| The report to the 19th National Congress of the Communist Party of China（CPC）pointed out that comprehensive control of desertification,stony desertification,and soil erosion and the construction of an ecological civilization are the millennium project for the sustainable development of the Chinese nation.The construction of ecological civilization has once again risen to the height of the destiny of the nation and the country.In the fragile ecological environment of karst area,studying the process of water and soil migration and putting forward the control technology of water and soil loss and resistance can control rock desertification and promote the construction of ecological civilization.Based on the fragile ecological environment of karst,the main scientific research method to control rocky desertification is to study the process of soil and water migration in rocky desertification area and put forward the technology to stop soil and water loss and underground leakage and resistance,which has important significance to promote the construction of ecological civilization.Based on the basic knowledge of environmental science,geography,ecology and other disciplines,soil and water conservation and mixed crops,forest and grass planting measures configuration and other theories,we choose Bijie Salaxi karst plateau mountain which has potential and mild rocky desertification,Guanling-Zhenfengli Huajiang karst plateau canyon which has become intensity of rocky desertification and the Shibing karst mountain canyon which has no rocky desertification as our research regions in Guizhou karst plateau mountain plateau mountainous area.We are aiming at the research of hydrological process and soil and water loss on sloping land and the scientific problems and technological needs on the demonstration and verification of mixed agriculture and forestry resistance control.From2019 to 2021,stable hydrogen and oxygen isotopes were used to distinguish the water sources of plants by means of sample plot selection and investigation,slope vegetation sample plot investigation,soil basic physical and chemical properties determination,saturated water conductivity measurement and soil moisture content and meteorological monitoring.Statistical methods have been used in this process,including in-situ monitoring,laboratory tests,variance analysis and correlation analysis.Based on the condition of karst hydrological process,the soil properties,the degree of soil and water loss,the research of agriculture,forestry and resistance control,the development of the key technology,we will carry out the design of the whole chain,demonstrate the application of the integration module propulsion system.We clarify the change law of vertical soil slope soil moisture content variation law with time,reveal the interaction mechanism between hydrological process and soil and water loss on sloping land,construct and demonstrate the control technology of soil and water loss on karst slope with agroforestry,in order to provide scientific and technological reference for comprehensive control of rocky desertification and ecological civilization construction in other karst areas.（1）It is found that the soil hydrological process on the slope has heterogeneity in time and space scale.Soil water was distributed vertically in the three study areas and the overall underground water storage capacity of different agroforestry samples was strong.In the long time scale,the variation degree and activity degree of soil water on sloping land in rainy season were generally higher than that in dry season,and the hydrological process of soil on sloping land in rainy season was intense,but with different characteristics.During the monitoring period,the variation characteristics of soil moisture on different slopes are different.The average soil moisture of samples in The Sala River study area of Bijie is the highest in the b J-SY60-75 cm layer,indicating that the lower soil has a strong storage capacity.The maximum value of b J-CD soil moisture appeared in the middle-layer soil,and there was a certain relationship between soil moisture and root distribution due to the shallow root system of grassland.The average soil moisture content of the samples in Shibing Karst study area was the highest in the 60-75 cm layer of HC-TL,which indicated that the soil bottom water storage capacity in Shibing karst study area was the strongest.In the guanling-Zhenfeng Huajiang study area,the maximum soil moisture value is 30-45 cm in HJ-JYH.Based on the statistical analysis of the variation coefficient of soil moisture in rainy season,dry season and whole monitoring period,the variation degree and activity degree of soil moisture on sloping land in Sala Creek of Bijie were higher in rainy season than in dry season.In the guanling-Zhenfeng Huajiang study area,there is little difference between rainy season and dry season,the coefficient of variation is higher,and the soil layer is the most active.In the shibing karst study area,the variation degree and activity degree of slope plots in rainy season and whole monitoring period are close to each other,and are higher than dry season on the whole.（2）The K values of soil erodibility in the three study areas were all >0.25,indicating poor soil erodibility.However,the coefficient of variation of K values of BJ-SY,HJ-SDG and HC-TL were 1.01%,0.28%and 1.36%,respectively,indicating that the three monitoring sites had high soil stability and strong water retention ability.The mechanism of rainfall characteristics and vegetation types affecting the hydrological change and soil water supply characteristics on sloping land was clarified.There was a strong response relationship between soil moisture change and rainfall distribution on sloping land.With the increase of rainfall level,the response time of soil water to rainfall events shortened,and the effective water supply of each layer of soil increased obviously.The soil moisture curve and rainfall distribution on the slope of Sala River in Bijie showed a consistent trend during heavy rain events,but had no effect during light rain events,and some soil depth did not respond significantly to moderate rain events.In the study area of Shibing karst,the variation curve of soil moisture on sloping land showed a consistent trend with rainfall distribution.The variation of soil moisture on sloping land was obvious in light rain events,moderate rain events and heavy rain events,and soil water supply increased and lag time shortened.The increase range of soil moisture in slope soil increased in Salaxi study area and Shibing karst study area of Bijie,but the increase and lag time of soil moisture content in each layer of slope soil did not have a certain regularity between soil layers,which may be caused by the different absorption depth of plant roots.（3）We create a control technology for soil and water loss resistance in the mixed agriculture and forestry karst area,and we demonstrate and examine this technology in the demonstration area.It is found that soil bulk density,soil total porosity,soil saturated water conductivity,precipitation and vegetation types are the important factors that affect the variation characteristics of soil moisture content,recharge characteristics and soil erosion resistance on sloping land.In the research regions of Shibing,Bijie Salaxi,and Guanling-Zhenfeng Huajiang,we determine to develop the control technology of mixed soil and water loss resistance of agriculture and forestry.We should not only keep the existing in the process of biological engineering technology,but also keep the soil retention by making use of the plants roots,based on the research of new mixed agroforestry configuration technology and the mixed agroforestry configuration technology which applied on the slope in Bijie Salaxi as walnuts + potatoes/buckwheat（potato and buckwheat crop rotation）.In the research of Guanling-Zhenfeng Huajiang,it was found that the mixed cropping of Sphygma root and Prickly ash has the best effect on soil and water conservation.In the Shibing karst research area,it was found that the configuration of peach tree + mutia has the best effect on soil and water conservation.In the three study areas,the plant water absorption efficiency is also higher,which makes full use of water and plays a role of soil fixation and water conservation.This technology will be verified and promoted in the research area. |
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