[Promoting Ecological Protection and Restoration (3)]

◎ Reporter Ma Aiping

Driving more than 400 kilometers north from Beijing, there is a "dark green", like an eagle with wings spread, tightly guarding the southern edge of the Hunshandak Sandy Land in Inner Mongolia. It is connected with the dense forests of Chengde, Zhangjiakou and other places in Hebei Province to build a green Great Wall, and become a wind and sand barrier and water source guardian in Beijing-Tianjin-Hebei and North China. Here, it is the Saihanba Mechanical Forest Farm.

From the vast wasteland to the reckless forest sea, the green waters and green mountains of Saihanba have witnessed the vicissitudes of life for more than half a century. Saihanba Mechanical Forest Farm has successively won the "Champions of the Earth Award", the highest honor of the United Nations environmental protection, and the "Land Life Award", the highest honor in the field of desertification prevention, and has become a "Chinese model" for global environmental governance.

The world's largest plantation is grown

In the 20s of the 50th century, the Saihan Dam was gone, the yellow sand was filled, and the wind and sand surged. Due to the fact that the Saihanba Mechanical Forest Farm is only 180 kilometers away from Beijing in a straight line, with an average altitude difference of more than 1500,<> meters, Saihanba and the surrounding Hunshandak Desert have become the main source of sand and dust and the passage of wind and sand in the Beijing-Tianjin area.

Since its establishment in 1962, with the efforts of three generations, Saihanba has planted more than 110.5 million mu of forests and planted nearly 12 million trees. It is home to the world's largest plantation, and if the trees were arranged at a one-metre spacing, they would circle the Earth's equator <> times.

Yu Shitao, director of Saihanba Machinery Forest Farm, said: "Compared with the early stage of the establishment of the farm, the forest land area of the forest farm has increased from 24,115 mu to 1.33 million mu, the forest volume has increased from 6,1036 cubic meters to 8.11 million cubic meters, the forest coverage rate has increased from 4.82% to 2%, and the forest volume per unit area has reached 76.<> times the national average level of planted forests, becoming an important ecological barrier to protect Beijing and Tianjin." ”

It is understood that since 2012, Saihan Dam has completed afforestation of 10,6 mu. At present, all the stony barren mountains in the forest farm have been greened, and the forest area of the forest farm has increased to 115.1 million mu.

In addition to trees, there are also natural ecosystems and natural vegetation communities in the grassland and wetland ecotone in Saihanba Mechanized Forest Farm. The good ecological environment and abundant species resources make Saihanba a natural gene bank of animal and plant species. Open the computer of the staff of the Forest Farm Reserve Management Section, and the photos of wild animals such as red foxes, red deer, leopard cats, black grouse, and white-headed cranes paint an ecological picture of harmonious coexistence between man and nature.

According to the statistics of biodiversity survey, there are 261 species of terrestrial wild vertebrates, 32 species of fish, 660 species of insects, 179 species of macrofungi and 625 species of plants. "Roe deer, cranes, whooper swans, wild boars... In recent years, there have been more and more animal species in the forest farm, and the images of animals captured by infrared cameras have become more and more abundant. Li Yongdong, deputy director of Saihanba Machinery Forest Farm, said.

In addition, according to the assessment of the Chinese Academy of Forestry, the Saihan Dam can conserve water and purify 2 million cubic meters of fresh water in the lower reaches of the Luan and Liao rivers every year, reduce soil loss by 84,513,55 tons per year, fix 86,03 tons of carbon dioxide and release 59,84 tons of oxygen per year. Today, the forest ecosystem of Saihanba provides more than 100 billion yuan of ecological service value every year.

Overcome technical challenges

A natural ecosystem is an organic life body, which has its own objective laws of development and evolution, and has the ability of self-regulation, self-purification and self-restoration. To heal the harm caused by human beings to nature, we must first fully respect and conform to nature, give nature enough time and space to recuperate, and rely on the power of nature to maintain the balance of the ecosystem.

The vivid practice of the construction of Saihanba Mechanical Forest Farm fully proves that for areas with serious ecological damage and difficult to recover on their own, it is necessary to give full play to people's subjective initiative, take scientific and appropriate artificial restoration measures, create conditions and environment for natural restoration, accelerate the restoration process, and improve restoration efficiency.

It is difficult to plant and construct steep slopes, it is difficult to protect moisture with less soil, and it is difficult to survive in barrenness... Carrying out afforestation means that the people of Saihanba must overcome one technical problem after another and deal with one natural challenge after another.

Seedling cultivation is the foundation of afforestation. In the early days of the establishment of the farm, due to the lack of successful experience in afforestation in the arid and barren sandy land at high cold and high altitude, the survival rate of afforestation in Saihanba Mechanical Forest Farm in 1962 and 1963 was only 8% for two consecutive years. In the face of the failure of afforestation, the people of Saihanba fully realized the importance of using native seedlings for afforestation, explored and summarized the all-light seedling technology in the alpine region, cultivated high-quality strong seedlings, and laid a solid foundation for large-scale afforestation and greening in the whole field.

After years of exploration, Saihanba has summed up a set of technical specifications for tackling key afforestation, including guest soil backfilling, film mulching and water retention, seedling moisture preservation, and cold protection and wintering, which provides valuable experience for the development of plantation breeding in other regions of China.

"Although Saihanba is green, the forest ecology has problems such as single tree species, simple structure and high density, which makes it difficult to achieve survival of the fittest among species, and also adversely affects insect control, fire prevention and disease prevention." Yu Shitao said that in recent years, the forest farm has introduced tree species such as birch, plum, oak, ash, and pentagonal maple, as well as shrubs such as rowan, blue indigo, and barberry, to create mixed forests of different ages with rich color layers by introducing birch, plum, quercus, ash, and pentagonal maple, and gradually making the forest stand reach a near-natural state.

In 2022, the afforestation direction of Saihanba will be changed to afforestation under the canopy, and broad-leaved forests will be introduced, and a multi-species, multi-level and composite forest structure will be constructed by adopting mixed methods such as coniferous and broad-leaved forests. Up to now, 11500,<> acres of newly planted mixed forests have been planted in Saihanba, further building a solid ecological barrier between Beijing and Tianjin.

This year, for the first time, all 8000,<> acres of afforestation land in Saihanba Mechanical Forest Farm will adopt the mixed afforestation model.

"In the past two years, we have vigorously created mixed forests and planted broad-leaved tree species such as oak, rowan and purple-leaved plum, so as to enrich the diversity of tree species, effectively adjust the tree species structure, and make the forest ecosystem healthier and more stable. By 2040, the area of mixed forests is expected to increase by 24,4 mu, with a total area of 49,40 mu, and mixed forests account for more than <>%, making the forest ecosystem more stable and healthier. Yu Shitao said.

Use modern scientific and technological means to protect the forest farm

From the beginning of large-scale afforestation with tractors, to the introduction of "air-space-ground" integrated information technology to refine the management of forests, new technologies provide support for the development of Saihanba mechanical forest farm.

Liu Shirong, an academician of the Chinese Academy of Engineering, said in an interview with a reporter from Science and Technology Daily that in the second venture of Saihanba Mechanical Forest Farm, the Chinese Academy of Forestry pays attention to the application of science and technology in the efficient cultivation technology of larch, remote sensing technology monitoring, value assessment of forest wetland resources, and prevention and control of forestry pests, and provides strong support for the intelligent management of Saihanba forest resources through information management technology.

The most feared thing in the forest farm is fire. In the forest fire prevention command center of the forest farm, dozens of sets of images are arranged on the big screen, and the situation of the whole field is monitored in real time. At present, the "sky and ground" integrated forest and grassland fire prevention early warning and monitoring system established by Saihanba Machinery Forest Farm has realized the organic combination of satellites, helicopters, unmanned aerial vehicles, fire detection radars, video surveillance, alpine lookouts, and ground patrols, and built a relatively complete fire prevention and forest protection system.

In order to prevent and control biological diseases, Saihanba Machinery Forest Farm adopts aircraft control, physical control, natural enemy control, artificial spray control and other methods according to different kinds of pests. At present, Saihanba has preliminarily built a field monitoring system of the Internet of Things, making full use of modern scientific and technological means to establish a control and prevention system combining civil air defense, flight defense and technical defense, which has greatly improved the work efficiency and prevention effect.

In addition, Saihanba Mechanical Forest Farm has also become a demonstration base for a number of scientific research projects. For example, Zhang Shoufeng, an academician of the Chinese Academy of Engineering, presided over the "13th Five-Year Plan" national key research and development project - an important experimental demonstration base for the research of efficient cultivation technology of larch.

It is understood that on the basis of the qualitative identification index of the traditional target tree, the project team used the combination of machine learning and selection probability model to construct the quantitative selection model of the target tree, and proposed a half-mu sample circle target tree operation method that is easy to operate in production. After 40 years, the volume per hectare of larch stand can reach 193 cubic meters, which is 16.2% higher than that of traditional control management, and the proportion of large-diameter target timber species reaches more than 50%, which provides technical support for the cultivation of large-diameter timber. With the support of the project results, the "Forest Management Plan of Saihanba Mechanical Forest Farm (2021-2030)" has been completed. (Science & Technology Daily)