South China Karst Region Research Articles

Unraveling Trade‐Offs Among Reforestation, Urbanization, and Food Security in the South China Karst Region: How Can a Hinterland Province Achieve SDGs?

AbstractWhether the world can achieve the United Nations Sustainable Development Goals (SDGs) largely depends on the ability of less‐developed areas to cope with multiple socio‐economic changes. The challenges that hinterland areas would face during the realization of SDGs has not yet received enough attentions. In this study, a context‐based assessment of regional food balances was conducted, considering key challenges related to socio‐economic development as well as land use competition under the framework of the shared socioeconomic pathways (SSPs) and the implementation of reforestation. We examined one of the poorest hinterland provinces in China as a case study, projecting its food deficit and exploring the potential threats to and opportunities for SDG realization by 2030, including population growth, urbanization, urban land expansion and reforestation. The projections revealed a crop deficit of 4.9–9.8 million tonnes, corresponding to the food demands of 10.2–20.6 million people. Approximately 76%–81% of this deficit was expected to be caused by increased food demand, rather than reforestation policies. Therefore, for this less‐developed area with low agricultural productivity and large groups of vulnerable people, population growth and urbanization are likely to result in demands for food that cannot be met locally. In addition, large‐scale reforestation projects, while enhancing a number of key ecosystem services, will increase the local food deficit by promoting the abandonment of cropland. This will result in greater reliance on food imports, with potential impacts on SDG realization in other regions. These findings highlight the need for integrated governance across multiple scales to ensure hinterland sustainability.

Characterization and attribution of vegetation dynamics in the ecologically fragile South China Karst: Evidence from three decadal Landsat observations.

Plant growth and its changes over space and time are effective indicators for signifying ecosystem health. However, large uncertainties remain in characterizing and attributing vegetation changes in the ecologically fragile South China Karst region, since most existing studies were conducted at a coarse spatial resolution or covered limited time spans. Considering the highly fragmented landscapes in the region, this hinders their capability in detecting fine information of vegetation dynamics taking place at local scales and comprehending the influence of climate change usually over relatively long temporal ranges. Here, we explored the spatiotemporal variations in vegetation greenness for the entire South China Karst region (1.9 million km2) at a resolution of 30m for the notably increased time span (1987-2018) using three decadal Landsat images and the cloud-based Google Earth Engine. Moreover, we spatially attributed the vegetation changes and quantified the relative contribution of driving factors. Our results revealed a widespread vegetation recovery in the South China Karst (74.80%) during the past three decades. Notably, the area of vegetation recovery tripled following the implementation of ecological engineering compared with the reference period (1987-1999). Meanwhile, the vegetation restoration trend was strongly sustainable beyond 2018 as demonstrated by the Hurst exponent. Furthermore, climate change contributed only one-fifth to vegetation restoration, whereas major vegetation recovery was highly attributable to afforestation projects, implying that anthropogenic influences accelerated vegetation greenness gains in karst areas since the start of the new millennium during which ecological engineering was continually established. Our study provides additional insights into ecological restoration and conservation in the highly heterogeneous karst landscapes and other similar ecologically fragile areas worldwide.

Soil Organic Carbon Distribution and Its Response to Soil Erosion Based on EEM-PARAFAC and Stable Carbon Isotope, a Field Study in the Rocky Desertification Control of South China Karst.

Ecological restoration plays an important role in enhancing carbon sequestration ability in karst areas, and soil organic matter is one of the main carbon reservoirs in karst key zones. The serious soil erosion in karst areas leads to the loss of soil organic matter (SOM). However, the distribution characteristics of SOM and its response mechanism to soil erosion in the process of rocky desertification control have rarely been reported. In this study, soil samples of five restoration types (abandoned land, AL; grassland, GL; peanut cultivated land, PCL; Zanthoxylum bungeanum land, ZBL; forest, FS) were collected in typical karst rocky desertification drainage, south China. By measuring soil organic carbon (SOC), dissolved organic carbon (DOC), and δ13Csoc values and combining with spectral tools, the distribution and isotopic composition of soil shallow organic carbon in definitized karst drainage was definitized and the response of DOM spectral characteristics to soil erosion was explored. The results showed that three kinds of fluorescence components were detected by fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC), C1 and C2 were humus-like, and C2 was protein-like. Abandoned could be a more suitable control measure for enhancing SOC quality in the karst regions of south China. The variation trend of SOC content, δ13Csoc values, spectral indexes, and the distribution of fluorescence components from the midstream to downstream of the drainage indicated the soil redistribution. This study provides basic scientific data for karst rocky desertification control and for enhancing the soil carbon sequestration ability of karst.

Impacts of Anthropogenic Disturbances on Diatom Diversity in a Shallow Spring-Fed Pool

Human impacts cause significant problems for shallow lakes in the karst regions of South China. In recent years, the ecological issues related to managing and restoring these critical aquatic ecosystems have come to the fore. Lingshui Pool (LSP) is one of the most-studied spring-fed lake ecosystems in south China, and it has well-preserved chronological profiles. The LSP was a very shallow lake before dam construction in 1962. Due to the dam’s construction, rapid development and urbanization, this important freshwater ecosystem has suffered severe eutrophication and environmental degradation. In order to determine the environmental effects of recent anthropogenic disturbances and establish conservation recommendations for this lake ecosystem, we analyzed diatoms and weak-acid leachable elements from a well-dated sediment core from LSP to reconstruct the changes in aquatic conditions and diatom diversity during the period AD 1960–2013. This revealed shifts in diatom assemblages, diversity, and geochemistry that were strongly linked to the construction of a dam in 1962 and rapid eutrophication after 1990. Diatom diversity was stable and relatively high when submerged macrophytes were present between 1962 and 1990. Thus, the reintroduction of endemic macrophytes could benefit the ecological stability and diversity of this shallow lake.

Genetic and functional diversity of soil bacteria and fungi from different microhabitats in a karst region in Southern China

Little is known about the difference between bacterial and fungal genetic and functional diversity in karst regions of south China. In this study, the genetic and functional diversity of bacteria and fungi in nine types of soil microenvironments in the karst region in Maolan National Nature Reserve in Guizhou were investigated by PCR-DGGE (Denaturing Gradient Gel Electrophoresis) and BIOLOG EcoPlates. Maolan National Nature Reserve is a UNESCO Biosphere Reserve and plays an important role in protecting the karst forest ecosystem and rare and endangered wild animals and plants in central Asia. The results showed that the diversity of both bacteria and fungi was high and the main factors influencing the diversity of bacteria and fungi were different. The bacterial community structure from different microhabitats under the same vegetation type had higher similarity than similar microhabitats in different vegetation types, which could indicate that the bacterial community structure was mainly controlled by vegetation. For fungi, similar microhabitat species under different vegetation types had higher similarities than different microhabitats species under the same vegetation type, which could indicate that the fungal community structure is mainly controlled by microhabitats. In addition, the metabolic patterns of similar microhabitats in different vegetation were different, while the metabolic patterns of different microhabitats in the same vegetation were not obviously different. In conclusion, the effect of vegetation types on soil microbial functional diversity was greater than that of microhabitats, and this difference was reflected by the different degrees of influence on soil microbial genetic diversity and community structure.

Mitochondrial genome of Parasinilabeo longicorpus provides insights into the phylogeny of Labeoninae

Parasinilabeo longicorpus is an endemic species living in the karst regions of South China. In the present study, we firstly performed the complete mitogenome sequence of P. longicorpus (Cyprinidae: Labeoninae). Results showed that the mitogenome was 16,596 bp in length and contained 37 genes (i.e. 13 protein-coding, 22 transfer RNA, and two ribosomal RNA genes) and a single control region. The genetic arrangement and distribution of the mitogenome were consistent with that of other vertebrates. Phylogenetic analysis of the protein-coding genes indicated that Labeoninae species could be divided into three branches. Parasinilabeo longicorpus showed close evolutionary relationship with P. assimilis. This study should help to improve our understanding of the mitogenomes and phylogenetics of Labeoninae, and provide a foundation for further taxonomic, systematic, and genetic studies.

Breeding system and bird pollination of Camellia pubipetala, a narrowly endemic plant from karst regions of south China

AbstractCamellia pubipetala is an endemic and endangered species with small and isolated populations occurring only in karst regions in Guangxi of south China. To understand the reproductive biology of C. pubipetala and its possible influences upon its endangered status, its breeding system and pollination ecology were studied in the Longhushan (LHS) and Longzhao (LZ) populations of this species. The flowering duration of the C. pubipetala populations spanned from late January to early April and anthesis of a single flower usually lasted 5–7 days. This species is homogamous, and the pollen and stigma are viable throughout anthesis. Each bagged flower could secrete 141.5 μL of nectar at a sugar concentration of 25.0% during anthesis. The observed high pollen/ovule ratio, and the results of hand‐pollination experiments indicated that this species obligately outcrosses. Open pollination resulted in a significantly decreased fruit set (6.7%) and seed set (38.9%) compared to supplementary pollination treatment (23.3% and 64.7%, respectively), which is indicative of a pollen limitation in the process of pollination. The primary pollinator of C. pubipetala is the sunbird Aethopyga christinae and its visiting frequency is quite low, whereas the honeybee Apis cerana is only an occasional pollinator in wild populations. Low reproductive rates in C. pubipetala were found to be a consequence of few species of pollinators and their low visiting frequency. Pollen limitation may be a crucial factor that contributes to the endangered nature of this species. Artificial pollination and the release of pollinators are effective ways to increase the fruit and seed yield of this species.

Variation Characteristics of the Main Hydrochemical Indexes in Typical Subterranean Rivers in the South China Karst Region Based on Curve Fitting.

The water quality of subterranean rivers in the South China Karst region has undergone dramatic changes resulting from industrial and social development over the past 60 years. The combination of sampling results from subterranean rivers in four typical study areas in the South China Karst region from October to December 2015 (dry season) and correlation analysis using SPSS revealed that the main ions K+, Na+, and SO42- exhibited a significant correlation (p<0.01) and that Ca2+, HCO3-, and Mg2+ exhibited a good correlation (p<0.01). Additionally, we consolidated the data collected since 1960 and, by applying MATLAB, a variety of fitting curve methods were used to fit all the data, and the results showed that cubic spline interpolation fitting performed the best. The squared correlation coefficients (R2) of the obtained fitting curves for Ca2+, HCO3-, and Mg2+ are 0.8545, 0.8689, and 0.7632, respectively, and the corrected R2 values are 0.6739, 0.7088, and 0.4853, respectively. The R2 values of the obtained fitting curves for K+, Na+, Cl-, SO42-, and NO3- are 0.9085, 0.8964, 0.7531, 0.6222, and 0.7997, respectively, and the corrected R2 values are 0.7904, 0.7669, 0.5272, 0.2815, and 0.6127, respectively, indicating excellent fits. Based on the fitting curves, the overall water quality conditions in the karst region were analyzed and compared. Finally, the development of subterranean rivers in the South China Karst region was determined. Based on the results, the following conclusions can be drawn: the development of the subterranean rivers is indeed a slow process, but water quality can change rapidly in response to the transformation of industrial society. Additionally, the results indicate the crucial importance of urban planning that takes into account environmental protection during development in karst regions. This study aims to provide a basis for the management of karst areas and the improvement of groundwater quality by evaluating geochemical processes.

Satellite‐Observed Major Greening and Biomass Increase in South China Karst During Recent Decade

AbstractAbove‐ground vegetation biomass is one of the major carbon sinks and provides both provisioning (e.g., forestry products) and regulating ecosystem services (by sequestering carbon). Continuing deforestation and climate change threaten this natural resource but can effectively be countered by national conservation policies. Here we present time series (1999–2017) derived from complementary satellite systems to describe a phenomenon of global significance: the greening of South China Karst. We find a major increase in growing season vegetation cover from 69% in 1999 to 81% in 2017 occurring over ~1.4 million km2. Over 1999–2012, we report one of the globally largest increases in biomass to occur in the South China Karst region (on average +4% over 0.9 million km2), which accounts for ~5% of the global areas characterized with increases in biomass. These increases in southern China's vegetation have occurred despite a decline in rainfall (−8%) and soil moisture (−5%) between 1999 and 2012 and are derived from effects of forestry and conservation activities at an unprecedented spatial scale in human history (~20,000 km2 yr−1 since 2002). These findings have major implications for the provisioning of ecosystem services not only for the Chinese karst ecosystem (e.g., carbon storage, water filtration, and timber production) but also for the study of global carbon cycles.

Origin and effect factors of sedimentary organic carbon in a karst groundwater-fed reservoir, South China.

Reservoirs are commonly recharged by groundwater that is rich in bicarbonate ions in karst regions of South China, and the recharge of this groundwater to the reservoir can affect the biogeochemical processes of carbon sedimentation at the reservoir bottom. In this study, Dalongdong Reservoir, which is mainly recharged by two subterranean streams, was investigated based on a 42-cm-thick sedimentary core and the 210Pb/137Cs dating technique and isotope analyses to understand the sedimentary history and identify the carbon sources. The 210Pb/137Cs age model showed that the sediments were accumulated over the last 60years. The annual increase precipitation and temperature showed no obvious change compared with trends of δ13C in total organic carbon (δ13Corg), δ15N values in total nitrogen, and the carbon and nitrogen ratio (C/N). This shows that climate was not the main control of the variation in sediment factors. Based on δ13Corg, δ15N, C/N, and isotopic mixing modeling, sources of organic carbon in the sediments were derived from plankton (60.84%), soil (22.93%), waste water (14.56%), and terrestrial plants (1.67%). From 1958 to 1978, reservoir establishment and leakage affected the contribution of the four sources. The contribution of the plankton source increased from 1978 to 2015, resulting from change of water level and continued input of external nitrogen. However, because of the revegetation supplied by an economic aid project the contribution of soil showed a considerable decreasing trend from 1978 to 2002. After 2002, For "Grain for Green" project, the contribution from soil further decreased. After reservoir construction, the contribution of waste water stabilized. The contribution of terrestrial plants started increased rapidly after 2002. Karst groundwater, which contains more dissolved inorganic carbon containing lower δ13CDIC than the water sources of other lakes or reservoirs, makes the δ13Corg value of sediment more negative by phytoplankton photosynthesis in the reservoir.

典型喀斯特石漠化生态系统土壤有机碳时空分布格局及其与环境的相关性

PDF HTML阅读 XML下载 导出引用 引用提醒 典型喀斯特石漠化生态系统土壤有机碳时空分布格局及其与环境的相关性 DOI: 10.5846/stxb201510152081 作者: 作者单位: 贵州师范大学喀斯特研究院,贵州师范大学喀斯特研究院,贵州师范大学喀斯特研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 贵州省社会发展攻关计划课题（黔科合SZ字[2014]3036号）；国家水利部公益性行业科研专项经费项目（201401050）；贵州省水利科技经费项目（KT201409）；贵州师范大学博士科研启动基金（202） Distribution of soil organic carbon related to environmental factors in typical rocky desertification ecosystems Author: Affiliation: Institute of South China Karst,Guizhou Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选取中国西南3个典型喀斯特石漠化生态系统（贵州毕节鸭池高原山地石漠化区、贵阳红枫湖高原盆地石漠化区和关岭花江高原峡谷石漠化区）为研究区，广泛建立野外样地，开展石漠化生态系统土壤有机碳分布及其与石漠化等级、地形地貌、植被、土壤性质等环境因子的相关性研究。结果表明：1）喀斯特石漠化生态系统土壤有机碳含量较低，毕节鸭池、贵阳红枫湖和关岭花江3个石漠化生态系统平均值分别为23.42、25.78、26.03 g/kg，且3个不同地貌类型石漠化土壤有机碳含量无明显差异。2）土地覆被变化明显影响了土壤有机碳含量，原生森林土壤有机碳平均含量31.32 g/kg，是所有类型中最高的。随着土地覆被由原生森林至石旮旯地退化不断增加的过程，土壤有机碳含量显示先降低后增加的变化趋势。3）土壤有机碳与土壤特性有明显的相关性，与土壤总氮、水解氮、速效钾、总孔隙度、自然含水量、毛管持水量、田间持水量和上层渗透性存在极显著地正相关，与总磷、下层渗透性存在显著地正相关，与容重存在极显著地负相关。4）植物多样性的丰富度指数（R）和多样性指数（H）与土壤有机碳含量有明显的相关性，达到了极显著的水平。5）不同石漠化等级土壤有机碳含量有显著差异，随着石漠化干扰程度的递增，土壤有机碳含量显示了先减小后增加的趋势。研究结果对中国西南喀斯特森林生态保护、石漠化生态系统恢复重建以及应对全球气候变化碳循环的减源增汇具有重要的理论意义和实践指导价值。 Abstract:Karst rocky desertification is an important ecological issue hindering the socioeconomic development of the South China Karst region. In the present study, firstly, three typical rocky desertification regions-Bijie Yachi, Qingzhen Hongfenghu, and Guanling Huajiang, Guizhou Province, representing three different typical karst landforms-plateau mountain, plateau basin, and plateau gorge, respectively, were selected as experimental areas. Then, 90 sample plots with an area of 20 m×20 m each were established. The distribution of soil organic carbon (SOC) in relation to environmental factors (degree of rocky desertification, landform, vegetation, soil property, etc.) in these plots was determined using field measurements, laboratory detection, and mathematical statistics. The following results were obtained:1) The SOC content of karst rocky desertification ecosystems was low. The average content of the three experimental areas of Bijie Yachi (Plateau Mountain), Qingzhen Hongfenghu (Plateau Basin), and Guanling Huajiang (Plateau Gorge) was 23.42, 25.78, 26.03 g/kg, respectively. There was no significant (P=0.23) difference of SOC contents among the three different landform experimental areas. 2) Land cover change can affect the SOC content. The SOC content of virgin forest (31.32 g/kg) was the highest. With increased soil degeneration from virgin forest to gravel land, the SOC content first decreased and then increased. 3) The SOC content was correlated with soil physico-chemical properties. Specifically, the SOC content was extremely significantly positively correlated with total nitrogen content, hydrolyzed nitrogen content, available potassium content, total porosity, total phosphorus content, natural moisture capacity, field moisture capacity, capillary moisture capacity, and upper strata saturated permeability; significantly positively correlated with total phosphorus content and lower strata saturated permeability, and extremely significantly negatively correlated with soil bulk density. 4) The SOC content and plant diversity rich (R) and diversity (H) indices were extremely positively correlated. 5) There were significant differences of SOC contents between different degrees of rocky desertification. Along with increased degrees of rocky desertification, the SOC content initially decreased and then increased. Based on these results, the distribution pattern of the SOC content and its impact factors in karst rocky desertification ecosystems was clarified. These results have important implications for the protection of karst forest ecosystems, the reconstruction of rocky desertification ecosystems, and the response to global climate change. 参考文献 相似文献 引证文献

Quantitative Evaluation of Ecosystem Health in a Karst Area of South China

The purpose of this study is to propose a GIS-based mechanism for diagnosing karst rocky desertification (KRD) ecosystem health. Using the Huajiang Demonstration Area in Guizhou Province as a case study, this research offers a multi-factor indicator system for diagnosing KRD ecosystem health. A set of geologic, environmental, and socio-economic health indicators were developed based on remote sensing images from field-investigation, hydrological, and meteorological monitoring data. With the use of grid GIS technology, this study gives an indicator for diagnosing the spatial expression of desertification at a 5 m × 5 m grid scale. Using spatial overlaying technology based on grid data, the temporal and spatial dynamics of ecosystem health in the Huajiang Demonstration Area were tracked over a 10 year time span. The results of the analysis indicate that ecosystem health in the Huajiang Demonstration Area varies regionally, and has overall improved over time. The proportion of healthy area increased from 3.7% in 2000 to 8.2% in 2010. However, unhealthy and middle-health areas still accounted for 78.7% of the total area by 2010. The most obvious improvement of ecosystem health was in an area where comprehensive control measures for curbing KRD were implemented. These results suggest that comprehensive control of KRD can effectively mitigate ecosystem deterioration and improve ecosystem health in karst regions of South China.

Additions to Karst Fungi 1: Botryosphaeria minutispermatia sp. nov., from Guizhou Province, China

Botryosphaeria is a species rich genus of plant saprobes, pathogens and endophytes, with a global distribution, on a wide variety of mainly woody hosts. Recent studies have discovered a wide-ranging diversity of species in Botryosphaeria. This work adds to this increasing body of knowledge on the genus, by introducing a new species of Botryosphaeria occurring on dead wood in a terrestrial habitat in Guizhou Province, of the south China Karst region. Analysis of a combined ITS and EF1-α sequence data matrix was applied to infer the phylogenetic position of the new species in Botryosphaeria and B. minutispermatia is described and illustrated based on morphology and phylogeny. The new species is characterized by erumpent, botryose, clustered, ostiolate ascomata, bitunicate, clavate asci, filiform, rarely branched pseudoparaphyses, fusiform, hyaline ascospores and a fusicoccum-like asexual morph produced in culture and formed a distinct clade within the genus Botryosphaeria.

Trend of water resource amount, drought frequency, and agricultural exposure to water stresses in the karst regions of South China

Frequent drought occurrences have adverse effects on the availability of water resources and have consequently caused growing risks of water-related stresses in the karst regions of South China. For better water management, we investigated the trend of water resources in the past five decades and analyzed the drought frequency distribution in these regions with the of regional water resource amount series. Moreover, we assessed the decadal variability in the agricultural exposure to water stresses in the karst regions of South China. Results indicated that water resources were had a lower amount in most provinces during 2000–2013. Compared with 1961–1999, 2000–2013 showed a decline of 1139.3 × 108 m3 (8.51 %) in the average annual water resources. From the periodic pattern analysis, the periods 1987–1988 and 2009–2011 experienced a negative phase and the lowest amount of water resources in the cycle period of 20 years (dominant cycle period). The generated GEV distribution was a good fit to the probability distribution of extremely low water resource amount. Based on the analysis results, low water resource amount (lower than the value with a return period of 10 years) occurred 2.5 times on average in every province during 2000–2013. Moreover, the agricultural exposures to water stresses were investigated and found to exhibit different degrees of severity across regions and decades. The proportions of agriculture land areas exposed to water stresses in the 1960s, 1970s, 1980s, and 1990s are 39.31, 42.15, 41.28, and 45.78 %, respectively. In the 2000s, more and more agricultural lands (about 68.37 %) were exposed to water stresses, mainly in Yunnan, Guangzhou, Guangxi, and Sichuan. Particularly, large areas exhibited high agricultural exposures to water stresses in 2006 and 2009. The karst regions of south China are facing great challenges in managing water resources against droughts.

Bat species diversity and conservation in Libo World Natural Heritage Site of South China Karst

During field surveys between October, 2010 and October, 2011, we investigated bat species diversity in 69 caves in 6 townships in the Libo World Natural Heritage Site located in the South China Karst region. We also investigated bat specimens from the zoological museum of the School of Life Sciences, Guizhou Normal University, and reviewed pertinent literature as well. We uncovered 7 families encompassing 24 bat species in the area, including 2 new records of species for Guizhou Province, i.e., Myotis blythii and Hipposideros pomona, and 11 species first documented in Libo. Unfortunately, many caves have been exploited for tourism, thereby posing a great threat to the survival of cave-dwelling bats. We propose some special strategies that could be taken to protect the bats roosting in these caves.

Rare earth element geochemistry of waters and suspended particles in alkaline lakes using extraction and sequential chemical methods

The concentrations of rare earth elements in the waters and suspended particles from two alkaline lakes in a carbonate drainage basin of the South China Karst region were determined via ICP-MS. Sequential chemical extraction experiments were conducted on the suspended matter to investigate water-particle interaction processes. Due to their high pH, the alkaline lakes have lower concentrations of dissolved rare earth elements than those reported for most other terrestrial surface waters of the world. Linear regressions between pH and the rare earth element (REE) concentrations over a wide pH range show a “three stage model,” implying the geochemical behavior of dissolved REEs in surface waters is mainly controlled by pH. Shale-normalized patterns of dissolved REEs mainly show a marked enrichment in heavy REEs (HREE), while acid-extracted and organic REEs mainly show convex patterns and the residual fractions have flat patterns. Distinct positive La anomalies were observed in the Lake Aha and its river waters, which also exhibit a very high Mn concentration, indicating severe redox and scavenging conditions. Both negative and positive Ce anomalies were clearly observed in the dissolved phase and extracted fractions of suspended particulate matter. The positive correlation of Ce anomalies with Mn indicates that redox reactions control these Ce anomalies.

中国南方喀斯特石漠化演替过程中土壤理化性质的响应

以中国西南典型喀斯特石漠化生态系统土壤为研究对象,运用野外定点取样和实验室分析检测方法,研究不同等级石漠化环境土壤理化性质特征;运用空间代替时间方法,探讨石漠化演替过程中土壤理化性质的响应及其机制,旨在为中国西南喀斯特森林生态保护和石漠化生态系统恢复重建提供理论支撑。结果表明:1)不同等级石漠化环境土壤理化性质存在显著差异,土壤容重、毛管孔隙度、总孔隙度、田间含水量、毛管含水量、pH值、有机质、水解氮、有效磷和全钾均在不同等级石漠化环境间具有显著差异。但这些指标并不是随着石漠化程度增加而一直退化,而是一个先退化后改善的趋势;2)土壤有机质、氮素、毛管持水量、容重和孔隙度与土壤其它绝大多数理化因子具有明显的相关性,是土壤理化性质的关键因子,在改善土壤理化性质和促进养分循环方面起着关键作用;3)主成分分析也表明,土壤有机质、氮素、钾素、容重、持水状况、孔隙度等是基于土壤理化性质评价石漠化程度的关键指标。作者提出了强度石漠化环境裸岩对土壤养分的聚集效应学说和喀斯特石漠化演替过程中土壤理化性质的响应及其机制。研究结果对中国西南喀斯特森林生态保护和石漠化生态系统恢复重建具有重要的理论意义和实践指导价值。;Karst rocky desertification has been an important ecological issue hindering the economy and society development of South China Karst region, and the control of rocky desertification has been clearly listed in the national projects of economy and society development. But there are short of soil researches in karst rocky desertification ecosystem, and the succession of soil physical-chemical properties is still unclear in the process of rocky desertification, which hardly hinders the control of rocky desertification well work. <br>Based on these problems, in this study, firstly, three typical rocky desertification regions, that is, Yachi, Hongfenghu, and Huajiang of Guizhou Province, representing three different typical karst landforms of plateau mountain, plateau basin, and plateau gorge, respectively, were selected as experiment areas, and 45 sample plots with area of 20 m × 20 m, respectively, were set up for the 5 typical degrees of rocky desertification, that is, no, potential, low, middle, and high, in these three experimental areas. Then, the soil physical-chemical properties were surveyed and analyzed by the methods of chemical determination and mathematical statistics. Results show that 1) there are obvious differences of soil physical-chemical properties between different degrees of rocky desertification, specifically, bulk density, capillary porosity, total porosity, field moisture capacity, capillary moisture capacity, pH, organic matter content, hydrolysis nitrogen content, available phosphorus content, and total potassium content. But, not as expected, the soil degeneration do not always raise with the increased degree of rocky desertification. In fact, with the increased degree of rocky desertification, the soil degenerate firstly and then improve; 2) Organic matter content, nitrogen content, capillary moisture capacity, bulk density, and porosity all are remarkable correlation with other factors of soil physical-chemical properties, and they are the key factors of soil physical-chemical properties, which have important functions in advancing the soil nutrient cycle and improving the soil physical-chemical properties; 3) Principal component analysis also show that organic matter content, nitrogen content, potassium content, bulk density, moisture capacity, and porosity are the key factors in evaluating the degrees of rocky desertification. Based on these results, the theory, that is, bare rocks have a collected action for soil nutrients in karst rocky desertification ecosystem, was raised, and the response and its mechanism of soil physical-chemical properties to rocky desertification succession was presented. Results have important values in the protection of karst forest ecosystem and the control of rocky desertification.

Seasonal variation in nature and chemical compositions of spring water in Cuihua Mountain, Shaanxi Province, central China

Two springs (Cuihua Spring, Shuiqiuchi Spring) in Cuihua Mountain of the Qinling Mountains were observed and sampled monthly during 2004 and 2005 to trace their physical properties and chemical compositions with seasons. Although both pH values and cation (Ca2+, Mg2+, K+, and Na+) contents of Cuihua Spring are higher than those of Shuiqiuchi Spring, seasonal variations in both springs are obvious. The pH values of both spring waters are between 5.69 and 6.98, lower than that of rainwater during summer and autumn. From January to November, the pH values of both springs similarly vary from high to low and then to high again. Variations in electric conductivities of two spring waters are contrary, although their electric conductivities are positively correlative with the cation content respectively. This can be attributed to different water sources of the two springs or different acidic rocks they passed. The contents of HCO3−, Ca2+, Mg2+, K+, and Na+ are low, indicating a low silicate weathering that the strata in this district are mainly composed of granite and schist of quartz and mica. Differing from change in spring water in karst regions of South China where abundant precipitation and dilution of rainwater cause low pH and electric conductivity in summer and autumn, the seasonal variations in the pH values and the electric conductivities of two springs in Qinling Mountains are attributed to seasonal changes in CO2 produced by microorganisms’ activity in soil within respective year, rather than rainfall. The microorganisms’ activity in soil produces more CO2 during summer and autumn. Therefore, the water nature of springs in silicate regions chiefly reflects the seasonal changes of CO2 produced by the microorganisms in soil.

Hydrogeologie Characteristics and Deforestation of the Stone Forest Karst Aquifers of South China

AbstractStone forest aquifers comprise an important class of shallow, unconfined karstic aquifers in the south China karst belt. They occur under flat areas such as floors of karst depressions, stream valleys, and karst plains. The frameworks for the aquifers are the undissolved carbonate spires and ribs in epikarst zones developed on carbonate strata. The ground water occurs within clastic sediments which infill the dissolution voids.The aquifers are thin, generally less than 100 meters thick, and are characterized by large lateral permeabilities and small storage. The result is that the aquifers are difficult to manage because recharge during the rainy season moves rapidly out of the aquifers. Water levels fall sharply as the dry season progresses and the ground‐water supply falls off accordingly.The magnitude and duration of the seasonal recharge pulse that replenishes the stone forest aquifers have been severely impacted by massive post‐1958 deforestation in the south China karst region. Water that was formerly retained beyond the wet season in the forested uplands, later to be released to the stone forest aquifers under the lowland plains, now passes quickly through the system during the wet season. The loss of this seasonal upland storage has resulted in both a reduction in the volume of recharge to the lowland stone forest aquifers and a shortening of the seasonal recharge event. The result is accelerated water‐level declines in the stone forest aquifers as the dry season progresses which, in turn, causes premature dewatering of wells and decreased spring discharges. This response is compounded by increased ground‐water withdrawals as the people attempt to offset the declining supply. Management of the total water‐supply system requires not only tinkering with the aquifer, but massive reforestation efforts to restore dry season water retention in the upland parts of the watersheds.

On Limits to Seed Production

On Limits to Seed Production