CHEN Ke, YANG Shengtian, ZHANG Liping, GUAN Yabing, WANG Zhaoduo, ZHANG Xitong
Analysis of vegetation ecological water use growth in karst rocky desertification area under the background of rapid economic growth
[Background] Due to the special geological structure and the destruction of vegetation in karst rocky desertification area, the rainfall quickly leaks and is lost. With the rapid economic development, there are the dual pressures of ensuring water for production and domestic use as well as ecological water for vegetation. Guiyang city, the capital of Guizhou province, has developed rapidly in recent years and is located in the center of karst rocky desertification in southwest China, was selected as the study area to analyze the growth potential of vegetation ecological water use.[Methods] With a combination of vertical comparison and horizontal comparison, the change trends of production water usage, domestic water usage and ecological water usage in the study area from 2003 to 2013 were compared, and the total water resources of the study area were combined to analyze the growth potential of ecological water consumption. In addition, remote sensing technology was also combined to reveal the potential growth area of vegetation ecological water usage.[Results] 1) Guiyang is relatively rich in water resources, but the groundwater that was difficult to use directly accounted for up to 30.12% of local total water resources in every year. 2) Relative to annual change in precipitation, the production and domestic water usage were relatively stable, and maintained at around 1.023×109 m3 every year since 2008. 3) Compared with production and domestic water usage, Guiyang's ecological water consumption showed a slow growth trend, and it would be a substantial increase in the future. 4) The multi-year average green water in Guiyang city accounted for 48.71% of the precipitation, which was 16 percentage points lower than the global average(65%), and there will be growth potential.[Conculsions] For karst rocky desertification areas with relatively abundant water resources but severe vegetation destruction, increasing ecological water usage has great potential, and it is a more feasible way to increase ecological water usage by restoring vegetation. The above analysis presents certain reference significance for the study of ecological water usage and reduction of soil erosion in similar areas.
CAI Xiongfei, ZHAO Shijie, XU Pei, WANG Ji, WANG Yukuan
Soil conservation benefits of side ditches on slope farmland: Taking the sandy loam soil in Changling town, Wanzhou district, Chongqing as an example
[Background] Slope Farmland Side Ditch (SFSD) has been widely used in the prevention and control of soil and water loss in the hilly area of southern China for a long time, where the purple soil hilly area in East Sichuan is the most common. Although there is a long history of practice and application about confluence of long slope (block) on one side of trench, the mechanism of water and sediment transport and deposition is still unclear.[Methods] A typical of purple soil in terms of distribution area and type, Wanzhou district was selected as the experimental area to ascertain the benefit and mechanism of soil conservation. Therefore, 27 events of field simulation experiments based on artificial rainfall were done in the region of Wanzhou, Chongqing.[Results] 1) When the bottom slope of the SFSD was 1° or 0°, the SFSD had good soil conservation effect. The soil conservation was 50.7%-83.5%. When the bottom slope of the SFSD increased to 3°, the SFSD soil conservation was very poor, and the average soil conservation was only 13.6%. 2) The bottom slope of the SFSD was the main factor that affected the soil conservation effect of the SFSD and which had a significant linear negative correlation with soil conservation. 3) Under the same bottom slope of the SFSD,different rainfall intensity and sediment concentration, both sediment input and sediment deposition were different, but the sediment rate changed little. When the bottom slope of the SFSD was 0 °, the deposition rate of sediment was between 77.0% and 83.5%, with an average of 79.0%. When the bottom slope of the SFSD was 1°, the deposition rate of sediment was 50.7%-62.8%,with an average of 55.5%. As the slope increased to 3°, the deposition rate of sediment was 9.6%-19.1% with an average of 13.6%.[Conclusions] Under the condition of same rainfall intensity and the bottom slope of the ditch, the treatment methods of the plot were different. The total amount of sand on the slope and the total deposition in the ditch were different, but the deposition rate did not change much.
YANG Haozhou, HE Guangxiong, WANG Yandan, LI Zhiquan, YU Jianlin, RAN Lin, SHI Liangtao
Spatiotemporal distribution characteristics of moisture on dry red soil slope in dry-hot valley and its response to cover type
[Background] Soil moisture is the limiting factor of vegetation restoration in dry-hot valley. It is of great practical significance to study the spatiotemporal distribution of soil moisture in this region. Yuanmou is located in the middle and upper reaches of the Jinsha River. It is a typical dry-hot valley area of the Jinsha River basin. Exploring the spatiotemporal distribution of soil moisture in Yuanmou helps to provide data support for vegetation restoration in dry-hot valley.[Methods] In the Yuanmou Jinlei Soil and Water Conservation Demonstration Garden in Yunnan province, the runoff plots in farmland, shrub-grass land, arbor-shrub-grass land, and bare land were selected as the research objects, and samples were placed at the slope of each runoff plot at 0, 10, and 20 m from the top of the slope. Soil moisture content data of 10, 20, 40, 60, 80, and 100 cm soil layers were collected twice a month with a TDR moisture analyzer, and the collected data were analyzed with geostatistics.[Results] 1) The dry-hot valley area of Yuanmou was drought and less rain, and the soil moisture content in the rainy season was 4.22-4.95 times that of the dry season. With the increase of soil depth, the soil moisture activity decreased. In dry season, there was no significant difference in soil moisture activity between different vegetation restoration modes and the same soil layer, and the fast-changing layer and active layer were mostly concentrated in the range of 0-40 cm; but the soil moisture of each soil layer showed great difference, and the soil moisture activity of shrub-grass land and arbor-shrub-grass land was strong in the rainy season. 2) The high value of soil moisture content showed the phenomenon that from dry season to rainy season, it gradually transferred to deep soil. The soil moisture content of bare land was relatively uniform in each soil layer, and the types of residual vegetation cover showed the characteristics of concentration of high-value areas in different degrees. 3) The soil moisture content of bare land was expressed as slope bottom > slope middle > slope top, and the vegetation-covered plots had the characteristics of slope top > slope middle > slope bottom except for dry season agricultural land and dry season irrigated grassland.[Conculsions] In dry-hot valleys, different vegetation cover may lead to the reduction of soil moisture activity in dry season and promote soil moisture retention. In the rainy season, precipitation is guided to the deep soil by enhancing infiltration and other plant functions, thus coordinating the spatiotemporal distribution of soil moisture and effectively improving the soil water environment.
HUANG Zhaowei, DONG Lei, WANG Chenyi, FU Jiajia, CHEN Xianxian
Effects of novel urease inhibitors on soil urease activity and soil microbial diversity
[Background] The inhibitor regulation technology of urease activity is one of the most effective biochemical methods to improve urea utilization, the Schiff base complex type urease inhibitors with double active sites belong to the fourth type of urease inhibitors(C15H14N3O2SClCu, FTUI). The purpose of this study is to investigate the effects of FTUI on urease activity and soil microbial diversity, so as to reveal the microbiological effects of these urease inhibitors and fully develop their potential value.[Methods] A copper (Ⅱ) complex containing Schiff base was synthesized by a two-step synthesis method at room temperature, and characterized by melting point apparatus, infrared spectrometer and synchronous thermal analyzer. 5-point method was used for collecting soil samples. Indophenol blue colorimetric method and dilution coating plate counting method were used to test the enzyme activity and its toxic effect on soil microbial biomass, and Origin and SPSS software were used for data processing.[Results] For complex FTUI, results showed that the inhibitory effect of the complexes on jack bean urease activity was significantly higher than that of commercially available acetohydroxamic acid (C2H5NO2). The soil urease activity was strongly inhibited in the low concentration range of 0.1%-1.0%, and the inhibitory effect increased with the increase of concentration, and the highest inhibition rate was 71.20%. Meanwhile, FUTI had a certain promoting effect on the growth of soil bacteria, actinomycetes and fungi, and the highest growth rate reached 60.30%, 71.71% and 1 592.85%, respectively, and it effect on fungi was more sensitive.[Conclusions] FTUI has a good inhibitory effect on the urease and soil urease, and promotes the growth of soil microorganisms, and the effect is most significant when the concentration is 1.0%.
Construction and optimization of Urumqi ecological network based on the morphological spatial pattern analysis and MCR model
[Background] In the context of rapid urbanization, issues such as land desertification, soil erosion, and destruction of biodiversity threaten the safety of the regional ecological environment. Building an ecological network is an important means to effectively protect habitat patches.[Methods] This paper took Urumqi as the study area, based on the 2017 land use data, utilized the morphological spatial pattern analysis (MSPA) method to analyze the landscape pattern of the study area and extracted ecological source areas by landscape index, with data such as land use, elevation, and normalized difference vegetation index (NDVI) to construct a comprehensive resistance surface according to the actual situation of the study area, used the minimum cumulative resistance (MCR) model to identify the Urumqi ecological corridors.[Results] The core area of the MSPA landscape type accounted for 73.88% of the total area, it is more in the south and east of the study area, and the area of islet patch was the smallest. By calculating the landscape index, 10 core patches in the study area with the highest patch importance index was extracted and used as ecological sources. There were 45 general corridors and 9 important corridors distributed in the southwest and northeast of the study area. According to the distribution characteristics of the source area and the actual situation in the study area, 7 new planned source areas and 10 general corridors were added, and an important stepping stone was generated to solve the fault phenomenon of the southwest and middle east of the study area.[Conculsions] Constructing a reasonable ecological network can restore the blocked ecological corridors, significantly improve the landscape connectivity of the entire study area, help protect the living environment of the species and ecological breakpoints, avoid urban soil erosion. It is of great significance to promote the construction of ecological civilization, sustainable economic development and protection of the ecological environment in Urumqi.
LI Qiang, SU Yingqing, FENG Zhenzhen, ZHOU Xin, GUO Ligang, MA Xiaohong, LIU Geng
Study on production-living-ecological space function coupling coordination in Fen river basin
[Background] With the rapid development of industrialization and urbanization, the continuous expansion of living space and production space has restricted the development of ecological space, and the contradiction among production, living and ecology is increasing. Watershed is a complex system integrating society, economy and nature, with production, living and ecological functions. As the largest river in Shanxi province, Fen river basin is also an important population and economic agglomeration area. In the long-term process of industrialization and urbanization, there are many problems in production-living-ecology space function. Exploring coupling coordination of production-living-ecology space function of Fen river basin plays an important role in the scientific and rational utilization and sustainable development of the land sources.[Methods] This paper took Fen river basin as the research area. According to the background characteristics of Fen river basin and referring to the relevant research results with similar regional characteristics,18 indicators were selected from three aspects of production function, living function and ecological function, and then the evaluation index system of spatial function of production-living-ecological in Fen river basin was constructed. Among them, the original data of each index was processed by the standardized method of non-zero transformation, and the weight was determined by entropy method. Finally, the coupling coordination model was used to quantitatively measure the coupling degree of spatial function, coupling coordination degree and coupling coordination degree between two pairs of production-living-ecological space in the Fen river basin in 2006, 2013 and 2018, and to analyze the spatial and temporal pattern and explore the causes.[Results] 1) In terms of the spatial and temporal pattern, the coupling degree presented the spatial characteristics of "low in the north and high in the south" and the embedding of low-value "patches", and the evolution trend showed the curve feature of "parabola with upward opening". However, the coupling coordination degree presented the pattern in which "patches" in high-value areas were embedded in low-value areas, while the evolution trend showed a "wave" curve feature. 2) The coupling degree of the production-living spatial function was high, but it was low in production-ecology and living-ecology space functions and went through the process of "high-decrease-increase", while the coupling coordination degree was at a lower level. 3) The main types, temporal and spatial characteristics and evolution of the coupling and coordination degree of the production-living-ecology space function in the study area were significantly affected by the spatial heterogeneity of the Fen river basin.[Conclusions] There are prominent contradictions among production-living-ecological space function in Fen river basin. Affected by the accumulation of ecological debt in the historical period, there is a great challenge to completely improve the coupling and coupling coordination of production-living-ecology space function in the short term. In the future, it is urgent to increase the research on the path of coordinated development of production-living-ecology space function in Fen river basin.
A bibliometric review on the environmental effects by check dam on the Loess Plateau based on the Web of Science database
[Background] The Loess Plateau is the largest and most concentrated loess area in the world. In order to reduce the sediment load, a large number of check dams have been constructed. The researches of check dams in the soil erosion on the Loess Plateau have attracted widespread attention; however, they have seldom been studied systematically.[Methods] In this study, bibliometric analysis and visualization were used to understand the research status of the research of check dams in the soil erosion on Loess Plateau and to assist researchers in establishing future research directions. The core collection of the Web of Science (WOS) was used as the data source. The search terms included the following:TS (Topic Search)=((erosion* or soil erosion* or soil loss* or sediment*) and (check dam* or check-dam or dam*) and (loess plateau*)), and a total of 234 related studies were retrieved. In our study, 212 research papers and reviews selected from WOS were imported into CiteSpace for analysis. Moreover, Excel 2017 was used to analyze the scientific research output. We have examined these topics from the publication outputs, the cooperation between authors and institutions, the evolution of keywords, and cocitation analysis of references.[Results] The results showed that the number of articles issued increased rapidly in recent years. Additionally, the number continuously shows a trend of growth in the future. Institute of Soil and Water Conservation, Chinese Academy Science, Northwest A&F University, and Xi'an University of Technology were the most active institutions with the most publications. Regarding authors, MU Xingmin, ZHAO Guangju, GAO Peng and FANG Nufang were the core authors in this field. The keywords "runoff", "sediment load", "impact", "climate change", "soil organic carbon", "soil and water conservation", "deposition", "precipitation", "vegetation", "model", "sediment source", "cs 137" and "fingerprinting" precented higher frequency in the network of co-occurring keywords, and based on keyword evolution analysis, we concluded that researches mainly focused on the application of WATEM/SEDEM model, isotope Tracer Technology, calculation of sediment production modules, sediment reduction benefits of check dams and influence of check dam on the relationship between water and sediment in multiple time scales. Clustering analysis divided the citation into seven clusters, namely WATEM/SEDEM, isotopes, specific sediment yield, multi-temporal scale, arid region, flow-sediment relationship and fingerprinting. Accordingly, we concluded that sediment reduction benefits of check dam construction, sediment source tracing methods, environmental effects of check dam construction, and the mechanism of sediment reduction in check dam trenches were the hot research fields in the past 10 years.[Conclusions] Check dams are very important for soil and water conservation in the Loess Plateau. It is necessary for scholars to strengthen the depth of research on sediment reduction and environmental effects of check dams.
YAN Sihua, GAO Yanming, WANG Huiru, LI Jianshe, WANG Xiaoyan
Research status of agricultural brackish water irrigation based on CiteSpace
[Background] In the context of global freshwater shortage, the search for alternative water sources has attracted wide attention from researchers around the world, the brackish water is widely distributed and abundant, as an important supplement and alternative resource for freshwater, getting high attention. The rational utilization of brackish water can not only solve the shortage of water resources, increase the irrigation guarantee rate, but also improve the problem of reducing farmers' production due to the deterioration of soil and water ecological environment.[Methods] This study is based on the CNKI and Web of Science core database, using CiteSpace bibliometrics software to analyze literature on agricultural brackish water irrigation, aiming at visual presentation of the research authors, institutions, research fields and key words of agricultural brackish water irrigation, the knowledge structure of current international research, as well as research hotspots and regions, were more clearly obtained, aiming to reveal the development and research frontier of agricultural brackish water irrigation.[Results] 1) From 1999 to 2019, the number of publications related to agricultural brackish water irrigation fluctuated and increased, and a core author group composed of YANG Jinsong, WANG Quanjiu and LI Peiyue and HUO Zailin was formed; various research institutes of the Chinese Academy of Sciences, Xinjiang Agricultural University, China Agricultural University, and University of California Riverside, and other research institutions with a high number of publications, the core author group and various institutions mainly existed in small teams and distributed. 2) At present, domestic and foreign research on agricultural brackish water irrigation mainly focuses on agricultural basic science, physical geography and surveying and mapping, crops, agricultural engineering, water resources, environmental science and ecology, agronomy and other disciplines. The research on the interoperability of knowledge content among various disciplines is related to salt water. 3) Research on the internal mechanism of brackish water irrigation methods on soil water and salt transport, research on crop growth and development, research on desalination strategies, improvement of salt accumulation, etc., and the construction of different detection methods (models, stable isotopes) may become a new research hotspot in recent years.[Conculsions] Water shortage is one of the main factors leading to soil cracking and ecologically environmental deterioration in arid and semi-arid areas, which restricts the development of global economy. Therefore, by summarizing and analyzing the hot issues and future trends of agricultural brackish water utilization, it is helpful for researchers to fully understand the current situation of international research and provide theoretical basis for it.
Soil and water conservation tillage measure factor T in the CSLE model: A method review
[Background] The Chinese soil loss equation (CSLE) is an important tool for the quantitative evaluation and prediction of regional soil erosion in China. In this model, the soil and water conservation tillage measure factor (T) is one of the seven important factors, which reflects the potential impact of soil and water conservation tillage measures on soil erosion. It is essential to assess the T factor value in an accurate way for the regional soil erosion evaluation and dynamic comparative analysis using the CSLE model.[Methods] Numerous literature retrievals were carried out with "Chinese soil loss equation (CSLE)"and"tillage factors" as keywords, we selected the literatures for analysis and integration. Based on these references, we summarized six methods to obtain the T factor value, and compared the advantages,disadvantages and the applicable conditions of each method.[Results] 1)Inquiry Method of Water Conservancy Census Results is extensively used due to its convenience, while the T factor is revised combing with the data of investigation units and runoff plots in the study areas. 2)Dynamic Monitoring and Inquiry Method of Regional Soil and Water Loss is simple and easy to proceed,however it is difficult to determine the T value of other crops as it is only for 10 main crops in China. 3)Land Use Classification Formula Method is easy to be used, and can be applied at small watershed, watershed and regional scale, but it requires to integrate remote sensing interpretation and query method to generate the specific factor values of various land use types and tillage measures, and it is a cumbersome, high-cost and time-consuming task while used at large scale. 4)Runoff Plot Formula Method is the most fundament alway to obtain relatively accurate T factor method; however, it is difficult to compare the effects of different tillage measures on soil erosion, and sediment data in the runoff plots of control and soil and water conservation measures need regular management and long-term monitoring.Runoff, soil erosion and sediment yield vary significantly in different scale basins, thusit is difficult to compare the effects of different tillage practices on soil erosion. 5)Slope Classification Method is of strong operability, and it does not rely on standard runoff plot, but accurate extraction of slope is needed. 6)Value-Assigned Method of Tillage Measures for Soil and Water Conservation is simple and convenient;while the accuracy and applicability in different research areas are required to be investigated.[Conculsions] These findings are of great significance to the selection of the calculating methods of soil and water conservation tillage measures.Nevertheless, in order to ensure the accuracy of T factor values obtained in the study area, the dynamic monitoring of soil and water loss in runoff plots under different tillage measures should be carried out for a long time in combination with local rotation system. In the large-scale study area, it is necessary to assign the T factor in combination with the national rotation system regionalization, and to calculate the T factor of other tillage measures in the study area via spatial information technology and field investigation. Besides, it is necessary to fully consider the specialty of the study area and the application scope of the selected method. The selection of control plot for tillage measures varies when different researchers calculate T factor value by runoff plot formula method, which leads to the difference of T factor value actually obtained, thus, it needs further exploration.
