Weekly Science and Technology Talk丨"Forest Rangers" Flying in the Sky? See how satellites "protect" forests!

The 2022 China Land Greening Status Bulletin released by the Office of the National Afforestation Committee before the 2023 Arbor Day shows that by then, the country had completed afforestation of 3.83 million hectares, grass planting and improvement of 3.214 million hectares, and control of sandy and rocky desertification of 1.8473 million hectares. The forest area was 231 million hectares, and the forest coverage rate reached 24.02%; the grassland area was 265 million hectares, and the comprehensive vegetation coverage of grassland reached 50.32%... Faced with such a large scale of forests, wetlands, desertified land and other resources, what kind of scientific and technological means are used to provide early warning monitoring for forest fires and harmful biological disasters, as well as forestry ecological engineering monitoring work? It is - forestry remote sensing technology.

Application of Remote Sensing Technology in Forestry

Taking forestry resource survey as an example, relevant experts said that before the use of remote sensing technology, forestry resource survey work mostly relied on aerial photos, topographic maps, etc. for analysis, and went deep into the outdoors to make survey maps, and learned about the forest environment by mapping the site. This method takes a long time and requires a lot of human resources and a huge amount of funds. Most importantly, it is not accurate enough to meet the needs of work.

Remote sensing technology is a general term for comprehensive technical systems for observing the earth and celestial bodies from the ground to space. It consists of remote sensing platforms, remote sensing instruments, and subsystems such as information reception, processing, and analysis applications. Since 1951, my country's forestry remote sensing technology research has gone through three important stages: the visual interpretation and application stage based on aerial remote sensing images; the satellite remote sensing pioneering and innovative stage; and the quantitative remote sensing development and comprehensive application service platform formation stage.

The first forestry remote sensing research team, represented by Xu Guanhua, an academician of the Chinese Academy of Sciences, pioneered the intelligent extraction of forestry information using satellite remote sensing in the 1980s. Since 2000, forestry remote sensing technology research experts, represented by Li Zengyuan, a researcher at the Institute of Resources of the Chinese Academy of Forestry, have led the team to steadily promote the construction of a remote sensing technology forestry application system.

Satellites "protect" forests

In order to meet the development of forestry survey and monitoring business in my country, such as forest resource survey, wetland monitoring, desertification monitoring, forestry ecological engineering monitoring and forest disaster monitoring, and the major application needs of high spatial, high spectral and high temporal resolution remote sensing massive data processing, product production and system services, since 2011, Li Zengyuan has led the team to undertake the "High Resolution Earth Observation System" project research, one of the 16 major national science and technology projects deployed in the "National Medium- and Long-Term Science and Technology Development Plan (2006-2020)".

The project has overcome eight key technologies for high-resolution remote sensing forestry survey and monitoring applications, established a high-resolution forestry application service platform based on high-performance computing and cloud architecture for the first time, formulated nine high-resolution special standards and specifications, filled the gap in my country's high-resolution remote sensing forestry applications, formed a high-resolution remote sensing forestry survey, monitoring and evaluation technology system that conforms to my country's forest conditions, and led the high-quality development of my country's forestry remote sensing technology. During the implementation of the project, more than 120,000 pieces of high-resolution data and products were distributed to more than 50 forestry survey planning and design units and forestry management departments, significantly improving the rate of independent high-resolution remote sensing data replacing foreign data in forestry surveys and monitoring, promoting the widespread application of independent high-resolution remote sensing data in forestry resource surveys, monitoring, supervision and management, and asset evaluation, supporting the formation of the ability to increase the frequency of forest resource monitoring from once every 3-5 years to once a year, and generally improving the monitoring accuracy by 5% to 10%. Based on the common products generated by satellite data such as Gaofen-1, Gaofen-2, Gaofen-3 and Gaofen-4, the platform has developed 21 forestry thematic product production lines. While improving the scientific and technological content and technical level of forestry surveys, it has produced huge economic and social benefits. The project won the second prize of the National Science and Technology Progress Award in 2018.

With the increasing social demand, forest management technology represented by remote sensing can effectively strengthen human management of natural scientific processes such as forest carbon, water and nutrient cycles, expand the area and timeliness of traditional forestry resource management, and save costs. It can also provide new technical means for ecological environment protection and construction, forestry resource utilization, disaster prevention and mitigation, and response to global changes.

(Guardian expert: Li Zengyuan, chief expert of the Resource Institute of the Chinese Academy of Forestry)

China Association for Science and Technology Department of Science Popularization

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