Desertification In Karst Areas Research Articles

Zoning strategies for ecological restoration in the karst region of Guangdong province, China: a perspective from the “social-ecological system”

Ecological restoration holds great significance in addressing environmental degradation and rock desertification in karst areas. Zoning strategy is a fundamental task in understanding the interrelationship between human-environment to foster sustainable development. We explore “social-ecological” system and conduct a case study on the karst region in Guangdong Province, China. An evaluation framework consists of “development pressure”, “sensitivity status”, and “resilience potential” was established. The results show that: regions with high pressure of development are predominantly located in high-density urban areas. The generally distribution of the comprehensive status index exhibits significant spatial heterogeneity. Regions with low sensitivity are found on the eastern and western sides of the study area. The comprehensive resilience values are largely influenced by per capita energy-saving and environmental protection expenditures. The restoration zones mainly concentrated in the contiguous regions of the northwestern and southern parts, covering more than half of the total area. The conservation zones are more numerous and primarily situated in the northern and eastern parts. By integrating socio-economic and ecological factors, this study proposes ecological restoration strategies for specific zones. It helps for improve development issues arising from complex interactions between human-environment, facilitating the implementation of restoration practices.

Extraction of Rocky Desertification Information in the Karst Area Based on the Red-NIR-SWIR Spectral Feature Space

The complex topography, severe surface fragmentation and landscape heterogeneity of the karst region of southwest China make it extremely difficult to extract information on rocky desertification in the region. In order to overcome the disadvantages of the surface parameter-based feature space approach, which is difficult to construct and apply, this study uses the reflectance of Landsat 8 Operational Land Imager (OLI) in the red (Red), near-infrared (NIR) and shortwave infrared (SWIR) bands as the feature variables, and establishes a two-dimensional SWIR-NIR, Red-NIR and SWIR-Red reflectance spectral feature space. The three models of perpendicular rocky desertification index 1 (PRDI1), perpendicular rocky desertification index 2 (PRDI2) and perpendicular rocky desertification index 3 (PRDI3) were also constructed based on the variation of the degree of rocky desertification in each spectral feature space. The accuracy of the rocky desertification extracted by these three index models was verified and compared with the karst rocky desertification index (KRDI) and rocky desertification difference index (RSDDI), which are constructed based on the surface parameter feature space. The results show that: (1) The waveband reflectance-based feature space model provides a new method for large-scale rocky desertification information extraction, characterized by easy data acquisition, simple index calculation and good stability, and is conducive to the monitoring and quantitative analysis of rocky desertification in karst areas. (2) The overall accuracy and Kappa coefficient of PRDI1 are 0.829 and 0.784, respectively, both higher than other index models, showing the best applicability, accuracy and effectiveness in rocky desertification information extraction. (3) According to the results extracted from PRDI1, the total area of rocky desertification in Huaxi District of Guizhou province is 320.44 km2, with the more serious grades of rocky desertification, such as severe and moderate, mainly distributed in the southwestern, western and southeastern areas of Huaxi District. This study provides important information on the total area and spatial distribution of different degrees of rocky desertification in the study area, and these results can be used to support the local government’s ecological and environmental management decisions. The method proposed in this study is a scientific and necessary complement to the characteristic spatial methods based on different surface parameters, and can provide important methodological support for the rapid and efficient monitoring of karstic rocky desertification over large areas.

LANDSAT multispectral image analysis of bedrock exposure rate in highly heterogeneous karst areas through mixed pixel decomposition considering spectral variability

AbstractMixed pixels and spectral variations commonly occur in images of karst areas because these areas have rugged topography and high surface heterogeneity. Consequently, the bedrock exposure rate cannot be accurately estimated using the existing rock index method based on remote sensing and the fixed endmember mixed pixel decomposition model. In order to solve this problem, using LANDSAT operational land imager/thematic mapper (OLI/TM) images as the data source, this study estimated the bedrock exposure rate based on a generalized linear mixed model (GLMM) considering spectral variability. In addition, this approach was compared with existing commonly used methods for estimating bedrock exposure rate. The results show that: (1) GLMM showed the highest performance in estimating bedrock exposure rate, with a total accuracy of 88.05% and a kappa coefficient of 0.845, and the accuracy exceeded 70% for different levels of bedrock exposure rate. However, the total accuracy of other commonly used bedrock exposure methods is was below 66%, being higher only in areas with bedrock exposure rates less than 20% and more than 70%. (2) By applying each method to different terrain scenes, GLMM was found to be more stable than other methods, and the estimated bedrock exposure rate is the closest to the ground reference value with a root mean square error less than 0.093. Other methods, including fully constrained least squares unmixing (FCLSU) and karst bare‐rock index (KBRI), have a certain gap in different scenes, and their accuracy is not high. (3) Without any ground reference data, the accuracy of the direct unmixing result of GLMM is very close to that calculated by the regression model, and the accuracy difference among different grades of bedrock exposure rate is less than 5%, thus outperforming the other methods. GLMM can effectively estimate the bedrock exposure rate at different times using different data. Therefore, GLMM has great potential in extracting rocky desertification information in karst areas. It can also be a reference method for the rapid, accurate, and long‐term evaluation of rocky desertification in karst areas.

Reconstructing spatial pattern of historical cropland in karst areas of Guizhou, Southwest China

Karst regions are exceptionally responsive to global change with their harsh natural environment, fragile ecology, and acute human-land conflicts. The reconstruction of cropland spatial pattern in karst areas during the historical period is typical for studying human-land relations in karst areas and has important practical significance for climate study. The ecological environment changes at regional and global scales, primarily to provide essential data and a theoretical basis for studying the inverse evolution of rock desertification in karst areas. Guizhou province, a typical karst area, was selected as the research area in 1820. Based on the correction of historical population data and cropland data, a reconstruction model of cropland spatial pattern in karst areas during the historical period was constructed by selecting factors such as elevation, slope, soil types, organic matter content, climatic productivity potential, distance to river and distance from settlements to reconstruct the spatial pattern distribution of cropland in 1820 of Guizhou. The results show that the data on cropland recorded in Guizhou during the Qing dynasty is too low, mainly due to Yin-Ni and the policy of Tu-Di-Mian-Ke. In 1820, the total area of revised cropland in Guizhou was 1,851,792 hm2, with the highest proportion of 14.32% in Dading Fu and the lowest in Songtao Ting at 1.6%. Only 30% of the grid in Guizhou has a cropland distribution. It is mainly concentrated in the central part of Qianzhong District (Anshun and Guiyang Fu), the southern part of Qianbei District (Pingyue Fu and southern Zunyi Fu), the western part of Qiandongnan District, the central and eastern parts of the Qiandongbei District. The overall average reclamation rate of land in Guizhou is 10.93%, the highest reclamation intensity in Qianzhong District, with 8.5% of grids ≥ 50%, and the smallest in Qianxinan District, with only 1.65% of grids ≥ 50%. The analysis is validated by comparing the reconstruction model and the reconstruction results. It can be seen that the reconstruction model and research results of this paper can more objectively reflect the distribution of cropland in karst areas during the historical period, and the reconstruction model is suitable for karst areas with low productivity levels.

Study on the Coupling Relationship between Relocation for Poverty Alleviation and Spatiotemporal Evolution of Rocky Desertification in Karst Areas of Southwest China

The implementation of China’s ex situ poverty alleviation and relocation project has alleviated the further deterioration of the ecological environment in the relocation area. It can create favorable conditions for the management of ecological problems such as the natural restoration of rocky desertification and soil erosion. Panzhou City, Guizhou Province, is one of the key areas for the implementation of ex situ poverty alleviation and relocation projects in the 13th Five-Year Plan for China’s National Economic and Social Development. The typical ecological problem of karst rocky desertification is an important factor hindering the sustainable development of local society, economy, and ecology. Based on the five-phase remote sensing images and relocated population data, the dynamic change rate, transition matrix, and coupling coordination degree model are utilized to analyze the spatiotemporal changes in rocky desertification in Panzhou City. Meanwhile, the cellular automata (CA) Markov model is used to simulate its future scenarios of rocky desertification. The results show that (i) over the past 20 years, the vegetation coverage in Panzhou has generally increased. The implementation of the ex situ poverty alleviation and relocation project has significantly promoted the reduction of the area and degree of rocky desertification. After relocation (2015–2020), the positive improvement rate of rocky desertification accelerated. (ii) After relocation, the potential rocky desertification (PRD), light rocky desertification (LRD), medium rocky desertification (MRD), severe rocky desertification (SRD), and extreme severe rocky desertification (ESRD) showed a trend of transition to the no rocky desertification (NRD). The improvement effect of rocky desertification is remarkable, and the main contribution is from the PRD and LRD. (iii) The greater the relocation intensity is, the more obvious the improvement effect of the rocky desertification area is, and the higher the corresponding coupling coordination level is. The coupling coordination between LRD and relocation intensity is the highest. (iiii) The forecast results show that by 2025 and 2035, rocky desertification in Panzhou will continue to improve.

Dynamics of landscape ecological quality based on benefit evaluation coupled with the rocky desertification control in South China Karst

Human uncontrolled land use is the main cause of ecosystem degradation and increased rock desertification in karst areas of Southern China. Landscape ecological quality assessment (LEQA) based on land use plays a significant role in promoting sustainable ecological restoration in karst rocky desertification areas. This paper selects the karst plateau canyon rocky desertification comprehensive control demonstration area in South China as the research object to accurately quantify the impact of ecological management on landscape ecological quality changes (LEQ). Based on the characteristics of the karst ecological environment, the basic theory of spatial heterogeneity and landscape pattern is applied to evaluate the ecological quality of the study area at three levels: landscape stability, landscape disturbance degree, and ecological restoration and reconstruction ability. The results showed that the comprehensive score of regional ecological quality increased from 0.539 to 0.662 from 2015-2020. However, the ecological quality level of unused land and mining areas was still poor, and unsound production activities such as ore mining were the main hindrances to improvements in landscape ecological quality. Areas of better ecological quality were mainly distributed to the north and south of the study area. Treatment measures such as returning farmland to forest and agroforestry effectively improved the ecological environment quality of these areas, but the ecological benefits brought by the treatment in different areas varied significantly. The current analysis results show that the land use-based landscape ecological quality evaluation method is applicable in karst areas with special ecological environments. This work provides a new quantitative research method for the unique ecological environment in karst areas; it can accurately identify trends in ecological environment quality changes and provide a basis for sustainable ecological restoration.

A Study Revelation on Market and Value-Realization of Ecological Product to the Control of Rocky Desertification in South China Karst

The restoration of the ecological environment in rocky desertification areas and economic development go hand in hand. With the support of the national policies from the “Ninth Five-Year Plan” to the “Thirteenth Five-Year Plan”, the related ecological industries and products derived from the control of rocky desertification in karst areas continue to emerge. It not only restrains and repairs the development of rocky desertification but also produces a higher regional economic value than the replaced industry, which has practical significance for targeted poverty alleviation and rural revitalization in rocky desertification areas. The thesis classifies and summarizes the development status of ecological products from the perspectives of the basic theory of ecological products, industrial model construction, industrial demonstration, quality monitoring and evaluation, product sales space, product value realization and improvement research and proposes some scientific problems to be solved. The dual attributes of ecology and economy of ecological products are integrated, and a sustainable industrial model and industrial value-added enlightenment for consolidating the achievements of rocky desertification control is proposed.

Factors influencing the evolution of human‐driven rocky desertification in karst areas

AbstractKarst rocky desertification has become one of the most important e‐environmental problems in China. The mechanisms of rocky desertification caused by land resources use, settlement expansion, population growth, and corresponding ecological responses are unclear. High‐resolution images of a typical karst plateau (Houzhai River Basin) acquired in 1978, 2005, and 2010 and data samples collected in the field in 2015 were used to quantitatively study the factors governing the evolution of rocky desertification driven by human activities. They comprehensively reveal its causes and influencing factors. Results suggest that the rocky desertification in the eastern and southern parts was, generally, more severe than in the western and northern parts of the study region. In the period from 1978 to 2015, no significant changes in the degree of (moderate) rocky desertification were observed. However, decreasing trends were observed for the no‐rocky areas, and slight decrease in rocky areas. The comprehensive indices of rocky desertification in 1978, 2005, 2010, and 2015 were 1.33, 1.24, 1.22, and 1.24, respectively. The rock outcrops in the no‐rocky desertification and potential rocky desertification areas were closely associated with the gravel content, slope gradient, and soil thickness, whereas those in the slight, moderate, and severe rocky desertification areas were primarily associated with the land use, gravel content, and slope gradient. The results suggest that the land use and human settlement were important factors determining the rocky desertification. The rocky desertification in the study area has improved during the period from 1978 to 2015. The main contribution to this improvement originated from the change in land use patterns. Therefore, reasonable management of land use and human settlement distribution can effectively reduce the rocky desertification in a karst area.

Using depression deposits to reconstruct human impact on sediment yields from a small karst catchment over the past 600 years

Assessment of long-term human impact on sediment yields from karst settings can improve our understanding of the pattern of soil erosion causing rocky desertification in the historical context of environmental change influenced by human activity. Few previous investigations have estimated this impact over time-scales longer than 50 years. This study used dated depression deposits to reconstruct human impact on sediment yields from a small karst catchment in the Three Gorges Reservoir Region, China, over the past 600 years. 137Cs, 210Pbex, and 14C techniques were used to determine short-term (~50 yr), medium-term (~100 yr), and long-term (~600 yr) sedimentation in the karst depression, respectively. Sedimentation rates and specific sediment yields in the catchment during six distinct stages (1351–1462, 1463–1701, 1702–1809, 1810–1916, 1917–1962, and 1963–2017) were determined from core samples. The results indicate that soil loss during the period 1351–1962 was more intensive than that since 1963, which reveals changing sediment yields impacted by human activity over the past 600 years. The high values during the three stages before 1810 can be attributed to the impacts of large-scale migration of people from Huguang to Sichuan during the Ming and Qing dynasties; the higher values during 1810–1916 might reflect increasing disturbance related to rapid population expansion; the highest values (1917–1962) were caused by large-scale deforestation in 1958 and a consistently increasing population; and low values since 1963 reflect constraints on the supply of sediment source materials. These results suggest that rocky desertification might be a long-term land-surface process induced by human activity over timescales of >100 years rather than a short-term modern process occurring over a number of decades. This is the first attempt to examine the long-term history of human impact on sediment yields from a karst catchment using depression deposits. This work improves our understanding of the influence of human activities on soil loss at a depression-catchment scale, and of the evolution and dynamics of rocky desertification in karst areas.

Research Progress on Soil and Water Loss and Soil and Water Conservation in Karst Areas

Based on the research of soil erosion and soil and water conservation in karst areas in China in recent years, the status and progress of soil erosion and soil and water conservation in karst areas in China are discussed. The results show that the soil and water loss in the karst area mainly has two types of soil erosion: surface soil erosion and underground soil erosion. Soil and water loss management in karst areas mainly adopts measures to adjust land use structure, increase vegetation coverage, carry out slope-to-ladder construction, and promote clean energy applications. Different governance models should be adopted for different landform types, different landform parts, different slopes, and different levels of rocky desertification in karst areas.

贵州省后寨河小流域地形因子、人为干扰与石漠化定量研究

PDF HTML阅读 XML下载 导出引用 引用提醒 贵州省后寨河小流域地形因子、人为干扰与石漠化定量研究 DOI: 10.5846/stxb201809111955 作者: 作者单位: 贵州大学贵州省森林资源与环境研究中心/林学院,贵州大学贵州省森林资源与环境研究中心/林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重大科学研究计划项目（2013CB956702）；贵州省一流学科建设项目（GNYL[2017]007）；贵州省“百层次”培养计划（QKHRC-2015-4022） Quantitative relationships among topography anthropogenic disturbance, and rocky desertification in the Houzhai River Basin, Guizhou Province, China Author: Affiliation: Guizhou University, Institute for Forest Resources ＆ Environment of Guizhou/ College of Forestry,Guizhou University, Institute for Forest Resources ＆ Environment of Guizhou/ College of Forestry 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:为定量研究喀斯特区域地形因子、人为干扰和石漠化之间的关系。基于网格法和实地观测，建立后寨河流域石漠化信息数据库并分析。结果表明：后寨河流域石漠化面积为14.43 km2，不同利用类型石漠化面积呈以下规律：荒地 > 坡耕地 > 乔木林地 > 耕地 > 灌木林地 > 灌草地 > 草地 > 弃耕地 > 园地 > 乔灌木林地 > 水田 > 经果林地；流域内岩石裸露率和土壤厚度主要受到坡度、坡位和人为干扰的制约，而人为干扰具有主观性，主要在岩石裸露率低、土壤较厚和坡度较缓的区域进行农业生产活动。荒地和弃耕地占据了石漠化面积的32.64％，且存在较大潜在石漠化的风险。回归模型发现人为干扰程度对岩石裸露率（负效应-0.286）和土壤厚度（正效应0.264）的直接效应最大，坡向对岩石裸露率（正效应0.067）和土壤厚度（负效应-0.054）的直接效应最小。认清地形因子、人为干扰和石漠化之间的耦合关系有利于喀斯特小流域石漠化治理。 Abstract:The relationship among topographic factors, human disturbance, and rocky desertification in karst areas was quantitatively assessed. A rocky desertification information database was established for the Houzhai River Basin and analyzed using grid-sampling and field observation. Rocky desertification affected a total of 14.43 km2, and affected multiple land use types, including uncultivated lands, sloping croplands, arbor forestlands, arable land, shrub lands, shrub grass-lands, grasslands, abandoned lands, garden lands, arbor-shrub mixed forestlands, paddy lands, and artificial fruit forestlands. The rock exposure rate and soil thickness were mainly restricted by slope gradient, slope position, and human disturbance. Otherwise, human disturbance is subjective, mainly in areas with low rock exposure, thick soil, and gentle slope gradient. Uncultivated lands and abandoned lands accounted for 32.64% of the rocky desertification area, and there was a greater risk rocky desertification under these types of land use. A regression model revealed that the degree of human disturbance directly affects both rock exposure rate (negative effect:-0.286) and soil thickness (positive effect:0.264). However, only insignificant effects were observed for slope direction on either rock bareness (positive effect:0.067) or soil thickness (negative effect:-0.054). According to these findings, rocky desertification in karst mountainous basin can be easily remedied by, understanding its relationships with topography and human disturbance. 参考文献 相似文献 引证文献

不同岩性背景下土壤侵蚀与石漠化关联性分析

PDF HTML阅读 XML下载 导出引用 引用提醒 不同岩性背景下土壤侵蚀与石漠化关联性分析 DOI: 10.5846/stxb201807251583 作者: 作者单位: 贵州师范大学、中国科学院地球化学研究所、,中国科学院地球化学研究所、贵州师范大学,贵州师范大学,贵州师范大学 中国科学院地球化学研究所,贵州师范大学 中国科学院地球化学研究所,中国科学院地球化学研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划（2016YFC0502102）；中国科学院科技服务网络计划（KFJ-STS-ZDTP-036）；"西部之光"人才培养计划（A类）（〔2018〕X）；贵州省科技计划（2017-2966） Effect of lithology background on the correlation between soil erosion and rock desertification Author: Affiliation: Guizhou Normal Universiy、nstitute of Geochemistry, Chinese Academy of Sciences,,,,, Fund Project: This research work was supported jointly by national key research program of China (No. 2016YFC0502102 & 2016YFC0502300), 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:喀斯特地区土壤侵蚀与石漠化问题备受关注，为了定量分析不同岩性下土壤侵蚀与石漠化的关联性，为研究区优化生态环境提供决策依据，以贵州省沿河县为例，以Landsat遥感影像、1：5000地形图、岩性和石漠化为基础数据，采用监督分类方法、表面分析和栅格计算，提取出土壤侵蚀的各项指标因子。对不同岩性背景下土壤侵蚀与石漠化关联性分析，结果显示：（1）沿河县石漠化面积为284.44 km2，占全县国土面积的11.52%。已发生石漠化等级以轻度、中度、强度较显著；土壤侵蚀面积为1838.97 km2，占全县总面积的74.48%，已经发生土壤侵蚀等级以轻度、中度、强度侵蚀为主。（2）灰岩与碎屑岩互层和连续性白云中，石漠化与土壤侵蚀发生面积较显著，分别占石漠化与土壤侵蚀面积的57.99%和50.45%。（3）非碳酸盐岩、灰岩夹碎屑岩、灰岩与白云岩混合、灰岩与碎屑岩互层、连续性白云岩和石灰岩上，石漠化等级与土壤侵蚀程度在潜在和轻度呈负相关、轻度和中度石漠化内呈正相关、中度和极重度石漠化内呈负相关，土壤侵蚀等级与石漠化在微度和轻度侵蚀内呈正相关，在轻度和剧烈侵蚀内呈负相关，其中灰岩与白云岩混合和连续性白云岩上，石漠化等级与土壤侵蚀存在单一的负相关。 Abstract:The occurrence of both soil erosion and rocky desertification in karst areas of China have attracted much attention. In order to quantify the correlation between soil erosion and rocky desertification under different lithologies and to establish a basis for optimizing the area's ecosystem, the present study investigated the correlation between soil erosion and rocky desertification in Yanhe County (Guizhou Province, China) using Landsat remote-sensing data, a 1:5000 topographic map, and both lithology and rocky desertification data. Supervised classification, surface analysis, and grid calculation were used to extract a variety of soil erosion indices. (1) Rocky desertification affected 284.44 km2 of Yanhe County, thereby accounting for 11.52% of the county's total land area, and the grade of rocky desertification was mild, moderate, and strong. Meanwhile, soil erosion affected 1838.97 km2, thereby accounting for 74.48% of the county's total land area, and the grade of soil erosion was mostly mild, moderate, and intense. (2) Both rocky desertification and soil erosion were predominant in the interbedded and continuous limestone and clastic rock, with 57.99% and 50.45% of the rocky desertification and soil erosion found in this area, respectively.(3) Non-carbonate rocks, limestone clastic rocks, limestone and dolomite mixtures, limestone and clastic interbeds, continuous dolomite and limestone, rocky desertification grade, and degree of soil erosion were all negatively correlated with mild, positively correlated with Light and moderate rocky desertification, and negatively correlated with moderate and extremely severe rocky desertification. Soil erosion grade was positively correlated with rocky desertification in Potential and Light erosion. There was a negative correlation between Light and severe erosion. Among the limestone and dolomite mixtures and continuous dolomite, rocky desertification grade was negatively correlated with the degree of soil erosion. 参考文献 相似文献 引证文献

Study on comprehensive planning of rocky desertification in karst area of Chongqing

Chongqing is a key area for comprehensive treatment of rocky desertification in karst areas of china. Strengthening the comprehensive management of karst rocky desertification area, for the maintenance of ecological safety of Three Gorges Reservoir area, expanding the karst rocky desertification area people survival and development space, and improving the regional ecological conditions, have important practical significance to the construction of ecological civilization and building a harmonious society. Based on the investigation, analysis and arrangement of the data in the rocky desertification area, the paper puts forward the corresponding measures and phased targets for the treatment of the Rocky Desertification in the karst areas of Chongqing.

Integrated emergy and economic evaluation of three typical rocky desertification control modes in karst areas of Guizhou Province, China

Guizhou Province of China is a key karst area and is facing serious rocky desertification. Controlling the rocky desertification in karst areas in Guizhou has been formally established as a national goal. After decades of experience, some control modes are now recognized for their ability to reduce desertification and to provide income for the local community. However, a unified, integrated ecological and economic evaluation of these modes is lacking. The current study evaluated three modes (planting systems) and compared these modes with the planting of corn (CP), a traditional crop in this region. The three typical modes were pepper planting (PP), pitaya cultivation (PC), and honeysuckle-plum inter-planting (HPIP). Furthermore, the ecological and economic effects of adding livestock and biogas subsystems to the PP mode were quantified. The results showed that the PP mode provided the highest ecological-economic benefits, while the HPIP mode provided the highest ecological benefits. The addition of the livestock subsystem to the PP mode could improve the economic benefit density of the system with a tradeoff of environmental loading, while the addition of the biogas subsystem could partially correct for this. We suggest that local governments to strength the technology support for these modes in order to expand the production chains; this will include the development of processing facilities for livestock, biogas, and crops. Local governments should also help farmers maintain markets, create new markets (by branding the products, for example), and establish a short-term labor supply for crop harvesting.

Effects of Underground Pore Fissures on Soil Erosion and Sediment Yield on Karst Slopes

AbstractUnderground pore fissure is one of common ways of soil leakage, and the soil loss in underground pore fissure would aggravate the development of rocky desertification in karst areas. A designed steel tank with varied underground pore fissure degrees was used to measure how underground pore fissure affected soil erosion and sediment yield on karst bare slope. We found that sediment yield rates and its distribution ratios obviously differed between the surface and underground. Surface sediment yield rate greatly responded to rainfall intensity conditions, while underground sediment yield rate rarely changed. Both bed rock bareness and underground pore fissure degree had an insignificant effect on both surface and underground sediment yield rate, but the former greatly influenced sediment distribution between the surface and underground. With increasing of bed rock bareness rate, both the average surface and underground sediment yield rates first increased and then decreased. The later posed an effect on underground sediment yield rate, which increased with increase of underground pore fissure degree. With increase of underground pore fissure degree, critical rainfall intensity for producing surface sediment would increase from 0.8–1.3 mm min−1 to 1.3–2.0 mm min−1. The results provide a mechanistic understanding of how underground pore fissure affects soil erosion and sediment production. Copyright © 2017 John Wiley & Sons, Ltd.

Modeling of soil loss and its impact factors in the Guijiang Karst River Basin in Southern China

The Guijiang Karst River Basin (GKRB) is a typical karst river basin in southern China and one of the major tributaries to the Xijiang River in the Pearl River Basin. A portion of the main stem in the upper reach of GKRB is called the Li River known for its most scenic karst landforms in the world. Soil erosion has resulted in rocky desertification in karst areas of the basin. Excessive sediment load in rivers would affect tourism navigation in the Li River and the aquatic systems in the basin. This study employed the Revised Universal Soil Loss Equation Version 2(RUSLE2) model to estimate soil loss and to evaluate the impact factors for the spatial and temporal variation of soil erosion in the basin. The GKRB RUSLE2 model was calibrated with sediment yields from nine gaging stations with the Nash–Sutcliffe efficiency coefficient (NSE) as high as 0.69. This study showed that soil erosion occurred on 54.9 % of the land areas that are primarily forest and cropland and in low hills with elevations ranging from 30 to 600 m. It also showed that the soil erosion rate is higher in areas where the degree of rocky desertification is more severe, indicating area with high soil erosion intensity often has high risk of rocky desertification. Impacted by monsoons, soil erosion in the study basin showed clear seasonal variation. The second quarter of the year had highest erosion rate, mostly due to the intensive late spring and early summer rainstorms. This study has shown that the RUSLE2 model can be used for karst river basin with reasonable accuracy. Findings from this study may help in identifying locations for flow and sediment control structures to reduce the risk of soil erosion and subsequently rocky desertification.

Spatial Distribution Patterns and the Evolution Process of Carbon Storage in a Typical Karst Canyon Area

Qinglong County in Guizhou, China is a typical karst canyon area. Using quadrat methods and a land use transfer matrix we studied the carbon storage spatial distribution pattern and evolution process over three independent periods (1988, 1999 and 2009) in this area. Based on the results we estimated the carbon pool capacity of the entire karst canyon area in Guizhou and contribution ratios. Carbon storage and average carbon density of the karst area in Qinglong decreased at first, and then increased over the sampling period. The actual carbon storage of the karst canyon area in Guizhou was estimated to be 42.55 Tg. The average carbon intensity of the karst canyon area in Guizhou is far higher than that of national terrestrial ecosystems, especially in vegetation areas. Through cross comparison, we found that karst canyon areas have great carbon sequestration potential and we suggest that it is necessary to control and prevent rocky desertification in karst areas in China.

The role of policies in land use/cover change since the 1970s in ecologically fragile karst areas of Southwest China: A case study on the Maotiaohe watershed

Study of land use/cover change and its driving forces is one of the most significant fields in global environmental change research. Karst land is a type of important and unique terrain on the Earth's surface because of its extensive distribution, impressive landforms, and high ecological fragility. Recently, more and more researchers have realized that irrational land use practices are leading to a series of alarming environmental issues including rocky desertification in karst areas. Studies on land use/cover change and its driving forces in karst areas are significant in achieving regional ecological construction and sustainable development. Policy has long been considered as one of the major driving forces at national level for land use/cover change. In mainland China, designated and in-depth study on the interaction between land use/cover change and relevant policies is still very limited. Through an integrated technique of geographic information system (GIS), remote sensing (RS), and global positioning system (GPS), the authors attempted to address this issue by using the Maotiaohe watershed in Guizhou province in southwestern China as a case to examine its land use/cover change patterns, and the roles of policies in land use, agriculture, forestry, and eco-environmental protection from 1973 to 2007. The study indicated that land policies contributed largely to the increase of arable land in the 1980s, and helped prevent it from decreasing at the fringe of cities and towns since the 1990s; agricultural policies played active roles in the change of water area and indirectly contributed to the change of construction land. The forestry and eco-environmental policies were found to be the main reasons for the consistent increase of forest land since the 1980s and for the decrease of arable land and rocky desertification land since the 1990s.

Rocky desertification and its causes in karst areas: a case study in Yongshun County, Hunan Province, China

Rocky desertification, a process of land degradation characterized by soil erosion and bedrock exposure, is one of the most serious land degradation problems in karst areas, and is regarded as an obstacle to local sustainable development. It is well known that human activities can accelerate rocky desertification; however, the effects of climate change on rocky desertification in karst areas are still unclear. This study focused on the effects of temperature and precipitation changes and human activities on rocky desertification in karst areas to determine the impacts of climate change and human disturbances on rocky desertification. Areas of different level of rocky desertification were obtained from Landsat TM (1987) and Landsat ETM+ (2000) images. The results show that, although the total desertification area increased by only 1.27% between 1987 and 2000, 17.73% of the slightly desertified land had degraded to a moderate or intense level, 2.01 and 15.71%, respectively. Meanwhile, between 1987 and 2000, the air temperature increased by 0.7°C, and precipitation increased by 170 mm. Statistical results indicate that the increase in precipitation was caused by heavy rainfall. In addition, under the interactive influences of heavy rainfall and temperature, the average karst dissolution rate was about 87 m3 km−2 a−1 during the 14 years in the study area. Further analysis indicated that rocky desertification was positively related with the increase in temperature and precipitation and especially with the heavy rainfall events. Climate change accelerated rocky desertification in the karst areas.

Assessment of karst rocky desertification using the radial basis function network model and GIS technique: a case study of Guizhou Province, China

Karst rocky desertification in karst areas of Southwest China is an obstacle for the sustainable development of the locality. While many researchers have studied this issue, this study quantified the various indicators affecting desertification, using GIS technology to extract spatial data and to construct a RBFN (radial basis function network) model for Guizhou province. By calibrating sample data of the different levels of karst rocky desertification, the model parameters were established, and then the assessment of karst rocky desertification. Results show that in counties of Southwestern Guizhou Province karst rocky desertification is severe, counties in northern Guizhou have moderate desertification, and southeastern counties are affected lightly. Comparison of the results with other research shows conformity with actual conditions, proving the reasonability and applicability of the RBFN model.