one of the most important ecological systems. Dating back to the time of the first grassland ecosystem appeared on our planet, grassland ecosystem has been gravely influenced by the fire both positively and negatively, so the grassland fire is considered as one of the main impact factors that dominates grassland ecosystem's development, succession and recession, and to some degree, the grassland fire threats public security, people's lives and properties in agricultural and pastoral areas. Due to these reasons, how to control the grassland fire is currently a big challenge to human beings.China is among the countries that own rich grassland resource, which is 0.39 billion hectares (40% of national territorial area). However,33% of grassland area is under high potential risk of fire disasters, and the per capita grassland area of China is nearly as large as the half per capita grassland area of the whole world, so the grassland is greatly precious in China.For the above reasons, it is important and practical significance to launch the researches on something about grassland fire including early warning and forecasting, risk management, disaster management, making emergency response decision, fire ecology and fire behaviors. As the core content and the key basis of that research mentioned above, the study and analysis around spatial and temporal distribution of the grassland fire and its influence factors have more research values and significances.In this article, I select four regions of northeastern Inner Mongolia as research areas,Hulunbeier City, Hinggan League, Tongliao City and Chifeng City(eastern region of Inner Mongolia), and utilizing statistical analysis techniques, methods of geographic information system and spatial pattern analysis to have a deep research on the grassland fire and its influence factors. Some conclusions are as following listed.(1) As far as temporal distribution of the grassland fire concerns, not only does it exist a high-frequency grassland fire period (years between 1981 and 1987) and a low-frequency grassland fire period (years between 2000 and 2006), but exists two stable periods (years between 1988-1999; years between 2007and 2013). In a year, the high-frequency grassland fire period is in March, April, May, September and October, and one-to-one corresponded frequency is 15%,27%,17%,14% and 9%. Spring and fall are the highest-frequency of grassland fire, and each corresponded 59% and 30%.(2) As far as spatial clustering of the grassland fire concerns, Grassland in Hulunbeier has the highest-frequency times of grassland fire, while Chifeng has lowest-frequency times. Ewenki Autonomous has Banner has the most dynamic region of grassland fire among 37 banners, counties and districts covered by the four researched areas. Furthermore, distribution of grassland fire demonstrates the feature of cluster under small scale, but in other scales, the distribution of grassland fire is influenced by the elements of different year and month. The cluster peak and the change of the distribution of grassland fire are different.(3) As far as the spatial density estimation of the grassland fire concerns, the grassland hot spot regions are mainly distributed in north of Hulunberer including Orogen Autonomous Banner, New Barag Right Banner and Ergun City. Besides, the grassland hot spots and secondary hot spots inordinately exist at Horqin Right Front Banner and Horqin Right Middle Banner of Hinggan League as well as Jarud Banner of Tongliao City. Comparing the grassland hot spots between spring and fall in a year, these two seasons have common grassland hot spots, and there are high density values of grassland fire spots at the border of the northern of Horqin Right Front Banner and New Barag Right Banner. Grassland fire spots in other areas have big difference on these two seasons. For example, In Hulunbeir, grassland fire spots in spring gather at Oroqen Autonomous Banner, but these in fall obviously go to the north, so Oroqen Autonomous Banner gets to be a gathering place. Besides, the east of Horqin Right Front Banner of Hinggan League is an area of grassland fire spots at spring, but at fall it does not. The border of south of Ergun and Old Barag Banner has great changes in these two seasons, which becomes an area of grassland fire spots at fall.(4) On the spatial variability of grassland fire, the center of grassland fire of the areas are moved towards the southwest. From 1981 to 2013 the compass angle of moving trend line is 216.29°, orientation average value is 233.70°,the center coordinate of trend line is 120.80°E,48.32°E, the coverage moving distance is 34.23km.(5) In terms of impacts of distribution of grassland fire, roads, rivers, settlements, arable, these four geographic elements have a very significant negative correlation: with the increase distance between the geographic features and the locations of grassland fire, the counts of grassland fire are decrease, and the frequency of grassland fire become decrease; in terms of the usage index of landuse and unit area of grassland usage degree index, human activity is one of the main cause for different distribution of grassland tire; temperature, humidity, rainfall, wind speed, these tour meteorological factors also have a certain correlation with the spatial distribution of grassland fire. The change of climate factor would change the external condition of occurrence of grassland fire and flammability of grassland, thus affecting the occurrence and spread of the grassland fire... |
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