Abstract:[Objective] The impacts of soil erosion on reservoir carbon sinks in karst watersheds were studied, in order to provide scientific basis for regional soil erosion control and scientific assessment of carbon cycle in river ecosystems in karst areas.[Methods] Based on hydrological data of Nayong River from 2014 to 2018 and water chemistry monitoring data of Pingzhai Reservoir at the downstream from 2017 to 2018, regression analysis, correlation analysis, and water chemistry analysis were used to study the effects of soil erosion on reservoir carbon sinks.[Results] ① During period from 2014 to 2018, the flow of the Nayong River ranged from 1.151 to 1.663 billion m³/a, and sediment flux ranged from 25.36 to 1.224 7 million t/a. Sediment flux and water flow were not correlated between years but showed a highly significant positive correlation on the monthly time scale. The short-time intense rainfall was one of the main reasons for the occurrence of soil erosion in the watershed. The erosion was intense in spring and summer and weak in autumn and winter. ② Ca²⁺ and HCO₃^- were the main anions in Pingzhai Reservoir, which came from carbonate rock weathering. SO₄^2- was the second most important anion, participating in 30.30%~59.70% of carbonate rock weathering in the reservoir. Reservoir water chemistry type was HCO₃^--Ca type in autumn and winter, and mainly HCO₃^--SO₄^2--Ca type in spring and summer. ③ The partial pressure of carbon dioxide in the reservoir of Pingzhai Reservoir showed spatial and temporal heterogeneity as:winter > autumn > spring > summer, which were showed as carbon sources during autumn and winter, and as carbon sinks while spring and summer.[Conclusion] Soil erosion and reservoir carbon sink effect in Pingzhai Reservoir basin have the same periodic seasonal changes, soil erosion affects reservoir water chemistry and weakens reservoir carbon sink effect.

Abstract:[Objective] The effects of different vegetation cover on reducing runoff and sediment of slope were investigated, in order to provide reference for improving vegetation configuration and reducing soil and water loss of road bed slope.[Methods] The natural rainfall with different rainfall intensities (15,28,40,63 and 82 mm/h) during the observation period was selected to analyze the runoff and sediment yield on three different vegetation types, whcih located at Nanjing-Qidong railway of Nantong City of Jiangsu Province.[Results] Rainfall intensity had a significant effect on the initial runoff producing time (p<0.05). The initial runoff time of three different vegetation types was shortened with the increase of rainfall intensity, indicating the effect of rainfall intensity on the initial runoff generation time was very significant. The grass planting slope and grass irrigation combination slope could delay the initial runoff generation time effectively. Compared with bare slope, grass and grass irrigation combined slope had better effect on reducing slope runoff. Under the experimental conditions, grass irrigation combined slope reduction rate was 54.20%~63.68%, and grass vegetation slope reduction rate was 38.59%~55.37%. With the increase of rainfall intensity, the sediment yield on the exposed slope increase exponentially, especially when the rainfall intensity was more than 63 mm, the sediment of bare slope increased from 662.66 g (15 mm/h) to 2 002.95 g (82 mm/h). With the increase of rainfall intensity, the sediment yield on the slope combined with grass planting and grass irrigation did not increase significantly. Sediment yield ranged from 0.9 g to 4.9 g.[Conclusions] The runoff and sediment of railway bed slop increases with the increase of rainfall intensity, and rainfall has a significant effect on sediment yield on slope. Compared with bare slope, vegetation slope and grass-irrigated slope can reduce soil erosion significantly.

Abstract:[Objective] The micromorphology and erosion characteristics of the feldspathic sandstone under natural rainfall conditions were studied, in order to provide theoretical reference for understanding the mechanism of soil erosion in this region.[Methods] The exposed feldspathic sandstone slope was selected as the research object, and the field monitoring and 3D laser scanning technology were combined to analyze the dynamic changes of the number, shape and geometric characteristics of the rills during 13 rainfall events. The influence of rill micro-morphological change processes on slope runoff and sediment yield was analyzed.[Results] The total rainfall in the study area during the observation period was 267.40 mm, the total rainfall duration was 5 893 min, the total runoff was 294.05 L, and the total sediment was 111.34 kg. The contribution of rainfall to runoff and sediment followed the order of moderate rain>heavy rain>light rain. Moderate rain had the highest impact on slope erosion. After the erosion stopped, the overall morphology of the rill became more complicated, with a total length of 40.52 m, an average width of 4.31 cm, and an average depth of 1.22 cm. The development process of the rills on the slope surface during a single rainfall was as follows:splash erosion-sheet erosion-wide and shallow rills-continuous rill network-ditch wall collapse-channel stability, the rills tend to be narrow and deep.[Conclusion] The morphological indicators of the rills all present an obvious quadratic polynomial correlation, the ratio of rill width to depth and gully density have significant effects on sediment yield.

Abstract:[Objective] The transformation relationship between surface water and groundwater in Tarim River basin was explored, in order to provide scientific basis for the research on the formation mechanism of water resources and the promotion of rational development and utilization of water resources.[Methods] Using oxygen isotope (δ¹⁸O) as the tracer, the relationship between surface water and groundwater transformation in the Tarim River basin was analyzed by using stable isotope technique and hydrochemical principle. In 2018, about 90 groups of surface and underground water samples were collected along the upper, middle and lower reaches of the Tarim River, and their deuterium oxygen stable isotopes and hydrochemical ions (Cl^-, SO₄^2-, HCO₃^-, Ca²⁺, Mg²⁺, Na⁺) were measured. Gibbs diagram and Piper trigram were used to explore the chemical characteristics and their transformation relationship between surface and underground water in the Tarim River basin.[Results] ① The δ¹⁸O values of groundwater and river water varied differently. For groundwater, the δ¹⁸O values gradually enriched along with the flow direction, while the δ¹⁸O values changed little in surface water. According to total dissolved solids (TDS) analysis along the river, for the upstream groundwater, due to the infiltration and recharging of the river and the influence of lateral runoff, its δ¹⁸O decreased significantly. With the increase of the recharging of the river, its δ¹⁸O value continued to enrich. For surface water, the value of δ¹⁸O gradually decreased with the flow direction, and the groundwater was enriched at this stage, indicating that the groundwater can replenish the surface water during this period. ② The groundwater waterline and river water line were respectively established, both of which were lower than the slope of precipitation line, indicating that the isotopic composition of groundwater and river water was affected by evaporation to a certain extent. ③ The average rate of groundwater recharge to surface water in the upper reaches of Tarim River was 1.76 m³/(d·m), and was 1.71 m³/(d·m) in the middle reaches and 1.65 m³/(d·m) in the lower reaches.[Conclusion] The frequent conversion of surface water and groundwater is the main feature of water resources cycle in Tarim River basin, and groundwater recharge is the main source of water resources.

Abstract:[Objective] In order to provide scientific basis for effective control and ecological management of the invasive plants in China, the effects of invasive plants on soil nitrogen and metabolic enzyme activities were explored.[Methods] Field control experiments were conducted to study the soil nitrogen contents, enzyme activities and microbial characteristics of four exotic invasive plants (Lepidium apetalum, Ageratina Adenophora, Conyza canadensis, Flaveria bidentis) and native Petunia hybrida (control plant) for five consecutive years.[Results] ① Plant invasion reduced the nitrogen contents in leaves, stems and roots, which showed as follows:Petunia hybrida > Ageratina Adenophora > Lepidium apetalum > Flaveria bidentis > Conyza canadensis. ② Plant invasion reduced soil nitrogen contents (total nitrogen, mtrate nitrogen, and ammonium nitrogen), which showed as follows:Petunia hybrida > Ageratina Adenophora > Lepidium apetalum > Conyza canadensis > Flaveria bidentis. While the soil pH value revealed an opposite trend showing that plant invasion had increased pH value. ③ The activities of soil protease, urease, and nitrate reductase of different plants showed the same trends:Petunia hybrida > Ageratina Adenophora > Lepidium apetalum > Conyza canadensis > Flaveria bidentis(p<0.05). ④ The soil microbial biomass carbon and nitrogen of different invasion plants also showed the same trend:Petunia hybrida > Ageratina Adenophora > Lepidium apetalum > Conyza canadensis > Flaveria bidentis. Ageratina Adenophora and Lepidium apetalum were significantly higher than Conyza canadensis and Flaveria bidentis (p<0.05). Soil microbial biomass phosphorus showed as:Petunia hybrida > Ageratina Adenophora > Lepidium apetalum > Conyza canadensis > Flaveria bidentis. ⑤ Principal component analysis indicated that soil nitrate nitrogen, ammonium nitrogen and pH value were the main influencing factors of invasive plants.[Conclusions] Different invasive plants could change soil nitrogen form, enzyme activities and microbial characteristics, and the stronger nitrogen assimilation ability and the accelerated soil nitrogen could be regarded as one of the important mechanisms for successful plant invasion.

Abstract:[Objective] The influence of alder and cypress on the weathering and nutrient characteristics of purple soil profiles in the hilly area of Central Sichuan Province was analyzed, in order to provide a scientific basis for soil erosion control and agricultural production.[Methods] The Wanan basin in the hilly area of Central Sichuan Province was selected as the study area, and alder and cypress were used as the study objects. Field survey and profile excavation were conducted to study the effects of alder and cypress on the weathering and nutrients of purple soil profiles.[Results] ① The profile fractal dimension of alder and cypress were 2.07 and 2.13, respectively, which increased by 6.47% and 9.03%, respectively, compared with the control, among which the effect of cypress was better than that of alder. ② The differences in chemical weathering between alder, cypress, and control profiles were not significant. Alder and cypress growth has less effect on chemical weathering of the profile. ③ The integrated fertility index of alder and cypress profile increased by 14.08% and 11.27%, respectively, compared with the control. Alder showed a better enhancement effect than cypress, which was especially obvious in organic matter, total N, alkali-hydrolyzable N, and effective K. ④ The root distribution density of alder and cypress showed a significant positive correlation (p<0.05) with the profile fractal dimension and the integrated fertility index, however, the correlation with chemical weathering index was not significant (p>0.05).[Conclusion] Alder and cypress significantly promote the physical weathering rate and nutrients characteristics of purple soil in the hilly area of Central Sichuan Province.

Abstract:[Objective] The wind erosion control efficiency of windward and leeward edges of different shelterbelts was compared and analyzed, in order to provide theoretical basis for urban shelterbelt construction, sand control and ecological environment improvement in arid oasis.[Methods] Taking different shelterbelts in the suburbs of Tuokexun County, Xinjiang Wei Autonomous Region as the research area, by observing the near surface wind speed, sand driving wind speed, near surface roughness, sediment discharge, and structure of wind sand flow, a comparative study was conducted on the wind erosion control efficiency of windward and leeward edges of mixed forest 1(68% Populus euphratica + 32% Tamarix chinensis), mixed forest 2(65% Tamarix chinensis + 35% Populus euphratica) and Haloxylon ammodendron forest.[Results] The surface roughness, sand driving wind speed, wind speed profile and wind resistance efficiency of different shelterbelts were different. The roughness of different forest areas were in the decending order as:mixed forest 2(0.569 cm) > mixed forest 1 (0.378 cm) > Haloxylon ammodendron forest 0.123 cm. The sand-blowing wind speed from high to low was as:mixed forest 2 (6.17 m/s) > Haloxylon ammodendron forest (6.02 m/s) > mixed forest 1 (5.98 m/s). The effects of wind erasion control were in the decending order as:mixed forest 2 > mixed forest 1 > Haloxylon ammodendron forest. The sand-blocking efficiency was as:Haloxylon ammodendron forest (48.2%) > mixed forest 2(45.6%) > mixed forest 1(37.1%), the sand-collecting capacity of 0-10 cm and 10-20 cm vertical height was higher.[Conclusion] The mixed forest 2 could effectively reduce the wind speed and sediment transport at different vertical heights, and the mixed forest 2 had higher wind erosion control efficiency.

Abstract:[Objective] The relationship between natural plant community characteristics and soil physi-chemical factors in Ningdong mining area was studied, in order to provide basis for the selection of plant species for vegetation reconstruction in Ningdong mining area.[Methods] Six typical natural plant communities and soils in Ningdong mining area were taken as the research objects, and field investigation combined with indoor experiment were conducted to compare and analyze the plant community characteristics of different communities and their relationship with soil physi-chemical properties.[Results] A total of 55 plant species were found in 6 natural plant communities of Ningdong mining area, which belong to 15 families and 48 genera. They were concentrated in 4 families, such as Compositae, Leguminosae, Chenopodiaceae and Gramineae. The vegetation coverage and height of shrub layer in the Hedysarum scoparium+ Caragana korshinskii-Artemisia sacrorum community were the highest among the 6 communities, with values of 48% and 202.54 cm, respectively. Caragana korshinskii, a shrub species, was distributed in 5 of 6 communities, with a good growth. Patrick richness index of shrub layer was positively correlated with soil alkali-hydrolyzale nitrogen, gravel content, available potassium and organic matter, and negatively correlated with pH value. Patrick richness index of herbaceous plant species was positively correlated with soil organic matter, field water holding capacity and available phosphorus.[Conclusion] Shrub species such as Caragana korshinskii, Hedysarum scoparium, Artemisia ordosica and Calligonum mongolicum should be preferred in vegetation reconstruction of coal gangue hill in Ningdong mining area when the soil cover is loamy sand or sandy loam; Ammopiptanthus mongolicus and Caragana korshinskii should be preferred when the soil cover is sandy soil with less gravel; shrub species such as Caragana tibetica, Gymnokarpos przewalskii and Lespedeza bicolor can be selected when the soil cover is sandy soil with a large amount of gravel. Soil bulk density had a greater contribution rate to shrub species diversity, and soil field water holding capacity and organic matter had a greater contribution rate to herbaceous plant diversity.

Abstract:[Objective] The effects of different stubble height on the growth and photosynthetic physiological characteristics of Caragana microphylla were studied, in order to provide theoretical basis for determing the most suitable stubble height of Caragana microphylla.[Methods] Taking the Caragana microphylla planted in 2003 as the research material, and setting six treatments of unflat stubble (CK), stubble height 5 cm (T₁), 10 cm (T₂), 15 cm (T₃), 20 cm (T₄) and 25 cm (T₅) in autumn, 2018, the study measured the aboveground growth and photosynthetic physiological characteristics respectively in the next growing season.[Results] The different stubble height treatments listed in order of effect on the aboveground growth indicators and photosynthetic characteristics as follows:T₃>T₁>T₂>T₄>T₅>CK. T₃ treatment, compared with the CK treatment, exhibited the largest increases in plant height, crown length and width, and new branch among all treatments, with respective increases of up to 203.44%, 278.10%, 292.59%, 385.43%. T₅ treatment only increased by 25.15%, 26.38%, 25.93% and 88.48%, respectively. A certain stubble height treatment significantly increased the net photosynthesis (P_n), transpiration rate (T_r) and water use efficiency (WUE) of Caragana microphylla. The diurnal changes of Caragana microphylla for all treatments showed photosynthesis and transpiration midday depression. The daily average value of P_n, T_r and WUE of T₃ treatment increased by 2.52, 0.37 and 1.52 times, respectively. The P_n and WUE of T₅ treatment only increased by 0.45 and 0.32 times, while that of the T_r decreased by 0.02 times.[Conclusion] In the growth season of next year after coppicing, Caragana microphylla with 15 cm stubble height has strong growth compensation and photosynthetic capacity, followed by plants with 5, 10 and 20 cm stubble, and plants with 25 cm stubble have the weakest growth compensation and photosynthetic capacity.

Abstract:[Objective] The scouring of cross-ridge slope land in the Manchuan-Manggang black soil area was studied, in order to provide a theoretical basis for black land conservation.[Methods] Field scouring experiments were performed on runoff plots in 10, 30, 50, and 70 m sloping farmland with ridge farming, to investigate the processes of runoff and sediment production with different volumes of upslope inflow.[Results] Under the three scouring flow rates of 0.34, 0.67, and 1.00 L/min, the runoff coefficients and sediment contents fluctuated continuously with increasing slope length, but they stabilized at different magnitudes and times at different scouring flow rates. The cumulative runoff production and cumulative sediment production both increased with increasing scouring flow rate, but the maximum values of both occurred at different slope lengths under the same scouring flow rate. When the scouring flow rate was 0.34 L/min, there was a significant correlation between the runoff coefficient and sediment content for the four slope lengths (10, 30, 50, and 70 m). The cumulative sediment production increased with the increase of the cumulative flow rate, with shorter slope lengths exhibiting a stronger linear relationship. When the scouring flow rate was 0.34 L/min, the ranking of the different slope lengths by the amount of soil erosion was 30 m> 10 m > 70 m > 50 m. At scouring flow rates of 0.67 and 1.00 L/min, the order was 30 m > 50 m > 70 m > 10 m. Under the scouring flow rate of 1.00 L/min, the erosion of the 30 m slope was 4.2 times the erosion of the 10 m slope.[Conclusion] Slope erosion increases with increase of scouring flow rate; However, 30 m is the critical slope length for erosion of cross-ridge slope land, and rill development is the main source of soil erosion on cross-ridge slope land.

Abstract:[Objective] The mechanism of Helianthus tuberosus in the improvement of coastal saline soil was explored, the compositional differences of root exudates of Helianthus tuberosus and Suaeda salsa was analyzed, and the changing laws of the soil micro-ecological environment were clarified, in order to provide a theoretical basis for saline soil improvement.[Methods] The root exudates of Helianthus tuberosus and Suaeda salsa were compared and analyzed, and the changes of soil microbial quantity, microbial biomass carbon and nitrogen, microbial community structure and soil enzyme activity under the action of root exudates were studied, so as to systematically clarify the microbial mechanism of saline soil improvement mediated by root exudates.[Results] The rhizosphere soil of Helianthus tuberosus contained fructose (2.343×10^-3 g/kg), glucose (4.235×10^-3 g/kg), and sucrose (2.67×10^-3 g/kg), which were 9.28, 1.52, 2.43 times of that in Suaeda salsa rhizosphere soil. The difference between the content of fructose in the rhizosphere and non-rhizosphere of Helianthus tuberosus was significant (p<0.05), and the content in the rhizosphere was 12.02 times of that in the non-rhizosphere. Helianthus tuberosus soil also contained oligofructose (sucrose triose, sucrose tetraose and sucrose pentaose), but no fructooligosaccharides were detected in the soil of Suaeda salsa. In addition to sugars, Helianthus tuberosus root exudates also contained alkanes, phenols, aldehydes, esters, organic acids, alcohols, ketones, and amides. Its components were more complex than Suaeda salsa soil and some components were unique to Helianthus tuberosus[1-Chloro-octadecane, n-hexadecanoic acid, 2-methyl-Z-4-tetradecene, dodecone, (Z)-9-octadecyl amide, and hexadecyl phenylpropionate Esters.] . Functional root exudates (such as oligofructose, fructose, hexadecane, and octadecanoic acid.) provided carbon source, nitrogen source and nutrient elements for rhizosphere microorganisms. The number of microorganisms in the rhizosphere soil of Helianthus tuberosus increased significantly (p<0.05), and the soil microbial biomass carbon and nitrogen were significantly higher than that in Suaeda salsa soil (p<0.05), which were 1.95 and 1.6 times of that in Suaeda salsa soil, and the microbial biomass carbon and nitrogen of Jerusalem artichoke rhizosphere were about 1.69 times and 1.50 times higher than that in non-rhizosphere soil. And the dominant flora (Proteobacteria, Actinomycota, Chloroflexum, Acidobacteria) accounted for 90%. The relative abundance of soil beneficial bacteria (Actinobacteria and Acidobacteria) increased significantly, and soil biological activity was significantly improved. In addition, the unique secretions of Helianthus tuberosus rhizosphere (hexadecane, and enal.) inhibited the growth of pathogenic bacteria and optimized the microbial community structure. Except for catalase, the activities of soil urease, invertase and alkaline phosphate were significantly increased (p<0.05), and their activities were 1.83 times, 1.88 times and 3.30 times higher than those in Suaeda salsa soil, respectively.[Conclusion] After planting Jerusalem artichoke, through the mediation of rhizosphere exudates, the structure and function of soil microbial community were improved, soil enzyme activity was increased, and soil biological activity was improved as a whole. Compared with the native vegetation Suaeda salsa, it reduces the salt content of the soil and plays a role in improving saline soil.

Abstract:[Objective] Soil evaporation under poplar shelterbelts was investigated, and the in situ soil evaporation estimating method was developed, in order to provide support for water cycle pattern and efficient water use research in forestry.[Methods] Soil evaporation and water surface evaporation under the forest were measured by micro-lysimeters and the standard 20 cm evaporation pan. Reference water temperature in the pan and soil temperatures were also measured. Then the relative evaporation (RE), the ratio of soil evaporation to pan evaporation, and the relative temperature difference (RT), the ratio of temperature difference between soil and water temperature to water temperature were calculated.[Results] The solar radiation was the major factor for the evaporations of the under-forest soil and water surface. Air temperature, humidity, and wind speed have poor correlation with soil evaporation because of the low soil water content. The relationship between RE and RT could be described with a two-stage function, RE decreased with the RT increasing for RT being less than 0.11, after that the RE approached a constant of 0.164, indicating a water vapor diffusion process.[Conclusion] Under poplar shelterbelts, RE decreases gradually with the growth of RT and eventually tends to be a constant. The developed method was validated using an independent data set with relative error of less than 2%, indicating an excellent predication of soil evaporation. Therefore, this study provides a new method for the estimation of soil evaporation and the developed method can be used to estimate soil evaporation.

Abstract:[Objective] The pollution characteristics and risk assessments of heavy metals in soils of different Pogostemon cablin production areas in Guangdong Province and Guangxi Zhuang Autonomous Region were analyzed, in order to provide scientific basis for the prevention and control of heavy metal pollution.[Methods] The Pogostemon cablin and corresponding root zone soil in representative production areas were collected to analyze both of the total and available content of heavy metals, including Cu, Hg, As, Pb, Cd, Cr, Ni and Zn. The pollution characteristics and risk assessments of heavy metals in Guangdong and Guangxi were compared by methods of single-factor pollution risk index and Nemerow-factor pollution risk index. The enrichment coefficient of heavy metals together with the correlation of heavy metals in soil and Pogostemon cablin were investigated to expound the effects of soil heavy metals pollution on the safety of Pogostemon cablin.[Results] ① The risk of heavy metal pollution in the soils of Pogostemon cablin in both Guangdong and Guangxi have reached the warning level, while the heavy metal pollution in the soils of Pogostemon cablin in Guangxi is even higher than Guangdong. The Cd pollution of Pogostemon cablin soil is most widespread with the highest value (0.95) of the average single-factor risk index, which needs more attention. ② The overall situation is safe since the content of every heavy metal in Pogostemon cablin is lower than the corresponding limit value in the Chinese pharmacopoeia. ③ Pogostemon cablin has a weak ability to absorb As, Hg, Cu and Pb, but its stem tends to accumulate Cd which is not affected by soil differences. The accumulation of Cd in leaf is more evident compared with stem.[Conclusion] The prevention and control of heavy metal pollution in the soils of Pogostemon cablin production areas should focus on the control of available content of Cd.

Abstract:[Objective] The factors affecting the reduction of pollutants by improved green space media were analyzed, in order to provide a scientific reference for the construction of green space in sponge cities.[Methods] This experiment investigated the pollutant retention characteristics of urban green space[soil:sand:coir (4:4:2) + 1% PAM] under the combined influence of the repetition period of rainfall, leaching time and depth through indoor simulation experiments, with a view to providing some reference for greenfield construction in sponge cities.[Results] The main factors affecting the different pollutant types in the modified media varied depending on the pollutant type. Among them, the depth factor had a greater contribution to the leaching concentration of nitrogen and COD, and the repetition period of rainfall had a greater contribution to the leaching concentration of phosphorus. The decreasing trend of nitrogen and COD leaching concentration over time could be expressed by a power function or an exponential function. Phosphorus leaching concentration changed with time, showing a trend of first decreasing and then increasing. The overall leaching concentration of nitrogen and COD showed an increasing trend with the increase of the repetition period of rainfall and substrate depth. The phosphorus leaching concentration showed an increasing trend with the increase of the repetition period of rainfall, and showed a decreasing trend with the increase of the depth. On the whole, soil mixed with sand and coir (4:4:2) + 1% PAM had a stronger ability to reduce phosphorus, but a weaker ability to reduce nitrogen and COD.[Conclusion] Soil mixed with sand and coir (4:4:2) + 1% PAM improved medium can effectively intercept phosphorus pollutants in rainwater, and can be used in the construction of sponge urban green space.

Abstract:[Objective] The content characteristics of heavy metals in slope soil and sediment in fluctuating zone in the Three Gorges reservoir area were studied, in order to provide theoretical and data support for heavy metal pollution assessment in this area.[Methods] Three Gorges reservoir area was selected as the study area. Fifty-three sample points were selected to analyze the contents of heavy metals (Cr, Cu, Pb, Zn and Mn) in slope soil and fluvial zone sediments. The pollution situation was assessed by the methods of the single factor pollution index, Nemero pollution index, geo-accumulation index and potential ecological risk index, and the map of heavy metals content was formed by combining the geographic information system.[Results] The average contents of heavy metals were Mn>Zn>Cr>Cu>Pb, and only Cu, Zn, and Zn had pollution. Zn and Mn enriched in both sediment in water level fluctuating zone and slop soil, while Cu only enriched in slop soil. The spatial distribution of heavy metals showed a pattern as high in upper and lower reaches while low in the middle reach. The singe factor pollution index method show that there were only light pollution of Zn and moderate pollution of Mn in study area. The Nemerow composite index of the study area was 2.93, which was moderate. According to the geo-accumulation index, there was only slight pollution of Mn, the other heavy metals were pollution-free. The potential ecological risk of Cr, Cu, Pb, Zn, and Mn were slight ecological hazard. The comprehensive ecological risk index of the study area was 14.09, which was slight ecological risk.[Conclusion] The content of Cr in the study area is mainly affected by the geological background contents of the study area, while the content of Cu, Pb, Zn, and Mn are affected by both geological background contents of the study area and human activities. There are Mn and Zn pollution in the study area, and there is slight ecological harm.

Abstract:[Objective] Based on the improved transpiration observation method, the transpiration characteristics and energy budget of common ecological restoration tree species in coal mining subsidence areas were studied in order to provide a theoretical basis for the selection of tree species and water regulation in ecological restoration in mining areas.[Methods] The reference leaf type was selected, and transpiration of Salix psammophila, Hippophae rhamnoides and Caragana korshinskii were determined by "three-temperature model" + thermal infrared remote sensing method in the field environment. The transpiration characteristics and the energy budget during the transpiration process were analyzed.[Results] ① Green cardboard could replace dried plant leaves at 9:00-15:00 as a reference leaf for plant transpiration determination. ② The diurnal changes of transpiration rate of Salix psammophila, Hippophae rhamnoides, and Caragana korshinskii were all single-peak curves. The highest instantaneous transpiration rate were 0.57, 0.61, 0.71 mm/h, respectively. And the daily transpiration rate was 3.24, 3.27, 3.80 mm,respectively. ③ The daily variation of the hat(which meant plant transpiration diffusion coefficient, used to evaluate plant water deficit status) value of Hippophae rhamnoides was "single-peak type", while that of Caragana korshinskii and Salix psammophila was a "double-peak type". The daily average value of transpiration diffusion coefficient was in descending order:Salix psammophila (0.18)> Hippophae rhamnoides (0.11)> Caragana korshinskii (0.03). ④ The sensible heat flux (H) of Salix psammophila, and Caragana korshinskii were less than 0 at 15:00.[Conclusion] Salix psammophila, Hippophae rhamnoides and Caragana korshinskii can all absorb heat from the surrounding environment through the cold island effect for transpiration and reduce the environmental temperature. Salix psammophila is suitable for planting in areas with flat terrain and abundant water. Hippophae rhamnoides and Caragana korshinskii can be used for ecological restoration by aerial seeding in areas hard to reach by humans and with water deficit.

Abstract:[Objective] The evaluation index system, evaluation model and evaluation standard of water and soil conservation benefits were studied, in order to provide technical support for the performance evaluation and post implementation effect evaluation of national key projects of water and soil conservation.[Methods] The frequency analysis method was used to screen the evaluation indexes, and the analytic hierarchy process was used to determine the index weight.[Results] The evaluation index system of the benefits of national soil and water conservation projects was proposed, and the comprehensive evaluation model was established. The model included 15 indicators in five categories:soil fixation and protection, water conservation, ecological improvement, income increase, disaster prevention and reduction. Based on this, the evaluation criteria was proposed including:excellent, good, slow improvement, deterioration and extreme deterioration.[Conclusion] The comprehensive evaluation model for soil and water conservation benefit evaluation covers many factors such as ecology, economy and society, and it also covers the interaction relationship between different factors, which can provide intuitive, comprehensive and quantifiable evaluation results for the implementation effects of national key soil and water conservation projects.

Abstract:[Purpose] The water safety in Gansu Province was evaluated, in order to provide scientific basis for local departments to formulate corresponding regional water safety measures.[Methods] By constructing DPSIR evaluation index system, water safety of Gansu Province in 2000, 2005, 2010, 2015 and 2018 was evaluated by using the method of entropy value and single index quantification, multi-index synthesis and multi-criteria synthesis.[Results] The water safety and health of Gansu Province had increased from unsafe in 2000 to less unsafe in 2018, showing an upward trend on the whole but to a lesser extent, it was still below the basic safety line. As for the criterion level, the driving force rose slowly and the pressure was still high, while the response level was limited, which was the main limiting factor for the development of water safety and health to a better state. Although the state and influence were in a less safe state, they increased steadily year by year, which was an important driving force for the development of water safety and health to a higher level.[Conclusion] The current situation of water safety in Gansu Province is not optimistic and unsafe. It is necessary to change the current situation of water safety from three aspects:water resources, ecological environment and social economy.

Abstract:[Objective] The interannual dynamic changes and causes of soil and water loss in the contiguous area of Shanxi, Shaanxi and Inner Mongolia during 1990-2020 was analyzed, in order to provide scientific support for the development of effective soil and water conservation in this area.[Methods] Based on the monitoring data of soil and water loss in 1999, 2018, 2019 and 2020, the interannual dynamic changes of soil and water loss in the study area were analyzed. By comparing the monitoring results in 2020 and 1999, the dynamic changes and their causes were analyzed.[Results] Due to the effective implementation of water and soil conservation guidelines, policies and measures formulated at the national and local government levels, the area of soil and water loss in the study area decreased from 4.71×10⁴ km² to 2.45×10⁴ km² during 1990-2020, reduced by 47.98%.[Conclusion] The intensity of soil and water loss in this area has been significantly decreased from strong and above erosion intensity to light and medium erosion intensity, and the ecological environment has been significantly improved. In the future, in accordance with the characteristics of regional soil erosion, further investment and more effective soil and water conservation measures should be implemented.

Abstract:[Objective] The ecological networks in Nanchang City were constructed scientifically and rationally, and the optimal strategies for the defects of the ecological network were researched, in order to provide a scientific basis for ecological construction and help to guide urban planning for biodiversity conservation.[Methods] Based on morphological spatial pattern analysis (MSPA) and landscape connectivity index, the ecological source was selected, the comprehensive resistance surface was constructed considering natural and human factors, the ecological corridor was extracted by minimum cumulative resistance (MCR), and finally the ecological network of Nanchang City was constructed.[Results] The ecological source areas were mainly distributed in the western, northern and eastern regions with higher habitat quality and better connectivity. The distribution characteristic of resistance value was high in the middle area while low in the fringe areas. The spatial distribution of ecological corridor was uneven and the structure was single. The important corridors identified based on gravity model were mainly distributed in the eastern and northern urban fringe area.[Conclusion] It was suggested to strengthen the protection of core habitat patches, increase ecological sources, repair ecological fracture points and optimize network connection. The combination of MSPA and landscape index can effectively identify ecological sources with good ecological quality and high connectivity. In future, we also need to pay attention to the protection of ecological land and improve the landscape connectivity.

Abstract:[Objective] The ecological security of cultivated land in the lower reaches of the Yellow River was dynamically evaluated to diagnose the factors of man-made obstacles, in order to discover the harm caused by unreasonable human behaviors to the ecological security of cultivated land and provide realistic scientific basis for ecological protection and high-quality development of the lower reaches of the Yellow River.[Methods] The cultivated land ecological security evaluation index system was established based on PSR model in 49 counties along the lower reaches of the Yellow River, and matter-element extension and Markov chain model were used in the analysis.[Results] ① From 2000 to 2018, the ecological security level of cultivated land in counties along the lower reaches of the Yellow River showed an overall upward trend, from level Ⅳ to level Ⅰ, especially after 2010. ② From 2000 to 2018, the cultivated land ecological security level of each county and district had a transition from unstable to stable, showing a spatial transition from higher in the northeast and lower in the central and western regions to higher in the northeast-southwest and lower in the central region, and the spatial differences continued to shrink. ③ Per capita arable land area, population density, and the amount of chemical fertilizer used per arable land area were the main human obstacles affecting the ecological security of cultivated land in the lower reaches of the Yellow River.[Conclusion] During the study period, the ecological security level of cultivated land along the lower reaches of the Yellow River showed an upward trend, and the spatial difference of cultivated land ecological security level in each county continued to narrow, which was greatly affected by human activities. In the future, we should promote the improvement of cultivated land ecological security level in the Yellow River basin from three aspects:expanding new agricultural management subjects, implementing geese returning project and constructing intelligent cultivated land platform.

Abstract:[Objective] The changes of eco-hydrological regime in the source region of Dongjiang River basin were studied, in order to provide a basis for clarifying the objectives of eco-restoration and carrying out eco-restoration measures, and to provide experience for the smooth development of the pilot work of water environment and water ecology monitoring of the Ministry of Water Resources.[Methods] The daily flow data of Xunwu shuibei hydrological station in Xunwu County of Jiangxi Province and Dingnan Shengqian hydrological station in Dingnan County from 1980 to 2020 were selected, to comprehensively evaluate the degree of hydrological change of the basin by using IHA-RVA (indicators of hydrologic alteration, IHA; range of variability approach, RVA) method and hydrologic change degree method.[Results] ① The hydrological change degree of the source region of Dongjiang River was 50.1%, which belonged to moderate change, in which the effect of Xunwu Water was greater than Dingnan Water. ② Among the 32 IHA hydrological indexes, the frequency and delay of high and low flow were the least affected, and the degree of change was 26.3%. ③ The maximum flow change rate was 61.5%, which belonged to moderate change, especially the maximum 1-day flow, transformation times, the mean flow in January, the mean flow in May and other indicators have serious variation. ④ According to the analysis of fish resources change, the fish resources in the source region decreased.[Conclusion] The operation of the reservoir has a great impact on the surrounding ecosystem of the source region of the Dongjiang River, and it is urgent to regulate the flow of the river to coordinate the development of regional economy and ecological environment protection.

Abstract:[Objective] The natural capital stocks in Shanxi mining areas were dynamically assessed, in order to provide theoretical basis for the ecological environment protection and ecological compensation for the mining area.[Methods] In terms of natural capital of mining area, and based on the ecological footprint and ecological carrying capacity of the mining area, a three-dimensional ecological footprint model was used to calculate the depth and breadth of the ecological footprint in the Shanxi mining area during 2010-2019. Its dynamic evolution characteristics were further analyzed with the help of the scissors difference between the depth of the footprint and the breadth of the footprint, and then explains the mechanism of the dynamic evolution of the ecological occupation of the mining area.[Results] ① The ecological deficit per capita in Shanxi mining areas increased from 4.40 hm² in 2010 to 6.31 hm² in 2016, and then decreased to 5.02 hm² in 2019. The gap between ecological footprint and ecological carrying capacity tends to narrow overall. ② From 2010 to 2019, the breadth of the per capita ecological footprint generally showed a declining trend, from 0.63 hm² to 0.47 hm², and the depth of the per capita ecological footprint showed an inverted U-shaped change trend that first increased and then decreased. ③ The temporal and spatial dynamic evolution of the natural capital stocks for the mining area was the comprehensive effect of multiple factors such as the endowment of coal resources, the scale of mining, the ecological supply and demand of the mining area, the ecological footprint and carrying capacity, the flow of capital, and the depth and breadth of the stock.[Conclusion] The gap between the ecological footprint and carrying capacity in the Shanxi mining area tends to be improved, but the ecological occupation deficit still exists.

Abstract:[Objective] The effects of landscape change on the sediment transport process were studied in order to provide an important basis for the optimization of land use to control soil loss.[Methods] The earliest shale gas mining area in the eastern part of Fuling District of Chongqing City was selected as the research area. The changes in the landscape pattern before and after shale gas mining between 2010 and 2019 were analyzed. Moreover, the response of sediment connectivity and sediment transport to landscape changes was analyzed. The observing data from 16 runoff plots were used to calibrate sediment loads.[Results] ① From 2010 to 2019, the cultivated land decreased, and the construction land, forest and grass land increased; ② The change in soil erosion caused by landscape pattern change was weak, and the amount of soil erosion in the entire study area was 2.78 t/(ha·yr) in 2019. The source of erosion in the entire region was dry farmland; ③ The connectivity index IC of the entire study area decreased from -0.46 in 2010 to -0.65 in 2019. The sediment transport coefficient in the entire region decreased, and the soil loss modulus in the entire region decreased from 0.83 t/(ha·yr) in 2010 to 0.62 t/(ha·yr) in 2019.[Conclusion] The land use change reduced the amount of soil loss by affecting the connectivity of sediment in addition to soil erosion. The shale gas mining in Chongqing City has not caused a significant increase in regional soil erosion. Blocking the connectivity of sediment in dry farmland is still an effective way to control regional soil erosion.

Abstract:[Objective] The applicability of six multi-source gridded soil moisture datasets was evaluated, in order to provide scientific precision information of soil moisture and selection basis for land-atmosphere coupling study, drought monitoring and land water resources monitoring under the background of climate change in Inner Mongolia Autonomous Region.[Methods] Using the soil moisture data observed by 63 meteorological stations in every ten days at 0-10 cm level from May to September from 2016 to 2020 in Inner Mongolia Autonomous Region, and taking correlation coefficient, mean absolute error and root mean square error as evaluation indexes, the accuracy and spatio-temporal variation of the SMAP soil moisture from NASA, ESA CCI from the European Space Agency(ESA), CLDAS from the China Meteorological Administration(CMA), ERA5 and ERA5 Land from the European Centre for Medium-Range Weather Forecasts(ECMWF) and NOAH from the global land surface data assimilation system(GLDAS/NASA) were systematically evaluated.[Results] ① Six gridded soil moisture datasets could truly reflected the spatial distribution characteristics of soil moisture in Inner Mongolia, and SMAP was the best. ② According to the statistical characteristics of the time series of soil moisture in Inner Mongolia Autonomous Region and its three climatic regions, the six gridded soil moisture datasets better reflected the temporal variation trend of soil moisture. SMAP was the closest to the measured data, and the other five datasets were generally higher in semi-humid and semi-arid regions of Inner Mongolia, and ERA5 and ERA5Land overestimated higher. In arid regions of Inner Mongolia, SMAP, ERA5 and ERA5Land were closer to the observations. ③ Six gridded soil moisture datasets in Inner Mongolia and its three sub-regions had very significant correlation coefficients, and the correlation coefficients between SMAP, ESA, CLDAS, ERA5, ERA5Land and the observed data was obviously better than that of NOAH. The mean absolute error and root mean square error of SMAP data are significantly smaller than those of the other five datasets.[Conclusion] Six gridded soil moisture datasets have different applicability in Inner Mongolia area. The quality and applicability of SMAP soil moisture are the best, ESA is the second, NOAH is the worst.

Abstract:[Objective] The carbon emissions in the process of land consolidation projects was scientifically measured, in order to provide support for the implementation of low-carbon land use and the realization of carbon peaking and carbon neutralization goals.[Methods] The carbon emission mechanism in the construction process of land consolidation project was analyzed according to specification of PAS2050 in the field of international architecture. Based on the carbon emission coefficient method, the budget quota of land consolidation project was converted into carbon emission quota, and the total carbon emission of the land consolidation project was measured and calculated according to the idea of construction project budget.[Results] ① The carbon emission quota of land consolidation project was based on the relevant budget quota given in the budget quota of land development and consolidation project. The carbon emission coefficient method was used to calculate the carbon emission of a certain amount of manpower, materials and machinery contained in each budget quota, and then convert it into carbon emission quota, so as to finish the calculation of the total carbon emission. ② According to specification of PAS2050, the space-time boundary, object boundary, element boundary and carbon source type of carbon emission of land consolidation project were clear. Based on these, the total carbon emission of the case would be calculated as 194 225.95 kg.[Conclusion] The carbon emission quota method has a good application prospect in the systematica comprehensive and accurate calculation of carbon emission in the construction process. Through compiling the standard of carbon emission quota of land development and consolidation project, developing the software of carbon emission quota of land consolidation project and optimizing and adjusting quota, the carbon emission quota method is applied in land consolidation practice, which would be beneficial to promoting energy conservation and emission reduction of land consolidation.

Abstract:[Objective] The spatial and temporal distribution characteristics of ecological vulnerability along Sichuan-Tibet railway from 2010 to 2020 was explored, and the pattern and spatial correlation of ecological vulnerability was clarified, in order to provide scientific basis for ecological environment protection and sustainable development after construction.[Methods] Taking the Sichuan and Tibet railway (Ya'an-Xinduqiao section) as an example, 15 factors closely related to ecological vulnerability were selected based on the field characteristics and SRP model to construct the ecological vulnerability evaluation index system. Spatial principal component analysis (PCA), spatial autocorrelation, hot spot analysis and geographic detector were used to carry out the research.[Results] ① In terms of spatial and temporal distribution, the overall vulnerability of the study area decreased from west to east, and the ecological status of the study area improved from 2010 to 2020. The severe and extremely vulnerable areas were small, accounting for 3.95% of the total area, and mainly distributed in the junction of Kangding City, Tianquan County and Luding County, which was an alpine zone with the most serious freezing-thawing erosion. ② The distribution of ecological vulnerability in the study area has strong clustering characteristics, with high and low values co-existing. In the west, hot spots are highly concentrated, while in the east, cold spots are highly concentrated. ③ Elevation, average annual temperature and net primary productivity of vegetation were the main factors leading to ecological fragility in the study area.[Conclusion] The construction of the Sichuan-Tibet railway (Ya'an to Xinduqiao section) was greatly affected by precipitation and temperature, and the terrain was complicated. Therefore, attention should be paid to geological disaster prevention and control, environmental protection and ecological maintenance.

Abstract:[Objective] The spatial-temporal changes and associated driving forces of land use in the Beiluo River basin were investigated in order to provide a scientific basis for the optimization of land resources, the improvement of environmental quality and further exploration on runoff-sediment dynamics in the area.[Methods] Based on the google erath engine (GEE) platform, we sorted and processed six-phase remote sensing images acquired in 1970-2019 for the Beiluo River basin. The characteristics of land use change in the basin were captured from the perspectives of temporal variation, dynamics attitude, transfer direction and spatial structure, and the associated driving factors were explored.[Results] During the study period, the land use types in the Beiluo River basin were mainly woodland, cultivated land and grassland, and the quantitative structure changed from 1:1.1:0.6 before 2000 to 1:2.7:0.7 after 2000. During 1970-2019, cultivated land, grassland and water area in the basin decreased by 16.6%, 6.7% and 0.1%, respectively, while contrarily woodland and construction land have increased by 19.9% and 1.3%, respectively. The patches of cultivated land and grassland in the basin tended to be dispersed and simple, while the woodland tended to be aggregated and complicated. Land use transfer mainly occurred as the conversion of cultivated land to woodland and construction land, and the conversion of grassland to woodland. The comprehensive land use dynamic attitude of the basin increased firstly and then decreased, reaching a peak during 2000-2010. In the basin, the upstream hilly and ravine area saw the most significant change of land use structure, followed by Ganquan, Yijun, Huachi and Heshui counties in the middle reaches.[Conclusion] The evolution of national policies, socio-economic development and population growth determine the direction and extent of land use change, and natural factors are long-term auxiliary influencing factors.

Abstract:[Objective] The health of the grassland ecosystem before and after grazing in the Altay forest area was assessed, in order to provide a scientific basis for the restoration and management of degraded grassland in the area.[Methods] The VOR ecosystem health evaluation model was used combined the Margalef richness index, Simpson dominance index, Shannon-Wiener diversity index, and Alatalo evenness index to evaluate the overall status of the grassland ecosystem in the Aletai forest area.[Results] ① The Margalef index of each monitoring point was high significantly different before and after grazing in tourist areas (p<0.01), and was significantly different before and after grazing in pastoral roads (p<0.05); The Simpson index and Shannon-Wiener index of the front mountain slopes and pastoral roads showed extremely significant differences before and after grazing (p<0.01); The Altalo index of each monitoring site had no significant difference before and after grazing. ② The structure of the grassland ecosystem after grazing in the Aletai forest area was relatively stable; The organizational strength (O) and the resilience (R) value of the healthy grassland ecosystem before and after grazing in the Aletai forest area were significantly different (p<0.05). ③ The VOR index showed that the difference before and after grazing was extremely significant (p<0.01), while the VOR index of other monitoring points had no significant difference. ④ The evaluation results of the health status of the grassland before and after grazing at each monitoring point were consistent, which was a "healthy" state, but the VOR composite index value of each monitoring point was different.[Conclusion] The grassland ecosystem structure is relatively stable after grazing in the Aletai forest area. The Margalef abundance in the tourist area of the monitoring point is significantly different before and after grazing (p<0.01). The Simpson dominance and Shannon-Wiener diversity of the front mountain slopes and pastoral roads are all different before and after grazing. The health status of the grassland before and after grazing at each monitoring point was evaluated as "healthy".

Abstract:[Objective] The spatial pattern of soil nutrient content in cultivated land and its spatial correlation with environmental factors were studied, in order to provide a theoretical basis for regional cultivated land soil fertilization control and agricultural ecological environmental protection.[Methods] Taking the cultivated land in Zaoyang City of Hubei Province as the research object, five soil nutrient indicators including soil organic matter, total nitrogen, available potassium, slow-acting potassium and available phosphorus were selected, and 10 environmental factors including soil parent materials, soil types, soil pH value, Elevation (DEM), surface undulation, slope, vegetation coverage index (NDVI), average temperature, average precipitation, and land use types were collected to analyze the spatial distribution characteristics of each soil nutrient and the correlations between the spatial differentiation characteristics of each soil nutrients and environmental factors by using ordinary Kriging interpolation and information entropy principle.[Results] The spatial heterogeneity of soil slow-acting potassium in Zaoyang City was not obvious, and the content of the whole area was relatively high; the other four nutrients all showed different degrees of spatial heterogeneity. The results of information entropy showed that the spatial patterns of the five soil nutrient contents were strongly correlated with soil-forming parent materials, soil type and climate shadow, but the degree of correlation was different; the topographic factors had a strong spatial correlation with total nitrogen and organic matter contents, and soil pH value. The value had a strong correlation with soil available potassium, slow-acting potassium and available phosphorus.[Conclusion] The soil nutrient pattern in Zaoyang City is strongly affected by natural factors, but the correlation index K value is low, indicating that it is affected by the chemical reaction of soil water and nutrient loss caused by man-made fertilization, crop consumption and irrigation and drainage in the later period.

Abstract:[Objective] A database and an arrangement strategy of rocky desertification control technologies were constructed to provide references for the future control of karst rocky desertification.[Methods] Based on a large number of references, and followed the orientation of soil and water conservation, the existing techniques and modes for rocky desertification combating were systematically summarized.[Results] A database system for rocky desertification control technologies, which met the need of control at different land types and at different scales, was constructed. Furthermore, a set of methods for fast selection and multi-scale arrangement of optimal technologies under different control backgrounds were proposed. Meanwhile, some vital concepts related to rocky desertification control were clarified.[Conclusion] Rocky desertification control in the new era is a path to integrate rocky desertification control into regional green development, and to ensure high-quality development with high-quality ecological construction. Thus there is no universal formula for rocky desertification control, and any control scheme should be determined and refined based on the site conditions and regional socio-economic conditions of the target area.

Abstract:[Objective] The performance level and its obstacle factors of rural community environment construction were analyzed, in order to provide a basis for improving the performance level of rural community environment construction.[Methods] The PSR model, matter element analysis and improved entropy method were used to diagnose the performance level of rural community environment construction in Jiangsu Province.[Results] From 2006 to 2019, the performance level of rural community environment construction in Jiangsu Province improved gradually from poor to good, but the coefficient of the correlation of the assessed rank for class of good was very weak in 2019. The proportion of environmental sanitation investment in municipal public facilities, public financial expenditure for energy conservation and environmental protection, proportion of administrative villages for domestic sewage treatment, application intensity of chemical fertilizer, use intensity of pesticide, use intensity of agricultural plastic film, energy consumption per unit GDP was verified to be the key obstacles for the further improvement of the performance level of rural community environment construction.[Conclusion] In order to effectively improve the performance level of rural community environmental construction, we should further improve the diversified investment mechanism of community environmental construction, strengthen the treatment of rural domestic sewage, effectively improve the agricultural ecological environment, promote the reduction and efficiency increase of chemical fertilizers and pesticides, strengthen the pollution control of agricultural plastic films, comprehensively promote high-quality development, reasonably improve the utilization efficiency of energy and resources, effectively reduce the energy consumption per unit of GDP, and so on.

Abstract:[Objective] The dynamics of the coupling and coordinated development of impervious surface area (ISA) and socio-economic development in China since the 21st century was explored, and the spatiotemporal pattern of the contradictions and synergies between landscape urbanization and socio-economic development was analyzed, in order to provide a scientific basis for soil and water conservation, and the formulation of differentiated regional urban and rural development strategies.[Methods] The decoupling model and coupling coordination degree model were used to investigate the spatiotemporal variation characteristics of ISA and socio-economic coupling coordinated development in 355 prefectures in China from 2000 to 2018.[Results] ① The continuous expansion of ISA in China was inconsistent with the socio-economic development, which showed a significant regional difference. From 2000 to 2018, in the relationship of ISA-economy in each prefecture, the ISA growth generally lagged behind the economic development, except for northeast and north of Chinese prefectures experienced a process from lagging to overtake. Meanwhile, the proportion of weak decoupling type decrease by 38.59% and the proportion of negative decoupling type increased by 30.70%. In the relationship of ISA-population in each prefecture, ISA expansion rate was ahead of the population growth in most of prefectures, especially in central, northwest and southwest of Chinese prefectures. Moreover, the proportion of strong negative decoupling type increased by 23.94%. ② From 2000 to 2018, the degree of coupling coordination in ISA-economy-population decreased, while the expansion rate of ISA increased. As shown in the triangle diagram, the coupling coordination relationship between ISA-economy and ISA-population showed an antagonistic relationship, in a special region of ISA below 0.25.[Conclusion] Since the 21 st century, the dynamic relationship among ISA-economy-population in China tended to be uncoordinated. In the future, it is necessary to strictly control the outward spread of impervious surface in urban and rural areas, improve the land use intensity, and promote the sustainable development of urban and rural areas.

Abstract:[Objective] The pattern evolution and driving force of ecological-productive-living spaces in the area around Dianchi Lake was investigated, in order to provide scientific basis for the optimization of land space and the protection of Dianchi Lake in the study area.[Methods] Based on the land use and social economic data in 2000, 2005, 2010, 2015 and 2020 in the area around Dianchi Lake, the spatial analysis, dynamic degree, transfer matrix, landscape pattern index and geographical detector were used to analyze the pattern evolutions and driving forces of ecological-productive-living spaces in the area around Dianchi Lake from 2000 to 2020.[Results] ① The ecological space and productive space around Dianchi Lake continued to shrink, and the living space gradually increased. The comprehensive dynamic degree of ecological-productive-living space fluctuated, but the single dynamic degree of production space and ecological space continued to decline. The reduction of ecological and production space area and the expansion of living space area were mainly located around Dianchi Lake. Guandu District, Anning City and Chenggong District had the most drastic changes in ecological-productive-living space. ② The characteristics of spatial transfer were as follows:ecological space and production space mainly were converted to living space, and living space mainly to production space. On the other hand, the ecological space mainly transferred from the productive space, the production space mainly from the ecological space, and the living space mainly from the production space and the ecological space. ③ The landscape pattern index showed that the fragmentation of ecological-productive-living space decreased, but it was still at a high level. The patch shape was first complex and then simple, and the degree of cohesion decreased first and then compacted. The patches in ecological-productive-living space showed a trend of uniform distribution, and the landscape diversity increased. ④ The physical and geographical factors were the basic determinants of the evolution of ecological-productive-living spatial pattern, the socio-economic factors were the direct driving forces, and the policy planning factor was the indirect driving force.[Conclusion] The spatial dynamic change of ecological-productive-living space in the area around Dianchi Lake is significant and the spatial difference was obvious. The pattern evolution is affected by multiple factors such as physical geography, social economy and policy planning.

Abstract:[Objective] The spatial and temporal shifts in land use structure and changes in ecosystem service values in Yan'an City of Shaanxi Province from 1990 to 2020 were analyzed, in order to provide scientific references for the effective implementation of regional ecological restoration projects and the designation of policies according to local conditions.[Methods] The land use data of Yan'an City obtained from the interpretation of seven periods of remote sensing images from 1990 to 2020 were used to explore the changes in land use structure and the changes in ecosystem service value (ESV) in the study area based on information entropy and offset share models.[Results] ① The information entropy of land use structure in Yan'an City from 1990 to 2020 decreased from 1.14 Nat to 0.99 Nat, and the order of land use structure increased while homogeneity decreased. ② From 1990 to 2020, the construction land, forest land and water area in Yan'an City were the growth structures. In the northern part of Yan'an City, the competitive advantage of construction land, forest land and water area were obvious. In the central area, the competitive advantage of grassland was obvious. And in the southern area, the competitive advantage of arable land was obvious. From 1990 to 2020, the ESV of Yan'an City increased from 2.375 billion yuan to 3.145 billion yuan, and the growth rate of ESV was characterized by "high in the north and low in the south".[Conclusion] Construction land, forest land and water area are the causes of land use growth in Yan'an City, and the ESV growth rate is consistent with the competitive deviation of land use structure.

Abstract:[Objective] The ecological carrying capacity of water resources in Fujian Province was studied, in order to provide a scientific basis for the sustainable utilization of water resources in this area.[Methods] Based on the theory of ecological footprint, the 3D model of water ecology carrying capacity was imposed and the data from 2010 to 2019 in Fujian Province was used, to analyze the water ecological footprint, water ecological carrying capacity and spatial pattern of water resources.[Results] From 2010 to 2019, the general trend of per capita water ecological footprint in Fujian Province showed a decreasing trend with a range of 0.696 hm²/person to 0.928 hm²/person. The per capita water ecological carrying capacity ranged from 2.602 hm²/person to 10.944 hm²/person and was greatly affected by precipitation. Water resources showed ecological surplus. The tendency of ecological footprint of ten thousand-yuan GDP showed an obvious downward trend. The water carrying capacity in the western part was obviously better than that in the eastern coastal area. The water resources footprint depth was 1, and the value of water resources footprint size was below 1 in recent years. Meanwhile, it showed a downward trend.[Conclusion] Water resources are rich in Fujian Province. In recent years, water resources well supported the local development. However, the water carrying capacity in Fujian Province varied greatly from year to year and the spatial distribution is quite different. With the development of social economy, there are still some risks in water resources.

Abstract:[Objective] The spatial and temporal characteristics of soil conservation function and its influencing factors in Danjiangkou Reservoir area were scientifically evaluated, in order to provide a scientific basis for the establishment of soil erosion control models in the water source area of the middle route of the south-to-north water transfer project and the soil and water conservation and ecosystem safety management in the basin.[Methods] The InVEST model and the geographical detector method were used to quantitatively analyze the temporal and spatial characteristics of soil conservation function and its influencing factors in Danjiangkou Reservoir area in 2010, 2015 and 2020.[Results] Firstly, from 2010 to 2020, both of the actual amount of soil erosion and the soil erosion grade in the Danjiangkou Reservoir area decreased, and the spatial distribution trend in each year was basically consistent. Secondly, the conserved soil in Danjiangkou Reservoir area in 2010, 2015 and 2020 was 6.25×10⁹ t, 6.62×10⁹ t and 7.12×10⁹ t, respectively, which showed a gradual upward trend, indicating that the soil conservation function of the Danjiangkou Reservoir area has been continuously enhanced. Thirdly, the soil conservation function was varied in different altitude ranges. The quantity of soil conservation was larger in higher altitude areas, such as Funiu Mountains in the northeast, Qinling Mountains in the west, and Wudang Mountains in the southwest. The quantity of soil conservation was smaller in lower-altitude areas, such as the area around the Danjiangkou Reservoir. The quantity of soil conservation of different land-use types was also quite different, with wood land being the largest, followed by shrub rangeland, garden land and cultivated land. Last, the geographical detector analysis results showed that the changes in soil conservation function in the Danjiangkou Reservoir area were mainly affected by topographic factors.[Conclusion] In recent years, the soil conservation function in the Danjiangkou Reservoir area has been changed in a positive trend in general, although the quantity of soil conservation in some areas is still small. In the future, the returning farmland to forest land (or grassland) should continue to be promoted, and forest land and shrubland with strong soil conservation capabilities should be focused and protected so as to enhance the soil conservation function of Danjiangkou Reservoir area.

Abstract:[Objective] The changes of productive-living-ecological land use and cost-benefit of ecosystem service in Yuanzhou District of Ningxia Hui Autonomous Region after returning farmland to forestland were analyzed, in order to provide a scientific support for the development of land space and the optimization of main functions in this area.[Methods] Based on the principle of dominant function, the land use classification system of productive-living-ecology was established. Based on the identification of productive-living-ecological land types and the analysis of land use structure and spatial pattern in Yuanzhou District from 2000 to 2018, the impact of the change of productive-living-ecological land on the value of ecosystem services (ESV) was quantitatively assessed by using the equivalent factor method.[Results] ① From 2000 to 2018, the production land decreased by 7 062.96 hm², and the proportion decreased from 42.88% to 41.88%, but the area of irrigated land and garden land increased significantly. Ecological land decreased by 3 259.06 hm², and the proportion decreased from 54.66% to 52.52%, but the internal structure optimization features were significant where the proportion of forest land was improved. Living land expanded by 10 272.63 hm² and increased rapidly from 2.46% to 6.19%, which was mainly characterized due to the increase of urban area. ② In the productive-living-ecological land category, the dynamic change of the living land area was the highest, which was -3.31%. In the secondary land category, the irrigable land, garden land, urban land, woodland and grassland were the highest in the productive-living-ecological land category, respectively. In addition, the dynamic change of land use in the early stage of the study was significantly greater than that in the later stage. ③ Spatially, the increase of irrigated land and garden land in Qingshui valley was the main trend. The urban area, Sanying Town, Touying Town and other urban construction land expanded rapidly. The forest land in Liupan Mountains area and loess hilly and gully area increased greatly. ④ During the study period, the ESV of Yuanzhou District increased by 10.06 hundred million yuan, and the supply, regulation, support and cultural functions were greatly improved. The main transfer directions resulting in the decrease of ESV were dryland to residential land, dryland to industrial and mining water conservancy land, grassland to dryland, grassland to industrial and mining water conservancy land, grassland to residential land, woodland to dryland, woodland to grassland, and other transfer modes were beneficial to the growth of ESV.[Conclusion] During the research period, the evolution of productive-living-ecological land in Yuanzhou District gradually slowed down, and ESV increased year by year. The change of productive-living-ecological pattern showed that the living land was concentrated in the center and expanded outward, and the production land was distributed around towns. Ecological land was expanding to the edge.

Abstract:[Objective] The impacts of landscape pattern on urban thermal environment were studied to support the strategies that can mitigate extreme thermal environment caused by rapid urbanization in living environments and industrial production.[Methods] Based on Landsat images in 1996, 2008 and 2017 in Zhangjiakou City of Hebei Province, land surface temperature (LST) retrieval was conducted to quantify and map the thermal environment. Meanwhile, the landscape pattern index was obtained by moving window method at a grid scale. Finally, the specific relationship between the landscape pattern and LST was analyzed quantitatively and spatially.[Results] ① The changes of landscape pattern were featured by the expansion of impervious surface landscape with an increase of more than 81.26 km² from 1996 to 2017, followed by the reduction in vegetation landscape (61.78 km²). ② During the study period, the average LST of the study area increased by approximately 3℃, and the impervious surface landscape and vegetation landscape as the "heat source" landscape and the "cold source" landscape maintained the average LST of 27.29℃ and 23.77℃, respectively. ③ For every 10% decrease in the proportion of vegetation landscape and water landscape area, the corresponding LST decreased by 2.71℃ and 5.77℃, respectively. For every 10% increase in the proportion of impervious surface area, LST increased by 0.25℃. Landscape aggregation, shape index and proportion of cultivated area all maintained a non-linear correlation with LST.[Conclusion] The urban's thermal environment has developed towards a high level in Zhangjiakou City in the last two decades, which was strongly related to both the increase in impervious surface and reduction in vegetation.

Abstract:[Objective] The spatial and temporal characteristics of ecosystem service value (ESV) in Datong City of Shanxi Province after returning farmland to forestland was analyzed, in order to provide a reference for land spatial planning and ecological restoration project in Datong City.[Methods] The remote sensing image of Landsat TM/ETM was used as the data source, and RS and GIS technology was used to extract the land use data of 2000, 2005, 2010, 2015 and 2019 in the study area. Based on the land use dynamic and land use transfer matrix, the land use change of Datong in recent 20 years was revealed, and the value equivalent method was used to analyze the ecosystem service value of Datong City.[Results] ① In recent 20 years, cultivated land, grassland and woodland were the main land use types in Datong City, and the dynamic attitude of comprehensive land use was the highest from 2005 to 2010. The land use transfer was mainly from grassland to woodland, and from cultivated land to construction land. ② The overall ecosystem service value of Datong City decreased significantly, and the total value decreased by 316 million in 20 years. ③ The values of each individual ecosystem service function were as follows:regulating service> supporting service> supplying service> cultural service. ④ Ecosystem service value of each district and county was divided into five levels, and the overall trend of spatial distribution was higher in the south and lower in the north, showing a fluctuating state.[Conclusion] Woodland and grassland contributed the most to ecosystem services, and the negative value of construction land was very high. Therefore, in the land spatial planning, people should improve the utilization efficiency of construction land, control the scale of construction land, and focus on the constructed woodland and grassland in the ecological restoration project.

Abstract:[Objective] The impacts of the transformation of productive-living-ecological space on the change of ecological risks in oasis cities were analyzed to realize the coordinated development of productive-living-ecological space, in order to provide scientific basis for solving the disorder of land development, resource and environment problems caused by rapid economic development and social transformation.[Methods] Based on the vector data of productive-living-ecological space in Urumqi City during 2000, 2010 and 2018, as well as the methods of GIS spatial analysis and ground statistics analysis, the ecological risk index on grid scale was constructed to quantitatively evaluate the spatial-temporal differentiation characteristics of ecological risk in Urumqi City.[Results] ① During the study period, the area of living and productive space increased significantly, with a growth rate of 169.78%. The area of ecological production space increased gently, and the area of ecological and production ecological space decreased by 4.27% and 21.79%. The comprehensive dynamic degree of productive-living-ecological space was 0.40%, and the center of gravity shifted southward. ② During the past 20 years, the risk levels were mainly high and relative higher in the ecological space area, accounting for 92.15%, while the risk levels in other spaces were relatively low, and the risk levels in the living and productive ecological space areas incrased. ③ From 2010 to 2018, the degree of ecological risk in the region slowed down, and the change of ecological risk levels mainly declined, which was 1.95 times of the increase area. ④ The response elasticity of the ecological risk to the change of productive-living-ecological space in the study area decreased, indicating that the factors affecting ecological risk showed diversified characteristics.[Conclusion] ① During 2000-2018, the area of living production space in this region has significantly expanded with an increase of 606.99 km², mainly from the surrounding ecological space and production ecological space. ② The ecological security situation in the region tended to be improved, but it still belong to the middle and high-risk areas, which need to strengthen the management of the extremely unstable ecological space.

Abstract:[Objective] The spatiotemporal changes in land use types in Pingtang, Huishui, and Luodian counties surrounding the FAST (five-hundred-meter aperture spherical radio telescope) were analyzed, and the relation between land use changes and the ecological environment was explored, in order to provide reference suggestions for the environmental protection and improvement of the ecological environment around the FAST.[Methods] Based on the TM remote sensing image data of 2000, 2005, 2010, 2013 and 2017, RS and GIS technology were used to interpret the remote sensing image data to obtain the productive-living-ecological space of Huishui County, Luodian County and Pingtang County of Guizhou Province surrounding FAST. With these land use data, the regional ecological environment quality index and its ecological contribution rate were calculated, and the evolution characteristics of land use function and the response status of regional ecological environment in the past 20 years were analyzed.[Results] ① The forest land around FAST occupied the largest proportion, but showed a decreasing trend. The land use area of productive-living-ecological space was as follows:ecological area> productive area> living area. The area of living and production land increased from 1 671.74, 12.84 km² to 1 674.07, 25.66 km², respectively, the ecological land area decreased from 6 610.55 km² to 6 590.86 km². ② The construction of the FAST project accelerated the transformation of land use types and promoted the mutual conversion of forest ecological land, grassland ecological land, agricultural production land, and water ecological land around FAST. Among them, forest ecological land had the largest transfer area, accounting for 46.14% of the transferred area. ③ The eco-environmental quality index around FAST dropped from 0.471 0 to 0.468 1, and the eco-environment showed a downward trend. The development around FAST promoted the conversion of land use with high ecological environment to land use with low ecological environment.[Conclusion] There is a coupling relation between the ecological environment and land use changes around FAST. The quality of the ecological environment shows a downward trend as the ecological land changes to production and living land. Improving the ecological land around FAST is beneficial to safe operation of FAST project.

Abstract:[Objective] The spatiotemporal evolution characteristics and its driving factors of cultivated land in Yibin City, Sichuan Province were analyzed, in order to provide support for decision-making in regional land resource management and agricultural development planning.[Methods] Based on land use data and socio-economic data, the characteristics of spatiotemporal pattern change and its driving mechanism of cultivated land in Yibin City from 1980 to 2018 were explored with the help of land use transfer matrix, kernel density analysis, landscape index and PLUS model.[Results] ① The cultivated land area continuously decreased since 1980, with a total reduction of 247.92 km², mainly transferred to construction land and forest land. ② The distribution of cultivated land had obvious spatial differences, showing a spatial pattern of "more in the north and less in the south", and its spatial density decreased year by year. ③ The degree of spatial aggregation of cultivated land was continually decreasing, while the degree of dispersion was constantly increasing, resulting in an increase in fragmentation of cultivated land. ④ Socio-economic factors such as population, GDP, roads, and natural environmental factors such as elevation and water are the main driving factors of cultivated land change.[Conclusion] Under the constraints of natural factors such as elevation and water area, socio-economic factors such as population, economy and transportation conditions work together to drive the changes in cultivated land, with a continuous decrease in area and a gradual increase in the degree of fragmentation.

Abstract:[Objective] The vegetation greenness dynamics and attributions of land use/cover change in Bashang Plateau were analyzed, in order to provide scientific reference for the construction of local ecology and the environment support area for Beijing-Tianjin-Hebei region, and to support decision-making for land use planning and ecological environment protection.[Methods] MODIS MOD13Q1 NDVI dataset and Landsat-derived land use data in Bashang area were used to analyze the change trend of vegetation greenness during 2000-2019 and its attribution by linear tendency estimation and partial derivative attribution method.[Results] The average vegetation greenness during the main growing season (April to October) was generally high in the east, while low in the west of the plateau. Moreover, the average vegetation greenness was the highest on the woodland, while the lowest on the cultivated land. During 2000-2019, the maximum and the average NDVI in Bashang area showed an obvious increasing trend, with the rates of 0.063/10 a and 0.044/10 a, respectively, and areas with significant improvement of vegetation greenness accounted for 60%~83%. According to the quantitative analysis of the interannual land use and land cover changes in Bashang Plateau, the contribution rate of cultivated land, woodland and grassland was 50.51%~57.22%, 21.73%~28.62% and 14.41%~15.07%, respectively, during 2000-2019. The total contribution rate of water area, construction land and unused land was only 6%.[Conclusion] During 2000-2019, cultivated land contributed the most to vegetation greenness increase in Bashang area of Hebei Province, but the contribution rate shows a downward trend, and the contribution rates of woodland and grassland increases gradually.

Abstract:[Objective] The spatiotemporal change characteristics of land use pattern and the effect of ecological environment in Fushun City, Liaoning Province after returning farmland to forestland were discussed, in order to provide reference for the optimization of land use structure in this area.[Methods] Based on the remote sensing images in 2000, 2010 and 2020, the spatial and temporal change characteristics of land use pattern and the ecological environment effect in Fushun City were quantitatively analyzed by using the methods of land use dynamic degree, land use degree comprehensive index, land use transfer matrix, NDVI difference analysis and regional ecological environment quality index.[Results] ① From 2000 to 2020, there was a mutual transformation relationship between various land types in the study area, among which, the change of woodland and cultivated land was more obvious. During the past 20 years, the area of cultivated land decreased by 825.59 km², with a growth rate of -7.32%. Forest land area increased by 591.14 km², with a growth rate of 5.24%. Urban land area increased by 182.36 km², with a growth rate of 1.62%. ② In 2000, 2010 and 2020, the comprehensive index of land use degree in the study area was 224.48, 225.57 and 226.12, respectively, with year-on-year growth of 0.49% and 0.24%. The intensity of land development and utilization in the study area increased slowly. ③ During the past 20 years, the vegetation coverage in the study area showed an upward trend. The decreased areas of NDVI basically coincided with the expanding areas of urban land. ④ The environmental quality index of land use transition in the three periods were 0.744 8, 0.775 4 and 0.782 6, respectively. During the past 10 years, the environmental quality index increased by 4.11% and 0.93%, respectively, and the overall environmental quality showed an upward trend.[Conclusion] In the past 20 years, the rapid urbanization process in the study area has been promoted, the overall environmental quality has been improved, and the improvement and deterioration of ecological environmental quality coexist in some local areas. The transformation among urban land, cultivated land and woodland is the main reason. The environmental protection policies such as returning arable land to forest make the environmental quality in the study area continuously improve. But the upward trend flattens out over time.

Abstract:[Objective] The changes of NDVI in the Beipan River basin of Guizhou Province and its relationship with terrain gradients and population distribution were studied in order to provide scientific reference for vegetation restoration, implementation of returning farmland to forest land, land space optimization and renovation in karst areas.[Methods] Based on NDVI data of the Beipan River basin in Guizhou Province from 2000 to 2018, the temporal and spatial change characteristics and their relationship with altitude, slope, population density and other influencing factors were analyzed.[Results] ① From 2000 to 2018, the NDVI of Beipanjiang River basin showed an overall upward trend, the annual average growth was stable, and the vegetation showed a trend of continuous recovery. ② In 2000, the spatial distribution of NDVI in the Beipanjiang River basin was the highest in the southeast while the lowest in the northwest. The distribution of the high NDVI area was fragmented in the central region. By 2018, the difference of NDVI values in different regions was significantly reduced, and the change was the most obvious in the low NDVI regions in the northwest and central region. ③ From 2000 to 2018, the areas with significant decrease, slight decrease and slight increase of NDVI in Beipanjiang were less than 10%. The area of the significantly increased region was 19 986.04 km², accounting for 90.93%. ④ From 2000 to 2018, the altitude effect of NDVI in the Beipanjiang River basin was characterized by phase changes. Among them, the NDVI value from 2000 to 2010 showed an overall downward trend with the increase of altitude, while the NDVI value from 2010 to 2018 showed an overall upward trend with the increase in altitude. The value of NDVI showed an up-down trend with the increase of slope. The value of NDVI decreased with the increase of population density.[Conclusion] Topographic factors laid the foundation for vegetation growth, while social and human factors had great influence on the variation of NDVI.

Abstract:[Objective] In order to provide scientific basis for desert regionalization and desertification control, this paper tries to classify desertification areas on the county scale of the Qinghai-Tibet Plateau and analyze the distribution and characteristics of different desert types.[Methods] Based on TM images from 2018, MODIS images from 2000 to 2018, combined with GIS mapping technology and long-term field investigation, the study selected Chengguan District of Lhasa City as a case to explore the desert classification system in the alpine region.[Results] According to the main influencing factors of desert formation, the main principles and indexes of desert classification were put forward. Based on the indexes of climate regionalization, surface material composition, geomorphic morphology, and vegetation coverage, the desert in the Chengguan District of Lhasa City was divided into 2 first-level types, 7 second-level types, 18 third-level types, and 31 fourth-level types, and the area and spatial distribution of each desert type were determined.[Conclusion] This study determines the index of desert classification, and classifies the desert area of the Chengguan District. The desert classification system in the Qinghai-Tibet Plateau is preliminarily established, which is the basis for the alpine classification research in the Qinghai-Tibet Plateau.