LOU Yibao, SHI Dongmei, JIANG Guangyi, JIN Huifang, CHEN Zhengfa, LIN Zi
Evaluation of soil quality in the cultivated-layer of sloping farmland in purple hilly area based on minimum data set
[Background]The soil quality of a plowing layer directly affects the productivity of sloping farmland, in order to accurately evaluate the soil quality characteristics of a plowing layer for purple sloping farmland, objectively evaluate the soil quality in the plowing layer of purple soil sloping farmland is an important basis for preventing the soil erosion and degradation of purple soil sloping farmland and ensuring the high efficiency and stability of the soil productivity in plowing layer.[Methods] The plowing-layer (0-20 cm) soil of purple sloping farmland of Chuxiong-Yunnan, Guilin-Guangxi, Xingguo-Jiangxi and Nanxiong-Guangdong were collected as the research objects. The minimum data set (MDS) was established and the cultivated-layer soil quality was evaluated by the combination of principal component analysis (PCA) and correlation analysis based on the 12 soil property indexes which were selected.[Results] 1)Soil quality of cultivated-layer for sloping farmland varied significantly among different purple soil sites. Soil nutrients of cultivated-layer were poor relatively, soil organic matter (14.89 g/kg) and total nitrogen (0.85 g/kg) were on the fourth level, and available phosphorus (28.84 mg/kg) on the secondary level of the classification criterion of soil nutrient, pH value was faintly acidity. The ranges of soil bulk density was 0.93-1.62 g/cm3, and the cultivated-layer thickness varied of 15-30 cm, The variability of soil bulk density, silt content, cultivated-layer thickness, pH value variability were small. Sand content, penetration resistance, shear strength and total nitrogen with general variability, and the clay content, saturated water conductivity, organic matter and available P were in large variability. In general the variability of soil chemical indexes were greater than that of physical indexes. 2)The MDS on soil quality evaluation included the seven indexes of soil bulk density, available phosphorus, organic matter, saturated hydraulic conductivity, penetrate resistance, sand content and cultivated-layer thickness, which reflected the effective information of soil quality of cultivated-layer with accuracy evaluation result for soil and water conservation fertilizer conservation and yield-increasing potential. 3)The soil quality of cultivated-layer for purple sloping farmland was ordered as Chuxiong-Yunnan > Guilin-Guangxi > Xingguo-Jiangxi > Nanxiong-Guangdong. The obstacles of cultivated-layer with low penetrate resistance and soil bulk density in Chuxiong-Yunnan, lower organic matter and cultivated-layer thinning were the obstacles of cultivated-layer for Guilin-Guangxi and Nanxiong-Guangdong seperately, Xingguo-Jiangxi with the obstacle of slightly higher sand content and lower saturated water conductivity.[Conclusions]The results may provide some useful scientific supports not only for the soil quality recovery of the cultivated-layer but for the sustainable utilization of crop growth and the control of soil and water loss of purple soil sloping farmland,which are also conducive to soil improvement, reasonable cultivated layer construction and sustainable utilization of the sloping farmland recourses in purple hilly area.
LIU Linqi, LI Yang, WANG Qian, CHEN Jingling, YANG Xitian, FAN Wei
Dynamic characteristics of Quercus variabilis seedling growth
[Background] Plant growth dynamics reveals the impacts of the environment on plants. Quercus variabilis is one of the afforestation species widely used in rocky mountainous areas. It is prone to growth retardation or death under environmental stress. In order to further reveal the reasons for the stunted seedling growth and death, this paper traced the life course of each organ.[Methods] In this study, the seedlings of Quercus variabilis were sampled by hand-excavation in the nursery field. The sampling interval was 10 d in the first year, one month in the second year, and one season in the third year, and the growth, dry biomass and sugar concentration of every organ in the seedlings were measured by drying and Anthrone colorimetry.[Results] 1) During the first growing season, there was obvious growth-stasis-regrowth of stem and leaf, showing the phenomenon of blocked growth in summer.2) Except for the winter season (December-March of the next year), the roots of 1/2-year-old seedlings grew continuously. At the age of 3, the rate of root elongation was slower than at 1/2 years, with root thickening and lateral root growth being the main growth.3) Analysis of seed kernel dry matter consumption and total sugar concentration showed that the growth of seedlings in their first summer (from early June) was blocked, which was in line with the lowest seed kernel residue and total sugar. 4) In early June, the total sugar concentration of the seed kernel began to fall beneath the total sugar concentration of the leaf, indicating that the seed kernel was no longer the main nutrient donor of the plant.5) Seedlings aged 2 to 3 years began to grow from the middle of March, and growth slowed down in July, and they did not show the phenomenon of blocked growth.[Conclusions] The ecological strategy of 0-3 years old seedlings of Q. variabilis was to ensure the growth of the main roots, the 1-year-old seedlings have stunted growth in summer, which is closely related to the period of weakest seedling resistance transform (heterotrophic autotrophic transformation), and there was no stagnation in the growth of 2 or 3 year old seedlings.
MUHADAISI Ariken, MAMAT Sawut, YIKELIMA Abudoumiti, MA Chunyue
Spatial distribution characteristics of surface water quality in the Ugan-Kuche river oasis
[Background]Water resources have become a global issue, especially in arid and semi-arid regions, where water resources are scarce and water quality is deteriorating.However, there are few studies on the spatial distribution of surface water quality in typical arid areas(Ugan-Kuche river oasis), thus the objective of this work is to study the spatial and temporal distribution characteristics of surface water quality in Ugan-Kuche river oasis.[Methods] The water quality indexes of the sampling points were taken as the research object, and the water quality variations in 2016-2017 were compared and analyzed by descriptive statistical methods, and the water chemical type was judged by combining the Piper diagram, the time trend of surface water chemistry characteristics were analyzed by GIS and statistical methods.[Results] 1)The river water quality indices such as pH, EC(Electrical Conductivity), TDS(Total Dissolved Solids), Cl-, Ca2+, K+, and Mg2+ in 2016 were higher than in 2017, but SO42-, HCO3-, Na+ concentration in 2017 were higher than in 2016. 2) The sampled water chemistry also showed the similar spatial variations, mainly expressed as Cl-SO4-Na-Mg、Cl-SO4-Ca-Mg and HCO3-Cl-SO4-Na-Ca-Mg.The dominant mechanism of natural control of surface water chemical sources was the evaporation concentration type. 3) The river water quality indices such as EC, Ca2+, Na+, Mg2+, Cl-, and SO42- showed a similar stripped distribution pattern. The value of each parameter showed an increasing trend in the upstream to downstream process.[Conclusions] From the spatial scale, the main reason for the surface water quality in the middle and lower reaches of Kuche River is that the natural factors such as the terrain of north high and south low of the study area and the human factors exacerbate the degree of salinization, which destroys the ecological environment. From the time scale, the water-salt stress is becoming more and more significant due to the lack of water and soil resources and the unreasonable use of human and soil resources in Ugan-Kuche river oasis.
LI Zedong, LI Yiran, ZHOU Xiaoying, ZHANG Ruming, CHENG Tiantian, ZHANG Yongtao
Drought resistance evaluation of three afforestation tree species in lithoid hilly area of North China
[Background] The soil in the lithoid hilly area of North China is poor and the soil erosion is serious, which severely restricts the productivity of these undeveloped mountains. Vegetation restoration is an important measure in recovering ecological environment. A large number of studies have shown that when plants are subjected to drought stress, a series of physiological changes will be produced in plants to adapt to drought stress, but the response characteristics, adaptability and physiological mechanisms of different plants to drought stress vary. Therefore, studying the response characteristics and physiological mechanisms of different tree species under drought stress has important practical significance for its application in barren hills greening and vegetation restoration.[Methods] Using the test method of potted water control, 10 2-year old plants and consistent Fraxinus chinensis, Quercus acutissima and Gleditsia sinensis seedlings were selected as test materials, and their photosynthesis parameters, MDA content,cell membrane permeability,relative water content, leaf chlorophyll content, SOD activity, and proline content in response to drought stress under continuous drought conditions were determined. The relationship between each physiological index and drought resistance was compared by grey relational analysis, the drought resistance of three tree species was comprehensively evaluated by membership function method.[Results] 1) With the drought increasing, the MDA content, membrane permeability and SOD activity of three tree species increased, while the relative water content and net photosynthetic rate of leaves decreased, and the chlorophyll content of Q. acutissima increased. 2) The proline content of the G. sinensis was greatly increased, and the proline content of the F. chinensis and Q. acutissima remained substantially unchanged. The drought resistance of three tree species under moderate or severe drought stress was ranked by membership function method, the results showed as G. sinensis > Q. acutissima > F. chinensis. 3) Grey correlation analysis showed that the correlation between the indexes of moderate drought conditions and drought resistance was as follows:leaf relative water content (0.784) > SOD activity (0.723) > chlorophyll content (0.652) > cell membrane permeability (0.527) > MDA content (0.526) > net photosynthetic Rate (0.506) > proline content (0.503). The correlation between various indicators and drought resistance in severe drought conditions was as:leaf relative water content (0.749) > cell membrane permeability(0.632) > net photosynthetic rate(0.563) > SOD activity (0.543) > MDA content (0.528) > chlorophyll content (0.508) > proline content (0.506).[Conclusions] The three tree species have certain commonality in the means of resisting drought, that is, to prevent drought stress by maintaining the leaf water and SOD to eliminate free radicals and reducing the degree of lipid membrane peroxidation. This research can distinguish the differences between different physiological indicators in the drought stress of plants and screen the drought-resistant tree species to provide reference for the selection and ecological restoration of afforestation species in the lithoid hilly area of North China.
On the spatio-temporal pattern of desertification in Zhenglan banner, Hunshandake sandy land
[Background] The development of desertification in Hunshandake sandy land seriously endangers the ecological environment and obstructs the sustainable development of economy, the control of desertification is urgent, it is of great significance to study the changing process and main causes of desertification in order to control desertification. Therefore, taking Zhenglan banner in the hinterland of sandy land as the study area to accurately analyze the process and causes of desertification change in this area would provide the basis for desertification control and ecological environment restoration in Hunshandake sandy land.[Methods] LandsatTM/OLI remote sensing image from 1985 to 2015 in the study area were used to calculate the normalized difference vegetation index and to construct the desertification index based on normalized difference vegetation index, the temporal and spatial variation of desertification index was analyzed using the index classification method,Theil-Sen trend analysis method and Mann-Kendall test method. Then based on the annual precipitation, annual average temperature from 1985 to 2015 in the study area, spearman grade correlation method was applied to analyze the spatio-temporal difference of the driving effect of meteorological factors on desertification. The influence of human activities on desertification was analyzed by using socio-economic data.[Results] 1) The desertification in the study area has expanded and aggravated in the past 30 years, and experienced 4 evolution in the process. From 1985 to 1989,desertification began to expand in the west and the degree of desertification increased; from 1989 to 2000, desertification continued to expand but the severity decreased; from 2000 to 2004, desertification shrank, the degree of desertification alleviated; from 2004 to 2015, desertification was reversed, the degree of desertification increased, and the degree of desertification expanded again. 2) From 1985 to 2015, the dominant trend of desertification in Zhenglan banner was non-significantly changed, its area reached 69.92% of the total desertification,and between the significantly change trends, the upward trend was mainly located in the east, its area reached 18.46%,the downward trend mainly located in the west, its area reached 11.62%. 3) The correlation between climate and desertification is mainly non-significantly correlation in space, which indicated that climate was not the most important influencing factor for the change of desertification in this area,the main factor was human activity.Therefore, the desertification change in Zhenglan banner was the result of the superposition of climate and human activities, especially animal husbandry. there are temporal and spatial differences in the superposition effects of climate and human activities.[Conclusions]The main reason for the increase of desertification in Zhenglan banner in the past 30 years is human activities, thus human activities should be restricted under the current unfavorable climate conditions, so as to achieve the purpose of ecological control.
Physical and mechanical properties and microstructure of black soil modified by natural zeolite
[Background] The black soil area in northeast China is one of the important commercial grain supply areas such as corn and japonica rice. However, studies show that the soil erosion in this area is deteriorating, which seriously affects the fine fertility of black soil, and soil erosion is the main reason for this situation. Therefore, improving the anti-erosion ability of black soil is a necessary means to alleviate the current situation of soil erosion. Physical and mechanical properties and microstructure are the basic properties of black soil, which can indicate its resistance to erosion.[Methods] Natural zeolite used in this study was mainly inclined zeolite. XRF, XRD and SEM respectively were used to determine the main chemical composition of natural zeolite, mineral composition and surface morphology and structure. The black soil was taken from Songliao Plain as the research object. Natural zeolite was mixed into the black soil in the proportions of 0, 5%, 10%, 15% and 20%, and after 60 d of pot culture, triaxial compression test method, ring knife method, mercury injection instrument method were adopted to determine and analyze the mechanical properties, physical properties and microstructure change rules of different remolded soil.[Results] 1) With the increase of dosage of added natural zeolite, the cohesive force of the black soil increased gradually and was positively related with added natural zeolite dosage. Internal friction angle increased more than that of control group with added natural zeolite dosage, but there was no obvious regular pattern. The density of black soil increased gradually and was positively related with added zeolite dosage. Total porosity decreased and negatively related with added zeolite dosage. 2) As the mixing dosage of natural zeolite gradually increased, the microstructure of black soil changed, and the total pore volume showed a decreasing trend. The changes at both ends of each curve showed a slight upward trend of small pores and a slight downward trend of large pores, indicating that the proportion of smaller diameter pores in the black soil increased slightly. 3) Based on the analysis of relevant literature, it is reasonable and economic to select 10% natural zeolite to improve black soil.[Conclusions] Natural zeolite may improve the mechanical properties, physical properties and microstructure of black soil. The changes of microstructure and macroscopic physical properties are consistent with each other, which will lead to the changes of mechanical properties of the black soil and effectively improve the shear strength of the black soil. And this change can be explained to some extent by the internal structure changes of the black soil.
ZHANG Xingyi, QI Zhi, ZHANG Shengmin, LI Hao, DU Shuli, HU Wei, DING Chao, HAN Xing
Rehabilitation engineering of gully filling in the Mollisols farmland of Northeast China
[Background] Gully erosion greatly harms the ability of crop production and agroecosystem due to the loss of arable soil and the obstacle of tractor travel. Gully erosion is a big issue and urgently needed to renovate for the agricultural sustainable development in the Molliosls area of Northeast China.[Methods] An innovative rehabilitation engineering of gully filling in the farmland was set up. The basic design principle was the gully disappearance with the gully body filled by straw and its surface covered by soil. A drainage system consisting of conceal conduit and seepage pit was established under ground. New gully will be not formed in the filled area, and tractors can move freely.[Results] The rehabilitation engineering consists of gully reshaping, conceal conduit laying, straw bundling, straw bundle stacking, surface earthling, earth bund constructing, seepage pit building and exit protecting. The land destroyed by gully erosion was filled and gully disappeared. The stream on the surface of rehabilitation gully got into the conceal conduit through the infiltration of gully surface covered soil and the seepage pit to straw layer, then concentered to the conceal conduit. More than 90% of the converged flow was drained out the field from underground, which greatly decreased the power of water flow and no new gully was formed. Small gully or the brand of median and large gully with the depth ≤ 2 m could be rehabilitated by this engineering. Up to now, over 300 gullies was rehabilitated by the national projects of gully controlling, Mollisols land protecting and territorial controlling in the Mollisols area of Northeast China, and 1.33 km2 farmland was rehabilitated. More than 0.2 million gullies and 1 333 km2 farmland are expected to be rehabilitated by the engineering in the northeast of China. About 0.6 billon kg grains would be increased each year.[Conclusions] The key technology of the gully rehabilitation engineering is to change the surface water flow to the conceal conduit and seepage pit drainage. The optimal gullies for the rehabilitation are formed in the farmland and their depths are <2 m.
DUAN Qian, YUE Youzhi, QI Fei, LIU Xia, YANG Xiangwei, LI Jiazuo, YUAN Xigong, YUAN Li
Spatio-temporal distribution and compliance analysis of disturbance patches in production and construction projects
[Background] In recent years, with the development of regional social economy, production and construction projects are increasing day by day. The phenomenon of soil erosion caused by production and construction projects is becoming more and more serious. In order to strengthen overall supervision of production and construction projects, to effectively curb man-made soil erosion, and to ensure the sustainable development of regional ecological environment and social economy, this paper takes Huoqiu county in Anhui province as the research area and explores the spatial-temporal distribution and compliance analysis and evaluation of disturbance pattern spots in production and construction projects.[Methods]Using multi-source data, combined with ArcGIS platform, UAV aerial photography, field survey and other technical means, the disturbance pattern features of production and construction projects in the region were explored.[Results]1)From 2015 to 2016, there were 780 disturbance patches of production and construction projects with an area of >0.1 hectares in Huoqiu county, covering a total area of 8 442.14 hectares. Disturbance pattern spots were concentrated in the northwest and southwest of Huoqiu county. The types of production and construction projects were mainly metal ore mining, and the disturbance pattern area of production and construction projects mainly concentrated in 1-5 hm2, and the main disturbance change type was the continuation pattern. 2)Houqiu county has approved 20 production and construction projects. Well mining Metai ore accounted for 70% of the approved projects. The scope of responsibility for prevention and control of approved production and construction projects involved 51 map spots, among which 12 were in compliance, and the main type was well mining metal ore. There were 39 non-compliant spots, including 16 that were suspected to have changed construction sites, and 23 that were suspected to be beyond the scope of responsibility for prevention and treatment. 3)In Huoqiu county, 580 suspected unapproved map spots with an area of more than 1 hectare accounted for 88.68% of the total number. Most of the projects were not implemented in the production and construction activities, but also highlighted the lack of local supervision and other issues.[Conclusions]The situation and task of water administration department's supervision and management is severe. It is still necessary to strengthen the precise supervision and management of production and construction projects to effectively curb man-made soil erosion.
Research status and hotspots of biological soil crust based on CiteSpace and HistCite
[Background] Biological soil crust (BSC) is an integral part of ecosystems, playing an important role in soil hydrology, nutrients cycling and stabilizing soils. Summarizing the research trends of BSC in China and abroad would provide reference basis for relevant research.[Methods] CiteSpace and HistCite were employed to explore the number, keywords and research team based on the literatures selected from CNKI and Web of Science core database. In Web of Science,searching pattern was TS=(biological crusts or biological soil crusts or biocrust or moss soil crusts or lichen soil crusts or cyanobacterial soil crusts or algal soil crusts) not TS=(sea or marine or ocean or reservoir or lake or physical soil crusts or salt crusts or bread or aquatic or drug or crystalline lattice) and TS=soil. In CNKI, searching pattern was SU=‘biological crusts’ or SU=‘crust*’ or SU=‘biological soil crusts’ or SU=‘algal crust’ or SU=‘moss crust’ or SU=‘lichen’ or SU=‘mixed algal-moss crust’.[Results] 1) The number of published articles in the field of BSC appeared an overall upward trend. More specifically, USA and China were the top two countries contributing to these articles, while Cold and Arid Regions Environmental and Engineering Research Institute and Xinjiang Institute of Ecology and Geography of Chinese Academy of Sciences were the top two institutions in China. 2) Compared with other countries, China's BSC research started relatively late, but the numbers of articles increased sharply since 2000; further, some research area in China have been hot regions of international BSC research. The composition, succession and seasonal change of BSC and their effects on carbon and nitrogen cycling, soil physical and chemical properties, soil hydrological process and soil erosion, as well as responses of BSC to disturbance were research hotspots. 3) It has formed some core academic teams with LI Xinrong in the Cold and Arid Regions Environmental and Engineering Research Institute of CAS, ZHANG Yuanming in the Xinjiang Institute of Ecology and Geography of CAS, ZHAO Yunge in the Northwest A&F University and BU Chongfeng in the Northwest A&F University, and LIU Yongding in the Institute of Hydrobiology, CAS. Moreover, there was a strong cooperative relationship among three teams of LI Xinrong, ZHANG Yuanming and ZHAO Yunge.[Conclusions] Through summarizing and analyzing research focus issues and research hotspot BSC, it is conducive to researchers to comprehensively understand research history and present situation of BSC at home and abroad.
