Rocky Desertification Area Research Articles

Evaluation of soil fertility in the succession of karst rocky desertification using principal component analysis

Abstract. Expanding of karst rocky desertification (RD) area in southwestern China is strangling the sustainable development of local agricultural economy. It is important to evaluate the soil fertility at RD regions for the sustainable management of karst lands. The changes in 19 different soil fertility-related variables along a gradient of karst rocky desertification were investigated in five different counties belonging to the central Hunan province in China. We used principal component analysis method to calculate the soil data matrix and obtained a standardized integrate soil fertility (ISF) indicator to reflect RD grades. The results showed that the succession of RD had different impacts on soil fertility indicators. The changing trend of total organic carbon (TOC), total nitrogen (TN), available phosphorus, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) was potential RD (PRD) > light RD (LRD) > moderate RD (MRD) > intensive RD (IRD), whereas the changing trend of other indicators was not entirely consistent with the succession of RD. The degradation trend of ISF was basically parallel to the aggravation of RD, and the strength of ISF mean values were in the order of PRD > LRD > MRD > IRD. The TOC, MBC, and MBN could be regarded as the key indicators to evaluate the soil fertility.

Using stable isotopes to quantify water uptake by Cyclobalanopsis glauca in typical clusters of karst peaks in China

In this study, stable isotopes (18O and 2H) were used to determine the sources of water for Cyclobalanopsis glauca in two habitats: limestone outcrops and thin soils in clusters of karst peaks in southwest China, where soils are scattered only in rock gaps and are underlain by rigid carbonate rocks. We used a direct inference approach and the IsoSource mixing model to estimate the contributions of different sources to the plant xylem water. The results showed that adult C. glauca growing on limestone outcrops mainly used water from soils in rock gaps, which comprised 65 % of all water sources during the rainy season, and water from rainwater sources during the rain-dry season and dry season; the proportion of deep water used increased during the dry season. In contrast, young C. glauca growing on limestone outcrops relied on a mixture of rainwater and soil water during the rainy and the rain-dry seasons, and on rainwater in the dry season, accounting for 66.3 and 64.0 % of water use, respectively. Adult C. glauca on thin soils mainly used soil water in rainy seasons, a mixture of soil water and rain water in the rain-dry season, and rainwater in the dry season. Water held within bedrock was essential for meeting plant transpiration requirements in karst peak cluster areas. The results will provide knowledge for the effective protection of vulnerable karst environments and for the recovery of vegetation on karst rocky desertification areas.

Contribution of Arbuscular Mycorrhizal Inoculation to the Growth and Photosynthesis of Mulberry in Karst Rocky Desertification Area

The photosynthesis effect of arbuscular mycorrhizal fungi (AMF) on mulberry was evaluated in karst rocky desertification area. Three-month-old sterile mulberry saplings were transplanted in karst rocky desertification area and were inoculated with Gigaspora rosea. Some growth parameters and photosynthesis indexes were measured to study the physiological responses after inoculating for 1 year. The results showed mulberries that were inoculated with AMF had greater height, larger stem diameter and leaf area, more leaf number per plant, more fibrous root number and biomass of shoots and roots, as well as higher chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance compared with non-AMF plants. The research results confirmed that AMF markedly enhanced the absorptive ability of root system, promoted the vegetative growth, improved the photosynthetic capacity, and obviously increased mulberry survival rate in karst rocky desertification area. These results provided a theoretical base for the ecological restoration in karst rocky desertification area.

Remote Sensing Integration Survey of Typical Land Types and Analysis of its Spectral Properties in Southeast of Yunnan Province

Karst rocky desertification is a major ecological disaster faced by the southeastern region of Yunnan Province, in China. The research of land use status in rocky desertification area is more and more concerned by human. Through remote sensing integrated survey ways to establish the spectral database of six kinds of typical land types, such as water, forest land, paddy field, grassland, dry land and bare land; then, Normalized Difference Vegetation Index (NDVI) processing and Tasseled Cap transformation processing for the spectral data; finally, the spectral characteristics and the variation of typical land types was analyzed and studied. The results indicated that, there are no significant differences of spectral of the six kinds of typical land types, after the processing of NDVI, the water, the forest land and grassland with larger vegetation coverage, and the paddy land, dry land and bare land with smaller vegetation coverage, can be well distinguish, but the distinction between forest land and grassland is bad, the distinction of paddy land, dry land and bare land is also bad; after the Tasseled Cap transformation processing, the dispersion degree of water, forest land, paddy field and grassland is better, the dispersion degree of dry land and bare land is a bit poor, need to be further studied. The remote sensing integrated survey and the analysis of spectral properties are important foundation for the Land Use / Land Cover Change (LUCC) and the dynamic monitoring of rocky desertification in southeastern rocky desertification region of Yunnan province.

Poverty Alleviation and Development Path Analysis: A Case Study on Rocky Desertification Area of in Yunnan Guangxi Guizhou Province in China

Yunnan Guangxi Guizhou provinces are concentrated areas of rocky desertification in China. In this paper, the poverty status of Yunnan Guangxi Guizhou provinces rocky desertification areas can be analysed in multidimension. We can improve many aspects such as the ecological environment, infrastructure, education skills training and others for poverty alleviation and development. According to the poverty theory and related theory in applying to poverty alleviation of the Yunnan Guangxi Guizhou rocky desertification area, combined with their self-conditions of Yunnan Guangxi Guizhou provinces rocky desertification area, strive to solve the bottleneck problems of the development and curb desertification expansion trend, fundamentally change the face of the Yunnan Guangxi Guizhou provinces rocky desertification area, promote the sustainable development. On the basis of these, we can build the model of poverty alleviation and development of Yunnan Guangxi Guizhou provinces rocky desertification area.

The Relationship between Soil Characteristics and Community Structure in Different Vegetation Restoration in Guangxi Karst Region

The space instead of time method was used to determine the species diversity and soil property in different succession stages in Karst rocky desertification area, in China. The species diversity of herb layer was digressive and that of tree layer, shrub layer and the whole community were increased first and then decreased, the peak value appeared in the rattan thorn scrub stage, the lowest appeared in the grass stages. At the beginning of succession, the species diversity of herb layer was higher than that of shrub layer. With the closing time increased, the diversity of the shrub layer increased more than that of herb layer. There had the same change trend in velocity nitrogen, organic matter, total nitrogen and total phosphorus. There was significantly linear positive correlation between the total nitrogen, phosphorus, magnesium, calcium, pH, available phosphorus and the species diversity and richness of the herb layer.

Comparative studies of the distribution characteristics of rocky desertification and land use/land cover classes in typical areas of Guizhou province, China

The Huajiang and Hongfenghu demonstration areas represent typical karst landforms and rocky desertification landscapes in Guizhou, China. These were selected for a comparison of rocky desertification and land use cover. Based mainly on 5 m resolution Spot 5, remote sensing images, topographic maps (1:10,000) and land use maps, the intensity and extent of rocky desertification, and slope characteristics of the two areas were interpreted. Spatial overlay analysis was used to compare the land use/land cover (LULC) and rocky desertification within each. The results were compared using the concepts of rocky desertification occurrence (RDO) among LULC classes and the structure value of desertification land (SVDL). The results demonstrated that (1) the landforms and extent of rocky desertification in the two areas are significantly different and the proportion of very steep slopes is one of the reasons leading to large areas of rocky desertification; (2) the RDO and SVDL show significant differences between the two areas; also rocky desertification intensity in various LULC classes cannot be measured in terms of RDO. High RDO may occur in low-intensity desertification land, and vice versa; (3) the structural characteristics of rocky desertification among various LULC are consistent among the woodland, "bare land" and "other grassland" land use classes in the two areas, but sequence slight > moderate > intense is not consistent between the areas. For the rocky desertification control, the present authors consider that the spatial distribution differences of rocky desertification and LULC among areas with different landform types area combined with the intensity of rocky desertification should be used in designing appropriate measures for control of desertification and rehabilitation of land.

基于Le Bissonnais法的石漠化区桑树地埂土壤团聚体稳定性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于Le Bissonnais法的石漠化区桑树地埂土壤团聚体稳定性研究 DOI: 10.5846/Stxb201305070977 作者: 作者单位: 西南大学资源环境学院,西南大学蚕学与系统生物研究所,西南大学资源环境学院,西南大学动物科技学院,重庆市水土保持生态环境监测总站,西南大学资源环境学院,西南大学资源环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 三峡建设委员会(三峡水库生态屏障区典型经果林生态功能建设与评价研究 2012-2015);国家农业综合开发水土保持重点科技项目(2013);农业部(现代农业产业技术体系专项(CARS-22-ZJ0503)) Study on soil aggregates stability of mulberry ridge in Rocky Desertification based on Le Bissonnais method Author: Affiliation: College of Natural Resources and Environment,Institute of Soil and Water Conservation and Eco-environment,Southwest University,Institute of Sericulture and Systems Biology,Southwest University,College of Natural Resources and Environment,Institute of Soil and Water Conservation and Eco-environment,Southwest University,Faculty of Animal Science and Technology,Southwest University,,College of Natural Resources and Environment,Institute of Soil and Water Conservation and Eco-environment,Southwest University,College of Natural Resources and Environment,Institute of Soil and Water Conservation and Eco-environment,Southwest University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:石漠化区独特的水土流失作用使该区土壤严重退化,地埂植物作为一种独特的农林复合模式对石漠化区土地质量改善和坡耕地土壤生态修复作用明显,能有效保证坡耕地的生态条件和生产性能。选取石漠化区3种不同管理方式的桑树地埂为研究对象,采用传统湿筛(Cаввинов法)和Le Bissonnais法测定土壤团聚体分布与稳定性特征。结果表明:基于Cаввинов法测定的土壤团聚体稳定性以天然林最好,桑埂自然生草地和清草地相对居中,桑埂农地最差;3种管理方式的桑树地埂土壤团聚体稳定性指数(ASI)随地埂距离均表现为ASI90cm > ASI60cm > ASI30cm,主要原因在于桑树地埂对坡耕地土壤团聚体影响的作用范围主要集中在距株30 cm以内,而在地埂30 cm以外田面农耕活动对土壤团聚体结构影响较大,而受桑树地埂影响作用较小。基于Le Bissonnais法快速湿润(FW)处理后土壤团聚体集中分布在0.5-0.25 mm之间,慢速湿润(SW)和湿润振荡(WS)处理后团聚体主要分布在5-1 mm之间。Le Bissonnais法处理后土壤团聚体稳定性表现趋势与Cаввинов法一致,3种处理后的团聚体分形维数D、MWD和GMD均表现为FW < SW < WS。Le Bissonnais法FW和SW处理后团聚体稳定性指标与Cаввинов法达到极显著相关,说明Le Bissonnais法测定石漠化区土壤团聚体稳定性是可行的;石漠化区土壤团聚体稳定性与有机质和粘粒含量呈显著正相关(0.586 ≤ R ≤ 0.864),这说明石漠化区土壤团聚体稳定性是以上两种土壤胶结物质的黏聚作用形成的,且两种土壤胶结物质对土壤消散作用和粘粒膨胀作用引起的团聚体破坏抵抗性强烈,而对低强度机械干扰引起的团聚体破碎没有明显抵抗性,研究结果对石漠化区坡耕地土壤保持具有重要指导意义。 Abstract:Soil aggregate is the basic unit of soil structure, and its stability is closely related to soil erosion-resistance. Soil and water loss makes the soil degradation severer in the specific rocky desertification area. Ridge plant, one of the special agroforestry pattern, plays important roles in improving soil quality and ecological restoration of slope land in rocky desertification area. Qianjiang is a typical rocky desertification area in Chongqing, where mulberrywas widely planted and becomes one of the main economic forest and ridge plants. In order to explore the stability mechanism of soil aggregate, mulberry ridges with three different management modes were selected in this study. The distribution and stability of soil aggregates were measured by traditional Cаввинов method and Le Bissonnais method. The results showed that the stability of soil aggregates based on Cаввинов methods was the best in natural forest land, followed by natural grassland and weeded land, and was the worst in farmland. The aggregate stability index (ASI) followed the order of ASI90cm > ASI60cm > ASI30cm in the three management models. The R0.25 water stable aggregate increased with increasing distances from ridge, while the aggregate destruction rate (PAD) decreased. The possible reason might be as follows: The effects of mulberry ridge on soil aggregates mainly cover areas within 30 cm, while the agricultural cultivation greatly influenced soil aggregates structure in areas beyond 30 cm with little effect from the ridge. Based on Le Bissonnais methods, the majority of aggregates were broken down to small aggregates by fast wetting (FW) treatment. The distribution of soil aggregates was in the category of 0.5-0.25 mm with diameter after FW, and 5-1 mm after SW and WS. The fractal dimensions (D) of aggregates was the highest (2.53) after FW and the lowest after WS (2.33). The changes of soil aggregates stability with Le Bissonnais and Cаввинов method were similar. The fractal dimensions (D), mean weight diameter (MWD) and geometrical mean diameter (GMD) presented the trend of FW < SW < WS, which indicates that the collapse mechanism of soil aggregates was the air pressure dissipation after fast wetting, followed by clay expansion, and the mechanical vibration in rocky desertification area. MWD with Le Bissonnais method was positively correlated with ASI, R0.25, MWD and GMD from Cаввинов method and negatively correlated with PAD and Dwet-dry values. The results indicated that Le Bissonnais method was feasible in measuring soil aggregates stability in rocky desertification area. The soil aggregates stability was positively correlated with the contents of clay and soil organic matter in rocky desertification area (0.586 ≤ R ≤ 0.864), indicating that the soil aggregates stability might be formed by cohesive forces of the soil cementing matters. The cementing matters had strong resistance to the collapse process of soil aggregates caused by soil dissipation and clay expansion, while had no obvious resistance to the collapse process caused by mechanical vibration. Therefore, in ecological restoration and agricultural activities, plant species should be chosen according to the criteria of improving soil organic carbon, soil texture and increasing clay content in short period in rocky desertification area. The results had important roles in conserving cultivated soils in rocky desertification area. 参考文献 相似文献 引证文献

Assessment of sediment yield in a small karst catchment by using 137Cs tracer technique

There is very thin soil layer in karst rocky desertification areas in Southwest China, sediment deposition and sediment yield in the karst area affects the development of vegetation greatly. In the present study, the 137Cs technique was used to assess the rate of sediment deposition and sediment yield in a small karst catchment. The 137Cs inventory within the depression varied between 800 m−2 and 2,200 Bq m−2, with the mean value of 1,500.1 Bq m−2. The 137Cs reference inventory at a nearby reference site was 805.9 Bq m−2. It could be inferred to that sediment deposition had occurred in the catchment. The mean depth of sediments deposition in the depression was 6 cm and the deposition rate was approximately 0.13 cm yr−1. The analysis of the topographic characteristics of the catchment revealed that the sediment deposition occurred mainly at the lower part of the small catchment. Although, there was a sinkhole in the depression, little sediment had drained out with runoff through the sinkhole, because the local people built ridges around the sinkholes for storing water. According to this, sediment yield rate in the small catchment was estimated to be approximately 19.25 to 27.5 t km−2 yr−1, and the extremely low sediment yield was maybe the main obstacle to vegetation restoration in karst rocky desertification areas.

Fractal characteristics and stability of soil aggregates in karst rocky desertification areas

Karst rocky desertification is one of the major ecological and environmental problems that threaten the sustainable development of southwestern China. This study focuses on a case study of the small watershed in Chenqi where karst rocky desertification is particularly severe. This paper considers samples of soils from six different land use patterns in Chenqi village. Various correlations are observed by using fractal theory, including an emerging model for studying soil aggregates. This study demonstrates how the fractal characteristics of soil structure and the stability of soil aggregates are crucial to better understanding karst rocky desertification. The fractal dimension of different land use patterns can be used to indicate the magnitude of soil destruction. Soil fractal dimension can be applied using different methods to characterize the changes in factors influencing the stability of soil structure. The results indicate a significant negative relationship between fractal dimension of soil aggregates and large aggregate content (of diameters 5–10 mm) and a significant positive relationship between fractal dimension and micro-aggregate content (<0.25 mm). The fractal dimension of soil aggregates is also significantly negatively correlated with both clay content and organic matter content. These results suggest that fractal dimension can be used as a reliable indicator of soil quality and presents advantages compared to using mean weight diameter.

Quantitative Prediction of Karst Rocky Desertification Deterioration Based on RS and GIS: A Case Study of Typical Karst Rocky Desertification Area of Du’an County, Guangxi

Taking Du'an County of Guangxi as the study area,using the TM remote sensing images acquired in 1999 and 2009 as the data source,adopting RS and GIS as the technical means and platform,and utilizing the carbonate rock type,land use type,karst landform type,slope of the terrain and population density as the influencing factors,the authors calculated the rocky desertification deterioration index(RDDI) by using the analytical hierarchy process-certainty factor(AHP-CF) method,and then predicted the trend of rocky desertification deterioration quantitatively with RDDI as parameters.The prediction results can provide a scientific basis for making a prospective and specific plan concerning ecological environment protection and recovery and promote the work of rocky desertification prevention and control.

Practaculture Current Situation and its Development Response of Guizhou Rocky Desertification Area

There are two challenges in front of Guizhou rocky desertification area’s development: environment protection and economic development. There are several ways to solve this contradiction, and grassland agriculture is one effective method. Combined with the management situation of rocky desertification, the writer took field survey to the whole province, got knowledge of the grassland source and the main issues in the rocky desertification area. Some scientific responses were raised for exploring or using the limited grassland resource.

Analysis on Changes of Land Use in the Township Based on the Remote Sensing Technology — Choosing Fadou Town of Xichou County as an Example

Choosing Fadou Town of Xichou County in Yunnan province as an example, and supported by the GIP, this paper uses the analysis result of dynamic monitor on the land use for the renewal of land use, thus forming the current situation chart of the land use after renewal. According to the area changes and types, etc. of the land use, this paper then does a qualitative and quantitative study on the project zone, and based on the dynamic changes of the land use and the conversion between its different types, this paper in the end sets up the matrix of the land use types and provides suggestions and measures to restore the ecological benefit in the rocky desertification area in the light of the practical condition of the project zone.

Study on Low-Carbon Community Evaluation Index System in Karst Rocky Desertification Areas under the Perspective of Ecological Civilization

Three typical karst rocky desertification sites in Guizhou including Yachi demonstration site in Bijie, Huajiang demonstration site in Guanling-Zhenfeng and Hongfeng Lake demonstration site in Qingzhen were chosen to research the low-carbon community construction under the perspective of ecological civilization. Many times investigations and discussions were carried out. Conclusions were drawn that: the ecological civilization has special meanings and characteristics featured by strong regionalism and entire systematicness; the key points for the construction of low-carbon community in karst rocky desertification areas includes low carbonization of ecological environment, low carbonization of productivity activities, low carbonization of energy consumption structure, low carbonization of lifestyle and low carbonization of institutional policy; the index system of low-carbon community in karst rocky desertification areas was established including target layer, criterion layer and index layer. Five criteria and 35 indices were figured out for evaluating low-carbon community in karst rocky desertification areas.

Study on the Design and Matching of the Measures for Karst Rocky Desertification Control in Small Catchment Scale

The Renjiang River Catchment in Zunyi City, Guizhou Province of China was selected as the study area to research how to design and match the measures for rocky desertification control and ecosystem restoration. SPOT satellite image (resolution 2.5m), the topographic maps (1:10000), regionalism Map (1:50000), hydrogeological map were used to research under the 3S-Technology (GPS, RS, GIS) and software including ArcView, ArcGIS and Erdas. Many times of field survey and discussions with the local people and government were also carried out. Conclusions were drawn that: the design and match of the measures for the Renjiang River Catchment is scientific and rational; land use conditions, rocky desertification grades, land suitability assessment and prediction of the cultivated land demanded are very important for the design and matching of the measures for the rocky desertification control; a comprehensive idea for each small catchement how to select and design individual measure and how to match the measures together to achieve the best effect of rocky desertification control is also important. Finally, suggestions are given for the karst rocky desertification areas that land use conditions, rocky desertification grades, land suitability assessment and prediction of the cultivated land demanded should be fully considered in the process of designing and matching the measures; the land use should be matched with the rocky desertification and should support the scale of measured designed; measures can be implemented only when these measures do not threat the basic cultivated land demand; the land suitability should also support the area of the measures designed.

Recovery Dynamics of Vegetation and Soil Properties in Karst Rocky Desertification Areas in Guizhou, China

Abstract. Dynamics of vegetation and soil properties responses to vegetation recovery in the selected 72 Karst desertification sites in Guizhou, China were studied. Six typical and representative vegetation types along a chronosequence of vegetation recovery (corn land, sparse grass, regeneration forest, shrub, grass and shrub, and native forest with 0, 3-5, 10-15, 20-30, 30-40, and &gt;100 yrs, respectively) were selected for the study of the plant species, vegetation features as well as soil physical &amp; chemical properties in order to assess interaction between soil properties and vegetation structure. It was found that vegetation species had dry-resistant characteristics because of their extensive exposure to the basement rocks and thinness soil. Grass community was always coarse grass, shrub was generally dominated by vines, thorn bushes and tree species were almost leather-like, single and mini-type leaf plants. Factor analysis showed that the 3 factors, soil fertility, pH and clay, explain 67.97 % of total variance among the 19 soil property parameters. Soil fertility changed significantly effects included the increasing of soil organic matter, total and available nitrogen, humic acid, CEC, fuvic acid, exchange Ca, porosity and total P but decreasing bulk density. This trend was followed by enhancing of bio-enrichment capacity along the chronosequence of vegetation recovering process. Soil pH had no significant correlation with the vegetation recovery stages because it was determined by soil forming process and characteristic of parent materials. The factor clay only decreased slightly in the recovery stages. Cluster analysis indicated that vegetation structure could develop within short time under anthropocentric interfering, but soil fertility only accumulated with annual litter decomposing. We can conclude that recovery of vegetation community structure proceeded restoration of soil function.

Analysis of Ecological Service Value in Vulnerable Karst Area of Southwestern Guizhou

The domestic and foreign evaluations of ecosystem service value are difficult to draw on results accepted by the public and academia. This reflects the research methods are still not mature, need to continue to be improved. In this paper, an attempt has been made to give urban unit value of ecosystem services and set up the values per unit area in southwestern Guizhou of China, in accordance with unit value of global ecosystem services developed by Costanza, et al., Chinese one by Xie, et al. and the actual situation of karst region. The analysis revealed that in the study area, the total ecosystem service value is $1.876×109 in 2006, equivalent to 104.3% of 2006 GDP (Gross Domestic Product), $1.799×109（1US$=7.8136，2006）. If the rocks change into forest in the study area, ecosystem service value will add $0.221×109, equivalent to 12.28% of GDP in 2006. Therefore, we conclude that the ecosystem services value is higher, compared to the local economy. In addition, the rocky desertification area is larger, and has already seriously influenced ecosystem service function. The tasks of ecological environment protection, propaganda and education in this region are of great significance.

REMOTE SENSING ANALYSIS AND PROGNOSIS OF DESERTIFICATION IN DU'AN

This paper has discussed the similarities and differences between remote sensing and remote sensinggeological mapping in the rocky desertification area and drawn a mathematical analytical conclusion that the determination of the rocky desertification area is equivalent to the determination of the area that satisfies the condition D R∈ D C∩ D V . On such a basis, two schemes for extracting information from remote sensing images of rocky desertification are advanced. One is to extract the information of remote sensing images of the rocky desertification directly from brightness (or gray level) of every pixel based on the frequency characteristics of limestone rocks and the heat characteristic parameters, in which the relevant method used is called pixel analysis method or direct recognition method. The other is to extract the whole graphical information of the outcrop distribution area of limestone rocks indirectly through logical correlation operation between image areas D C and D V based on the model of vegetation image frequency and topology, in which the relevant method used is called graphic analysis method or indirect recognition method. The optimum scheme for pseudo-color composition with the Axis of TM6 as the central waveband has been determined through two times of 30×2 tests of pixel analysis method for images in the test area. Through comprehensive interpretation, it is concluded that the expansion of the rocky desertification area in Du'an is related to excessive human activities. This achievement is attributed to the utilization of this scheme to TM image processing in Du'an County in 1991 and 1998.

Characteristic of Rocky Desertification and Comprehensive Improving Model in Karst Peak-Cluster Depression in Guohua,Guangxi,China

Karst rocky desertification is a geo-ecological problem in Southwest China. Preventing and controlling rocky desertification has become critical. So,the Longhe,Pingguo,Guangxi Province in southwestern china, a typical serious rocky desertification area, were selected as the study area. After investigation and researches to the environments and regional economics in detail, the stereo eco-agriculture in different geomorphologic position of the peak -cluster depression has been built and was considered as an available model for the comprehensive improvement to rocky desertification. For about four years, the comprehensive improvement of rocky desertification in the experimental area has achieved good results. The vegetation is gradually restored, the annual mean income of the local people has increased by about 20%, and the new local ecological industry is formed.

Mechanism of cultivation soil degradation in rocky desertification areas under dry/wet cycles

Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement rocks. It leads to drastic decrease in soil productivity and formation of a desert-like landscape. In this regard, changes in climatic conditions are the main origin of the soils degradation. Indeed, soils subjected to successive dry/wet cycling processes caused by climate change develop swelling and shrinkage deformations which can modify their water retention properties, thus inducing the degradation of soil–water capacity. The ecological characteristics of cultivation soils in karst areas, Southwest of China, are extremely easy to be affected by external environmental factors due to its shallow bedding and low vegetation coverage. Based on the analysis of the climate (precipitation) of this region during the past decades, an experimental study has been conducted on a cultivated soil obtained from the typical karst area in southwestern China. Firstly, the soil–water properties have been investigated. The measured soil–water retention curve shows that the air-entry value of the soil is between 50 and 60 kPa, while the residual saturation is about 12%. Based on the experimental results, three identifiable stages of de-saturation have been defined. Secondly, a special apparatus was developed to investigate the volume change behavior of the soil with controlled suction cycles. The vapor equilibrium technique was used for the suction control. The obtained results show that under the effect of dry/wet cycles, (1) the void ratio of the cultivated soil is continuously decreasing, leading to a gradual soil compaction. (2) The permeability decreases, giving rise to a deterioration of water transfer ability as well as a deterioration of soil–water retention capacity. It is then obvious that the long-term dry/wet cycling process caused by the climate change induce a continuously compaction and degradation of the cultivated soil in karst rocky desertification areas.