Forest fire video monitoring is the key means of forest fire monitoring in forest management agencies. Reasonable spatial distribution pattern can improve monitoring efficiency, reduce monitoring blind spots, detect fires in time, and reduce losses from forest fires.

Taking 216 state-owned forest fire video monitoring points in Hunan Province as study objects, the spatial distribution type, spatial distribution density and spatial distribution direction of forest fire video monitoring points were analyzed by using the nearest neighbor index, kernel density estimation method and standard deviation ellipse, respectively. The spatial distribution pattern of forest fire video monitoring points in state-owned forest farms in Hunan Province was studied, and the influencing factors of site selection of forest fire video monitoring points were discussed from four aspects: topography, traffic, fire risk and social economy.

There are 645 forest fire video monitoring points in the state-owned forest farms in Hunan Province, showing a significant agglomeration pattern in space. From the distribution of forest fire video monitoring points in various cities and prefectures of Hunan Province, Shaoyang City has the largest number of forest fire video monitoring points, and Xiangtan City has the least, accounting for 17.36% and 0.31% of the total number of the provinces, respectively. From the perspective of distribution density, the spatial distribution shows a regional difference of ‘less in the north and more in the south’. There are four high-density area centers, located in Changsha City, Zhuzhou City, Yongzhou City and Shaoyang City; in addition, there is a sub-intensive area center located in Xiangxi Tujia and Miao Autonomous Prefecture. The numerical difference between the long and short axes is large, indicating that the spatial distribution of forest fire video monitoring points has a strong directionality, and presents a northwest-southeast distribution trend.

The spatial distribution of forest fire video monitoring points in state-owned forest farms in Hunan Province is significantly affected by factors such as elevation, slope, traffic accessibility, number of graves, operating area of state-owned forest farms, and number of tourist attractions. It provides a reference for strengthening the construction of forest fire prevention and extinguishing capacity in Hunan Province and the rational layout of forest fire video monitoring points.

Monochamus alternatus is the main vector of Bursaphelenchus xylophilus. The transmission of Bursaphelenchus xylophilus is closely related to ambient temperature. It is of great significance to study the effect of temperature on the transmission of Bursaphelenchus xylophilus by Monochamus alternatus.

150 Monochamus alternatus were divided into 3 groups by setting 3 constant temperatures (15, 20, and 25°C). The life span of Monochamus alternatus and the survival rates of Bursaphelenchus xylophilus under different temperatures were measured to explore the effect of temperature on the transmission of Bursaphelenchus xylophilus by Monochamus alternatus.

The average life span of Monochamus alternatus decreased with the decrease in temperature. The three temperature treatments had significantly different effects on the average life span of Monochamus alternatus, which had no effect on the number of initial Bursaphelenchus xylophilus. The life span of Monochamus alternatus was related to temperature, but not to body weight. The number of Bursaphelenchus xylophilus carried by Monochamus alternatus was basically unchanged in the first 5 days, which then decreased with the increase of the age of Monochamus alternatus. When the initial load of Bursaphelenchus xylophilus was between 100 and 999, the average transmission efficiency decreased with the decrease in ambient temperature. There were significant differences in the effect of temperature treatment on the average transmission efficiency of Bursaphelenchus xylophilus when the initial load was from 1 to 9 or from 10 to 99. With the decrease in temperature, the time required for Bursaphelenchus xylophilus to leave Monochamus alternatus increased. The time required for Bursaphelenchus xylophilus to leave Monochamus alternatus was the shortest at 25℃ and the longest at 15℃. Under the 3 temperature treatments, the transmission efficiency of Bursaphelenchus xylophilus showed a single peak transmission curve, and the maximum carrying capacity of Bursaphelenchus xylophilus decreased with the decrease in temperature.

With the decrease in ambient temperature, the life span of Monochamus alternatus is shortened, the transmission efficiency of Bursaphelenchus xylophilus is reduced, and the transmission peak of Bursaphelenchus xylophilus is delayed, which value is reduced with the decrease of ambient temperature. These results indicate that the transmission efficiency of Bursaphelenchus xylophilus can be controlled by low temperatures.

Forests are the most widely distributed, complex, and resources- abundant ecosystems on dry land. Wildfire is a special and important factor affecting forest ecosystem. Discovering the dynamics and trends of forest fires in time and space helps to grasp the rules of forest fire occurrence, which is a fundamental work for deploying fire prevention priorities.

Using forest fire archive data from Hunan province over the past 24 years (1999-2022) as the data source, spatial statistical methods such as Ripley K function, center point and standard deviation ellipse method, and kernel density analysis were used to analyze the spatial clustering, forest fire density changes, and expansion trends of forest fires in Hunan province.

The total density of forest fires in Hunan province from 1999 to 2022 was 0.008 7 times /(km²·a), and there were three forest fire aggregation points in space. The annual forest fire density of unit area from 1999 to 2003 was 0.016 7 times, from 2004 to 2008 it was 0.034 8 times, from 2009 to 2013 it was 0.021 times, from 2014 to 2018 it was 0.005 times, and from 2019 to 2022 it was 0.006 times. The forest fire distribution in Hunan province during the 3 periods from 1999 to 2013 had multiple aggregation areas, and since 2014, the forest fire aggregation areas have not been obvious.

There is a significant spatial clustering and geographical correlation in the spatial and temporal distribution of forest fires in Hunan province from 1999 to 2022 and the overall forest fire density shows a fluctuating downward trend. There are obvious high-density areas of forest fires, including Loudi city, Zhuzhou city, Chenzhou city, and the eastern part of Shaoyang city, the overall average center of forest fires from 1999 to 2022 is located in Shaoyang city, the spread trend of forest fires in Hunan province is to expand towards Yongzhou and Chenzhou cities in the southeast; And the forest fire density significantly decreased between 2013 to 2018, as well as 2019 to 2022. The GDP development distribution of various districts in Hunan province from 1999 to 2022 shows a high degree of aggregation, mainly in the Changsha-Zhuzhou-Xiangtan region, as well as Hengyang and Yiyang cities. There is a tiny spatial variation of GDP distribution, and the overlapping area of GDP distribution and the spatial distribution of forest fires accounts for 71.29%, which is relatively high.