The Impact of Urban Expansion on Plant Diversity Change in Karst Regions of Southwest China

Biodiversity is vital for the integrity and stability of ecosystems and sustainable development.Karst regions of Southwest China is featured for undulating and broken karst terrain as well as high plant diversity.Land use changes induced by the growing population and expanding human settlement have threatened biodiversity preservation in this region.However,the impact of urban expansion on plant diversity remains unclear here.This study focuses on how expanding countryside landscapes affect the recovery rate of plant diversity and demonstrate how urban expansion affects plant diversity conservation in karst regions of Southwest China.In situ biodiversity investigations and multisource remote sensing images were combined to analyze the role of human settlement evolution in the conservation of plant diversity using descriptive statistics and regression analysis.Unmanned vehicle images,historical aerial photographs,and long-term remote sensing images were used to observe the human settlement pattern changes over 40 yr and found that plant diversity is restored faster in countryside ecosystems than in island ecosystems restricted by water.Forests,however,contribute the most to plant diversity conservation in both ecosystems.While the forest area is stable during urban expansion,massive forest patches play an essential role in plant diversity conservation.Arable lands and grasslands shrank but with a fragmenting trend,which was conducive to preserving plant diversity,whereas increased and regularized large patches of built-up areas were not beneficial to plant diversity.Accordingly,forest protection should be prioritized to coordinate future socioeconomic development and plant diversity conservation in karst and broader regions.Furthermore,large built-up patches should be limited,and the irregularity should be improved during urban expansion.Irregular shaped cultivated land and grassland were suggested to promote biological information exchanges as landscape corridors.

Landscape structures of different rural landscape connectivity in typical plateau karst regions: Taking the Houzhai River area of Anshun City, Guizhou Province as an example

Landscape connectivity is important for energy and material flow in ecosystems as well as for the survival of species. The landscape structure influences and reflects the degree of landscape connectivity. In order to study the coupling relationship between landscape structure and connectivity and reveal the succession relationship between its structure and connectivity in the typical karst plateau area. The study analyzed the typical area of Houzhai River in Puding County, Anshun City, Guizhou Province, according to the landscape pattern index and probability landscape connectivity index. The results show:(1) The landscape structure of the study area A is mainly characterized by large patches and uniform distribution. The main land is woodland and cultivated land, and the overall landscape is low fragmentation.(2) The landscape structure of the study area B is mainly characterized by the clustering of a certain type of land cover and the uneven distribution of the patches, for example, cultivated land. Other types of patches are scatteredly distributed, and the overall landscape is highly fragmented.(3) The study area A, B in 100, 500, 1000, 2000, 3000, 5 distance thresholds of landscape connectivity were 1.55, 1.99, 2.26, 2.49, 2.58 and 0.02, 0.10, 0.15, 0.19, 0.20, respectively. The average landscape connectivity is 2. 18 and 0. 13, respectively. Study Area A has a higher degree of landscape connectivity than B. Landscape pattern indicators can represent the landscape structure and probability landscape connectivity index calculates the landscape connectivity in the study area. The results of the study can provide a basis for ecological restoration of plateau karst regions and well-oriented rural development planning.

The comprehensive evaluation of sustainabledevelopment in karst regions-Taking Shishanareas in Guangxi of China as an example

This paper works out a practical evaluation method of sustainable development for theundeveloped the regions and take Shishan areas of Guangxi Zhuang Autonomous Region of Chinaas an example. First of all, according to the actual conditions of the karst regions in Guangxi and thetheory of regional sustainable development this paper estabishes an index system of comprehensiveevaluation, then takes twenty-eight representative cities and counties within the karst regions ofGuangxi as research objects to evaluate the level of sustainable development. It basically illustratesthe state of regional sustainable development of the karst regions in Guangxi.

Aging Characteristics and Influencing Factors of the Sheds of Composite Insulators in Karst Regions of China

In recent years,more and more high-voltage overhead transmission lines were built passing through the karst regions in southwestern China.This type of special landform seems to have an adverse effect on the aging of the sheds of the line suspension composite insulators,which may lead to unexpected flashover and line tripping.In order to find out the particularity of the aging characteristics of insulators operating in the karst regions,samples in operation were selected from both the karst regions and the flatlands.Hydrophobicity,amount of surface contamination,and contaminant composition of the sheds were studied,then a comparison of performance between the two was made,and the possible influencing factors that cause such differences were discussed.The results show that the overall aging of the sheds of the composite insulators operating at the karst regions is more aggravated,which is caused by the combined influence of factors including the special topography,climate,and pollution in the area.The strong wind crossing the col will bring about the mutual scraping on the edges and stress concentration at the root of the sheds,leaving scratches and root cracks;the infiltration from these rupture of acid liquid,if any,will accelerate the aging and corroding of the internal silicone rubber material;moreover,the carbonates enriched on the surface of the sheds will gradually transform into more corrosive sulfates in an acidic environment,leading to further deterioration and chalking of the sheds of the insulators.The research work in this paper can provide guidance for the current operation and maintenance of composite insulators in the karst areas,as well as having important reference values for the layout design and insulation configuration of transmission lines to be built across karst landforms in the future.

Genotype-Specific Microsatellite (SSR) Markers for the Sugarcane Germplasm from the Karst Region of Guizhou, China

Genetic variability among sugarcane genotypes from the Karst region of China was evaluated using genotype-specific microsatellite (SSR) markers. Eighteen sugarcane genotypes including 13 active cultivars and five elite QT-series clones bred locally were screened for genetic variability with 21 SSR primer pairs. All the primer pairs were highly polymorphic and amplified a total of 167 alleles with an average of eight alleles per primer pair. The average polymorphism information content (PIC) value was 0.86 with a range of 0.68 and 0.92. A UPGMA dendrogram categorized the 18 sugarcane genotypes into three major groups containing three, ten and five genotypes, respectively. No geographical affinity was observed among genotypes within the same group. Eight SSR primer pairs produced cultivar-specific alleles, of which five alleles were unique to the QT-series clones, namely, SMC334BS-165 and SMC851MS-145 in QT 08-558, mSSCIR43-229 in QT 4, SM597CS-182 in QT 08-536 and SMC7CUQ-168 in QT 06-212. The clone-specific SSR alleles will be useful in identifying elite QT-series clones for use in the sugarcane crossing programs in China.

Study of soil and water conservation Function on Slope with Different Planting Patterns for a Typical Small Watershed in Karst Region of Guizhou Province

Ten runoff plots with different planting patterns were established for experimental observation in Yangjichong small watershed of Longli County in Karst region of Guizhou Province. Results show that under the same rainfall condition, shrub land, natural grassland and abandoned land presented the best function of soil and water conservation. The function of soil and water conservation was poor for arbor planting pattern, because the shrub layer, herb layer and forest floor were not formed. Because of no-tillage, surface crust and other effects, the function of soil and water conservation in slope farmland was better than that in runoffplots with arbor planting pattern.

Nitrous oxide emissions from different land use patterns in a typical karst region, Southwest China

Fluxes of nitrous oxide (N2O) from different land use patterns (matured forest, secondary forest, grassland and cropland) in a subtropical karst region of Guizhou Province, Southwest China, were measured for one year with a closed static chamber technique and by gas chromatography. The results showed that soil under different land uses was a source of atmospheric N2O. The cropland was a source with relatively high N2O as compared to forest and grassland, but no significant differences were observed. N2O emissions from soils varied with land use change and fertilizer application. There were two peaks of N2O flux occurred following the combination of two obvious precipitation and fertilizer events in the cultivated land. Converting from the matured forest to secondary forest tended to increase annual emissions of N2O (from 1.40 to 1.65 kg N ha -1 a -1 ), while changing land use from secondary forest to scattered grassland tended to decrease annual emissions of N2O slightly (from 1.65 to 1.45 kg N ha -1 a -1 ). Our range of cumulative annual N2O emission across different land uses (1.40-1.91 kg N ha -1 a -1 ) in a karst region is in general agreement with previously published data in a non-karst region. However, in the maize field, N2O emission factor (EF) was 0.34% for fertilizer application, which is about 71.2% lower than the IPCC default value. It is suggested that current IPCC (Intergovernmental Panel on Climate Change) EF methodology could overestimate N2O emission from the karstic cropland. Anyway, the N2O emission from cropland in the karst region would contribute significantly to the global N2O budget, so reducing fertilization frequency during the crop growing season could lead to a decrease in N2O emission in the whole year.

Soil Ecosystem Degradation of Karst Regions in Southwestern China

Deeply influenced by karst geological environment, the structure of the soil ecosystem in the southwest karst area of China is characterized by strong vertical variation and space variation, structural feature of nonrenewable soil, and functional feature of poor circulation of nutrient elements and limited vegetation growth. On the basis of analyzing vulnerability in structure and function of soil ecosystem in China's southwestern karst regions, we discussed the degradation process and mechanism of soil structure, nutrient, water and microorganism in the course of soil erosion from the perspective of material and energy cycle. Finally, we put forward some recommendations for recovery of degraded soil, transformation and rational utilization of soil.

Evaluation of the Land Production Potential in the Context of Returning Farmland to Forest in Karst Region:A Case Study of Guizhou Province

In this paper, we take Guizhou Province (the heart of southwestern Karst region in China) as the research object. By establishing gray forecasting model and time series forecasting model, we conduct the accuracy test on the actual production capacity of land and the forecasted production capacity of land in 2007 and 2008, and then conduct comprehensive forecast of the land production potential in Guizhou Province in 2020. On this basis, considering the nutritional standards needed by three kinds of life type (dressing warmly and eating one's fill, well-off life, relatively affluent life), we evaluate the land production potential in Guizhou Province under the project of returning farmland to forest. Based on the evaluation results, we put forth the relevant recommendations for achieving sustainable land use in the context of returning farmland to forest in Guizhou Province.

Variability of Aquatic Chemistry in CentralGuizhou Karst Region,China

It is necessary to understand the aquatic chemical characteristics of natural surfacefresh water for water quality assessment. The chemical data from different kinds of water inthe central Guizhou karst area showed that spring water from carbonate rock cracks (crack-water) is of neutrality or meta-alkalinity and [C] Ca Ⅱ type. The amounts of all ions and theconcentrations of HCO3 and Ca2+ were higher in the autumn than in the spring. the crack-water was influenced by the infiltration of surface water in the process of erosion and/or transportation with decreasing HCO3- and increasing PH, SO, Cl, K+ and Na+ during runningin a certain distance on the land suffice. In particular, the chemical compeitions of the watersat Tianxingqiao (upper-stream), Shuiliandong (mid-waterfall) and Luoshuitan (down-pool)near the Huangguoshu Waterfall were much different from those of the crack-water. The concentrations of , Na+, Fe3+ and NO3- varied closely with seasons. The CaCO3 depositedviolently with CO2 release in the spring. In Lake Hongfeng the HCO3- /So- equivalent ratioswere only 2. 1 - 2. 4, but Ca2 + /Md+ up tO 2. 4 - 4. 2. The CI- concentration increased by afactor Of 1 and Na+ by order of magnitude relative to the spring water. These indicated the in-crease in artificial pollutant discharge in the Lake Hongfeng watershed. In addition, porewater in the soils coveing carbonate rocks belongs to strongly mineralized water. The obvious differences in water quality were controlled by carbonate despition, sulphate mineralization and nitrogen fixation as well as ammonification. It is indicated that the chemical compeitions in thewaters from the karst region were unstable and changeable.

Comprehensive Management Measures for Chicken Rearing in Tea Gardens in Karst Region

In karst region,industrial development is closely related to rocky desertification control. Using abundant natural resources in karst areas to develop chicken rearing in tea gardens can not only make full use of natural resources and alleviate the contradiction between development and governance in rocky desertification areas but also produce good quality chicken. In this paper,the comprehensive management measures related to chicken farming in tea gardens in karst region were elaborated,in order to provided certain guiding significance for practical production.

Performance of a deep excavation and the influence on adjacent piles:A case history in karst region covered by clay and sand

This paper presents a case study of deep excavation adjacent to an existing bridge in karst region of Guangzhou city,China.The movements of retaining structures,settlements of surrounding ground and pipelines,and the responses of bridge piles were measured and evaluated.A sudden surge of groundwater was recorded at the north pit when excavated halfway.Soil-cement columns using the Metro Jet System(MJS)method was employed along the outer perimeters of the diaphragm wall where water inflow occurred,for the sake of blocking the flow channels.The measured maximum wall deflection dhm in this case ranged from 0.13%H to 0.3%H,with a mean value of 0.2%H(H is the excavation depth),which agreed well with the empirical prediction in mixed ground.During the MJS treatment,the wall and surrounding soils experienced notable lateral deflection and settlement.The bridge piles experienced significant settlement since the excavation commenced,which might be attributed to the inherent deficiency in geological condition and pile length.The soil disturbance induced by the adjacent deep excavation accelerated bridge settlement.The finite element analysis revealed that the excessive settlement of the bridge piles and ground surface resulted from confined-water withdrawal in sand layers.

Groundwater quality and land use change in a typical karst agricultural region:a case study of Xiaojiang watershed,Yunnan

Taking the typical karst agricultural region, Xiaojiang watershed in Luxi of Yurman Province as a research unit, utilizing the groundwater quality data in 1982 and 2004, the aerial photos in 1982 and TM images in 2004, supported by the GIS, we probe into the law and the reason of its space-time change of the groundwater quality over the past 22 years in the paper. The results show： （1） There were obvious temporal and spatial changes of groundwater quality during the past 22 years. （2） Concentrations of NH4^＋, SO4^2- , NO3, NO2^-, Cl^- and the pH value, total hardness, total alkalinity increased significantly, in which NH4^2-, NO3, and NO2^- of groundwater exceeded the drinking water standards as a result of non-point pollution caused by the expansion of cultivated land and mass use of the fertilizer and pesticide. （3） Oppositely, Ca^2＋ and HCO3^- showed an obvious decline trend due to forest reduction and degradation and stony desertification. Meantime, there was a dynamic relation between the groundwater quality change and the land use change.

The impact of land use on soil properties in a karst agricultural region of Southwest China: a case study of Xiaojiang watershed, Yunnan

Supported by RS and GIS, the land use change from 1982 to 2003 were analyzed and the impacts of land use changes on pH value, organic matter, total N, total P, total K, available N, available P, and available K in soil of Xiaojiang watershed, a typical karst agricultural region of Yunnan Province, Southwest China were assessed. The following aspects are concluded. （1） The total land use converted during the past 20 years in Xiaojiang watershed covers an area of 610.12 km^2, of which 134.29 km^2 of forestland was converted into cultivated land, and 210 km^2 of.unused land was converted into cultivated land. （2） The rapid growth of population and the economic development were the main driving forces of land use change. （3） With the change in land use, the soil properties have been changed significantly. The pH, organic matter, total N, total P, total K, available N, available P and available K in soil in 1982 were 6.3, 38.02 g·kg^-1, 1.86 g·kg^-1, 1.63 g·kg^-1, 10.94 g·kg^-1, 114.42 g·kg^-1, 11.65 mg·kg^-1 and 64.69 mg·kg^-1g, respectively; and those in 2003 were 6.73, 25.26 g·kg^-1, 1.41 g·kg^-1, 0.99 g·kg^-1, 12.6 g·kg^-1, 113.43 mg·kg^-1, 11.11 mg·kg^-1 and 151.59 mg·kg^-1, respectively. Pared samples t-test of the tested indices of soil properties indicate that those indices have changed significantly during the last 20 years. But the soil properties changed differently, due to the differences in land use change. （4） Also, with the change in land use and management measures of soil, the modifications in soil properties which developed from carbonate rocks were more sensitive than those in the soil developed from sandstone.

Environmental Geochemistry of Fluorine in the Rock-Soil-Water System in the Karst Region of Central Guizhou Province

Systematic determination of and adsorption experiment on fluorine in the carbonate rock\|soil\|water system in the karst region studied in Guizhou Province, in conjunction with the mineral surface and soil chemistry data, have revealed the geochemical characteristics of F and the mechanisms of its transport and enrichment in the rock\|soil\|water system of the karst region, central Guizhou Province. Deep\|seated underground waters (-100m or lower) and soil layers in the karst region of central Guizhou are characterized by high\|F anomalies whereas shallow\|level underground and surface waters by low contents of F (mostly lower than 0.5 mg/L). Fluorine in soil and water in the region studied comes largely from Triassic marine strata dominated by gypsum\|bearing carbonate rocks. The special adsorption and desorption of F on the surface of geothite in soil layers are the important mechanisms of its transport and enrichment in the rock\|soil\|water system of the karst region studied.

Research on soil multi-media environmental pollution around a Pb-Zn mining and smelting plant in the karst area of Guangxi Zhuang Autonomous Region,Southwest China

The method of principal component analysis was applied to systematical research on the soil multi-media environment, including soil, surface water, ground water, waterbody sediment and agricultural crops, as well as pollution-inducing wastewater, mullock (or waste ore) and slag in the periphery of a large-sized Pb-Zn mining and smelting plant in a karst area of Guangxi Zhuang Autonomous Region. The results revealed that soils in the area studied have been heavily polluted by Cd, Zn, Pb and Hg, and the levels of these metals in the samples of agricultural crop greatly exceed the standards. The above-mentioned pollutants exist in all soil-multi-media environments. The mullock, slag, wastewater, surface water, ground water, soil, and agricultural crops constitute a composite ecological chain. Therefore, the improper disposal of mullock and slag, and the use of polluted wastewater for agricultural irrigation are the main causes of soil pollution. Heavy metals in the soil have three transition progresses: point (improved soil with slag, ground water inflow plot), linear (river transition) and non-point transition (regional pollution by slag) patterns, and the tailing yard is the most important locus for heavy metals to release into the environment.

喀斯特地区尾矿库周边植物重金属富集特征及空间分布

目的:了解典型喀斯特地区尾矿库周边植物的重金属富集特性和空间分布特征,筛选优势植物品种。方法:计算富集系数来判断不同植物对不同重金属的富集能力;采用地理信息分析软件(GIS)通过普通克里金插值和半变异函数分析,建立植物重金属空间分布模型;计算皮尔逊相关系数,以分析植物体内各重金属之间及与土壤pH值的相关性。结果:该尾矿库周边28种植物中,茄科植物红丝线、菊科的野茼蒿和荨麻科的八角麻对Cd有较强富集能力,植物中Cd污染严重;乌毛蕨科的苏铁蕨、海金沙科的小叶海金沙和大戟科的禾串树对Pb有较强富集能力;各植物对Cu和Zn均无富集作用。重金属空间分布模型显示,Cd主要分布在尾矿库南面、西南面、东南面和西北面;Pb主要分布在东南部、坝下小溪及正南面;Cu主要分布在正南、西南和坝下小溪方向;Zn主要分布在西面、西南、西北和正北面。在半变异函数模型参数中,Cd和Zn以随机性因素误差为主,各点的空间相关性弱,Pb、Cu以结构性因素误差为主,空间相关性较强;植物体内重金属含量空间变异性和空间相关性排序为Zn<Cd<Cu<Pb。Cd与Cu存在中等程度正相关关系,Cd与Pb、Zn呈正弱相关关系;植物体内各重金属含量与土壤pH值相关性不强。结论:筛选出的部分优势植物可作为矿区土壤重金属富集转移和生物修复的备选品种,初步了解了该区域重金属在土壤和植物之间的迁移规律,为开展矿区重金属污染治理提供了依据。

贵州裸露岩溶地下河系统污染通道识别钻探技术

贵州裸露岩溶区地下河系统发育、岩溶发育强烈、水文地质条件复杂,地下河系统易受地面污染源渗滤液浸入引发严重污染问题。地下河系统污染通道隐蔽性强、空间狭窄、各向发育不均匀,精准识别难度大。为揭露识别污染通道,钻探成孔施工面临软硬互层与软弱不均、强岩溶地层易孔斜、大溶洞钻孔轴线易偏移和套管拆断、自然水力坡度小的地下河系统示踪剂迁移缓慢等难题,污染通道揭露识别难度大、效率低。采用防斜保直、大岩溶套管穿越封隔、孔内激化促示踪剂迁移等技术措施,保证了勘查孔垂直度,并为测井、示踪试验及水样采集等工作提供精准的钻孔通道,实现了污染通道的精准揭露和快速识别。对同类地层精准揭露和高效识别污染通道的钻探施工有参考和借鉴意义。

Evolution and Effects of the Social-ecological System in Karst Mountainous Regions:A Case Study of Guangxi,China

Karst regions are the typical areas of interaction between human society and natural ecosystems.Understanding the historical mechanisms of the evolution of social-ecological systems(SES)is crucial for the future sustainable management of karst regions.This study selected Guangxi,a typical karst mountainous region in Southwest China,as the study area,and used population,cropland area,and forest coverage as the SES elements.Based on the framework of SES research in the karst region,it adopted segmented linear regression to identify the stages of the interactions among these elements,to reveal the evolutionary stages of social development from the long-term perspective.In addition,the driving factor indicators were constructed from the aspects of natural environment,social development,government policy,and climate change,and then the feedback changes brought about by the evolution were investigated.The results show that the evolution of SES in Guangxi from 1363-2020 can be divided into seven stages.In the first,second,and early period of the third stages,the government of Guangxi mainly focused on agricultural activities,although the only way to meet the growing demand for food was by expanding the area of cropland,and the timber trade’s pursuit of economic development,resulting in an increase in rocky desertification.In the fourth stage,the ecological environment improved under the implementation of measures such as the control of rocky desertification and the compensation of forest ecological benefits.After the fifth stage,the effect of rocky desertification control has been remarkable.Although the implementation of relevant policies has alleviated the environmental problems to some extent,the continual changes in the structure and function of SES can challenge further progress towards sustainability in karst regions.This study aims to provide a reference for the long-term national spatial planning and the development of environmental policies in karst regions.