To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migong...To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.展开更多
Terrestrial ecosystems heavily depend on vegetation,which responds to carbon dioxide(CO_(2))fertilization in hot and humid regions.The subtropical humid karst region is a hot and humid region;whether and to what exten...Terrestrial ecosystems heavily depend on vegetation,which responds to carbon dioxide(CO_(2))fertilization in hot and humid regions.The subtropical humid karst region is a hot and humid region;whether and to what extent CO_(2)fertilization affects vegetation changes in such regions remains unclear.In this study,we investigated the degree to which CO_(2)fertilization influences vegetation changes,along with their spatial and temporal differences,in the subtropical humid karst region using time-lag effect analysis,a random forest model,and multiple regression analysis.Results showed that CO_(2)fertilization plays an important role in vegetation changes,exhibiting clear spatial variations across different geomorphological zones,with its degree of influence ranging mainly between 11%and 25%.The highest contribution of CO_(2)fertilization was observed in the karst basin and non-karstic region,whereas the lowest contribution was found in the karst plateau region.Previous studies have primarily attributed vegetation changes in subtropical humid karst region to ecological engineering,leading to an overestimation of its contribution to these changes.The findings of this study enhance the understanding of the mechanism of vegetation changes in humid karst region and provide theoretical and practical insights for ecological and environmental protection in these regions.展开更多
Research on the ecohydrological processes of terrestrial plants is a frontier field comprising ecology,hydrology and global change research,yielding the key theoretical foundations of ecohydrology.In karst areas,due t...Research on the ecohydrological processes of terrestrial plants is a frontier field comprising ecology,hydrology and global change research,yielding the key theoretical foundations of ecohydrology.In karst areas,due to its unique geological background,the karst landscape is strongly developed,with high bedrock exposure,high permeability,fragmented soils,shallow soils,and high spatial heterogeneity,resulting in very limited water storage for plant uptake and growth in rock fissures and shallow soils.Therefore,water conditions are an important ecological factor influencing plant growth.To comprehensively understand the current progress and development trends in plant water use research focusing on karst areas,this paper uses the VOSviewer software to analyze the literature on plant water use in karst areas between 1984 and 2022.The results showed that:(1)Research on plant water use in karst areas has developed rapidly worldwide,and the number of relevant studies in the literature have increased year by year,which together means that it is attracting more and more attention.(2)The investigation of plant water sources,geological background of karst areas,seasonal arid tropical climates,the relationship betweenδ13C values and plant water use efficiency,karst plant water use in karst savannas and subtropical areas,and ecosystems under climate change yields the knowledge base in this field.(3)Most studies in this area focus on the division of water sources of plants in karst areas,the methods of studying the water use sources of plants,and the water use strategies and efficiency of plants.(4)Future research will focus on how plant water use in karst areas is influenced by Earth’s critical zones,climate change,and ecohydrological separation.These studies will provide a key scientific basis for guiding ecological restoration and promoting sustainable development in karst areas.展开更多
Ecological security provides the basis of maintaining both a sustainable regional ecosystem and economic development.However,few studies have focused on how the features such as topography and geomorphology,lithologic...Ecological security provides the basis of maintaining both a sustainable regional ecosystem and economic development.However,few studies have focused on how the features such as topography and geomorphology,lithologic stratigraphic assemblages,and geohazard distribution affect the construction of ecological security patterns and the layout of optimization measures.In order to comprehensively reveal the key areas and key objects of ecological restoration in karst basins,this study takes the Beipan River Basin(BRB)as an example,constructs an ecological security pattern(ESP)based on the methods of morphological spatial pattern analysis(MSPA),landscape connectivity analysis and circuit theory,and lays out the optimization measures in combination with the spatial distribution characteristics of topographic and geomorphological differences and lithological stratigraphic combinations.The results show that 151 ecological sources,343 ecological corridors,121 pinch points and 178 barriers constitute the ESP of the BRB.Lithology is closely related to the spatial distribution characteristics of ecological source sites.Level 1 and 2 ecological sources(The ecological sources were categorized into level 1,level 2,and level 3 source from high to low importance.)are concentrated in the Emeishan basalt region of the upstream and the clastic and impure carbonate rock region of the downstream part of the BRB;level 3ecological sources are concentrated in the carbonate rock region of the midstream.Taking into account the outstanding ecological problems in the basin,and based on the characteristics of lithology and geohazard distribution,we propose the optimization scheme of“three axes,three zones and multiple points”for the ESP and the layout of specific measures of the BRB.The results can provide scientific references for maintaining ecological security maintenance in karst ecologically fragile areas.展开更多
Land use change is a fundamental factor affecting ecosystem’s structures and functions.However,few studies have explored the ecological disturbance caused by land use change from a combined structural and functional ...Land use change is a fundamental factor affecting ecosystem’s structures and functions.However,few studies have explored the ecological disturbance caused by land use change from a combined structural and functional perspective.In this study,the ecological structural disturbance index(SDI)and functional disturbance index(FDI)were introduced to quantitatively evaluate ecological disturbance caused by land use change in a typical karst area—Huangping County,Guizhou Province,China during 2009–2019.Results show that although the area of ecological land increased during past 10 yr,there had been a fragmentation trend of ecological land.Agricultural occupation was more severe than construction encroachment on ecological land.The grids with negative structural disturbance were consistent with areas of obvious dynamic loss and gain of ecological land.Ecological fragmentation had a greater impact than habitat gain in grids with negative structural disturbance.The ecosystem service functions of supply,adjustment,support,and culture were obviously affected by land use change,and the total FDI reflects the trade-off among them.Negative FDI values were easily observed in the rocky desertification area or water and soil loss area.The combination analysis of the SDI and FDI indicated the characteristic of codirectional ecologically structural and functional disturbance in the majority of grids.The findings improve our understanding of multiple relationships among ecological disturbances and provide valuable information for guiding land use activities.展开更多
In Southwestern China,the development of karst landforms and planation surfaces is closely related to local tectonics,fluvial incision,and base level changes,and climate changes.However,researches on when these karst ...In Southwestern China,the development of karst landforms and planation surfaces is closely related to local tectonics,fluvial incision,and base level changes,and climate changes.However,researches on when these karst landforms and planation surfaces formed and how they evolved along drainage development are scarce.Fortunately,horizontal caves with numerous fluvial deposits in high karst mountains can be served as time markers in landform evolution.Here we select large horizontal caves to perform studies of geomorphology,sedimentology,and geochronology.Fieldwork revealed that more than 25 km long horizontal cave passages are perched 1500 m higher than the local base level,but filled with several phases of fluvial sediments and breakdown slabs.The first phase of fluvial gravels and related cave drainage was dated back to 6.4 Ma using cosmogenic nuclide burial dating,and the stalagmite covering the cave collapse was dated by the U-Pb method to be older than 1.56 Ma.These results show that the continuous horizontal cave drainage system and the planation surface were developed before the Late Miocene.The lowering process of the base level as a result of the sharp fluvial incision and water level lowering,along with the regional uplift,led to the abandonment of the horizontal cave and the elevated planation surface at the Late Miocene.After that,the phase of cave collapse,thick fluvial sand,and clay sediments in the recharge of cave areas were deposited at around 1.6 Ma and during the Middle Pleistocene,respectively.Subsequently,speleothems were widely deposited on the collapse and clay sediments during the period from 600 to 90 ka,whereas the deposition of cave fluvial sediments terminated suddenly.The tectonic could control the denudation of surface caprocks and the development of karst conduits before the Late Miocene,whereas the river incision acted as the main driver for the base level lowering and the destruction of the horizontal cave drainage at high altitudes.In addition,the rapid incision and retreat of Silurian gorges finally caused the formation of karst mesas in the Middle Pleistocene.展开更多
Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The ...Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The method employed four parameters:P(the existence of ponor/swallow hole),L(lineament density),U(sinking stream to an underground river),and S(distance to spring/pumping site).These parameters are essential for identifying contaminant pathways and transport from the surface to the karst groundwater/springs.COCKPIT-PLUS has been developed and validated in the Gunungsewu karst in Java,Indonesia.This research considers a cockpit as a single hydrological unit that uniquely recharges karst groundwater.We analyzed 2,811 cockpits and 81 other closed depressions to develop a land use planning map.The research used the time to first arrival(Ta),time to peak(Tp),and Q_(max/min)ratio parameters of two karst springs and two underground pumping sites for validation.Cockpits with ponors/swallow holes,sinking streams,high lineament density,and short distances to springs are vulnerable to groundwater and thus must be restricted areas for any land uses.The findings show that though the COCKPIT-PLUS uses a limited karst dataset,the proposed method seems reliable enough for a rapid land-use zoning approach in cockpit karst areas.展开更多
In this paper the author gives a definition of the karst ecosystem and discusses the characteristics of the karst environment and karst ecosystem and the relationship between life and the karst environment. Finally he...In this paper the author gives a definition of the karst ecosystem and discusses the characteristics of the karst environment and karst ecosystem and the relationship between life and the karst environment. Finally he clarifies the structure, driving force and functions of the karst system.展开更多
Soil nitrogen(N)cycling is one of the most critical biogeochemical cycles,and N cycling-related microorganisms are the primary driving force behind N cycling in natural environments.The large karst sinkholes in China,...Soil nitrogen(N)cycling is one of the most critical biogeochemical cycles,and N cycling-related microorganisms are the primary driving force behind N cycling in natural environments.The large karst sinkholes in China,known as Tiankengs,harbor abundant unique biological resources due to their particular environmental conditions.However,N cycling-related microorganisms in Tiankeng soils and their connection to ecosystem processes remain poorly studied.In this study,we investigated the distribution patterns and genomic diversity of N cycling-related microorganisms both inside and outside the Luohun cave Tiankeng in Guizhou,China,utilizing high-throughput sequencing and other techniques.The results indicated that the diversities and abundances of denitrifying bacteria,ammonia-oxidizing bacteria,and ammonia-oxidizing archaea communities inside the Tiankeng were higher than those outside the Tiankeng;however,the microbial network relationships were more fragile inside the Tiankeng.The most abundant species of denitrifying bacteria,ammonia-oxidizing bacteria,and ammonia-oxidizing archaea inside the Tiankeng were unclassified_p_Proteobacteria(47.8%),unclassified_k_norank(AOB,OTU121,37.3%),and unclassified_g_norank_f_norank_o_norank_c_environmental_samples(55.7%),respectively;outside the Tiankeng,they were unclassified_k_norank_d_bacteria(54.5%),unclassified_k_norank(AOB,OTU121,48.1%),and unclassified_k_norank(AOA,OTU70,49.6%),respectively.Additionally,the N content inside the Tiankeng was significantly lower(P<0.05)under the influence of these N cycling-related microorganisms,whereas the nutrient contents were higher than that outside the Tiankeng.To the best of our knowledge,this is the first report on the crucial microbial distribution patterns driving N cycling in karst Tiankengs and provides new insights into the structure and potential functions of N cycling-related microorganisms in the unique ecological environment of fragile Tiankeng ecosystems.展开更多
Mushroom Mountain karren with predominantly flat tops that formed along the stylolites and bedding planes dictated the special features of this karst landscape. Their features and rock relief clearly reflect the geolo...Mushroom Mountain karren with predominantly flat tops that formed along the stylolites and bedding planes dictated the special features of this karst landscape. Their features and rock relief clearly reflect the geological conditions and development. The subsoil karren with conical tops dissected by subsoil rock relief were exposed from beneath the soil. Below tree vegetation, the subsoil karren are to a great extent covered by moss and lichen, under which they acquire their characteristic shape. On the bare surface they were reshaped by rainwater that carves flutes and solution pans. The old cave that opens below the top of one of the cones reveals the period before its dissection into hills and cones when this part of the karst aquifer was still deep under the water table.展开更多
The Baiyun cave is a 380 m long karst cave in the Naigu Shilin, situated 70 km southeast of Kunming, Yunnan Province, China. The prevailing orientations of the cave passages are N110°–120°E and N0°-10&...The Baiyun cave is a 380 m long karst cave in the Naigu Shilin, situated 70 km southeast of Kunming, Yunnan Province, China. The prevailing orientations of the cave passages are N110°–120°E and N0°-10°W and those of the fissures in the cave are N30°–40°W and N20°–30°W. The cave is developed in the thick-bedded Lower Permian Qixia Formation. The cave has an active water flow and is currently at the near water-table stage. There are large amounts of different infills of cave sediments. The cave shows different stages of paragenesis. The palaeomagnetic analysis of cave sediments shows that their ages are younger than 780 ka B.P. (the Brunhes Chron). The upper part of the sampled profile belongs to the reverse Blake event (112.3–117.9 ka B.P.). The formation of the Baiyun cave is directly connected with the development of the Naigu Shilin. The formation of karst underground and surface features depends on the regional tectonic deformation and the Cenozoic extension of the study area.展开更多
Four species of the genus Karstsinnectes,which live in dark,low-energy groundwater ecosystems,are currently recorded,mainly distributed in the upstream of the Pearl River,the Youjiang River and the Hongshui River.Comp...Four species of the genus Karstsinnectes,which live in dark,low-energy groundwater ecosystems,are currently recorded,mainly distributed in the upstream of the Pearl River,the Youjiang River and the Hongshui River.Completing biodiversity surveys is particularly difficult due to the particular cave habitats inhabited by these species.In this work,we describe a new cave fish of the genus Karstsinnectes,namely K.cehengensis Luo,Zhao&Zhou,sp.nov.,collected from the Beipanjiang River,the upstream of the Hongshui River.Genetically,the four individuals of the new species form a phylogenetically separate lineage,as the sister clade of K.acridorsalis,with a 9.4–9.5%genetic difference in mitochondrial Cyt b.Morphologically,the new species can be distinguished from its congeners by a combination of the following morphological characteristics:body naked,without body color;eyes reduced,diameter 1.4–3.8%of head length;anterior and posterior nostrils adjacent,anterior nostril not elongated to a barbel-like tip;lateral line incomplete;caudal fin forked;dorsal-fin rays iii-7,pectoral-fin rays i-11–12,pelvic-fin rays i-7,anal-fin rays iii-5,with 14 branched caudal-fin rays.The discovery of this new species represents the northernmost distribution of species within the genus Karstsinnectes and the first record from Guizhou Province.All currently known species of this genus inhabited in caves,making them ideal organisms for studying historical river connectivity and cave formation process.展开更多
Using the Guancun River, an underground stream-fed river, in Rong＇an County of Guangxi, China as a case study, the daily biochemical cycle was examined in this paper based on the data collected a weeklong via high re...Using the Guancun River, an underground stream-fed river, in Rong＇an County of Guangxi, China as a case study, the daily biochemical cycle was examined in this paper based on the data collected a weeklong via high resolution data logger monitoring and high-frequency sampling. Furthermore, the loss of inorganic carbon along its flow path was estimated. Results show that chemical components of the groundwater input are quite stable, showing little change extent; while all of the chemical parameters from two downstream monitoring stations show diel variation over the monitoring period, suggesting that plant activity in the river has a strong influence on water chemistry of the river. The comparison of the input fluxes from the groundwater with the output fluxes of HCO~ estimated at the downstream monitoring station during the high-frequency sampling period shows a strong decrease of HCO~, indicating that the river is losing inorganic carbon along its flow path. The loss is estimated to be about 1,152 mmol/day/m of HCO~ which represent about 94.9 kg/day of inorganic carbon along the 1,350 m section of the Guancun River. It means that HCO~ entering the river from karst underground stream was either consumed by plants or trapped in the authigenic calcite and thus constitutes a natural sink of carbon for the Guancun karst system.展开更多
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...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.展开更多
Groundwater from karst subterranean streams is among the world's most important sources of drinking water supplies,and the hydrochemical characteristics of karst water are impacted by both natural environment and ...Groundwater from karst subterranean streams is among the world's most important sources of drinking water supplies,and the hydrochemical characteristics of karst water are impacted by both natural environment and people.Therefore,the study of hydrochemistry and its solutes'sources is very important to ensure the normal function of life support systems.In this paper,thirty-five representative karst groundwater samples were collected from different aquifers(limestone and dolomite)and various land use types in Chongqing to trace the sources of solutes and relative hydrochemical processes.Hydrogeochemical types of karst groundwater in Chongqing were mainly of the Ca-HCO3 type or Ca(Mg)-HCO3 type.However,some hydrochemical types of karst groundwater were the K+Na+Ca-SO4 type(G25 site)or Ca-HCO3+SO4 type(G26 and G14 site),indicating that the hydrochemistry of these sites might be strongly influenced by anthropogenic activities or unique geological characteristics.The dissolved Sr concentrations of the studied groundwater ranged from 0.57 to 15.06~tmmol/L,and the STSr/S6Sr varied from 0.70751 to 0.71627.The j34S-SO42-fell into a range of-6.8%o-21.5%o,with a mean value of 5.6%o.The variations of both 87Sr/S6Sr and Sr values of the groundwater samples indicated that the Sr element was controlled by the weathering of limestone,dolomite and silicate rock.However,the figure of STSr/S6Sr vs.Sr2+/[K++Na+]showed that the anthropogenic inputs also obviously contributed to the Sr contents.For tracing the detailed anthropogenic effects,we traced the sources of solutes collected karst groundwater samples in Chongqing according to the j34S value of potential sulfate sources.The variations of both j34S and 1/SO42-values of the groundwater samples indicated that the atmospheric acid deposition(AAD),dissolution of gypsum(GD),oxidation of sulfide mineral(OS)or anthropogenic inputs(SF:sewage or fertilizer)have contributed to solutes in karst groundwater.The influence of oxidation of sulfide mineral,atmospheric acid deposit and anthropogenic inputs to groundwater in Chongqing karst areas was much widespread.展开更多
On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale,this paper provides four pieces of evidence for;the integration of geology and ecology during the carbon cycle proce...On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale,this paper provides four pieces of evidence for;the integration of geology and ecology during the carbon cycle processes m the karst dynamic system,and estxmated the karst carbon sink effect using the methods of comparative monitoring of paired watersheds and the carbon stable isotope tracer technique.The results of the soil carbon cycle in Maocun,Guilin,showed that the soil carbon cycle in the karst area,the weathering and dissolution of carbonate rocks under the soil,resulted in a lower soil respiration of 25% in the karstoarea than in a non-karst area (sandstone and shale),and the carbon isotope results indicated that 13.46% of the heavy carbon of the hmestone is involved in the soil carbon cycle.The comparative monitoring results m paxred watersheds,suggesting that the HCO3 concentration m a karst spring is 10 times that of a rivulet in a non-karst area,while the concentration of inorganic carbon flux is 23.8 times.With both chemical stoichiometry and carbon stable isotopes,the proportion of carbon in karst springs derived from carbonate rocks was found to be 58.52% and 37.65% respectively.The comparison on carbon exchange and isotopes at the water-gas interface between the granite and carbonate rock basins in the Li River showed that the CO2 emission of the karst water is 10.92 times that of the allogenic water from the non-karst area,while the carbon isotope of HCO3^- in karst water is lighter by 8.62%.However,this does not mean that the karst water body has a larger carbon source effect.On the contrary,it means the karst water body has a greater karst carbon sink effect.When the karst subterranean stream in Zhaidi,Guilin,is exposed at the surface,carbon-rich karst water stimulated the growth of aquatic plants.The values of carbon stable isotopes in the same species of submerged plants gradually becomes heavier and heavier,and the 512 m flow process has a maximum range of 15.46%.The calculation results showed that 12.52% of inorganic carbon is converted into organic carbon.According to the data that has been published,the global karst carbon sink flux was estimated to be 0.53-0.58 PgC/a,equivalent to 31.18%-34.41% of the global forest carbon sink flux.In the meanwhile,the karst carbon sink flux in China was calculated to be 0.051 PgC/a,accounting for 68% of its forest carbon sink flux.展开更多
Through utilizing water flow monitoring, rock scratching, soil wood piles and radionuclide ^(137)Cs tracing in the Longhe karst ecological experimental site(hereinafter referred to"Longhe site"), Pingguo Cou...Through utilizing water flow monitoring, rock scratching, soil wood piles and radionuclide ^(137)Cs tracing in the Longhe karst ecological experimental site(hereinafter referred to"Longhe site"), Pingguo County, Guangxi Province, the features and values of soil erosion and soil leakage in different geomorphologic locations and land uses in the karst peak-cluster depressions are showed clearly. There are four kinds of geomorphologic locations in the karst peak-cluster depression, namely peaks, strip, slopes and depression. The soil leakage modulus in the peaks and strips respectively occupy 92.43% and 96.24% of the total mean soil erosion modulus at experimental sites. On the slope, soil leakage accounted for about 75%. At the bottom of depression, surface water was the main factor of soil erosion, and at last most soil leaked into underground rivers from sinkholes. The total soil erosion modulus and the contribution rates of relative surface soil erosion in regard of peaks, slopes and depressions gradually increased. There are also five major types of land use in the karst peak-cluster depressions, farmland, Kudingcha tea plantations, young Lignum Sappan fields, shrub-grassland and pastures. The soil erosion modulus of slope farmland has the highest value with an increasing trend year by year. But soil erosion modulus of other four land use types decreased by year, which shows the "grain for green" will result in better soil protection. By handling with rocky desertification and ecological rehabilitation in Longhe site, the mean soil erosion modulus of the karst peak-cluster depression has decreased about 80% from 2003 to 2015.展开更多
Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distri...Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distribution. In this study, considering soil distribution, SOC content and density were investigated along positive successional stages （cropland, plantation, grassland, scrubland, secondary forest, and primary forest） to determine the effects of land cover type on SOC stocks in a subtropical karst area. The proportion of continuous soil on the ground surface under different land cover types ranged between 0.0% and 79.8%. As land cover types changed across the positive successional stages, SOC content in both the 0-20 cm and 20-50 cm soil layers increased significantly. SOC density （SOCD） within O-lOO cm soil depth ranged from 1.45 to 8.72 kg m^-2, and increased from secondary forest to primary forest, plantation, grassland, scrubland, and cropland, due to discontinuous soil distribution. Discontinuous soil distribution had a negative effect on 8OC stocks, highlighting the necessity for accurate determination of soil distribution in karst areas. Generally, ecological restoration had positive impacts on SOC accumulation in karst areas, but this is a slow process. In the short term, the conversion of croplandto grassland was found to be the most efficient way for SOC sequestration.展开更多
This research examines the distribution features of 4960 caves across Guizhou Province, while probing the relationship between the caves＇ spatial patterns and geographic elements. This study is based on hydrogeologic...This research examines the distribution features of 4960 caves across Guizhou Province, while probing the relationship between the caves＇ spatial patterns and geographic elements. This study is based on hydrogeological and topographic maps of Guizhou. ArcGIS software was used to process the adjacent index, spatial analysis, and coupling analysis of the caves altitude and longitude, as well as the rock properties, lithology, drainage and tec- tonic division of almost 5000 caves. Based on a point pattern analysis of Guizhou caves, the adjacent index is 0.53, and the coefficient of variation verified by Tyson polygon reached 72.469%. This figure reflects the clustered distribution pattern of the caves. Across the entire province, caves are divided into four concentrated areas and one weakly affected area. The four concentrated areas are Zunyi-Tongren, Bijie, Qianxinan-Liupanshui, and Gui- yang-Anshun-Qinan. The one weakly affected zone is Qiandongnan. The most concentrated among them is the Guiyang-Anshun-Qiannan area, which covers 24.67% of the total province area, and accounts for 36.63% of the total province＇s caves. Cave distribution in Guizhou is characterized as dense in the western part and sparse in the eastern part. Under this study background, the natural elements of formation, including lithology, structure, climate, hydrol- ogy, and altitude, and their effects on the distribution, number, and spatial pattern of cave development is analyzed.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42007178 and 41907327)the Natural Science Foundation of Hubei(Nos.2020CFB463 and 2019CFB372)+4 种基金China Geological Survey(Nos.DD20160304 and DD20190824)Fundamental Research Funds for the Central Universities(Nos.CUG 190644 and CUGL180817)National Key Research and Development Program(No.2019YFC1805502)Key Laboratory of Karst Dynamics,MNR and GZAR(Institute of Karst Geology,CAGS)Guilin(No.KDL201703)Key Laboratory of Karst Ecosystem and Treatment of Rocky Desertification,MNR and IRCK by UNESCO(No.KDL201903)。
文摘To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.
基金National Natural Science Foundation of China,No.41761003The Karst Science Research Center of Guizhou Province,No.U1812401。
文摘Terrestrial ecosystems heavily depend on vegetation,which responds to carbon dioxide(CO_(2))fertilization in hot and humid regions.The subtropical humid karst region is a hot and humid region;whether and to what extent CO_(2)fertilization affects vegetation changes in such regions remains unclear.In this study,we investigated the degree to which CO_(2)fertilization influences vegetation changes,along with their spatial and temporal differences,in the subtropical humid karst region using time-lag effect analysis,a random forest model,and multiple regression analysis.Results showed that CO_(2)fertilization plays an important role in vegetation changes,exhibiting clear spatial variations across different geomorphological zones,with its degree of influence ranging mainly between 11%and 25%.The highest contribution of CO_(2)fertilization was observed in the karst basin and non-karstic region,whereas the lowest contribution was found in the karst plateau region.Previous studies have primarily attributed vegetation changes in subtropical humid karst region to ecological engineering,leading to an overestimation of its contribution to these changes.The findings of this study enhance the understanding of the mechanism of vegetation changes in humid karst region and provide theoretical and practical insights for ecological and environmental protection in these regions.
基金This work was supported by the National Key Research and Development Program of China(2021YFE0107100)Guangxi Key Research and Development Program(GuikeAB22035004)Guangxi Science and Technology Base and Talent Special Project(Guike AD20297090).
文摘Research on the ecohydrological processes of terrestrial plants is a frontier field comprising ecology,hydrology and global change research,yielding the key theoretical foundations of ecohydrology.In karst areas,due to its unique geological background,the karst landscape is strongly developed,with high bedrock exposure,high permeability,fragmented soils,shallow soils,and high spatial heterogeneity,resulting in very limited water storage for plant uptake and growth in rock fissures and shallow soils.Therefore,water conditions are an important ecological factor influencing plant growth.To comprehensively understand the current progress and development trends in plant water use research focusing on karst areas,this paper uses the VOSviewer software to analyze the literature on plant water use in karst areas between 1984 and 2022.The results showed that:(1)Research on plant water use in karst areas has developed rapidly worldwide,and the number of relevant studies in the literature have increased year by year,which together means that it is attracting more and more attention.(2)The investigation of plant water sources,geological background of karst areas,seasonal arid tropical climates,the relationship betweenδ13C values and plant water use efficiency,karst plant water use in karst savannas and subtropical areas,and ecosystems under climate change yields the knowledge base in this field.(3)Most studies in this area focus on the division of water sources of plants in karst areas,the methods of studying the water use sources of plants,and the water use strategies and efficiency of plants.(4)Future research will focus on how plant water use in karst areas is influenced by Earth’s critical zones,climate change,and ecohydrological separation.These studies will provide a key scientific basis for guiding ecological restoration and promoting sustainable development in karst areas.
基金jointly supported by the Key Project of the Natural Science Foundation of Guizhou Province(No.Qiankehe Jichu-ZK[2023]Zhongdian027)the Project of the Science and Technology Innovation Base Construction of Guizhou Province(No.Qiankehe Zhongyindi[2023]005)Philosophy and Social Science Planning Subjects in Guizhou Province in 2022(No.22GZYB53)。
文摘Ecological security provides the basis of maintaining both a sustainable regional ecosystem and economic development.However,few studies have focused on how the features such as topography and geomorphology,lithologic stratigraphic assemblages,and geohazard distribution affect the construction of ecological security patterns and the layout of optimization measures.In order to comprehensively reveal the key areas and key objects of ecological restoration in karst basins,this study takes the Beipan River Basin(BRB)as an example,constructs an ecological security pattern(ESP)based on the methods of morphological spatial pattern analysis(MSPA),landscape connectivity analysis and circuit theory,and lays out the optimization measures in combination with the spatial distribution characteristics of topographic and geomorphological differences and lithological stratigraphic combinations.The results show that 151 ecological sources,343 ecological corridors,121 pinch points and 178 barriers constitute the ESP of the BRB.Lithology is closely related to the spatial distribution characteristics of ecological source sites.Level 1 and 2 ecological sources(The ecological sources were categorized into level 1,level 2,and level 3 source from high to low importance.)are concentrated in the Emeishan basalt region of the upstream and the clastic and impure carbonate rock region of the downstream part of the BRB;level 3ecological sources are concentrated in the carbonate rock region of the midstream.Taking into account the outstanding ecological problems in the basin,and based on the characteristics of lithology and geohazard distribution,we propose the optimization scheme of“three axes,three zones and multiple points”for the ESP and the layout of specific measures of the BRB.The results can provide scientific references for maintaining ecological security maintenance in karst ecologically fragile areas.
基金Under the auspices of the National Natural Science Foundation of China(No.41661088,32101593,42361028)Science and Technology Program of Guizhou Province(No.Qiankehe Zhongyindi[2023]005)+1 种基金2024 Humanities and Social Science Research Project of Guizhou Provincial Department of Education(No.24RWZX007)Graduate Research Fund Project of Guizhou Province(No.2024YJSKYJJ153)。
文摘Land use change is a fundamental factor affecting ecosystem’s structures and functions.However,few studies have explored the ecological disturbance caused by land use change from a combined structural and functional perspective.In this study,the ecological structural disturbance index(SDI)and functional disturbance index(FDI)were introduced to quantitatively evaluate ecological disturbance caused by land use change in a typical karst area—Huangping County,Guizhou Province,China during 2009–2019.Results show that although the area of ecological land increased during past 10 yr,there had been a fragmentation trend of ecological land.Agricultural occupation was more severe than construction encroachment on ecological land.The grids with negative structural disturbance were consistent with areas of obvious dynamic loss and gain of ecological land.Ecological fragmentation had a greater impact than habitat gain in grids with negative structural disturbance.The ecosystem service functions of supply,adjustment,support,and culture were obviously affected by land use change,and the total FDI reflects the trade-off among them.Negative FDI values were easily observed in the rocky desertification area or water and soil loss area.The combination analysis of the SDI and FDI indicated the characteristic of codirectional ecologically structural and functional disturbance in the majority of grids.The findings improve our understanding of multiple relationships among ecological disturbances and provide valuable information for guiding land use activities.
基金supported by the foundation of the Institute of Karst Geology,Chinese Academy of Geological Sciences(Nos.201317,2014005,2014034,2016011)National Natural Science Foundation of China(No.41270226)。
文摘In Southwestern China,the development of karst landforms and planation surfaces is closely related to local tectonics,fluvial incision,and base level changes,and climate changes.However,researches on when these karst landforms and planation surfaces formed and how they evolved along drainage development are scarce.Fortunately,horizontal caves with numerous fluvial deposits in high karst mountains can be served as time markers in landform evolution.Here we select large horizontal caves to perform studies of geomorphology,sedimentology,and geochronology.Fieldwork revealed that more than 25 km long horizontal cave passages are perched 1500 m higher than the local base level,but filled with several phases of fluvial sediments and breakdown slabs.The first phase of fluvial gravels and related cave drainage was dated back to 6.4 Ma using cosmogenic nuclide burial dating,and the stalagmite covering the cave collapse was dated by the U-Pb method to be older than 1.56 Ma.These results show that the continuous horizontal cave drainage system and the planation surface were developed before the Late Miocene.The lowering process of the base level as a result of the sharp fluvial incision and water level lowering,along with the regional uplift,led to the abandonment of the horizontal cave and the elevated planation surface at the Late Miocene.After that,the phase of cave collapse,thick fluvial sand,and clay sediments in the recharge of cave areas were deposited at around 1.6 Ma and during the Middle Pleistocene,respectively.Subsequently,speleothems were widely deposited on the collapse and clay sediments during the period from 600 to 90 ka,whereas the deposition of cave fluvial sediments terminated suddenly.The tectonic could control the denudation of surface caprocks and the development of karst conduits before the Late Miocene,whereas the river incision acted as the main driver for the base level lowering and the destruction of the horizontal cave drainage at high altitudes.In addition,the rapid incision and retreat of Silurian gorges finally caused the formation of karst mesas in the Middle Pleistocene.
文摘Karst groundwater is highly vulnerable to contamination,which urges better land use zoning.This paper proposes a new approach,called COCKPIT-PLUS,to minimize groundwater contamination within cockpit karst regions.The method employed four parameters:P(the existence of ponor/swallow hole),L(lineament density),U(sinking stream to an underground river),and S(distance to spring/pumping site).These parameters are essential for identifying contaminant pathways and transport from the surface to the karst groundwater/springs.COCKPIT-PLUS has been developed and validated in the Gunungsewu karst in Java,Indonesia.This research considers a cockpit as a single hydrological unit that uniquely recharges karst groundwater.We analyzed 2,811 cockpits and 81 other closed depressions to develop a land use planning map.The research used the time to first arrival(Ta),time to peak(Tp),and Q_(max/min)ratio parameters of two karst springs and two underground pumping sites for validation.Cockpits with ponors/swallow holes,sinking streams,high lineament density,and short distances to springs are vulnerable to groundwater and thus must be restricted areas for any land uses.The findings show that though the COCKPIT-PLUS uses a limited karst dataset,the proposed method seems reliable enough for a rapid land-use zoning approach in cockpit karst areas.
基金supported by the Special Commonweal Research Project(No.164)of the Ministry of Science and Technologykey Project(No.2000208)of the Ministry of Land and Resources+1 种基金Natural Science Foundation Project(No.49632100)UNESCO Project IGCP 379 and IGCP 448.
文摘In this paper the author gives a definition of the karst ecosystem and discusses the characteristics of the karst environment and karst ecosystem and the relationship between life and the karst environment. Finally he clarifies the structure, driving force and functions of the karst system.
基金supported by the National Natural Science Foundation of China(No.31860023)the Light of West China Program of Chinese Academic of Sciences(No.[2019]90)+1 种基金the Basic Research Fund of Guangxi Academy of Sciences,China(No.CQZ-D-1904)the Fundamental Research Fund of the Guangxi Institute of Botany,China(Guizhiye Nos.24010 and 24012).
文摘Soil nitrogen(N)cycling is one of the most critical biogeochemical cycles,and N cycling-related microorganisms are the primary driving force behind N cycling in natural environments.The large karst sinkholes in China,known as Tiankengs,harbor abundant unique biological resources due to their particular environmental conditions.However,N cycling-related microorganisms in Tiankeng soils and their connection to ecosystem processes remain poorly studied.In this study,we investigated the distribution patterns and genomic diversity of N cycling-related microorganisms both inside and outside the Luohun cave Tiankeng in Guizhou,China,utilizing high-throughput sequencing and other techniques.The results indicated that the diversities and abundances of denitrifying bacteria,ammonia-oxidizing bacteria,and ammonia-oxidizing archaea communities inside the Tiankeng were higher than those outside the Tiankeng;however,the microbial network relationships were more fragile inside the Tiankeng.The most abundant species of denitrifying bacteria,ammonia-oxidizing bacteria,and ammonia-oxidizing archaea inside the Tiankeng were unclassified_p_Proteobacteria(47.8%),unclassified_k_norank(AOB,OTU121,37.3%),and unclassified_g_norank_f_norank_o_norank_c_environmental_samples(55.7%),respectively;outside the Tiankeng,they were unclassified_k_norank_d_bacteria(54.5%),unclassified_k_norank(AOB,OTU121,48.1%),and unclassified_k_norank(AOA,OTU70,49.6%),respectively.Additionally,the N content inside the Tiankeng was significantly lower(P<0.05)under the influence of these N cycling-related microorganisms,whereas the nutrient contents were higher than that outside the Tiankeng.To the best of our knowledge,this is the first report on the crucial microbial distribution patterns driving N cycling in karst Tiankengs and provides new insights into the structure and potential functions of N cycling-related microorganisms in the unique ecological environment of fragile Tiankeng ecosystems.
基金supported by Slovenia's Ministry of Higher Education,Science and Technology(Slovenian Research Agency),and China's Ministry of Science and Technology. included in the IGCP projects 448 and 513
文摘Mushroom Mountain karren with predominantly flat tops that formed along the stylolites and bedding planes dictated the special features of this karst landscape. Their features and rock relief clearly reflect the geological conditions and development. The subsoil karren with conical tops dissected by subsoil rock relief were exposed from beneath the soil. Below tree vegetation, the subsoil karren are to a great extent covered by moss and lichen, under which they acquire their characteristic shape. On the bare surface they were reshaped by rainwater that carves flutes and solution pans. The old cave that opens below the top of one of the cones reveals the period before its dissection into hills and cones when this part of the karst aquifer was still deep under the water table.
文摘The Baiyun cave is a 380 m long karst cave in the Naigu Shilin, situated 70 km southeast of Kunming, Yunnan Province, China. The prevailing orientations of the cave passages are N110°–120°E and N0°-10°W and those of the fissures in the cave are N30°–40°W and N20°–30°W. The cave is developed in the thick-bedded Lower Permian Qixia Formation. The cave has an active water flow and is currently at the near water-table stage. There are large amounts of different infills of cave sediments. The cave shows different stages of paragenesis. The palaeomagnetic analysis of cave sediments shows that their ages are younger than 780 ka B.P. (the Brunhes Chron). The upper part of the sampled profile belongs to the reverse Blake event (112.3–117.9 ka B.P.). The formation of the Baiyun cave is directly connected with the development of the Naigu Shilin. The formation of karst underground and surface features depends on the regional tectonic deformation and the Cenozoic extension of the study area.
基金supported by the Guizhou Province Top Discipline Construction Program Project(QianjiaoKeyan Fa[2019]125)the Guizhou Normal University Academic Emerging Talent Fund Project(Qianshi Xin Miao[2021]20)the Postgraduate Education Innovation Programme of Guizhou Province(Qianjiaohe YJSKYJJ[2021]091)。
文摘Four species of the genus Karstsinnectes,which live in dark,low-energy groundwater ecosystems,are currently recorded,mainly distributed in the upstream of the Pearl River,the Youjiang River and the Hongshui River.Completing biodiversity surveys is particularly difficult due to the particular cave habitats inhabited by these species.In this work,we describe a new cave fish of the genus Karstsinnectes,namely K.cehengensis Luo,Zhao&Zhou,sp.nov.,collected from the Beipanjiang River,the upstream of the Hongshui River.Genetically,the four individuals of the new species form a phylogenetically separate lineage,as the sister clade of K.acridorsalis,with a 9.4–9.5%genetic difference in mitochondrial Cyt b.Morphologically,the new species can be distinguished from its congeners by a combination of the following morphological characteristics:body naked,without body color;eyes reduced,diameter 1.4–3.8%of head length;anterior and posterior nostrils adjacent,anterior nostril not elongated to a barbel-like tip;lateral line incomplete;caudal fin forked;dorsal-fin rays iii-7,pectoral-fin rays i-11–12,pelvic-fin rays i-7,anal-fin rays iii-5,with 14 branched caudal-fin rays.The discovery of this new species represents the northernmost distribution of species within the genus Karstsinnectes and the first record from Guizhou Province.All currently known species of this genus inhabited in caves,making them ideal organisms for studying historical river connectivity and cave formation process.
基金supported by the Special Fund for Public Benefit Scientific Research of Ministry of Land and Resources of China(No.201111022)IGCP/SIDA 598the China Geological Survey Projects (No.1212011087122,No.1212011220230)
文摘Using the Guancun River, an underground stream-fed river, in Rong＇an County of Guangxi, China as a case study, the daily biochemical cycle was examined in this paper based on the data collected a weeklong via high resolution data logger monitoring and high-frequency sampling. Furthermore, the loss of inorganic carbon along its flow path was estimated. Results show that chemical components of the groundwater input are quite stable, showing little change extent; while all of the chemical parameters from two downstream monitoring stations show diel variation over the monitoring period, suggesting that plant activity in the river has a strong influence on water chemistry of the river. The comparison of the input fluxes from the groundwater with the output fluxes of HCO~ estimated at the downstream monitoring station during the high-frequency sampling period shows a strong decrease of HCO~, indicating that the river is losing inorganic carbon along its flow path. The loss is estimated to be about 1,152 mmol/day/m of HCO~ which represent about 94.9 kg/day of inorganic carbon along the 1,350 m section of the Guancun River. It means that HCO~ entering the river from karst underground stream was either consumed by plants or trapped in the authigenic calcite and thus constitutes a natural sink of carbon for the Guancun karst system.
基金Doctorate Foundation of Southwest University, No.SWNUB2005035 Open Foundation of Physical Geography of Southwest University, No.250-411109+2 种基金 Foundation of Science and Technology Committee of Chongqing, No.20027534 No.20048258 The project of Ministry of Land and Resources, No.200310400024
文摘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.
基金supported by the National Natural Science Foundation of China(No:41072192)the Natural Science Foundation Project of Chongqing,CSTC(No.CSTC2010BC7004)+2 种基金the Special Fund for Public Benefit Scientific Research of Ministry of Land and Resources of China(201111022)the Guangxi Natural Science Foundation Project(2012GXNSFBA053137)IGCP/SIDA 598 Project
文摘Groundwater from karst subterranean streams is among the world's most important sources of drinking water supplies,and the hydrochemical characteristics of karst water are impacted by both natural environment and people.Therefore,the study of hydrochemistry and its solutes'sources is very important to ensure the normal function of life support systems.In this paper,thirty-five representative karst groundwater samples were collected from different aquifers(limestone and dolomite)and various land use types in Chongqing to trace the sources of solutes and relative hydrochemical processes.Hydrogeochemical types of karst groundwater in Chongqing were mainly of the Ca-HCO3 type or Ca(Mg)-HCO3 type.However,some hydrochemical types of karst groundwater were the K+Na+Ca-SO4 type(G25 site)or Ca-HCO3+SO4 type(G26 and G14 site),indicating that the hydrochemistry of these sites might be strongly influenced by anthropogenic activities or unique geological characteristics.The dissolved Sr concentrations of the studied groundwater ranged from 0.57 to 15.06~tmmol/L,and the STSr/S6Sr varied from 0.70751 to 0.71627.The j34S-SO42-fell into a range of-6.8%o-21.5%o,with a mean value of 5.6%o.The variations of both 87Sr/S6Sr and Sr values of the groundwater samples indicated that the Sr element was controlled by the weathering of limestone,dolomite and silicate rock.However,the figure of STSr/S6Sr vs.Sr2+/[K++Na+]showed that the anthropogenic inputs also obviously contributed to the Sr contents.For tracing the detailed anthropogenic effects,we traced the sources of solutes collected karst groundwater samples in Chongqing according to the j34S value of potential sulfate sources.The variations of both j34S and 1/SO42-values of the groundwater samples indicated that the atmospheric acid deposition(AAD),dissolution of gypsum(GD),oxidation of sulfide mineral(OS)or anthropogenic inputs(SF:sewage or fertilizer)have contributed to solutes in karst groundwater.The influence of oxidation of sulfide mineral,atmospheric acid deposit and anthropogenic inputs to groundwater in Chongqing karst areas was much widespread.
基金the National Key Research and Development Program project (2016YFC0502500)a Key project of National Natural Science Foundation (41530316)the China Geological Survey Programs of the Geological Environmental Innovation.
文摘On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale,this paper provides four pieces of evidence for;the integration of geology and ecology during the carbon cycle processes m the karst dynamic system,and estxmated the karst carbon sink effect using the methods of comparative monitoring of paired watersheds and the carbon stable isotope tracer technique.The results of the soil carbon cycle in Maocun,Guilin,showed that the soil carbon cycle in the karst area,the weathering and dissolution of carbonate rocks under the soil,resulted in a lower soil respiration of 25% in the karstoarea than in a non-karst area (sandstone and shale),and the carbon isotope results indicated that 13.46% of the heavy carbon of the hmestone is involved in the soil carbon cycle.The comparative monitoring results m paxred watersheds,suggesting that the HCO3 concentration m a karst spring is 10 times that of a rivulet in a non-karst area,while the concentration of inorganic carbon flux is 23.8 times.With both chemical stoichiometry and carbon stable isotopes,the proportion of carbon in karst springs derived from carbonate rocks was found to be 58.52% and 37.65% respectively.The comparison on carbon exchange and isotopes at the water-gas interface between the granite and carbonate rock basins in the Li River showed that the CO2 emission of the karst water is 10.92 times that of the allogenic water from the non-karst area,while the carbon isotope of HCO3^- in karst water is lighter by 8.62%.However,this does not mean that the karst water body has a larger carbon source effect.On the contrary,it means the karst water body has a greater karst carbon sink effect.When the karst subterranean stream in Zhaidi,Guilin,is exposed at the surface,carbon-rich karst water stimulated the growth of aquatic plants.The values of carbon stable isotopes in the same species of submerged plants gradually becomes heavier and heavier,and the 512 m flow process has a maximum range of 15.46%.The calculation results showed that 12.52% of inorganic carbon is converted into organic carbon.According to the data that has been published,the global karst carbon sink flux was estimated to be 0.53-0.58 PgC/a,equivalent to 31.18%-34.41% of the global forest carbon sink flux.In the meanwhile,the karst carbon sink flux in China was calculated to be 0.051 PgC/a,accounting for 68% of its forest carbon sink flux.
基金the financial support by IGCP 661, CAGS Research Fund (Grant No. YYWF201725)the National Natural Science Foundation of China (Grant No.41571203)+1 种基金the Ministry of Science and Technology of China (Grant No. 2016YFC0502403-2) the Bureau of Science and Technology of Guangxi (Grant No. 2014GXNS FAA118280)
文摘Through utilizing water flow monitoring, rock scratching, soil wood piles and radionuclide ^(137)Cs tracing in the Longhe karst ecological experimental site(hereinafter referred to"Longhe site"), Pingguo County, Guangxi Province, the features and values of soil erosion and soil leakage in different geomorphologic locations and land uses in the karst peak-cluster depressions are showed clearly. There are four kinds of geomorphologic locations in the karst peak-cluster depression, namely peaks, strip, slopes and depression. The soil leakage modulus in the peaks and strips respectively occupy 92.43% and 96.24% of the total mean soil erosion modulus at experimental sites. On the slope, soil leakage accounted for about 75%. At the bottom of depression, surface water was the main factor of soil erosion, and at last most soil leaked into underground rivers from sinkholes. The total soil erosion modulus and the contribution rates of relative surface soil erosion in regard of peaks, slopes and depressions gradually increased. There are also five major types of land use in the karst peak-cluster depressions, farmland, Kudingcha tea plantations, young Lignum Sappan fields, shrub-grassland and pastures. The soil erosion modulus of slope farmland has the highest value with an increasing trend year by year. But soil erosion modulus of other four land use types decreased by year, which shows the "grain for green" will result in better soil protection. By handling with rocky desertification and ecological rehabilitation in Longhe site, the mean soil erosion modulus of the karst peak-cluster depression has decreased about 80% from 2003 to 2015.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05070403)the National Natural Science Foundation of China (Grant Nos. 41171246, 41301273)the National Science-technology Support Plan Projects (Grant No. 2012BAD05B03-6)
文摘Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distribution. In this study, considering soil distribution, SOC content and density were investigated along positive successional stages （cropland, plantation, grassland, scrubland, secondary forest, and primary forest） to determine the effects of land cover type on SOC stocks in a subtropical karst area. The proportion of continuous soil on the ground surface under different land cover types ranged between 0.0% and 79.8%. As land cover types changed across the positive successional stages, SOC content in both the 0-20 cm and 20-50 cm soil layers increased significantly. SOC density （SOCD） within O-lOO cm soil depth ranged from 1.45 to 8.72 kg m^-2, and increased from secondary forest to primary forest, plantation, grassland, scrubland, and cropland, due to discontinuous soil distribution. Discontinuous soil distribution had a negative effect on 8OC stocks, highlighting the necessity for accurate determination of soil distribution in karst areas. Generally, ecological restoration had positive impacts on SOC accumulation in karst areas, but this is a slow process. In the short term, the conversion of croplandto grassland was found to be the most efficient way for SOC sequestration.
基金National Natural Science Foundation of China, No.41361081 High-level Innovative Talents Cultivation Program of Guizhou Province （Qian Ke He SY [201615674） Project of Innovation Program for Postgraduate Education of Guizhou Province, No.[2016]04
文摘This research examines the distribution features of 4960 caves across Guizhou Province, while probing the relationship between the caves＇ spatial patterns and geographic elements. This study is based on hydrogeological and topographic maps of Guizhou. ArcGIS software was used to process the adjacent index, spatial analysis, and coupling analysis of the caves altitude and longitude, as well as the rock properties, lithology, drainage and tec- tonic division of almost 5000 caves. Based on a point pattern analysis of Guizhou caves, the adjacent index is 0.53, and the coefficient of variation verified by Tyson polygon reached 72.469%. This figure reflects the clustered distribution pattern of the caves. Across the entire province, caves are divided into four concentrated areas and one weakly affected area. The four concentrated areas are Zunyi-Tongren, Bijie, Qianxinan-Liupanshui, and Gui- yang-Anshun-Qinan. The one weakly affected zone is Qiandongnan. The most concentrated among them is the Guiyang-Anshun-Qiannan area, which covers 24.67% of the total province area, and accounts for 36.63% of the total province＇s caves. Cave distribution in Guizhou is characterized as dense in the western part and sparse in the eastern part. Under this study background, the natural elements of formation, including lithology, structure, climate, hydrol- ogy, and altitude, and their effects on the distribution, number, and spatial pattern of cave development is analyzed.
