The purpose of forest resources survey is to obtain data like the volume, quality, growing and demising laws of forest resources and its links with the natural environment, economic and operating conditions and provide data supports for making forestry policies, plans and evaluate the forest operation performances. It contributes to an optimized utilization of the resources in the national economic construction and fosters its underlying productivity.
The conventional investigations are in-the-field ones conducted by investigators who base their work on topographic maps. While the disadvantages like large human cost, long working cycles, high laboring intensity and low efficiency make them unbefitting for the present demands of a market economy. Therefore, a fresh investigation method is in urgent need.
A Brand-New Solution
The superiorities of the satellite remote sensing (RS) technology lie in the macroscopic view, dynamic monitoring, convenient access to information, intuitive images and large-coverage ability. The extensive utilization of high-resolution satellite images in forest resources investigation has begun to gain its social-economic benefits.
The high resolution of the Jilin-1 satellite imagery and its multi-spectral images can reflect the characteristics of vegetation. It is widely used by forestry workers in forest fire investigation and prevention.
（1） RSimage data of the photographed area collected by Jilin-1.
（2）Extraction of the spatial distribution information of forestry and non-forestry lands from data source..
（3）Analyses of the vegetation contained in forestry lands, e.g., coniferous forest, broad-leaved forest, shrubbery and bare lands.
（4）Analyses of the non-forestry lands, e.g., construction land for urban and rural residents, arable land and water areas.
（5）Thematic map drawing.
The spatial distribution characteristics of forestry and non-forestry lands in the target city could be clearly observed from the RS thematic map above. Conclusions are as follows:
（1）The abundant forest resources are directly related to the elements like topography, climate, and social construction of the target city.
（2） Forestry land is predominant in the target city, while the non-forest is mainly in the more populated central and southern plains. There are a total of 4367.59㎞² of forestry land and 1060.69㎞² of non-forestry respectively.
（3）The forest plants in the north are mainly shrubbery and broad-leaved woods; while coniferous ones accounts for the most in the central area, on both riverbanks and in a small part of the southern area.
（4）Terrain and climate are among the key factors of plants distribution.
（5）Coniferous forests are basically distributed in mountainous areas with high altitude and cold climate.
（6）Shrubbery and broad-leaved forests are primarily distributed in plains and other low-lying areas.
We Can Do More
Our forestry satellite project aims to build a customized satellite constellation for forestry remote sensing usage. It will provide images of spatial resolution less than 5m and up to 25 spectral channels. Forestry remote sensing data services will be supported and generally elevated in terms of forest resources investigation, disaster monitoring, eco-value assessment and other fields.
A four-star networking scheme consisted of sun-synchronous orbit, orbital plane and equiphase distribution is applied in the forestry satellite. The minimum interval between two adjacent satellites in networking takes 30 minutes or less to image the same object. Each star has the capability of large side-sway imaging, which can meet the real-time monitoring requests of natural disasters such as floods and fires.
19 visible near-infrared spectral bands, including 1 panchromatic band and 18 multi-spectral bands are configured in the forestry satellite; 4 short wave infrared spectral bands, 1 medium wave infrared spectral band and 1 long wave infrared spectral band, of a total of 25 spectral bands.
（1）Forest Fire Prevention
The forestry satellites collected RS imagery makes it possible for us to figure out the fire conditions before it occurs, as a forewarning of scientific fire prevention; identify and locate the fire spot and make quick response according to the assessment of fire behavior; help post-disaster assessment and vegetation recovery monitoring.
（2）Forest Resources Survey
25 spectral bands are configured in the forestry satellite to enable it to extract and distinguish the obtained images via varied reflection spectrums from different trees species, such as the evergreens, aquatic plants, ground flora, deciduous forest and shrub, offering basis for forestry resources investigation and protection.
（3）Supervision of Pests and Diseases
Multi-spectral remote sensing imagery of forestry satellites is able to identify, extract, analyze the information of forest diseases and pests and offer pre-warning, evaluation, management and control for the forest diseases and pests, providing basis for the forest resources conservation.
Forestry satellites are enabled to accurately estimate forest vegetation parameters such as chlorophyll content, leaf area index and biomass to foster forest resources management and a healthy and sustainable development of forestry.
Multi-spectral RS data is applied to acquire the status quo, spatial distribution, coverage and dynamic changes information of the forest resources, including its coverage changing and overall tendency based on the establishment and demonstration of a 3D model of the forest.
Wetland RS monitoring and researching can be carried out by means of multi-phase RS imagery. Accurate distribution and dynamic changes data of various wetlands will serve to provide a foundation of scientific decisions for conservation, management and ecological restoration of degraded wetlands to realize the sustainable development of wetland resources.
（6）Land Desertification Monitoring
Forestry satellite RS images can also be used in the surveillance of land desertification. By analyzing the RS data of the same area during different phases, monitoring and statistical analyses of the evolution of the desertification progress can be realized, to provide data basis for desertification prevention.