Research status and main problems

1. Current status of foreign research

The development of rocky desertification and its harm to human beings is a global problem. Since the 1960s, with the rapid increase in population and ecological destruction, rocky desertification in karst areas around the world has been intensifying. For example, the Mediterranean karst areas, the Bruce Peninsula in southeastern Canada, the Chichibu region of Japan, and the Tasmania region of Australia are all facing serious rocky desertification problems. All countries have attached great importance to the problem of rocky desertification and have carried out efforts to control it. A lot of effective experience has been gained in developing karst aquifer water resources in rocky desertification areas, returning farmland to forests, and using fast-growing tree species and seedling nutrient solutions for ecological reconstruction in rocky desertification areas. However, the population density of foreign rocky desertification areas is small, and the conflicts between water, soil, and people are not as prominent as in our country. Treatment is relatively easy, and there are few reports on technical achievements.

2. Current status of domestic research

In the past ten years, the country has implemented the "87" poverty alleviation plan, the shelterbelt project in the middle and upper reaches of the Yangtze River, the soil and water conservation project, and the World Food Plan , World Bank loans and assistance projects from Australia and New Zealand, a lot of work has been done in afforestation, mountain closures, returning farmland to forests, converting slopes into terraces, building walls to protect soil, improving soil, developing karst water, and planting suitable cash crops. It has gained a lot of successful experience in rocky desertification environmental remediation, and summarized engineering management measures to solve a single goal from different perspectives, as well as a comprehensive rocky desertification control model.

(1) Main engineering measures for rocky desertification control

1. Ecological restoration measures

Including afforestation, returning farmland to forest, closing mountains for afforestation, and artificial grass planting , grassland improvement as the main part of the ecological restoration project, and combined with the construction of economic trees, planting of Chinese medicinal materials, etc. to expand the vegetation coverage area.

2. Farmland infrastructure construction measures

In order to improve the quality of farmland, increase land productivity, reduce damage to farmland and soil erosion caused by natural and human activities, increase farmers' economic income, and then To achieve the purpose of curbing deforestation and land reclamation. This type of measures focuses on the management of cultivated land with slopes of 6° to 25°, through "slope to terrace" (slope land converted into terraced fields and terraced soil), "dry land converted into irrigated land, flat dry land converted into paddy fields, and Wangtian Tian". Farmland transformation such as irrigation and irrigation), "fragmentation" (small pieces into large pieces, chaos into regularity), newly opened fields, cold rotten and rusty fields, lowland drainage and other farmland transformations can effectively prevent or reduce water and soil erosion.

3. Water conservancy and water conservation construction measures

Water resources are a necessary condition for the survival of animals and plants, an important part of the natural environment, and the basis for sustainable development. The measures pay equal attention to "open source" and "interception". Through the renovation of irrigation areas, the management of dangerous reservoirs, and the construction of "three small" (small mountain ponds, small water cellars, and small pools) projects on the surface, we are committed to solving the problem of drinking water for humans and animals in rocky desertification areas. Farmland irrigation improves human living conditions, increases land productivity, promotes agricultural structural adjustment, promotes economic development in rocky desertification areas, and ensures the effective implementation of returning farmland to forest, closing mountains for forestation, and curbing deforestation and land reclamation.

4. Agricultural industrial structure adjustment measures

According to regional resource and environmental conditions, adjust the industrial structure, rationally utilize resources, layout industries suitable for local resource and environmental advantages, and promote regional economy development. For example, Guizhou Province has implemented the policy of returning farmland to grassland and developing grassland animal husbandry in some alpine areas based on the local topography and climate, and has developed pepper cultivation on both sides of the Beipan River; Guangxi has implemented the planting of "beheaded trees" and developed aquaculture in rocky desertification areas.

5. Rural energy transformation measures

Aiming to solve the problem of farmers’ livelihood and fuel production in areas lacking coal resources, through the development of family breeding, biogas projects, firewood-saving stoves, rural small Measures such as hydropower construction and solar energy utilization have been implemented to curb man-made deforestation and destruction of forests.

6. Ecological migration measures

The main method is relocation. Through the construction of small towns and the development of townships and private enterprises, we can effectively concentrate the population and human engineering activities in rocky desertification areas (bad ecological areas) to areas with superior resource and environmental conditions, transfer the rural labor force, and increase the employment rate of the rural population. On the one hand, it can help people in poverty-stricken areas get rid of poverty as soon as possible; on the other hand, it can reduce the pressure on the resource environment of rocky desertification areas and the damage caused by human activities to the environment, so as to achieve a balance between human needs for resources and the carrying capacity of natural resources, and gradually restore the ecological environment.

7. Others

Mainly include policy guarantee measures, scientific and technological support systems, etc.

Including policy support for rocky desertification control, scientific and technological research on governance methods, demonstration projects, rocky desertification monitoring, scientific and technological training, publicity and education, organizational guarantees, etc.

(2) Main modes of comprehensive control of rocky desertification

The control of rocky desertification is a systematic project, which generally depends on the specific local resource environment and socio-economic environmental conditions. According to local conditions, we adopt a multi-method, multi-functional and multi-level combination model for comprehensive management. At present, the comprehensive management models adopted in domestic karst mountainous areas mainly include the following categories.

1. Comprehensive management model of small watersheds

Controlled by topography, geomorphology, hydrological network, geological structure and other conditions, the karst rock mountain area is composed of many small watershed units with independent functions. The contents of the comprehensive management model of small watersheds are: determining the ecological and economic functions based on the specific social and environmental conditions in the upper, middle and lower reaches of the small watershed, rationally configuring the ecological protection system, and through a series of assembled and supporting science and technology, with soil and water conservation as the core , based on water resources development and industrial structure adjustment as a means, realize comprehensive planning of the river basin, comprehensive protection system and compound agricultural production system construction layout, and form an agricultural, forestry and animal husbandry compound agricultural production system that meets the characteristics of mountainous areas.

2. Comprehensive management model of the ecological environment

In view of the characteristics of water shortage, lack of soil, serious soil erosion and prominent contradiction between man and land in karst mountainous areas, water storage, soil management and afforestation are the main tasks. The core is to manage the fragile ecological environment. Utilizing slope rainwater runoff and surface karst water combined with three small projects (small mountain ponds, small water cellars, and small pools) to form a micro water conservancy system to achieve the purpose of preventing soil erosion and solving the problem of farmland irrigation water during drought; Implement the "slope to terrace" project on cultivated land, and combine it with the planting of grass and fruit (trees) with economic value, and cooperate with the sand-blocking and valley squares to prevent strong soil loss and ravine erosion; carry out the construction of ecological forests and integrate them into ecological forests. Combined with economic forest planting, it not only enhances soil and water conservation in the basin, but also increases economic income. Through the above means, the ecological and environmental conditions in the river basin will be improved.

3. Ecological agriculture construction model

Based on the characteristics of karst mountainous areas with many mountains and few dams, combined with regional resources and environmental structure, we will implement an industrial structure integrating agriculture, forestry and animal husbandry. model. Comprehensive consideration of the regional agricultural resource advantages in the region, with the protection and expansion of forest coverage as the core, with the goals of soil and water conservation, economic development and environmental protection, rationally adjust the regional economic structure and agricultural (plant) structure, maintain ecological balance, and move forward The path of ecological agriculture. At the same time, develop characteristic agriculture and the cultivation of famous and high-quality products, integrate the planting industry, breeding industry and product deep processing industry, increase the economic added value of agricultural products, promote the orderly development and dynamic balance of the ecological economy, and form a complete and coordinated agriculture The ecological cycle system not only improves the utilization of resources, but also protects the ecological environment.

4. Grassland animal husbandry model

Rain and heat occur in the same season in the karst mountainous areas of southwest China. The climate is mild and humid, which is conducive to the growth of pasture and provides excellent conditions for the development of animal husbandry. In some areas with low population density and large grassland areas, this advantage can be used to develop ecological agriculture that combines animal husbandry and agriculture, using grass to raise livestock and livestock to raise agriculture, and further develop the deep processing industry of agricultural and animal husbandry products. Substituting grass for forest for food and combining grass, agriculture, animal husbandry and forest can preserve water and soil in the short term, and develop forest resources in the long term, which has both short-term and long-term benefits.

5. Ecological migration model

Moderate and above rocky desertification areas have large areas, lack of water and land resources, low land productivity and population carrying capacity. For such areas, Residents can be moved to areas with better environmental conditions and higher resource carrying capacity through ecological migration. On the one hand, it can reduce the damage caused by human beings to the already fragile ecological environment in order to survive, so that the ecological environment system can be restored and reconstructed. On the other hand, On the one hand, through off-site development, we can improve the living environment of the poor people in rocky desertification areas and promote poverty alleviation, thereby achieving coordinated and sustainable development of the social economy, resources and environment in rocky desertification areas.

6. Courtyard ecological economic model

With the construction and utilization of biogas as a link and on the basis of improving and stabilizing "fruit forest-livestock and poultry breeding-biogas", make full use of the front and rear of farmers' courtyards and Cultivated land resources, with the purpose of improving farmers' living infrastructure conditions, with the main content of planting economic trees, Chinese medicinal materials and raising high-quality livestock and poultry, carry out comprehensive planning and construction of mountains, water, forests, fields, roads and networks in rocky desertification mountainous areas.

By optimizing the planting structure, breeding structure, energy structure and technology structure in the economic system of karst rocky desertification areas, we can increase farmers' income and optimize the rural environment. The efficient operation of the courtyard ecological economic model can change the living environment conditions and uncivilized phenomena in rural courtyards, and gradually form a system based on planting, with breeding as the backbone, with biogas as the link, with planting and processing supporting each other, and the coordinated development of agriculture, forestry, animal husbandry and sideline industries. The rural ecological economic system is integrated with the prevention and control of rocky desertification to promote the comprehensive management of rocky desertification.

(3) Typical work in theoretical research on rocky desertification

1) Academician Yuan Daoxian, in "Karst Ecosystem and Rocky Desertification Control", combined with the actual situation of the karst rock mountain area in southwest China Based on the situation, a large amount of scientific data and charts were used to conduct detailed analysis and demonstration of the karst environmental ecosystem.

2) From 1999 to 2002, the China Geological Survey completed a survey of groundwater and ecological geological environment in the karst mountainous areas in southwest my country. It used remote sensing interpretation, ground verification surveys and other means to basically identify the karst mountainous areas in southwest my country. Based on the current status, spatial distribution and development trends of rocky desertification in the region, the "Survey Report on Groundwater and Ecological Geological Environment in Southwest Karst Mountainous Areas" was compiled.

3) Researcher Wang Mingzhang of the Guizhou Provincial Bureau of Geology and Mineral Resources compiled and published the "Research on the Ecological Geological Environment of Karst Mountains in Guizhou Province" based on the results of the "Survey on Groundwater and Ecological Geological Environment of Karst Mountains in Guizhou Province" , conducted research and exposition on the status quo, distribution, causes, development and evolution of rocky desertification in Guizhou Province, and initially proposed ways to control rocky desertification from a geological perspective.

4) Dr. Kuang Shunda from the Regional Geological Survey Institute of Guizhou Provincial Bureau of Geology and Mineral Resources and others used the National High-Tech Research and Development Program (863 Program) project as a platform and used remote sensing technology to complete the research on rocky desertification evolution monitoring technology and methods. , submitted the "Research on Key Technologies for Remote Sensing Survey of Rocky Desertification in Southwest China and Early Warning and Forecasting Results Report".

5) Professor Xiong Kangning of Guizhou Normal University and others used remote sensing technology as the main method to investigate the current status of rocky desertification in Guizhou Province, and compiled and published the "Remote Sensing Investigation and Research on Karst Rocky Desertification Types in Guizhou Province" , expounded the methods of remote sensing investigation, the basic characteristics and current situation of rocky desertification in Guizhou Province.

6) The Institute of Geochemistry, Chinese Academy of Sciences, takes the lead, and Guizhou University, Guizhou Normal University, Guizhou Academy of Sciences, Guizhou Provincial Bureau of Geology and Mineral Resources, Hohai University, Tongji University and other units jointly undertake the national key foundation Research (973 Project), conduct research on material migration cycles in karst mountainous areas including rocky desertification issues from a geochemical perspective.

(4) Typical work in rocky desertification control

1) Since the 1980s, the forestry department has carried out "returning farmland to farmland" in conjunction with the national long-term defense and pearl defense projects. Ecological restoration projects focusing on "reforestation, afforestation, and mountain closure for afforestation".

2) The National Development and Reform Commission and the water conservancy and agricultural departments focused on solving the water shortage problem and adopted small watersheds as units to implement coordinated planning and comprehensive management projects of mountains, water, forests, fields, roads and networks; Comprehensive improvement of sloping farmland is a breakthrough, and slope-to-ladder projects are implemented for gently sloping farmland below 25° with less rocky desertification and thick soil layers; in areas with relatively low population density, ecological and natural restoration projects are vigorously implemented; Biogas construction will solve the problem of energy shortage; focusing on increasing people's income and promoting farmers to get rid of poverty and become rich, we will develop Chinese medicinal materials, pepper, Amomum villosum and other economic fruits with market advantages according to local conditions, and use this to cultivate and form ecological industries. Typical projects in Guizhou Province include the Shibanqiao small watershed treatment project in Ling County, the Huajiang Bangui small watershed treatment project, and the Sinanwan Dam small watershed treatment project.

3) Since 2003, the China Geological Survey has carried out comprehensive improvement demonstration projects for the geological environment of typical karst watersheds in the southwest karst rock mountain area, respectively in Guizhou Province, Yunnan Province, Guangxi Zhuang Autonomous Region, Hunan Province and other provinces ( District), taking the karst watershed as a unit, a demonstration project for comprehensive improvement of the rocky desertification geological environment was carried out with groundwater development as the leader. Typical projects include the Jumu Underground River Basin in Guizhou Province, which represents the peak-cluster depression type, the Daozhenshangba Underground River Basin in Guizhou Province, which represents the ridge-gang-trough-valley type, the Luxi Xiaojiang River Basin in Yunnan Province, and Luota in Hunan Province and other rocky desertification control projects. From the perspective of geoscience, we will carry out demonstration work on geological environment improvement with the purpose of comprehensive control of rocky desertification. Through years of work, we have initially achieved certain experience and results, enriching the theory of comprehensive control of rocky desertification.

The implementation of the above-mentioned demonstration projects will provide basic conditions for improving the living and production conditions of local people, alleviating poverty and becoming rich, and will play a positive role in promoting the comprehensive control of rocky desertification in karst mountainous areas. And this project became the basis for this study.

4) With the support of the State Forestry Administration, Guizhou Provincial Department of Science and Technology Xinghuo Technology plans to implement a rocky desertification ecological environment management project of 300,000 acres of honeysuckle planting in the karst rocky desertification areas in the province, and implement the "Forest The "grass-livestock" ecological research and development model develops animal husbandry, drives farmers to become rich, and at the same time protects and improves the ecological environment, achieving good social and economic benefits, and completing the "Ecological and Economic Benefits Report on Planting Honeysuckle in Karst Rock Desertification Areas" .

5) The Institute of Karst Geology of the Chinese Academy of Geological Sciences has carried out geological environment improvement demonstration projects focusing on groundwater development in Guohua, Guangxi, Luota, Hunan and other places.

6) The governments of China and South Korea jointly invested in rocky desertification control projects in Xiuwen County, Guizhou Province, focusing on afforestation, small water cellars and biogas projects, and achieved good results.

7) Since 2008, the country has selected 100 key counties in the karst mountainous areas of southwest China (including 55 in Guizhou Province) to carry out pilot projects for comprehensive control of rocky desertification. The pilot work is currently progressing normally.

3. Main existing problems

Research and control of rocky desertification have achieved fruitful results, but overall, there are still problems in the following aspects.

(1) Rocky desertification continues to develop, and the ecological environment situation remains severe

Currently, relevant personnel at home and abroad have conducted a large number of studies on the control of karst rocky desertification from different aspects. It has implemented many tests and demonstration projects, made significant progress in the theory of the causes and prevention of rocky desertification in karst mountainous areas, and provided more successful experiences for the control of rocky desertification in karst mountainous areas. However, it should be noted that the governance effect is still not very satisfactory. According to relevant data, since the 20th century, although my country has effectively controlled karst rocky desertification area of ??5,000 square kilometers, due to the complexity of geological environmental conditions and unreasonable human engineering activities, the area of ??karst rocky desertification has increased by 25,000 square kilometers. square kilometers. The area ratio between intensified and improved rocky desertification is 5:1. The situation of karst rocky desertification is still severe.

(2) The theoretical and practical measures for rocky desertification control need to be further enriched and improved

“The formation and development of rocky desertification are caused by fragile karst environmental conditions and unreasonable "The fragile karst geological environment is the basis for the occurrence of rocky desertification, and unreasonable human engineering activities are the driving force for the occurrence of rocky desertification"; "The control of rocky desertification must not only control the It has been widely recognized that the rocky desertification environment that has already occurred should be repaired, and more importantly, new rocky desertification should be prevented from continuing to occur and develop through scientific means. Therefore, a reasonable approach to control rocky desertification must not only curb unreasonable engineering activities, but also improve the fragile geological environment through scientific means in order to achieve the desired results. However, in current practice, the various governance models usually adopted mainly focus on curbing unreasonable human engineering activities, but not enough attention is paid to how to improve the fragile geological environment of rocky desertification areas.

In recent years, different departments have implemented a large number of rocky desertification control projects from the perspectives of different industries, achieved certain results and rich experience, and summarized different comprehensive control models. To sum up, these governance models are basically an integration of measures such as expanding vegetation coverage, land consolidation, development of surface water resources, adjustment of agricultural industry structure, ecological migration, and courtyard economy.

Although these models include projects to restore vegetation and repair the deteriorated rocky desertification ecological environment through natural and artificial intervention, they also use scientific means to improve the living and production environment of people in rocky desertification areas, develop the economy, and start from the source. measures to prevent the continued occurrence and development of rocky desertification. However, a comprehensive analysis shows that these governance models all have the same characteristics. They all focus their main goals on human intervention and control of the surface biosphere. However, the huge role of the geological environmental conditions supporting the biosphere in the development of rocky desertification has been ignored to varying degrees, which is manifested in the following: first, the lack of comprehensive improvement of the intrinsic basic environment for the formation of rocky desertification - the geological environment of rocky desertification areas; second, the lack of comprehensive control of the geological environment of rocky desertification areas; The reason is that in the selection of treatment measures and project layout, the suitability of the treatment measures is usually not fully considered by the geological environment background (hydrological and geological conditions, geochemical background, etc.) of the treatment area; thirdly, the development and utilization of the local richness are not well considered. The geological resources are fully utilized in the control of rocky desertification. As a result remediation projects are still mainly carried out on the basis of fragile geological environment. Although the country has invested a lot of money in ecological environment management work such as water and soil conservation and rocky desertification prevention and control over the years, and these management efforts have indeed played a good role, a comprehensive analysis of the development trend of rocky desertification in karst mountainous areas in southwest China in recent years , the degree and area of ??rocky desertification are still continuing to develop at a relatively fast rate. The reason can be considered as: in addition to insufficient investment in rocky desertification control, the reason for this problem is that the current governance model and too many projects It is based on the control of external causes of rocky desertification, but the governance of the geological environment is weak.

The geological environment is the basis for the formation of all ecological environments. The quality of the geological environment determines the quality of the ecological environment. "If the foundation is not strong, the earth will shake." It can be said that neglecting the geological environment Only through effective remediation can the rocky desertification prevention and control work based on the fragile geological environment achieve the desired desired results. Therefore, the existing comprehensive management model of rocky desertification needs to be further supplemented and improved.

(3) The problems of lack of water sources, lack of land and poor soil quality need to be solved urgently

The basic characteristics of the fragile ecological environment in rocky desertification areas are "shortage of surface water, little soil and poor soil quality" ” is the most fundamental reason for the formation and development of rocky desertification, and it is also the key point that is difficult to solve in the current rocky desertification control projects.

The strong karst development in karst mountainous areas has caused serious surface water leakage and serious drought and water shortages on the surface, causing difficulties in drinking water for humans and animals and water supply for industrial and agricultural production in karst mountainous areas, and has become a "bottleneck" for social and economic development.

“Little soil” is an alternative typical feature of the fragile ecological environment in karst rocky desertification areas. The soil-forming conditions of carbonate rocks are extremely poor. In addition, the terrain conditions are mainly mountainous. The land is mainly scattered in intermountain basins, valleys and depressions. The land area available for cultivation is small and land resources are limited. As the rural population increases, the per capita cultivated land continues to gradually decrease. In particular, the population in karst mountainous areas is growing rapidly, and low-carrying capacity land and high-density population will inevitably lead to an imbalance between food growth and population growth. Taking Guizhou Province as an example, the per capita cultivated land area in the province was 1.7 acres in 2005, of which the average cultivated land area per capita was only 0.68 acres. Although returning farmland to forest can effectively prevent the further development of soil erosion, the reality of overpopulation has correspondingly increased the pressure on land resources in rocky desertification areas. Although increasing the construction of small towns and ecological migration are effective measures to alleviate the contradiction between rural population and lack of cultivated land, it should also be noted that farmers will still have a strong dependence on land for a long time in the future, and ecological migration will also need to be carried out accordingly. of land and water resources. Therefore, the lack of arable land has become one of the "bottlenecks" restricting the implementation of ecological resettlement projects.

On the one hand, the cultivated land in carbonate karst areas has thin soil layers, discontinuous distribution, poor water retention and drought tolerance. On the other hand, there is a lack of nutrients in the soil. Severe soil erosion causes the loss of nutrients in the soil. The drastic reduction of cultivated land has resulted in poor soil quality, low land productivity, and low crop quality, which has become one of the important reasons limiting regional economic development.

Lack of water, lack of land and poor soil in karst mountainous areas are closely related to the geological environment. They are the difficulties in controlling rocky desertification and are also the most basic problems that must be solved.