Geoscience theory of rocky desertification control

First, the guiding ideology of establishing a geoscience model for rocky desertification control.

The guiding ideology of establishing a geoscience model is to restore the geological environment from the perspective of geoscience, improve the environmental carrying capacity and fragile environmental conditions by reasonably and effectively developing the rock, soil and water resources in karst mountainous areas, so as to coordinate the contradiction between human demand and resource carrying capacity, balance the demand for resources for human life and production in karst mountainous areas, and provide a geological foundation platform for rocky desertification control measures of other disciplines, so as to prevent the occurrence and development of rocky desertification from the source.

Based on this, a geo-model of rocky desertification control is established from the perspective of fragile karst geological environment control, which makes it a supplement to the comprehensive control theory and control engineering system of rocky desertification.

Second, the comprehensive control project system of rocky desertification

Rocky desertification and poverty are like twin brothers. Their occurrence and development are the products of fragile karst ecological environment, and there is a complementary relationship between them. Facts have proved that only by solving the living conditions and food and clothing problems of mountain people, improving farmers' economic income level and getting rid of poverty can the ecological environment of rocky desertification be effectively improved. Otherwise, no matter how many surface improvement projects are implemented, it is difficult to eliminate deforestation and land reclamation, and it is difficult to achieve good results in returning farmland to forests and closing hillsides to facilitate afforestation. Therefore, the prevention and control of rocky desertification must be combined with rural poverty alleviation. The important measures to promote rural poverty alleviation are to improve rural living and production conditions in karst mountainous areas, improve the carrying capacity of agricultural production environment through scientific ways and means, increase the economic income of farmers in rocky desertification areas, and promote economic and social development in karst mountainous areas. Therefore, rocky desertification control is a systematic project, which not only needs to rectify and repair the existing rocky desertification "landscape" and promote the restoration of ecological environment in rocky desertification areas, but more importantly, it needs to prevent new rocky desertification and curb the intensified development of rocky desertification in areas where moderate and mild rocky desertification has occurred. Realize the combination of "prevention" and "treatment", treat both the symptoms and the root causes, and effectively prevent and control rocky desertification. In view of this, the rocky desertification control project should include two subsystems: rocky desertification ecological restoration and rocky desertification prevention and control.

In the ecological restoration subsystem of rocky desertification, the effective engineering means at present are mainly "afforestation, returning farmland to forest and grassland, closing hillsides to facilitate afforestation", aiming at restoring and expanding the vegetation coverage area. Through vegetation restoration and water conservation, vegetation in rocky desertification areas has been gradually and effectively restored and the environment has been improved. In the implementation of the project, we should pay full attention to the reasonable selection of tree species and grass species according to the geological environment conditions and the suitability of tree (grass) species to the geological environment, and consider the economic rationality.

The subsystem of rocky desertification control should be mainly aimed at the causes of rocky desertification and composed of systematic engineering measures to prevent the occurrence and development of new rocky desertification. The occurrence and development of rocky desertification are controlled by two factors, one is fragile karst geological environment, and the other is unreasonable human engineering activities. The fragile karst geological environment is the root of the low environmental carrying capacity, and unreasonable human engineering activities are the result of the contradiction between the "excessive" demand for resources for human survival and the low environmental carrying capacity in karst mountainous areas. Therefore, in the subsystem of rocky desertification control, we should coordinate the contradiction between environmental carrying capacity and demand in karst mountainous areas, curb unreasonable man-made engineering activities that may cause and aggravate rocky desertification, and determine the control projects. The main engineering measures include improving the geological environment for the purpose of increasing the available natural resources, ecological migration for the purpose of reducing the environmental pressure in rocky desertification areas, agricultural science and technology development and agricultural infrastructure construction for the purpose of reducing the demand for natural resources.

Therefore, the comprehensive control engineering model of rocky desertification can be summarized as shown in Figure 2- 1 1.

Figure 2- Block diagram of rocky desertification comprehensive control project mode +0 1

Third, the theoretical basis of establishing the geoscience model of rocky desertification control

In the engineering system of comprehensive control of karst rocky desertification, relatively speaking, the rocky desertification control subsystem is a more comprehensive, scientific and complex system engineering. Past practice shows that although the state has invested a lot in rocky desertification control in southwest karst mountainous areas, it has also achieved remarkable results in local experimental sites. However, although some old rocky desertification ecological environment has been controlled or improved to some extent, new rocky desertification continues to develop, and the speed of development is faster than that of control and recovery. Through investigation and statistics, it is confirmed that rocky desertification in karst mountainous areas has developed rapidly since the 20th century. Only during the period from 1987 to 1999, the rocky desertification area in the whole southwest region expanded from 83,000 square kilometers to105,5438+000 square kilometers, with a net increase of 22,600 square kilometers. The area of rocky desertification in Guizhou Province has expanded from 1985 to 37,597 square kilometers in 2005, with a net increase of 23,700 square kilometers. The above rocky desertification area does not include the part that has been improved through the implementation of ecological restoration projects. The reason is that the current control projects are mostly concentrated in the "ecological restoration" projects in areas where rocky desertification has occurred, while the engineering measures and capital investment to prevent the occurrence and development of new rocky desertification are relatively insufficient, and the engineering means of prevention and control have certain defects in theory and practice. Although the population in rocky desertification areas is reduced through the construction of small towns and ecological migration; Through the construction of "three small" water conservancy projects on the surface, the basic construction of farmland, the development of courtyard economy and the adjustment of agricultural industrial structure, the land output rate will be improved to meet the needs of population life and economic and social development in rocky desertification areas; Solve the fuel structure of residents in rocky desertification areas through biogas projects and small hydropower projects, and avoid and reduce deforestation caused by fuel shortage. The combination of the above control projects has formed different comprehensive control models of rocky desertification. Through the implementation of these governance models and engineering measures, the excessive dependence of human life and production on natural resources in rocky desertification areas has been reduced, the contradiction between human demand for resources and environmental carrying capacity in rocky desertification areas has been alleviated to a certain extent, local economic development and people's poverty alleviation have been promoted, deforestation and excessive reclamation of sloping land have been reduced or even eliminated, ecological restoration projects such as "returning farmland to forests and closing hillsides to facilitate afforestation" have been guaranteed, and new rocky desertification has been prevented. However, these governance models all have the same problem-most engineering measures focus on the control and intervention of the surface biosphere, while less attention is paid to the restoration and improvement of the karst geological environment that controls the characteristics of the ecological environment, and insufficient attention is paid to the basic role of the karst geological background. The engineering measures involved are still the passive implementation of rocky desertification control project on the basis of the original fragile karst geological environment, which leads to the lack of good resource and environmental support for rocky desertification control, which is manifested as follows: ① Some surface water conservancy projects are unreliable. ② Some ecological migration bases are insufficient. ③ The problem of poor soil quality has never been completely solved, and the adjustment of agricultural industrial structure lacks the support of suitable geochemical background. As a result, drinking water for people and livestock can not be well solved, farmland irrigation lacks water source guarantee, crop yield is not improved much, quality is not high, rural economic development speed is still low, poor people can not get rid of poverty, and even some people and regions that have been out of poverty return to poverty. Although a lot of manpower, financial resources and material resources have been invested to control rocky desertification, it is difficult to achieve the expected results, and rocky desertification is still developing at a relatively fast speed.

It can be seen that the quality of natural geological environment in karst areas plays a vital role in controlling all engineering activities such as ecological environment quality, rocky desertification development, rocky desertification control and even social and economic development in karst mountainous areas. Without a good environmental foundation, it is difficult for all human engineering activities to achieve good expected results. Therefore, rocky desertification control should first rectify the fragile karst geological environment on the basis of finding out the geological environment conditions and resources and their spatial distribution, fully develop and rationally utilize the potential natural resources in rocky desertification areas by scientific means, improve the carrying capacity of resources and environment, improve the fragile geological environment, and provide good geological foundation support and resource environment for water conservancy project construction, farmland capital construction, agricultural industrial structure adjustment, ecological migration and other control measures. On this basis, combined with ecological restoration, land consolidation, water and soil conservation, agricultural industrial structure adjustment, ecological migration and other projects for comprehensive improvement, rocky desertification prevention and control can achieve the expected results. In view of this, there are sufficient reasons to believe that the remediation of karst geological environment is the basis of rocky desertification remediation.

Fourth, the basic connotation of the geoscience model of rocky desertification control

The geoscience model of rocky desertification control is a method of comprehensive geology, rock mineralogy, karst, hydrogeology, geochemistry and agricultural geology, and taking this as a guide, it is a method to prevent rocky desertification from a geoscience perspective. The main connotation of this model is to develop natural geological resources reasonably and effectively through scientific means, including karst groundwater resources, rock and soil mineral elements resources and abandoned land caused by natural factors. To improve the carrying capacity (environmental capacity) of the natural environment in rocky desertification areas, provide the necessary basic conditions for people's life and production in rocky desertification areas, solve or alleviate the contradiction between human needs and the carrying capacity of environmental resources, improve the land output rate and the quality of agricultural (forest and animal husbandry) products, promote the process of poverty alleviation in karst mountainous areas, and curb or reduce deforestation.

The research on the geological model of rocky desertification control not only faces up to the reality of fragile ecological environment in karst mountainous areas under natural conditions, but also emphasizes the improvement of fragile ecological environment in karst mountainous areas through effective development of resources under the interference of artificial scientific means.

In view of the fragile ecological characteristics of "less surface water, less soil and poor soil" in karst mountainous areas, the main engineering measures of the geoscience model for rocky desertification control include: first, aiming at the lack of surface water resources, rationally developing and utilizing karst groundwater resources, solving the problem of drinking water for people and animals in areas with water shortage of surface water, providing irrigation water for farmland, increasing land yield and improving people's living conditions in rocky desertification areas; Second, rationally develop many flood depressions, restore the use of land destroyed by water, alleviate the problem of "less soil" in rocky mountainous areas, and provide resettlement bases for ecological immigrants; Thirdly, according to the geochemical characteristics of rocks, soil and water and the suitability of plants (crops), the agricultural planting plan is compiled to provide geological basis for the adjustment of agricultural industrial structure. At the same time, study and develop the rock mineral elements needed for the growth of plants (crops) to supplement the deficiency of nutrient elements in the soil in carbonate rock distribution areas.