Abstract:[Objective] The characteristics of organic carbon, total nitrate, total phosphorus and its stoichiometry of the key species in primary succession stages of vegetaion were explored in the Hailuogou glacier forehead in Gongga Mountain, in order to provide better and exactly prediction of the vegetation succession under the background of the globing warming.[Methods] Combined with field investigation and indoor experimental analysis, the organic carbon, total nitrogen and total phosphorus of the roots, stems, leaves, seeds of Epilobium hirsutum and Astragalus mahoschanicus were analyzed.[Results] The range of organic carbon of the Epilobium hirsutum root changed between 436-445 g/kg, which was higher than that of the Astragalus mahoschanicus root (416-423 g/kg). The concentrations of the organic carbon of different organs of Epilobium hirsutum were as follows:in roots > in seeds > in leaves > in stems, the concentrations of the total nitrogen were:in leaves > in roots > in seeds > in stems, and the concentrations of the total phosphorus were:in seeds > in leaves > in roots > in stems. While the concentrations of the organic carbon of different organs of Astragalus mahoschanicus were:in roots > in seeds > in stems > in leaves, the concentrations of the total nitrogen were:in leaves > in roots > in seeds > in stems, and the concentrations of the total phosphorus were:in leaves > in seeds > in roots > in stems. The ration of organic carbon to total nitrogen of different organs of Epilobium hirsutum was higher than that of Astragalus mahoschanicus. The ratio of total nitrogen and total phosphorus changed between 5.94 and 17.82.[Conclusion] The high ratio of N/P and low C/P of Astragalus mahoschanicus, which reflects the higher growth ratio and propagation rates. It also indicates that the Astragalus mahoschanicus has stronger growth competition strategy than that of the Epilobium hirsutum and better compelling the succession process.

Abstract:[Objective] The development and distribution characteristics, formation mechanism and development trend of geological hazards induced by "5·25" heavy rainfall on May 25, 2020 in Gongshan County, Yunnan Province were studied, in order to provide scientific basis for geological hazards prevention and mitigation planning in this area.[Methods] Based on the first-hand data of the post-disaster emergency survey and the systematic collection of regional geological and rainfall data, the hazard process was analyzed and studied.[Results] The concurrence geological hazards in Gongshan County were mainly small landslides and debris flows, which were mainly distributed along the road and on both sides of Nujiang River. Most of the landslides were shallow surface, and debris flows were mainly initiated by landslide. The geological hazards showed typical characteristics of high-location, long-range and chain type disasters. It was very common for landslide or collapse to enter the channel and turn into debris flow.[Conclusion] In the investigation and assessment of geological hazards in Gongshan County, it is necessary to fully consider the investigation of high-location geological hazards, and scientifically evaluate the chain effect caused by geological hazards and the scope of the affected areas; due to the high vegetation coverage in the territory, debris flow will carry a large number of driftwood to rush out, which is easy to form blockage in narrow gully or at the bridge and culvert at the mouth of the gully, which will enlarge the instantaneous volume of debris flow. It is suggested to carry out large-scale geological hazard risk investigation and evaluation in Gongshan County, and organically integrate the evaluation results with the land spatial planning, so as to control the geological hazard risk from the source, and improve the protection standard of debris flow control engineering in the back mountain of the town.

Abstract:[Objective] The purification effects of aquatic vegetables on the eutrophication waterlogging pool were studied, in order to provide new ideas and theoretical reference for the application of aquatic vegetables and other economic plants to the ecological restoration of eutrophication closed water in rural areas of Northwest China.[Methods] Taking Spinacia oleracea and Oenanthe javanica as experimental materials, the floating bed cultivation method was used to explore the effect of two aquatic vegetables on nitrogen (N) and phosphorus (P) of water in water storage pond with different degrees of eutrophication.[Results] ① The related indicators of N and P were significantly decreased with two aquatic vegetables in the process of purifying the eutrophic water. Eventually, the water body of simulated pond had basically reached or exceeded the surface water quality standard of class Ⅴ water, and the purified water had reached the national standard. ② The average removal rates of S. oleracea and O. javanica to NH₄⁺-N, NO₃^--N and PO₄^3--P in water bodies were 94.37%, 96.66% and 88.95%; 97.27%, 94.64% and 83.48%, respectively, which were significantly higher than the control group (p<0.05), indicating that the two vegetables could efficiently recovery water from eutrophication. ③ The TN removal rate and average daily removal rate of two aquatic vegetables increased with the TN concentration, and showed that S. oleracea >O. javanica. With the TP concentration increasing, the TP removal rate of S. oleracea decreased, and the TP removal rate of O. javanica increased and showed that S. oleracea < O. javanica. It indicated that O. javanica was suitable for the eutrophic water with high N concentration, while S. oleracea was suitable for water with high P concentration.[Conclusion] Overall, S. oleracea and O. javanica have good absorption effects on TN and TP in three levels of eutrophic water bodies, and could play a vital role in water purification.

Abstract:[Objective] The process and outburst mechanism of moraine dam failure caused by glacier avalanches were studied, in order to provide scientific support for major engineering construction in glacial areas and disaster prevention of glacier lake outburst.[Methods] The model test in flume was carried out with the different volumes of blocks, sliding angle, sliding distance, composition materials and geometric morphology of the dam body. Based on the experimental phenomena, experimental data and theoretical derivation, the process of the surge, the starting mechanism of dam body materials, and the critical condition of outbursts was analyzed.[Results] ① The surge of glacier avalanches decreased with time and distance, and the attenuation was significant with time. ② The outburst process under the surge could be divided into four stages:slope surface erosion, scarp erosion, lateral erosion, and decline. The lateral erosion stage had the largest outburst discharge, the fastest velocity, and the strongest erosion capacity. ③ The starting velocity of particles was given from the perspective of the particle starting mechanism, and the results were in good agreement with that of the Shamov formula. ④ It was verified by the outburst event of Guangxiecuo ice-lake breach in Midui gully, in Bomi County, Linzhi City, Tibet Autonomous Region, and the result is reasonable.[Conclusion] The larger the ice lake storage capacity, the deeper the water depth in front of the dam, the higher the water level rise caused by a glacial landslide, and the more likely the dam body is to outburst. The higher the content of the fine particles in the accumulation of the moraine dam, the stronger the adhesion between the particles, and the more stable the dam body is. The wider the moraine dam and the lower slope foot are, the more stable the dam body is, and the longer the outburst time is.

Abstract:[Objective] The roles of rainfall and vegetation factors on controlling soil erosion were studied in order to provide guidance for policy-making of soil and water conservation strategy in the future and efficiency assessment of ecological projects.[Methods] The impacts of rainfall and vegetation on soil erosion were quantitatively evaluated with a case study in Yanhe River watershed by using the revised universal soil loss equation (RUSLE). The soil erosion was calculated under three scenarios, namely the natural state, the rainfall factor (rainfall erosivity, R) fixed-vegetation factor (vegetation coverage and management factor, C) change and C fixed-R change.[Results] ① Under the natural state and R fixed-C change scenarios,the soil erosion showed a decreasing trend in Yanhe River watershed, but an increasing trend under the C fixed-R change scenario from 2000 to 2018. ② Under the natural state and R fixed-C change scenario, most regions experienced decreased soil erosion from 2000 to 2018. The area with strong erosion, intensive erosion and severe erosion all showed decreasing trend, especially in the upper and middle reaches. ③ Vegetation played a positive role in controlling the soil erosion with a contribution of 77.20% from 2000 to 2018. In contrast, the rainfall promoted the increase of soil erosion, implying a negative contrition of 22.80% in controlling the soil erosion.[Conclusion] Vegetation is the dominate factor that controls the soil erosion. However, the soil erosion is still strong in the upper reach. Therefore, soil and water conservation measures should be enhanced, and the allocation of plant resources should be rationalized in the future.

Abstract:[Objective] The effects of soil water and salt factors on the distribution of vegetation communitis in the shelterbelt system of Jilantai Salt Lake were investigated, in order to provide theoretical basis for the maintenance and management of the shelterbelt in the salt lake.[Methods] The influences of soil water and salt factors on the distribution characteristics of vegetation community in Jilantai Salt Lake shelter forest system were studied by using quantitative classification and ordination method.[Results] There were significant differences in soil water and salt content between Nitraria tangutorum community and other community types, and there was no significant difference in soil pH value between different community types (p>0.05). The results of TWINSPAN showed that the relationship between plant species and plant community type was very good. The relationship between soil water and salt content was well verified in CCA ordination chart. Except for community Ⅰ, community Ⅵ, Ⅴ, Ⅳ, Ⅲ and Ⅱ were distributed along the decreasing direction of soil water and salt content, and the distribution of artificial vegetation community was relatively concentrated, which indicated that artificial vegetation configuration had a certain impact on the distribution of shelterbelt vegetation. The results of significance test of environmental factors showed that Mg²⁺, Na⁺ and soil water content had a significant effect on the distribution of vegetation community in shelterbelt system.[Conclusion] In terms of soil water and salt factors, soil Mg²⁺, Na⁺, SO₄^2- and soil water content are the main factors affecting the plant community distribution of shelterbelt system.

Abstract:[Objective] The effects of rock fissure angle on the in-situ shear characteristics of the base material under different plant root systems were studied, in order to provide a scientific reference for water and soil conservation and ecological restoration.[Methods] The samples were cured for 90 days under three conditions:plant-free, bermudagrass and multi-flowered magnolia. The in-situ shear test of the substrate was carried out under the angle of 15°, 30°, 45°, 60°, 75° and 90° between the rock crack and the vertical direction of shear.[Results] ①The shear strength and residual shear strength of bermudagrass and magnolia root-substrate composites were significantly greater than those of non-rooted substrates. The average increase in shear strength was 33.87%-65.18% and 44.94%-73.65% respectively. ② The shear strength of samples without plant substrate reached the peak value when the displacement was 8-11 mm, while the bermudagrass root-substrate composite and the multifloral magnolia root-soil composite reached the peak value when the displacement was 20-36 mm. The root system could lag the peak displacement of the vegetation concrete, and root-containing substrate sample could withstand greater deformation. ③ For the same plant, different distribution of rock fissures had different effects on the soil consolidation ability of the root system. As the fissure angle increased, its shear strength increased first and then decreased. When the fissure angle was 60°, its shear strength reached maximum.[Conclusion] The root system can significantly enhance the shear strength of the vegetation concrete substrate and increase the residual shear stress. The distribution of different cracks has different effects on improving the shear strength of the substrate, but the effect of crack distribution on residual shear strength is not obvious.

Abstract:[Objective] The spatial autocorrelation and influencing factors of soil erosion were studied, in order to provide references for vegetation construction and reducing coarse sand into Yellow River.[Methods] Through geostatistics analysis and grey relation analysis, The spatial autocorrelation and influencing factors of soil erosion in Baojiagou watershed in bare feldspathic sandstone region were studied.[Results] ① There was a significant spatial autocorrelation of the soil erosion intensity in the watershed, with a Z of 136.87. ② Baojiagou small watershed was the most typical watershed among bare feldspathic sandstone region. The dominant landscape in the basin was bare bedrock landscape, followed by a large area of Hippophae rhamnoides artificial vegetation landscape. ③ The area weight fractal index distribution had the most significant influence on high-high agglomerations, with associated degree of 0.774. And slope had the strongest correlation with low-low agglomerations.[Conclusion] Terrain is the main factor that leads to the fragmentation of vegetation landscape and determines the intensity of hydraulic erosion. In the gentle terrain, the connectivity of vegetation landscape is the main factor restricting the development of soil erosion.

Abstract:[Objective] The effects of vegetation cover and rainfall erosivity on the spatial and temporal changes of soil erosion in the black soil region of Northeast China were studied, in order to provide a scientific basis for soil and water conservation and sustainable development in this region.[Methods] The revised universal soil loss equation (RUSLE) was used to calculate soil erosion modulus and its distribution in the study region from 2000 to 2018, the spatial and temporal distribution of soil erosion modulus and the influencing factors were analyzed, and the sensitivity of the erosion modulus to changes of vegetation cover and rainfall factors was obtained.[Results] Soil erosion in the black soil region of Northeastern China was mainly affected by the changes in vegetation cover and management factor C and rainfall erosivity factor R. The erosion modulus in the study area decreased from 1 175.20 t/(km²·a) to 822.07 t/(km²·a) during 2000-2018, and slight and mild erosion dominated, with a spatial distribution from southwestern to northeastern parts of the black soil region.[Conclusion] The sensitivity coefficients of vegetation cover and management factor (C) are 0.95 and 1.00 in the southeast and southwest of the black soil region, which belong to intensely sensitive areas. In these places, the effective management method is to improve the vegetation cover. In contrast, the sensitivity coefficients of rainfall erosion force factor (R) are 0.45 and 1.00 in the northwestern and southwestern parts, which belong to moderately and intense sensitive areas, where the effective way to control soil loss is to reduce the impact of rainfall.

Abstract:[Objective] The dynamic change characteristics of soil water under different rainfall patterns were studied, in order to provide theoretical basis for judging the stability of community structure and optimizing the community structure.[Methods] Taking the soil of different depths in typical aerial seeding Hedysarum leave shrub land in Mu Us sandy land as the research object, The watchdog automatic water monitoring system was used to monitor the dynamic change of soil moisture content in different depths continuously. The temporal and spatial changes of soil moisture in 10, 30, 50, 70, 90 and 110 cm soil layers under different rainfall events were studied, and the characteristics of soil moisture infiltration, redistribution and water supply were analyzed.[Results] ① The change of soil moisture content in 0-110 cm depth of Hedysarum leave community was affected by rainfall, and had obvious vertical characteristics. The soil water content in 10 cm depth was changed greatly, that in 30 cm depth was changed weakly, and that in 50 cm depth was stable. ② The soil moisture at the depth of 10 cm showed an obvious response to rainfall and temperature. The rainfall intensity and initial water content showed a greater impact on the recharge of shallow soil and a certain impact on the infiltration depth. The response of the soil layer below 30 cm to rainfall lagged behind with the increase of depth. The soil layer between 30 to 50 cm was mainly affected by initial water content and rainfall, while the change of water content below 50 cm was mainly affected by rainfall. ③ The rainfall of > 8.8 mm had replenishment effect on the soil layer of 10 cm and below, and the rainfall >40 mm could reach at least 110 cm soil depth through precipitation redistribution.[Conclusion] The root system of Hedysarum leave community is mainly distributed at 0-40 cm soil layer. The rainfall of >8.8 mm can be effectively used by poplar and firewood community. The rainfall of >40 mm can recharge groundwater effectively, which is conducive to the stability of community structure and coping with the dry months with less rainfall in the early stage of vegetation growth in the next year.

Abstract:[Objective] The dynamic changes of physiological indexes of ryegrass under different pollution conditions were studied, in order to provide a preliminary theoretical basis for phytoremediation of contaminated soil.[Methods] Through indoor simulation of different types of soil pollution, 4 treatments were set up, namely uncontaminated soil + ryegrass (SH) as contorl, heavy metal contaminated soil (500 mg/kg Pb²⁺, 50 mg/kg Cd²⁺)+ ryegrass (SGH), petroleum contaminated soil (1 000 mg/kg petroleum) + ryegrass (SPH), petroleum and heavy metals combined contaminated soil (500 mg/kg Pb²⁺, 50 mg/kg Cd²⁺, 1 000 mg/kg petroleum) + ryegrass (SPGH). The root morphological index was measured by WINRHIZO root analysis system, and the pigment index of leaves was measured by spectrophotometer, to explore the influence of different types of soil pollution on the pigment content of ryegrass leaves.[Results] The root growth of ryegrass was stimulated by three different types of contaminated soil to varying degrees. Compared with control, on the 20 th day, the root length, root surface area, root volume, and root diameter of plant roots under the combined treatment of petroleum and heavy metals increased by 88.10%, 148.60%, 221.90%, and 32.20%, respectively. Compared with control, the underground biomass of each polluted treatment showed a trend of increasing firstly and then decreasing with the increase of cultivation time, while the above-ground biomass was always lower than that of control. Moreover, on the 10th, 40th and 80th days, the abovementioned biomass of the combined pollutted treatment was the smallest, which significantly decreased by 34.68%, 45.42% and 58.05% compared with that of the control. On the 80 th day, the chlorophyll content of ryegrass in heavy metal contaminated soil, petroleum contaminated soil and petroleum and heavy metals combined contaminated soil was significantly lower than that of control, which decreased by 26.84%, 44.82% and 47.02%, respectively.[Conclusion] Different pollutions could promote the morphological changes of ryegrass root system, and reduce the biomass and pigment contents of ryegrass, among which the combined pollution with petroleum and heavy metals have the greatest influence on the growth of ryegrass, followed by the treatment with petroleum pollution. Based on the difference of physiological response of ryegrass root morphology and growth to different polluted soils, some regulatory substances can be added to alleviate the toxic effect of pollution on plants in the future during the phytoremediation of contaminated soils, increase the biomass of plants and enhance the related physiological functions to improve the efficiency of pollution remediation.

Abstract:[Objective] Soil respiration and its temperature sensitivity of different vegetation types were studied, in order to provide theoretical support for the assessment of terrestrial ecosystem carbon cycle.[Methods] Soil hydrothermal factors, respiration characteristics and temperature sensitivity in different seasons were studied in bare land, grassland, shrub and woodland at the southern foothill of Taihang Mountains by long-term location observation and laboratory analysis.[Results] Soil temperature of different vegetation types varied greatly with seasons, with the lowest value in the early January and the highest value in the late August. After August, soil temperature gradually decreased with time. The soil temperature in the same month was generally showed an oreder of bare land > grassland > shrubland > forestland, with the local fluctuations. Soil respiration rate of different vegetation types was significantly different and the seasonal variation characteristics were consistent. Among them, soil respiration, heterotrophic respiration and autotrophic respiration had the same seasonal variation characteristics (inverted V-shaped variation), which roughly showed as follows:summer > autumn > spring > winter. Soil respiration humidity sensitivity of different vegetation types was as follows:bare land < grassland < shrubland < forestland, indicating that vegetation types were the important driving factor for soil respiration temperature sensitivity. Q₁₀ in summer and autumn was significantly higher than that in spring and winter. Correlation analysis showed that Q₁₀ was significantly negatively correlated with pH value(p<0.05), and negatively correlated with the bulk density; Soil organic carbon was positively correlation with Q₁₀ (p<0.05). Moreover, the contribution rate of soil heterotrophic respiration was the highest in summer and the lowest in spring. The contribution rate of soil heterotrophic respiration was as follows:in summer > in autumn > in winter > in spring, and the contribution rate of autotrophic respiration gradually increased with season.[Conclusion] Heterotrophic respiration contributed more to soil respiration than autotrophic respiration, and soil heterotrophic respiration with microbial participation is the most important component of soil respiration.

Abstract:[Objective] The influence of prescribed burning on accumulation and water holding capacity of litters in Pinus yunnanensis forest was investigated, in order to provide a scientific basis for predicting the environmental effects of prescribed fire.[Methodes] The litter accumulation amounts and hydrological characters were tested and compared between the unburned and burned forests by prescribed fire. Litter accumulation amounts were obtained by field positioning collector methods and the hydrological character was investigate indoor immersion method.[Results] ① The volume of combustion residue after prescribed fire sample plot was 3.84 t/hm², which was only 21% of the volume of litter in the unburned sample plot, and the volume of litter in the unburned sample plot was 18.64 t/hm². ② The maximum water-holding capacity of forest litters after prescribed fire was 14 t/hm², which was significantly lower than that in unburned forest with the total maximum water-holding capacity of 60.62 t/hm². The water-holding capacity of the litter layer and soaking time in both unburned and prescribed burned sample land showed a significantly logarithmic relationship, and the immersion time and the absorption rate of forest litters showed a significantly power function relationship with the immersion time. ③ The maximum amount of litter input was in April, accounting for 20%-24% of the annual increase. After 1 year, the effective water-holding capacity in the prescribed burnt land was restored to 73%.[Conclusion] After the prescribed fire, the litter storage and the waster holding capacity can decrease in short term. However, with the natural recovery, the water conservation of the litter of Pinus yunnanensis forest can gradually recover.

Abstract:[Objective] The effects of landscape composition and structure on water quality at different spatial scales in Yangcheng Lake watershed were explored, in order to provide references for the water quality improvement and landscape pattern optimization.[Methods] Taking 12 water quality sampling points in Yangcheng Lake as the center, the circular buffer zones of 6 different spatial scales were generated by using GIS software. Landscape pattern index, redundancy analysis and Pearson correlation analysis was used to identify the most effective buffer zone of landscape pattern on wetland water quality, and explore its relationship with water quality.[Results] ① In general, the proportions of arbor forests and lakes gradually decreased at the spatial scale, while the proportions of urban residential land, paddy fields, and aquaculture ponds gradually increased. ② The spatial scale of the impact of landscape pattern on wetland water quality was reflected in different circular buffers, and the maximum explained variation was 68.2% in the circular buffer zone with a radius of 800 m. ③ Landscape composition variables only had correlation with water quality parameters in the circular buffer zone with a radius of 1 000 m. ④ Aquaculture ponds had a greater impact on water quality in a circular buffer zone with a radius of 200 m. Paddy fields, arbor forests and lakes had a larger circular buffer zone (radius greater than 500 m), which was the main landscape type affecting water quality.[Conclusion] The most relevant spatial scale between landscape pattern and water quality is 800 m circular buffer zone. The interpretation ability of landscape structure variables on water quality in buffer zones of different scales is more obvious than that of landscape composition variables. The correlation between water quality parameters and landscape pattern index in wet season is greater than that in dry season.

Abstract:[Objective] Soil erosion in mountainous areas in Southern Anhui Province was accurately assessed and its temporal and spatial characteristics were analyzed, in order to provide a basis for comprehensive management of regional soil erosion.[Methods] With the support of GIS technology, the daily rainfall data, 30 m resolution DEM, soil data and land use data were used to estimate the soil erosion modulus in the mountainous area of Southern Anhui Province. The Chinese soil loss equation (CSLE) was employed, the temporal and spatial changes of soil erosion in the study area in 2000, 2010 and 2018 were analyzed.[Results] From 2000 to 2010, the soil erosion modulus increased by 963.96 t/(km²·a), and the area of soil erosion intensity shifted to high intensity level. In contrast, from 2010 to 2018, the soil erosion modulus decreased by 781.22 t/(km²·a), the area of soil erosion intensity shifted from high to low, and the overall soil erosion change showed a trend of first increase and then decrease. The spatial distribution pattern of soil erosion in the three periods of the mountainous area in Southern Anhui Province was basically the same. The southeast side of Chizhou City, Tongling City, and the surrounding areas of Huangshan City were key areas for soil erosion prevention and control. In the study area, the cultivated land was mainly eroded slightly and lightly, while the forest land was mainly eroded at moderate or lower levels. The area of cultivated land and woodland eroded at moderate and higher level decreased in 2010-2018, and the effects of soil and water conservation measures were remarkable.[Conclusion] In recent years, the intensity of soil erosion in the mountainous area of Southern Anhui Province increased first and then decreased. Generally speaking, mild erosion is the main erosion type, and the subsequent soil erosion control still needs to be strengthened.

Abstract:[Objective] The dynamic change characteristics of carbon density of arbor forest in Tianshan Mountains were analyzed, in order to provide scientific basis for accurate estimation of forest carbon storage and sustainable development in the future.[Methods] Based on the plots of arbor forest in Tianshan Mountains of Xinjiang area, that were investigated every five years from 2001 to 2016, the variation and related factors of carbon density of arbors in this region were analyzed statistically.[Results] From 2001 to 2016, the carbon density of arbor forests in the Tianshan Mountains of Xinjiang area increased with different degrees:the central part of Tianshan Mountains > the west part of Tianshan Mountains > the east part of Tianshan Mountains, and the carbon density change rate was higher in the central part of Tianshan Mountains than in the east part of Tianshan Mountains than in the west part of Tianshan Mountains. From the perspective of forest age, the carbon density of arbor forests in the central and Eastern Tianshan Mountains showed a trend of first rising and then falling with forest age, and the near mature forests had the highest carbon density. In the Western Tianshan Mountains, the carbon density rate showed an increasing trend with forest age. With terrain changes, the carbon density increased first and decreased afterwards with slope degrees. In the Western and Central Tianshan Mountains, the carbon density was the highest in the steep hill. And in East Tianshan Mountains, the highest carbon density was in gentle slope. With the increase of elevation, the carbon density increased first and decreased afterwards in the western and central parts and decreased in the East Tianshan Mountains. With the change of slope orientation, the carbon density in the south slope was the lowest, and no obvious pattern in others.[Conclusion] Since the implementation of Natural Forest Protection Project, the arbor carbon density increased in Tianshan Mountains, and the forest age has the most significant effect. Therefore, in order to improve the carbon sequestration function of natural forest in Tianshan Mountains and explore the greater carbon potential, we should strengthen the regeneration of young forest, optimize the structure of forest age, and promote the healthy and sustainable development of forest resources.

Abstract:[Objective] Based on the advantages of the "well and electricity dual control" platform that has been built in the irrigation area, the dynamic changes of the groundwater flow field during the mining period were obtained by using the water level of the pumping well, in order to provide technical support for the scientific management and rational utilization of groundwater resources.[Methods] Using Processing MODFLOW software to simulate the simulated flow field in the study area, and taking it as the criterion for determining the flow field of the pumping well water level, the fitting effect of the flow field was evaluated and improved.[Results] The flow field obtained by directly using the water level of the pumping well was smaller than the simulation flow field. The flow field obtained by using the water level after the corrected drawdown of the pumping well had a good fitting effect with the simulated flow field, but it should be calculated in combination with the model in practice. The dynamic flow field obtained was close to the simulated flow field and was easy to implement by installing water level monitoring equipment in some pumping wells and adding special monitoring wells, indicating that the method could be used for dynamic monitoring of the flow field in the study area.[Conclusion] The proposed method of using pumping wells as monitoring wells based on the "well and electricity dual control" system effectively can solve the problem of deviations in groundwater management caused by the low density of groundwater monitoring stations and poor information transmission timeliness. It has certain application value for strengthening the dual control management of groundwater level and water volume and the protection of regional groundwater resources.

Abstract:[Objective] The water retention effect of planting seedlings with desert planters on the southeastern edge of the Tengger Desert was explored to observe whether the desert planters are more conducive to the survival of seedlings, in order to provide scientific support for improving the survival rate of seedlings in desert areas.[Methods] Soil water content of different soil layers under two planting methods (shovel and desert afforestation device) was compared. The corresponding formula was used to calculate effective soil water content, soil water deficit degree and soil moisture variation coefficient, to comprehensively assess which planting method was better.[Results] ① The risk of soil moisture loss in each soil layer could be greatly reduced by using desert afforestation devices in grass square, and the soil moisture content under the action of afforestation devices was higher than that of shovel, with the highest being 1.42 times and the lowest being 1.04 times. ② The depths of the two planting methods were different, so that the roots of Caragana korshinskii distributed differently in soil layers, and thus the water use strategies were different. Caragana korshinskii in the shovel group mainly used soil water in the 15-40 cm soil layer, while Caragana korshinskii in the afforestation group mainly used soil water in the 20-50 cm soil layer. The soil moisture deficit of Caragana korshinskii roots in the afforestation group was less, which was more conducive to the initial growth of Caragana korshinskii. ③ In terms of the survival rate of planted seedlings, the survival rate of seedlings planted by shovel was 45%-55%; the survival rate of seedlings planted by desert afforestation tools was 70%-75%, which was increased by about 25%. The survival rate of seedlings planted by desert afforestation tools was higher.[Conclusion] According to soil moisture retention and the survival rate of the planted Caragana korshinskii, compared with shovel planting, the effect of planting Caragana korshinskii with desert afforestation equipment is better.

Abstract:[Objective] The mechanism of underlying vegetation restoration in sandy grassland when combined super absorbent polymers with lignin crust was studied, in order to provide a theoretical basis for the restoration of sandy vegetation in desert grassland.[Methods] The experiment was conducted in Urat Desert grassland in Inner Mongolia Autonomous Region. The two treatments were control and restoration measures (combined application of super absorbent polymers and lignin crust). The above-ground biomass, coverage, soil moisture content, proportion of soil aggregates, soil infiltration rate, stable infiltration rate, alkali-hydrolyzable nitrogen, available phosphorus and available potassium content were assessed.[Results] ① Restoration measure significantly increased the aboveground biomass and coverage of plants. ② Restoration measure increased the proportion of water-stable macroaggregates, soil infiltration rate, stable infiltration rate, and soil moisture content, but reduced the proportion of microaggregates. ③ Restoration measure significantly increased the soil alkali-hydrolyzable nitrogen, available phosphorus and available potassium contents.[Conclusion] The restoration measure can increase soil moisture and nutrient contents, improve plant productivity and promote the vegetation restoration in the sandy grassland.

Abstract:[Objective] The influences of cultivating Stropharia rugosoannulata with straw combined with slope reconstruction on clean water runoff, water-holding capacity and soil fertility of selected areas were investigated, in order to provide theoretical basis for the water conservation and ecological environment construction.[Methods] Under the canopy of cash forest, cultivating Stropharia rugosoannulata with straw and combined with slope reconstruction measures based on slope degrees, throgh samples collection and analysis, the effects of those measures on the water and soil quality of experimental area during different growing periods of Stropharia rugosoannulata were discussed.[Results] The cultivating Stropharia rugosoannulata on slope of small blocks by cutting slope length and setting transverse ditches(CM), cultivating Stropharia rugosoannulata on primary slope (PM) and cultivating Stropharia rugosoannulata on contour reverse-slope terrace (RM), could reduce the content of suspended solids (SS), total nitrogen (TN) and total phosphorus (TP) efficiently. The content of SS were decreased by 40.3%, 31% and 51.1% on average, respectively. The contents of TN were decreased by 37.8%, 25.1% and 56.1% on average, respectively. The contents of TP were decreased by 37.8%, 24.7% and 46.9% on average, respectively. In addition, the soil water content was improved (by 22.2%, 14.1% and 39.1% respectively), and the content of soil organic matter was significantly increased (by 32.1%, 29.3% and 31.5% respectively).[Conclusion] By cultivating Stropharia rugosoannulata with straw, and combined with slope reconstruction measures could reduce the content of SS, TN and TP in the runoff from the slope of the forest effectively, and increase the soil water content and organic matter in experimental area.

Abstract:[Objective] The relationship model of variation of water and sediment in the Yellow River basin was studied, in order to provide theoretical support for the study on the variation of water and sediment in the basin.[Methods] The driving factors of the variation of water and sediment in watersheds of middle and upper reseaches of the Yellow River were analyzed, and the relationship model of the variation of water and sediment was deduced based on differentiation.[Results] According to the simulation test of the variation of sediment transport rate and flow at seven stations in the Loess Plateau and the middle and upper reaches of the Yellow River, the average validity coefficient of the model was 0.860 and 0.887, and the average relative error was 14.8% and 6.7%, respectively.[Conclusion] The model have been tested from three aspects:the simulation accuracy of flow variation, sediment variation and the contribution ratio of variation of each factor, which preliminarily proves the rationality of the model structure and the high effectiveness of the simulated sediment variation.

Abstract:[Objective] The ecological effects before and after the construction of urban wetland were analyzed, and the key factors influencing the formation and development of wetland were determined in order to provide the scientific basis for urban wetland protection and ecological park construction.[Methods] Jixi National Wetland Park of Ji'nan City, Shandong Province, in the lower reaches of the Yellow River was selected as the research area. Remote sensing images and field survey data from 1990 to 2019 were the data sources. Based on the GIS platform, the ecological effects of urban wetlands were explored through spatial analysis of land use dynamics, transfer matrix, and landscape index. The driving factors of wetland change were studied by the grey correlation method.[Results] ① The mutual conversion between cultivated land and ecological land was the main type of land use change in the Jixi Wetland, and the mutual conversion between construction land and ecological land was the second type of land use change. Changes in landscape index and flora and fauna indicated an increase in wetland ecological diversity. ② The precipitation, groundwater and other water resources were positively correlated with wetland area, while the temperature was negatively correlated with wetland area.[Conclusion] Hydrological and meteorological factors played an important role in the natural evolution of wetlands, and were the key to the formation of perennial wetlands. Human disturbances such as urban planning affected the conversion of land use types in the wetland and were also the main factors leading to the evolution of the urban wetland.

Abstract:[Objective] The ecological corridor in Etuoke Banner, Inner Mongolia was constructed to improve the quality and stability of the ecosystem, and provide the path of biological migration, promote species exchange between different habitats, so as to provide a scientific basis for the implementation of ecological corridor construction project and the protection of biodiversity in Etuoke Banner.[Methods] Taking Etuoke Banner as the research area, the ecological source was determined by using the comprehensive results of ecological sensitivity evaluation and ecosystem service value analysis, and the minimum cumulative resistance model (MCR) and minimum cost path were used to construct the ecological corridor.[Results] ① The extreme and high sensitive ecological area of Etuoke Banner, mainly distributed in the border area of Mengxi Town and Qipanjing Town in the northwest, accounted for 41.31% of whole banner. ② The overall status of ecosystem service value was in poor condition, most of the areas were in the middle and low value areas, accounted for 95.37% of whole banner. ③ The ecological corridor system was constructed, and the ecological corridor and ecological source area roughly formed a ring in the closed area, among them the total length of important corridors was 721 km, and that of general corridors was 803 km.[Conclusion] On the whole, the ecological source areas of Etuoke Banner are mainly scattered on both sides of the east and west. Bulong Gacha and Chahannoer Gacha play a bridge role in the exchange of material and energy between the east and the west. In order to ensure the overall connectivity of the study area, it is particularly important to strengthen the protection of these sources.

Abstract:[Objective] The ecological security status of cultivated land was evaluated and its obstacle factors were diagnosed in Dongting Lake plain, in order to provide reference for rational utilization and pollution control of cultivated land.[Methods] The ecological security evaluation index system of cultivated land in Dongting Lake plain was established based on DPSIR model. From the county scale, the improved TOPSIS method based on entropy weight was used to calculate the cultivated land ecological security status in Dongting Lake plain from 2007 to 2017. And the obstacle degree model was employed to diagnose the main obstacle factors of cultivated land ecological security status.[Results] The ecological security degree of cultivated land in Dongting Lake plain was in a critical state from 2007 to 2017. The comprehensive index of cultivated land ecological security fluctuated and increased slowly during the study period. The change characteristics of cultivated land ecosystem security in different counties were different. The main obstacle factors restricting the ecological security of the cultivated land system included the improved proportion of medium and low yield field, the proportion of straw returning, the proportion of soil testing and formulated fertilization, the intensity of pesticide use, the intensity of plastic film use, the intensity of fertilizer use, and the proportion of agricultural natural disasters.[Conclusion] To improve current ecological security status of cultivated land in Dongting Lake plain, comprehensive land consolidation should be implemented and agricultural non-point source pollution control should be strengthened.

Abstract:[Objectives] In order to solve the environmental problems caused by excessive application of chemical fertilizer in Hexi irrigation region, the effects of organic nitrogen replacing part of inorganic nitrogen fertilizer on the growth, yield and quality of wine grape were explored to determine the appropriate amount of organic-inorganic nitrogen fertilizer for wine grape.[Methods] A field experiment was conducted at Linze County, Zhangye City, Gansu Province in 2018. Six treatments were set up:no fertilization input as control (CK), 100% chemical fertilizer (C), 100% organic fertilizer (O), 30%, 50% and 70% of the chemical fertilizer supplied by organic fertilizer, recorded as 0.7 CO, 0.5 CO and 0.3 CO. The effects of different ratios of organic and inorganic fertilizers on the growth, yield and quality of Merlot were studied.[Results] The yield and quality of wine grape could be improved by replacing part of chemical fertilizer with organic fertilizer, and the effect of 0.5 CO was the best. Under the same amount of organic fertilizer, 0.5 CO treatment could balance vegetation growth and reproductive growth. Compared with CK and C treatment, 0.5 CO treatment increased the grape yield, fruit soluble solid content, sugar content, tannin content, total phenol content, anthocyanin content and the ratio of sugar to acid by 120.76% and 32.59%, 46.72% and 25.21%, 39.36% and 37.46%, 23.05% and 39.06%, 72.07% and 54.77%, 44.42% and 48.48%, 50.42% and 40.78% (p<0.05), respectively, and the total acid content was decreased by 33.96% and 16.98% (p<0.05), respectively.[Conclusion] Under the premise of reducing chemical fertilizer, half of chemical fertilizer combined with organic fertilizer (0.5 CO) can not only effectively inhibite the vegetative growth of wine grape, but also improve the yield and fruit quality of wine grape. It is recommended that organic fertilizer (9 000 kg/hm²) combined with N of 150 kg/hm², P₂O₅ 135 kg/hm² and K₂O kg/hm² should be adopted for wine grape cultivation in the study area.

Abstract:[Objective] The soil respiration characteristics in terraced fields under different film mulching conditions in the loess area were studied, in order to provide scientific basis for exploring reasonable agricultural plastic film mulching measures of soil carbon cycle.[Methods] The study set up three treatments for experiments:bare land, white film land and black film land.[Results] ① The daily variation of soil respiration rate of corn fields with different film mulching conditions showed a single-peak curve trend, and the daily average value was as follows:black film land>white film land>bare land, and the soil respiration rate of different mulching treatments was significantly different. ② The change of soil respiration rate of the white film land and the black film land in different months was as follows:July > May > March > September > November. The change of soil respiration rate of the bare land in different months was as follows:July > March > September > May > November. The soil respiration activity in summer was very intense, and the soil respiration rate in different months of different film mulching conditions was significantly different. ③ The annual soil CO₂ emissions from the soil of different mulching films were as follows:black film land>white film land>bare land, and the annual CO₂ emissions from soil in summer and autumn were higher than those in spring and winter. ④ The soil respiration rate of different film-mulched corn fields had a good correlation with the surface temperature and 5 cm soil temperature, and both showed extremely significant correlations. The 5 cm soil temperature of the film-mulched corn field had a higher impact on the soil respiration rate than the surface temperature, and vice versa in bare land.[Conclusion] Under different mulching conditions, the soil moisture content from the surface to the deep layer changes in an S-shaped curve. The soil moisture in 0-60 cm soil layer was significantly lower in bare land than in the other two film-mulched land. Soil respiration rate and CO₂ release of soil respiration increased under different mulching conditions, which could effectively improve the soil carbon cycle environment of terraced land in loess area.

Abstract:[Objective] The physical properties of topsoil substitute materials formed by overburden materials in the open-pit coal mine with different ratios were explored, in order to provide a theoretical basis for the development of topsoil substitute materials and comprehensive utilization of stripping materials in open-pit coal mines.[Methods] Taking the stripping material of an open-pit coal mine in Eastern Inner Mongolia as the research object, the bulk density, porosity, field capacity, particle size, specific surface area and composition of topsoil substitute materials were determined by cutting ring method, laser particle size analyzer and X-ray fluorescence spectrometry. The relationships between physical properties of topsoil substitute materials were analyzed by the grey relational analysis and principal component analysis, and the core indexes affecting the physical properties of topsoil substitute materials were analyzed to obtain the most appropriate ratio of topsoil substitute materials.[Results] ① The two important indexes affecting the physical properties of topsoil substitute materials were bulk density and maximum field capacity, while the main indexes influencing the field capacity were specific surface area and total porosity of particles. ② The increase of the proportion of heart soil (Calcium layer soil) and fine sand by 30%, would lead to the decrease of the field capacity of topsoil substitute material by 22%. ③ Diameter span and D₁₀ were the key indexes determining the bulk density of topsoil substitute materials. ④ 5A (lower mudstone:upper mudstone:floor soil:heart soil:sand=3:3:4:1:2) and 7A (lower mudstone:upper mudstone:floor soil:heart soil:sand=2:1:2:2:2) had better bulk density and field capacity, both of them were the optimal substitute material ratio for the topsoil in this test.[Conclusion] The physical properties of topsoil substitute materials can be effectively improved by adjusting the ratio of overburden materials in open-pit coal mines. In the preparation process of topsoil substitute materials, the proportion of mudstone and floor soil should be increased and the proportion of calcium layer soil should be decreased to strengthen the water holding capacity. The suitable bulk density ratio of topsoil substitute materials formed by overburden materials in open-pit coal mines is mudstone:raw soil:sand=2:2:1.

Abstract:[Objective] The role of microorganisms in feldspathic sandstone soil remediation was explored, in order to provide new ideas for the scientific assumption of microbial enhanced plant improvement of feldspathic sandstone soil.[Methods] Ryegrass was used as the test crop, and the effects of inoculating Bacillus hallotolerans P75, humic acid fertilizer and different combinations of bacterial fertilizer on soil physical and chemical properties, growth and stress resistance of ryegrass were studied by pot experiments.[Results] Compared with the control, the synergistic treatment of Bacillus hallotolerans P75 fermentation broth and humic acid significantly increased the SOD activity (229.7%), POD activity (83.6%) and proline content (119.3%) in ryegrass leaves, significantly increased the contents of polysaccharide, organic matter, available phosphorus and available potassium and significantly reduced the soil water permeability in feldspathic sandstone soil.[Conclusion] The synergistic effect of Bacillus hallotolerans P75 fermentation broth and humic acid fertilizer can significantly control the water and nutrient loss of feldspathic sandstone soil, improve the stress resistance of ryegrass, and strengthen the improvement and repair of feldspathic sandstone by plants.

Abstract:[Objective] The specific situation of water resources carrying capacity in Yantai City of Shandong Province was quantitatively and qualitatively analyzed, and the corresponding countermeasures and suggestions was put forward to improve the water resources carrying capacity, in order to provide a reference for the sustainable development of water resources in Yantai City.[Methods] The evaluation index system covering water resources, society, economy and water environment was established, and the comprehensive evaluation of the water resources carrying capacity of Yantai City from 2003 to 2018 was carried out by CRITIC-GR-TOPSIS method, with a relative closeness C_j as a comprehensive evaluation value. The larger the C_j, the higher the water resources carrying capacity. The obstacle degree model was used to quantify the impact of each indicator on the water resources carrying capacity.[Results] From 2003 to 2018, the water resources carrying capacity of Yantai City showed an overall upward trend, from 0.449 7 in 2003 to 0.578 3 in 2018. Through the calculation of the obstacle degree model, it was found that the influence of each index of the social and water environment subsystems on the carrying capacity of water resources continues to increase, while the impact of the related index of the economic subsystem on the carrying capacity of water resources in Yantai City was weakening. Each index of the water resources subsystem maintained a stable and high level of influence during this period.[Conclusion] From 2003 to 2018, the water resources carrying capacity of Yantai City has increased, but the increase rate, is not obvious, and there is still broad space for improvement in the future.

Abstract:[Objective] The impact of land use change on carbon stocks under the expansion of urban construction land was explored, and the spatio-temporal evolution and future spatial distribution trend of carbon storage were revealed, in order to provide scientific basis for urban planning and the precise protection of ecologically fragile areas.[Methods] By coupling FLUS-InVEST models, this study simulated the spatial and temporal evolution of variation characteristics of land and carbon stocks in Guangzhou City from 1990 to 2018 based on the interpreted land use data and future land prediction, so as to analyze the impact of construction land expansion on carbon stocks distribution and evaluate the potential carbon stocks in the future.[Results] The land use change in Guangzhou City was characterized by the rapid expansion of construction land, mainly occupying arable land and forestland. The carbon stocks decreased by 2.47×10⁶ t from 1990 to 2018, with the largest decline from 2000 to 2005. High density carbon stocks were mainly distributed in the northern forest area, while low density carbon stocks were mainly distributed in the lower reaches of the Pearl River. The transfer of gravity center of construction land and low density carbon stocks had a high consistency. It was predicted that carbon stocks would decline by 1.20×10⁶ t between 2018 and 2034.[Conclusion] The expansion of construction land in Guangzhou City has significant impact on carbon stocks, and there is a greater risk of loss of carbon stocks in areas of the northwest and east in the future.

Abstract:[Objective] The spatio-temporal evolution characteristics of the ecological environment in Chengbi River basin from 1988 to 2019, and the causes of its change were studied, in order to provide scientific basis for the protection, management and development planning of the ecological environment in karst area, and scientifically evaluate the change of ecological environment quality in karst area.[Methods] Based on Landsat images, the normalized difference mountain vegetation index (NDMVI) was introduced, and the comprehensive ecological evaluation index (CEEI) model was improved. The ecological environment quality of a typical karst basin in Southwest China, the Chengbi River basin was dynamically monitored from 1988 to 2019. The spatial distribution characteristics of the ecological environment quality in the basin were quantitatively analyzed using spatial autocorrelation methods, and the causes of ecological environment quality changes in the study area were analyzed.[Results] ① CEEI could scientifically reflect the ecological environment quality of the study area. ② The quality of the ecological environment in the research area from 1988 to 2019 was at the middle and upper middle level, and the overall trend was increasing. The low value areas were mainly distributed in the karst peak forest area and surrounding the reservoir area in the northern part of the basin. ③ The ecological environment quality of the study area had a certain spatial positive correlation, but the aggregation gradually weakened. ④ Vigorously carrying out the construction of ecological civilization and the management of stone desertification had greatly promoted the improvement of ecological environment quality in karst areas.[Conclusion] The improved CEEI model can better reflect the ecological environment quality of Chengbi River basin, the average CEEI of Chengbi River basin is on the rise, and the ecological environment quality has been improved.

Abstract:[Objective] The coupling and coordination situation and driving mechanism of the socio-economic and eco-environment in the Yellow River basin were analyzed in order to provide a scientific basis for the overall developmental strategy of the Yellow River Basin Economic Belt.[Methods] On the basis of clarifying the coupling and coordination mechanism of social economy and ecological environment, the coupling coordination model was used to quantitatively measure the temporal and spatial pattern and relative development of the coupling and coordination of social economy and ecological environment in the Yellow River basin from 2009 to 2018.The driving effects of internal, government and external forces were studied through the fixed-effect regression model.[Results] ① The development of social economy and ecological environment in the Yellow River basin was insufficient and the overall level index was relatively small. ② The coupling and coordination value of the social economy and ecological environment of the Yellow River basin was between 0.354-0.562, which was in the running-in stage as a whole, and the coupling and coordination situation was within a marginally acceptable range. ③ The level of economic development, government capabilities, and the degree of opening to the outside world had a positive influence on the degree of coupling and coordination, and the level of regional innovation and industrial structure system had a significant negative impact on the degree of coupling and coordination.[Conclusion] In the context of the national strategy of ecological protection and high-quality development in the Yellow River basin, it is necessary to continuously strengthen the optimization of the industrial structure, improve the ability of transforming regional innovation achievements, as well as coordinate and give full play to the superimposed effect of multiple driving factors.

Abstract:[Objective] The spatial and temporal change of land use ecological risk along Yellow River was studied in order to provide theoretical basis for the protection of landscape resource, ecosystem optimization and the establishment of ecological environment protection and control measures.[Methods] Seven cities along the Yellow River in He'nan Province were taken as the research area. With the technical support of GIS and Fragstats software, based on the land use data in 2005, 2010, 2015 and 2018, the research areas were divided into 1 737 ecological evaluation units with area of 6 km×6 km. According to the ecological risk assessment model constructed by the landscape disturbance index and the landscape vulnerability index, the land use change, temporal and spatial changes of ecological risk and spatial correlation pattern in the study area were evaluated by land transfer matrix and spatial autocorrelation analysis method.[Results] ① From 2005 to 2018, the area of construction land within the study area increased rapidly, whilel other types of land area decreased in varying degrees. The increase of construction land was mainly from cultivated land, and woodland, grassland and waters were mainly converted into cultivated land. ② During the research period, the ecological risk of land use in the study area showed a significant positive correlation in space, with characteristics of spatial agglomeration. "High-high" and "low-low" were the main spatial agglomeration patterns of ecological risk. ③ From 2005 to 2018, the minimum and maximum values of ecological risk varied in "N" type roughly. The distribution areas of the high-risk areas were roughly the same over the four periods, with strip and block distributions. The strip high-risk areas were mainly distributed along the Yellow River, while the block high-risk areas were mainly distributed in plain areas with scattered rural settlements. Low and relative low risk areas were mostly distributed around the study area and the southwest area.[Conclusion] During the research period, the areas of low risk and medium risk area increased year by year. Relative low risk areas decreased firstly and then increased. While high risk area and relative high risk area decreased year by year. Each risk area was mainly transformed into adjacent risk area, only a small number of areas had cross-regional transfer, indicating that the ecological risk change of land use within the study area was relatively stable, and the area with rapid change was small.

Abstract:[Objective] The interaction between urban development and river network evolution in the main urban area of Zhengzhou City, He'nan Province was analyzed in order to provide scientific basis for rational regulation of urban water resources.[Methods] Taking the main urban area of Zhengzhou City as the research area, based on remote sensing image data in 1994, 2002, 2009 and 2019, the characteristic index of river network was calculated and the coupling coordination model was established to quantitatively analyze the evolution of river network and the interaction between river network and urban development.[Results] The interaction between urban development and river network evolution was manifested in the destruction and promotion of urban development on river network and the supporting and restricting functions of river network on urban development. Urban development led to the decrease of river network density, the single linear trend and simplified structure, but river network was the skeleton of urban form and material basis. When the bearing capacity of river network tended to the threshold, the urban development would be restrained in reverse, which caused the attention to the river network restoration. The change of coordination degree between urban development and river network could be divided into three stages:fluctuation, running-in and stable development:in the early stage, the high intensity development of the city made the coordination degree of the two decline rapidly. In the middle period, people began to pay attention to the repair and maintenance of river network, and the construction of artificial water system consolidated the structure of river network. Affected by the topography, the main urban areas avoided the southwest hilly areas to the east plain area expansion. In the later stage, the control and restoration of the water system achieved remarkable results, and the coordination degree was upgraded to the primary coordination level with the trend of gradual improvement.[Conclusion] The intervention of artificial water conservancy measures can alleviate the impact of urban development on river network, but the restoration effect of river network lags behind the process of urban development, therefor, it is still necessary to strengthen the restoration and protection of river network.

Abstract:[Objective] The agricultural ecological security of Huaihua City, Hu'nan Province was evaluated in order to provide scientific support for promoting the healthy and sustainable development of agriculture in Huaihua City.[Methods] The evaluation index system of agricultural ecological security was constructed based on the PSR index framework, the combination weight of evaluation indexes was determined by game theory, and the evaluation model of agricultural ecological security was established based on extension cloud model. Taking the agricultural ecosystem of Huaihua City as an example, the agricultural ecological security situation of Huaihua City from 2010 to 2019 was comprehensively evaluated.[Results] The agricultural ecosystem of Huaihua City changed from "relatively safe" state to "safe" state, and the security level increased, but the overall security level needed to be further improved.[Conclusion] In order to further improve the agricultural ecological security of Huaihua City, it is necessary to reduce the energy consumption per unit GDP, build agricultural water conservancy facilities, increase land output level, increase farmers' income, reduce the Engel coefficient of rural residents, and optimize the rural living environment to promote the healthy, safe and sustainable development of Huaihua agricultural ecosystem.

Abstract:[Objective] The characteristics and landscape pattern change of urban expansion in Bangladesh since 1980 were studied in order to provide differentiated development suggestions for urban land use and management in Bangladesh and other developing countries.[Methods] Taking Dhaka, Chittagong, Khulna and Sylhet, four major cities of Bangladeshi along the "One Belt and One Road" as the research objects, the characteristics of landscape pattern change in the process of urban expansion in 1980,1990,2000,2010 and 2017 were analyzed, and the pattern of urban expansion was identified.[Results] From 1980 to 2017, the expansion scale of the four major cities in Bangladesh was showed as:Dhaka > Chittagong > Khulna > Sylhet, and the expansion speed was showed as:Sylhet > Dhaka > Chittagong > Khulna. The trend of landscape pattern change of the four cities showed that the area continued to increase, the dominance strengthened, the degree of fragmentation fluctuated, the spatial pattern developed toward complexity and irregularity, and the space formation gradually diversified. From 1980 to 1990, external expansion was the main pattern of urban expansion in Dhaka, Chittagong and Sylhet, while adjacent expansion was the main pattern of urban expansion in Khulna. From 1990 to 2017, adjacent expansion became the main pattern of urban expansion in all the four cities, and the degree of urban connectivity increased gradually.[Conclusion] During 1980-2017, the city of Bangladesh was expanding continuously, and the landscape pattern changed significantly. The expansion pattern changed from external expansion to adjacent expansion.

Abstract:[Objective] The spatial pattern of the forest industry wetland ecosystem service function in Inner Mongolia was studied in order to provide theoretical basis for the sustainable utilization of forest industry wetland ecosystem and resources.[Methods] Based on the survey data of wetland resource in 2018 in Inner Mongolia forestry enterprise, the Inner Mongolia forestry enterprise wetland ecosystem was taken as the research object. According to the evaluation methods of wetland ecosystem service value which were commonly used at home and abroad such as market value, carbon tax method, industrial oxygen producing method, shadow engineering method, pollution control cost method, expert evaluation and so on, the values of eight service function such as water conservation, carbon fixation and so on were evaluated.[Results] The total value of the service function was 8.61×10¹⁰ yuan; and those of water conservation, carbon fixation and oxygen release, degradation pollution, soil conversation, nutrient accumulation, improving the microclimate, habitats, and scientific, cultural and recreation, were respectively 1.12×10¹⁰ yuan, 1.04×10¹⁰ yuan, 8.94×10⁹ yuan, 6.76×10⁹ yuan, 5.62×10⁹ yuan, 4.33×10⁹ yuan, 2.41×10⁹ yuan, and 5.53×10⁸ yuan, The total value of Dayangshu, Wuerqihan and Kudur Forestry Bureau ranked in the top three, which were 1.12×10¹⁰ yuan, 1.04×10¹⁰ yuan and 8.94×10⁹ yuan respectively.[Conclusion] Water conservation, degradation pollution and habitats are the leading service functions; With the nutrients accumulation as the minimum service function, from the perspective of the overall spatial pattern distribution, the overall trend of the spatial distribution of the value in all forestry bureaus is as follows:in the central > in the southwest > in the north.

Abstract:[Objective] The evolution and optimization mechanism of land use efficiency of counties (cities) in Zhejiang Province were analyzed in order to provide suggestions on realizing efficient and optimal allocation of land resources.[Methods] Using SBM-Undesirable model, entropy method, natural breakpoint method and geographical detector model, the evolution characteristics and optimization mechanism of land use efficiency of 69 counties (cities) in Zhejiang Province from 2007 to 2018 were studied.[Results] ① The evolution of land use efficiency of counties (cities) in Zhejiang Province was characterized by "three stages", and the difference between counties continued to narrow, showing a spatial differentiation trend of "high in the east and low in the west". According to the classification of land use efficiency of counties (cities) in 2018, Zhejiang Province could be divided into four zones:high efficiency, medium efficiency, medium efficiency and low efficiency. ② In 2007, 2012 and 2018, the importent driving factors of land use efficiency of counties (cities) in Zhejiang Province were the scale of capital investment, the regulation of resources and environment, and the ability of scientific and technological innovation. In 2018, the driving factors had different effects on land use efficiency of counties (cities) in different districts. ③ Based on the characteristics of land use efficiency of counties (cities) and their driving factors in 2018, this paper proposed land management and control policies for different districts and formulates differentiated land use optimization strategies based on the principle of "efficiency first".[Conclusion] The land use efficiency and its driving factors in Zhejiang Province have obvious temporal and spatial heterogeneity, and the ability of scientific and technological innovation is the primary driving factor at this stage.

Abstract:[Objective] The water quality and eutrophication status were studied in order to provide a basis for its ecological restoration and rational development and utilization in Taiyangshan Wetland of Ningxia area.[Methods] The water samples were collected in April, July, October, 2019, and January 2020, the physical and chemical indicators of water environment factors were tested, and the phytoplankton density, biomass, the dominant species, Shannon-Wiener diversity index (H') and Pielou uniformity index (J) of phytoplankton were analyzed in Taiyangshan Wetland.[Results] The water quality in summer and autumn of West Lake was class Ⅲ, and that in spring and winter was class Ⅴ and class Ⅳ respectively. The water quality in summer and autumn of Nanhu Lake was class Ⅱ, and that in spring and winter was class Ⅳand class Ⅴ respectively. The water quality in Xiaonan Lake and East Lake was the worst and that was class Ⅴ in the whole year. The phytoplankton diversity index (H') was high, the variation of evenness (J) was small, and the water pollution was light in West Lake and Nanhu Lake. The change of phytoplankton diversity index (H') was obvious, and the water quality was poor in Xiaonan Lake and East Lake. The water body of West Lake presented slight eutrophication in summer and moderate nutrition in other seasons. The water body was moderately nutritious in the whole year in Nanhu Lake. The water body of Xiaonan Lake was moderately eutrophication in summer and autumn, and slightly eutrophication in spring and winter. The water body of East Lake presented a moderate eutrophication in summer and a slight eutrophication in other seasons.[Conclusion] The water quality of the Taiyangshan Wetland lakes has been polluted, and the degree of eutrophication changes significantly with the seasons. The water quality and eutrophication status of the lake should be closely monitored, and corresponding treatment measures should be taken in time.

Abstract:[Objective] The spatiotemporal characteristics of potential evapotranspiration (ET₀) under climate change were studied in order to provide scientific basis for researching regional ecological water demand and water resource management.[Methods] Based on the daily meteorological data of Yanhe River basin from 1978 to 2017, ET₀ was calculated by Penman-Monteith method. The spatiotemporal variation characteristics of ET₀ were analyzed by Mann-Kendall trend test and Pettitt test. And the influencing factors of ET₀ change were analyzed by Pearson correlation analysis.[Results] The average annual ET₀ of Yanhe River basin was 923.53 mm, showing an overall upward trend. Monthly ET₀ showed unimodal distribution, and the highest value occurred from May to July. Seasonal ET₀ showed as follows:summer > spring > autumn > winter. ET₀ in summer, spring, and winter showed an upward trend, while it showed a downward trend in autumn. The spring evapotranspiration had the largest rate of change. Spatially, ET₀ increased from the west to the south and then decreased to the southeast. The evapotranspiration at Yan'an station was the highest, and that at Zhidan station was the lowest. ET₀ at other stations except Ganquan station was on the rise. There was an "evaporation paradox" phenomenon in the area around Ganquan station. The dominant factors were sunshine duration, 2 m high wind speed and precipitation. The change rate of ET₀ was higher in the southeast and lower in the northwest. The change rate of Yan'an station was the largest, while that of Ansai station was the least. The variation trend and rate of meteorological factors such as average temperature, sunshine duration, relative humidity, atmospheric pressure, 2 m high wind speed and precipitation were significantly different in time and space. The influence of the same meteorological factor on ET₀ was significantly different in time and space. The combination of different variation trends of the same factor had significant differences in the influence of ET₀.[Conclusion] In general, the change of ET₀ in Yanhe River basin is positively correlated with the change of average temperature, sunshine duration and 2 m high wind speed and negatively correlated with the change of relative humidity, atmospheric pressure and precipitation. The change of ET₀ is the most correlated factor with sunshine duration.

Abstract:[Objective] The multi-functionality of land use and its obstacles in Wuhan City during 2005-2017 was evaluated in terms of economy, society and ecology in order to improve the efficiency of land use and promote the rational regional land use and achieve regional sustainable development.[Methods] According to the target layer, index layer and element layer framework, an evaluation index system was constructed, and the entropy weight TOPSIS method was used to determine the index weight and calculate the obstacle degree.[Results] ① During the study period, the comprehensive function of land use in Wuhan City showed an overall upward trend, the coordination of functions showed a Z-shaped decline, the dominance of functional changes showed a wavy decline, and land use became increasingly diversified. ② The economic, social and ecological functions had different growth levels. Among them, the economic and social functions experienced low-intermediate-good-quality development stages, and the overall growth was rapid; the ecological functions experienced low-intermediate-quality development. At this stage, although there were small fluctuations, the overall growth was substantial. ③ The degree of economic and social dysfunction declined, while dysfunction of ecological functions continued to rise.[Conclusion] Wuhan City should pay attention to the improvement of ecological functions, transform the economic development mode, promote industrial upgrading, implement cleaner production, reduce the pollution of the three wastes, and pay attention to the protection of water resources and realize the sustainable use of land.

Abstract:[Objective] The ecosystem service value (ESV) of Yuncheng City, Shanxi Province was evaluated in order to provide scientific reference for the exploration of sustainable urban development model.[Methods] Based on the case study of ecological service value of prefecture-level cities in China, The independent variables and value transfer model of landscape ecosystem services in Yuncheng City were established based on Meta-analysis method. And the landscape ecosystem service values of Yuncheng City based on its landscape pattern from 2007 to 2017 were evaluated.[Results] ① The research time, research method and the population of the study area were positively correlated with the value transfer model, while the eeconomic variables were negatively correlated with the model. Among the location variables, the eastern and central regions had a negative effect on ecological service values, while the northeastern regions had a positive effect. ② The ecosystem service value of water landscape per unit area was the largest, followed by woodland, meadow and cultivated land landscape.[Conclusion] Ecosystem service values in Yuncheng City shows a change of "decrease-increase-decrease", which is basically consistent with the change of landscape area, and it is greatly affected by the woodland and grassland landscape.

Abstract:[Objective] The ecological security of Western Sichuan Province was evaluated in order to provide a scientific basis for the ecological environment construction and socio-economic development planning of the region.[Methods] Based on GIS and remote sensing technology, an evaluation index system was constructed from two aspects of natural and human impacts, and the ecological security status of Western Sichuan Province in 2000, 2005, 2010, 2015 and 2018 was evaluated through fuzzy mathematical models, respectively.[Results] The ecological security in 40% of the region in Western Sichuan Province was in a dangerous state, showing a spatial distribution pattern of "high in the east and low in the west". The overall change trend of ecological security in Western Sichuan Province from 2000 to 2018 was "rising first, then decreasing slightly, and then rising". The Moran's I index of ecological security in Western Sichuan Province was around 0.5. The ecological security situation in the Western Baiyu, Batang, and Litang areas had been improved, while the ecological security in Eastern Jiulong, Yajiang, Muli, and Ruoergai areas was declined. Topography and vegetation were the main factors influencing ecological security in Western Sichuan Province.[Conclusion] The overall ecological security situation in Western Sichuan is relatively poor, but it shows a trend of improvement, with strong spatial aggregation. The management of the ecological environment of West Sichuan Province should consider its spatial differentiation characteristics.

Abstract:[Objective] The dynamic changes of NDVI under the influence of human and natural factors in Southwest China were studied in order to provide a basis for the scientific implementation of natural forest protection policies in this region.[Methods] Based on MODIS NDVI, land use data and climate data from 2001 to 2018, combined with Theil-Sen median trend analysis and Mann-Kendall trend test, the dynamic changes of vegetation under human and natural factors in the Southwest China were investigated.[Results] ① NDVI of all types of vegetation increased year by year, with the fastest growth in agricultural land and savanna. The east of Minjiang and Wumeng Mountains was the region with high NDVI value and significant improvement trend; Combined with the southern margin of the Yunnan-Guizhou Plateau, the trend area of significant improvement accounted for 67.09% of the total area. ② One of the reasons for the increase of NDVI in Southwest China was that the natural forest protection and the forestry policy of returning farmland to forest/grassland promoted the transformation of low NDVI vegetation to high NDVI vegetation. The largest contribution was the conversion of woody savanna and savanna to forests. From 2001 to 2018, the conversion area reached 73 693 km², and the net conversion rate increased year by year, mainly distributed in the east part of the boundary of Minjiang River and Wumeng Mountain. ③ The positive correlation between temperature and NDVI was greater than that of annual precipitation. In the east of Minjiang River and Wumeng Mountains, the positive correlation between NDVI and meteorological elements was high. Under the condition of warming and getting wetter, 41.8% of NDVI growth was related to temperature and precipitation, and their contribution rates were 32.35% and 14.54% respectively.[Conclusion] With the implementation of natural forest protection policy and the warming and humidifying regional climate change in the last 20 years, the NDVI in the Southwest China continued to increase from 2001 to 2018. Based on the boundary of the Minjiang River and Wumeng Mountains, such increasing characteristics showed differences in the east and west parts, and the increasing forests area and the NDVI improvement trend on the east side was generally higher than that of on the west side.

Abstract:[Objective] The spatial distribution and ecological characteristics of Castanea mollissima in China under the current climate background were predicted in order to provide a theoretical support for the rational introduction and application of Castanea mollissima in soil and water loss areas.[Methods] Based on 261 occurrence points and 40 environmental variables, MaxEnt model was used to predict the potential distribution of Castanea mollissima. Environmental factors affecting the distribution of Castanea mollissima were also determined. The application scope was determined by comparing the potential distribution of Castanea mollissima with the national soil and water loss areas.[Results] Five environmental variables, including annual precipitation, annual mean temperature, topsoil pH value, mean diurnal range and temperature seasonality, contributed significantly to the distribution of suitable areas of Castanea mollissima, and the cumulative contribution rate was more than 83%. At the same time, Castanea mollissima likes water but is afraid of water logging, so it is suitable for growing in acid soils. The potential suitable areas were 2.92×10⁶ km², accounting for 30.46% of total nation land areas. The highly suitable areas were mainly in the northeast of Sichuan Province and Yunnan Province, most areas of Hubei Province, Hu'nan Province and Jiangxi Province, and some areas of Shaanxi Province, He'nan Province, Anhui Province, Zhejiang Province and Shandong Province. The distribution of moderately suitable areas expanded outward with the centre of highly suitable areas.[Conclusion] Compared with the national key prevention areas and key control areas of soil and water loss in China, Castanea mollissima can be selected as economic tree species for soil and water conservation in other areas, except for Qinghai-Tibet region, the northwest region and the northeast regions. The potential distribution prediction of Castanea mollissima based on MaxEnt model has expanded the understanding of the distribution of ecological characteristics of Chinese Castanea mollissima, and provided a scientific basis for the selection of tree species in the functional areas of soil and water conservation.