Abstract:[Objective] The response of carbon, nitrogen and phosphorus of each component (plant leaves, roots and soil) of grassland community to precipitation change was studied, in order to reveal the influence of precipitation on the stoichiometric characteristics of grassland ecosystem in loess hilly region.[Methods] The natural restored grassland in loess hilly region was taken as the research object, a field rain control test platform was established at Ansai experimental station during 2017-2018, with 7 treatments including 60% rain reduction, 40% rain reduction, 20% rain reduction, natural precipitation, 20% rain increase, 40% rain increase, and 60% rain increase. The canopy method was adopted to study the influence of precipitation change on the leaves, roots and soil ecological stoichiometric characteristics of plants.[Results] ① With the increase of precipitation, the water restriction in plant growth was effectively alleviated, and the effect of water stress gradually slowed down, so that the N and P contents in leaves showed a significant decline (p<0.05). And the C/N and C/P of the leaves also showed a significant downward trend (p<0.05). ② The change of precipitation gradient had a significant effect on the P contents of root system (p<0.05). The change of precipitation gradient had significant influence on root C/P and N/P (p<0.05). ③ Rain control treatment only had significant effect on soil C content (p<0.05), which may be because extreme precipitation affected the activity of soil microorganisms, resulting in a slow accumulation of soil organic C.[Conclusion] Water is the limiting factor for the absorption and utilization of N and P by grassland plants in loess hilly region. Precipitation can change the nutrient restriction pattern of grassland community. With the increase of precipitation, plant growth is more restricted by P, and plant growth will changed from being restricted by both N and P to being restricted by P.

Abstract:[Objective] The diversity and stability of the desert riparian forest community in the middle reaches of the Aksu River were studied to explore the complexity of the current community plant composition and the relationship between some environmental factors at the species level, aiming at provide theoretical support for the desert riparian ecosystem restoration.[Methods] Based on the sample survey, the plant community was comprehensively evaluated by pattern analysis method, species diversity index and evenness index, cluster analysis and M.Godron stability measure.[Results] The main plant populations of desert riparian forests in the middle reaches of the Aksu River showed an aggregated distribution pattern, and the community structure was simple, which characterized with single oligo-dominant communities. The species distribution of plant communities was relatively uniform across different locations, but the richness and diversity changed up and down; the desert riparian forest communities could be divided into six categories according to environmental factors, and the plant diversity of three types of plots was low. The specie composition was closely related to soil moisture, and the plant community species diversity was negatively correlated with soil moisture. The higher the water content, the more uniform the plant composition; the current plant community has not reached the stable stage, and there was no direct connection between plant diversity and community stability.[Conclusion] It is difficult to promote the restoration of plant diversity in the region by flood irrigation. Considering Populus euphratica and Tamarix chinensis as the main patterns, planting deep-rooted trees and shrubs to create a local microclimate, and indirectly improving habitats are the better ways for vegetation restoration in desert riparian forests.

Abstract:[Objective] The physical and chemical properties of sandy soil the growth status of Agriophyllum squarrosum with different amendments were studied, in order to provide scientific guidance for the follow-up work of desertification land management and the restoration of ecological environment.[Methods] Organic fertilizer, flaxseed meal, water-retaining material (potassium polyacrylate), humic acid and other materials were used to improve sandy soils in Northwest Margin of Kubuqi Desert. The effects of different soil amendments on the soil physicochemical properties, microorganism quantity, enzyme activities and dry matter weight of Agriophyllum squarrosum were analyzed.[Results] ① The sequence of the effect of amendments on reducing bulk density and infiltration rate of desertified soils, and increasing total soil porosity and soil field capacity were:water retaining agent (BSJ) > water and fertilizer retaining agent (BSBFJ) > adhesive (NHJ). As the soil layer depth increases within the layer of 0-30 cm, effects of the three treatments on regulating soil physical properties weakened gradually. ② The effects of amendments on reducing soil pH value and increasing soil available nitrogen and organic matter were not obvious. BSJ had the best effect on reducing soil pH value, increasing soil available nitrogen and available phosphorus, and BSBFJ was the most effective in improving soil available potassium and organic matter content. ③ Three amendments improved the dry matter weight of Agriophyllum squarrosum significantly, and the specific performance was BSBFJ > BSJ > NHJ. ④ The microorganism quantity and enzyme activity in desertified soil were greatly improved by the application of amendments. NHJ had the best effect on increasing the number of soil bacteria, actinomycetes and urease activity, while BSBFJ had the best effect on increasing the number of soil fungi, invertase activity and phosphatase activity.[Conclusion] Different types of soil amelioration materials can improve the physiochemical properties of desertified land and the growth of Agriophyllum squarrosum at vary degrees. Considering the improving effect of three soil amelioration materials, BSBFJ could be as preferred materials for improving desertification soil in the area.

Abstract:[Objective] The differences in soil respiration and its influencing factors between natural desert forest and farmlands were studied, in order to provide theoretical reference for the social development and ecological security maintenance in arid desert region.[Methods] Soil respiration rate and its influencing factors were investigated at three farmlands with different cultivation years (i. e., 30, 16, 3 years), and a natural desert forest in Ebinur Lake basin in the Xinjiang Uygur Autonomous Region. One-way ANOVA and multiple stepwise regressions were used for data analysis.[Results] ① Soil respiration rate increased significantly along the cultivation years (p<0.05). ② Soil respiration rate in three farmlands were signifiantly higher than that in natural desert forest (p<0.05). ③ Soil organic matter, soil moisture, total colony number, fine root biomass, soil salinity and pH value were significantly different between farmlands and natural desert forest (p<0.05), whereas there was no significant difference between soil temperature, air relative humidity and air temperature(p>0.05). ④ Soil moisture and salinity to soil respiration rate were the only remaining factores in the multiple stepwise regressions, and the standard coefficients were 0.67 and -0.42, respectively.[Conclusion] Agricultural activities increased soil moisture while decreased salinity in the reclaiming of natural desert forest into farmlands, and as a consequence, increased soil respiration rate along cultivation years.

Abstract:[Objective] The effects of runoff and sediment reduction by orchard grass cultivation in Northeast Guangxi Zhuang Autonomous Region was studied, in order to provide scientific reference for the development of soil and water conservation in this area.[Methods] Under the condition of natural rainfall, the runoff and sediment data of Paspalum thunbergii and Ageratum conyzoides were compared and analyzed in different slopes (i.e. 12°, 23°, 42°).[Results] ① When the slope was 12°, rainfall had a significant effect on runoff and sediment yield of Paspalum thunbergii and Ageratum conyzoides (p<0.05). ② Under the same life cultivation, the runoff and sediment yield increased with the increase of slope gradient. Compared with the clear cultivation, the runoff and sediment yield of Paspalum thunbergii decreased by 33.06%~50.35% and 67.09%~77%, respectively, while that of Ageratum conyzoides decreased by 21.89%~28.85% and 41.65%~47%, respectively. The runoff and sediment reduction effect of Paspalum thunbergii was better than that of Ageratum conyzoides. ③ The interaction effects of slope and grass cultivation were significant on runoff and sediment yield (p<0.001). With the increase of slope, the effects of grass cultivation on runoff and sediment yield on slope were gradually weakened, while the effect of slope was gradually enhanced. Nevertheless, the effect of Paspalum thunbergii cultivation on slope sediment yield was always greater than that of the slope.[Conclusion] The runoff and sediment reduction effect of Paspalum thunbergii was better than that of Ageratum conyzoides in the same slope. The effect of grass cultivation on runoff and sediment production on slope decreased with the increase of slope, while the effect of slope increased gradually. The effect of Paspalum thunbergii on slope sediment yield was always greater than slope.

Abstract:[Objective] The geomorphic differentiation characteristics of land use change in rocky desertification areas was explored, and the spatial-temporal change of land use under different geomorphologic conditions was investigated, in order to provide references for the rational use of land in rocky desertification areas.[Methods] Taking Guanling-Zhenfeng Huajiang rocky desertification comprehensive demonstration zone, Guizhou Province as a case study, the land use data, rocky desertification data, and geomorphic data in three periods of 2005, 2010, and 2013 were collected. The topographic distribution index and the comprehensive index of land use degree were derived by using GIS and RS technology, to study the geomorphic changes of the land use change.[Results] ① From 2005 to 2013, the area of grassland, construction land, forest land, unused land and water area in the karst areas was increased, while the area of cultivated land and garden land was decreased. The area of rocky desertification was decreased and the degree of rocky desertification was gradually reduced. ② Under different geomorphologic conditions, each land use type had its own dominant distribution area, the geomorphic differentiation of each land use type was basically stable. ③ The geomorphic differentiation of land use degree tended to be stable. From 2005 to 2013, the degree of land use showed as follows:erosion platform > peak-cluster depression > hill peak plateau > V-shape valley > dissolution-erosion of steep slope. ④ In terms of the distribution of different rocky desertification levels in different land types under the same geomorphologic conditions, rocky desertification mainly occurred in cultivated land, forest land, garden land and unused land, according to the distribution of rocky desertified land types in erosion platform, peak-cluster depression, hill-peak platform, V-shape valley, and dissolution-erosion of steep slope. There was no rocky desertification in the water area. From 2005 to 2013, rocky desertification in different geomorphologic conditions of the land type generally showed good transformation.[Conclusion] Each land use type has its dominant geomorphic area. Under different geomorphologic conditions, the distribution of rocky desertification vary in different land use types, mainly occurred in cultivated land, forest land, garden land and unused land.

Abstract:[Objective] The influence of cultivating Stropharia rugosoannulata with straw on clean water runoff, soil improvement and grass control in economic forests(especially in the newly economic forest) was explored, in order to provide technical support in water conservation capacity, ecosystem conservation, grass control and soil fertility improvement.[Methods] Two different kinds of slope land economic forests in the source area of Kulü River at upstream of Paihe River was selected, the technology of straw mulching was used to plant Stropharia rugosoannulata, and the water quality, soil organic matter and weed diversity of the slope land were analyzed in different growth periods of the mushroom.[Results] The cultivation of Stropharia rugosoannulata with straw effectively reduced the content of total nitrogen (42.68%~50.47%), total phosphorus (45.72%~46.74%) and suspended solids (SS, 33.41%~36.58%) in the water in this area. At the same time, it increased the content of soil organic matter by 10.17%~16.42% on average, and reduced the diversity and species of weeds in this area, thus, effectively reduced the water and fertilizer loss, and increased clean water runoff in a short period.[Conclusion] Cultivating Stropharia rugosoannulata with straw can effectively reduce the contents of total nitrogen, total phosphorus and SS in the runoff, increase the content of soil organic matter, reduce the diversity and species of weeds in this area, and play an important role in controlling water, fertilizer and soil erosion. In addition, the effect may be even more pronounced in the newly economic forest changed by uncultivated land.

Abstract:[Objective] The adaption of Amorpha fruticosa through root morphological responses to saline stress was explored, in order to provide support for vegetation optimization and restoration in saline areas.[Methods] we used the annual Amorpha fruticosa seedlings as test materials, and analyzed plant height, basal diameter and the root morphological characteristics such as root length, surface area, volume, and number of root tips of Amorpha fruticosa seedlings under saline stress.[Results] As the salt concentration increases, the plant height, basal diameter, and total root and middle root configuration indexes of Amorpha fruticosa increased first and then decreased. When the saline concentration was 0.3%, except for the fine root volume, all other indexes reached the maximum value, and all showed significant promotion effects (p<0.05). When the saline concentration was 0.9%, all indicators were significantly inhibited (p<0.05).[Conclusion] When the saline concentration was 0.3%, the root growth of Amorpha fruticosa was significantly promoted; when the concentration was higher than 0.5%, the root system showed different degrees of growth declining; when the saline concentration reached 0.9%, its growth was significantly inhibited.

Abstract:[Objective] The main factors affecting soil erosion in upper reaches of the Ganjiang River basin were analyzed, in order to provide a reference for local soil erosion control and scientific management.[Methods] The data involved in this paper including Landsat 8 remote sensing image in 2015, MODIS NDVI, digital elevation model (DEM), soil type and rainfall. The RUSLE model and the random forest algorithm were used to quantitatively analyze soil erosion and its influencing factors in the upper reaches of the Ganjiang River basin.[Results] In 2015, the soil erosion intensity was gradually increased from southeast to northwest in the upper reaches of the Ganjiang River basin, and the soil was at a mild erosion level in general. The total amount of the soil erosion was 3.45×10⁷ t/a. The average soil erosion modulus was 1 046.38 t/(km²·a), which was about two times higher than the allowable amount of soil erosion 500 t/(km²·a) in the red soil hilly region of Southern China. The average soil erosion moduli of sub-basins 9, 11 and 15 were 1 672.66, 1 715.83 and 1 565.36 t/(km²·a) respectively, which were at a moderate erosion level. These sub-basins were the key regions which need to be prevented and controlled in the study area. The rest of the sub-basins were under a mild erosion level.[Conclusion] Soil erosion in every sub-basin was greatly affected by the vegetation cover and management factor (C) and the slope length and slope (LS), and the importance of which was 30% and 20% respectively. The importance of soil erodibility factor (K) and the rainfall erosive force factor (R) were less than 10%. Among all sub-basins, sub-basin 9, 11, and 21 were mainly affected by LS factor, and the rest were mainly controlled by C factor.

Abstract:[Objective] The effects of canopy rainfall redistribution on surface runoff, erosion and leaching in poplar forests were discussed, in order to provide a theoretical basis for reducing soil erosion in agroforestry systems.[Methods] Taking the poplar-wheat intercropping system in Taihu Lake basin as the research object, the surface runoff, erosion and leaching were measured and analyzed, based on the field observation of rainfall, throughfall and stem flow of 101 rainfall events in 2013.[Results] ① The total rainfall was 943.5 mm.The throughfall, stem flow and interception were 796.2 mm, 7.3 mm and 140.0 mm, respectively, accounting for 84.4%,0.8% and 14.8% of the total precipitation. The small and medium-sized rainfall which was less than 10 mm occurred most frequently, accounting for 80.2% of the total rainfall events. ② Throughfall and stem flow were correlated with rainfall outside the forest (R²=0.993, R²=0.748 4). The stem flow started when the rainfall was greater than 5.5 mm. A negative function correlation existed between the rate of canopy interception and rainfall (R²=0.414 7). In addition to rainfall, the rate of canopy interception was also related to canopy leaf area index. ③ The higher the intercropping system stand density, the greater the canopy leaf area index, and the stronger the effects of canopy layer on surface runoff and erosion. ④ The average throughfall at 1.5 m from the trunk of a single poplar was reduced by 3.2% and 9.3% respectively compared with that at 0.5 m and 7.5 m, and the leached water decreased by 3.5% and 10.8% respectively. Besides, canopy structure played an important role in leaching loss.[Conclusion] ① The redistribution effect of poplar canopy on rainfall in intercropping system mainly depended on rainfall. The greater the rainfall is, the less significant the interception effect is. ② The increase of poplar intercropping can significantly reduce the surface runoff and erosion in the system. ③ The canopy of a single poplar tree at 1.5 m from the stem has the greatest effect on rainfall reduction and the least amount of leaching.

Abstract:[Objective] The characteristics of soil salinization and seasonal variation in the typical oasis irrigation areas were studied, in order to provide theoretical basis for agricultural production regulation.[Methods] Using GPS positioning technology to conduct the field survey in different seasons. Indoor sample measurement, classical statistical analysis and geostatistics were used to analyze soil salinity and salt segregation content in the 31 regiment irrigation area of the lower reaches of the Tarim River.[Results] The pH value of the soil in the study area was ranged from 8.09 to 8.24, there was little difference between the different seasons, and the soil was alkaline. The content of soil salinity was significantly affected by the season, and it showed in different depth as follows:autumn > winter > spring > summer. The main ions in the soil at different depths were the same in different seasons. The anions in the soil salinity were mainly SO₄^2- and Cl^-, and the cations were mainly K⁺ and Na⁺. Soil salinity types were mainly sulfate in spring and autumn, and chloride-sulfate in winter. The soil salt content in autumn and winter decreased gradually with the increase of soil depth and presented an overall surface aggregation pattern. The soil salt content in spring and summer decreased first and then increased with the increase of soil depth and presented an overall bottom aggregation pattern. In spring, the salt content in root domain layer (0-60 cm) was higher in the southeast and lower in the northwest, while the salt content of deep soil layer (60-100 cm) was lower in the southeast and higher in the northwest. The overall content of soil salinity in summer was low and the horizontal distribution was consistent. High value areas of soil salinity in autumn and winter were found in the southwest of the study area, close to the Tarim river, where there were many original reserves and wasteland.[Conclusion] The annual variation of soil salinity in the 31 regiment irrigated area is generally characterized by salt accumulation in autumn and winter, desalinization in spring and summer, and the horizontal distribution of soil salinity is mainly affected by land use type, topographical factors, and distance from the water source.

Abstract:[Objective] The evolution and driving forces of the sea reclamation in the Bohai Rim from 1985 to 2017 were analyzed, in order to provide support for the comprehensive management of the sea reclamation and promote the sustainable development of the region.[Methods] Using the remote sensing data, ENVI and ArcGIS were used to process and extract the sea reclamation coastline and land use types in each period, and the characteristics of reclamation evolution were analyzed by fractal dimension, coastal reclamation index, development intensity index and transfer matrix. The driving mechanism of reclamation activity was discussed by grey correlation degree method.[Results] ①From 1985 to 2017, the total area of reclamation around Bohai Sea increased by 4.25×10⁵ hm², with an average annual development intensity index of 2.6%. The reclamation coastline increased by 1 734 km, with an increase rate of 62%. In terms of time, the average annual development intesity index and coastal reclamation index changed in a similar way, showing a trend of decreasing, increasing and decreasing. In terms of space, the development intensity in the south was much higher than that in the north and the west was much higher than that in the East. ② There are two reclamation peaks in the study period, the first one was mainly for aquaculture, occupying a large number of vegetation land and unused land, and the second one was mainly for construction, taking up lots of natural sea areas. ③ The main driving forces of sea reclamation activities were social and economic development, among which aquatic product production, regional population and fishery industry development were the main driving forces. In addition, national policies and natural factors were of great significance to the sea reclamation activities.[Conclusion] The effective ways to restore the coastal ecological environment are to reasonably plan the aquaculture water area and increase the production capacity of unit area. Balancing the intensity of regional development and regulating the growth of regional population are of great significance to the realization of regional sustainable development.

Abstract:[Objective] The change of ecosystem carbon stock caused by the change of surface cover in Liping County, Guizhou Province was evaluated, in order to provide scientific basis for the management of regional carbon source and sink, and the development goal of "large ecology".[Methods] Based on the land use data of 2005, 2010 and 2015, the carbon sequestration capacity of the ecosystem of Liping County from 2005 to 2025 was quantitatively evaluated by combined the CA-Markov model with the InVEST carbon storage module.[Results] ① From 2005 to 2015, the cultivated land, forest land and unused land in Liping County decreased, while the grassland, construction land and water area increased generally. ② And the overall variation of land use change in 2015-2025 was consistent with that in 2005-2015. The cultivated land decreased from 2.37% in 2005-2015 to 4.21% in 2015-2025. ③ The total carbon stock and average carbon density of Liping County ecosystem were 9.12×10⁷ t and 206.61 t/hm², respectively in 2015, which has decreased by 2.00×10⁵ t and 0.45 t/hm² since 2005. In 2025, the carbon storage and average carbon density of Liping County was predicted to be 8.98×10⁷ t and 203.44 t/hm², respectively.[Conclusion] The carbon sequestration capacity of the ecological system in Liping County is weakening. The transfer of forest in large scale and the expansion of construction land are the direct reasons for the decline of carbon storage. In the future, the optimization of land use structure should be strengthened.

Abstract:[Objective] The spatial characteristics and distribution pattern of soil salt in irrigation area was studied, in order to analyze the relationship between the spatial pattern of soil salt and groundwater, soil physical parameters.[Methods] Jigesitai sub-district in the south bank irrigation area of the Yellow River was taken as an example. The soil samples in 0-20 cm, 20-40 cm and 40-60 cm layers were collected. The soil salt content, soil volume water content at 0-20 cm layer, particle composition, dry bulk density were measured, soil heat capacity and thermal conductivity were converted, and groundwater depth and salt content were monitored simultaneously. The spatial distribution characteristics of salt content and its spatial correlation were analyzed by classical statistical method and geostatistical method.[Results] The irrigation area was in the state of non-mild salinization. The soil salt showed a middle degree spatial variation and relatively independent random distribution. Spatial structure characteristics were fitted by Gaussian and exponential model. Soil salt was negatively correlated with groundwater depth, and positively correlated with groundwater salt content. The area with groundwater depth less than 1.6 m had a higher probability of slightly salinization. The soil salt at 0-20 cm layer was positively correlated with clay content, soil bulk density, moisture content, thermal conductivity and heat capacity in spatial range of 2~6 km, and negatively correlated with sand content in spatial range of 2~4 km. The soil salt at 20-60 cm layer was significantly related to clay content, sand content, thermal conductivity, heat capacity and water content of 0-20 cm soil layer, and the correlation range was slightly different from that of the soil surface.[Conclusion] The area with high clay content, high water content and groundwater depth less than 1.6 m is the key area of soil salinization control in the irrigation area.

Abstract:[Objective] The distribution characteristics of inorganic phosphorus in the soil profile during the ecological restoration process in the karst plateau canyon of Guizhou Province were studied, in order to provide a scientific basis for the research and scientific management of soil phosphorus in the ecological restoration process in karst mountain.[Methods] Four types of representative plots (cultivated land, converted cropland to grassland, barren grassland, and forest-grass intercropping land) were selected in Liancheng Town, Qinglong County, Guizhou Province, to study the morphological characteristics and influencing factors of soil inorganic phosphorus.[Results] The contents of total phosphorus and available phosphorus in four representative plots were 1.96~3.88 g/kg and 1.16~11.25 mg/kg, respectively. The total amount of inorganic phosphorus ranged from 591.39 to 1024.79 mg/kg, which was manifested as cultivated land > returning cultivated land to grassland > forest-grass intercropping land > wild grassland. Phosphorus activation coefficient (PAC) in different soil profiles was much less than 2%. The content of inorganic phosphorus in different forms was showed as follows:OP > Fe-P > Ca-P > Al-P. All forms of inorganic phosphorus showed a very significant positive correlation with fast-acting phosphorus (except OP). Inorganic phosphorus in different forms was positively correlated with available phosphorus. Different forms of calcium (water-soluble calcium and exchangeable calcium), as well as pH value and clay content, affected the proportion and conversion of inorganic phosphorus.[Conclusion] In the process of ecological restoration, the research area gradually recovered from cultivated land to grassland, to wild grassland, and to forest and grass intercropping. The soil physical and chemical properties were improved, and the soil phosphorus content was increased.

Abstract:[Objective] The rainfall redistribution characteristics of crop canopy were studied, in order to provide scientific basis for regional soil erosion control and ecological environment construction.[Methods] Soybean was used as the research object. The artificial rainfall simulation and spray method were used to observe the stalk flow, penetrating rainfall and canopy interception at different growth stages of soybean (seedling stage, initial blossoming stage, full flowering stage, pod bearing stage and initial pod filling stage) under different rainfall intensity (40, 80 mm/h), in order to explore the effects of canopy interception differentiation characteristics in the whole growth period of soybean and the influence of leaf area index and rainfall intensity on rainfall redistribution.[Results] The average stalk flow rate was 15.02%, the average penetration rate was 83.94%, and the average canopy interception rate was only 1.04%. It showed that the proportion of rainfall redistribution in canopy interception to rainfall redistribution was small, and its influence on rainfall spatial differentiation was relatively small. With the increase of leaf area index, the stalk flow rate and stalk flow rate, canopy interception and canopy interception rate of soybean increased significantly, but the penetration rain intensity and penetration rate decreased significantly. When the rainfall intensity increased from 40 mm/h to 80 mm/h, the stalk flow rate of soybean increased significantly, but there was no significant difference between stalk flow rate and rain intensity. The penetration rainfall increased significantly with the increase of rain intensity, but there was no significant difference between the penetration rate and the change of rainfall intensity.[Conclusion] The redistribution of rainfall by soybean canopy is mainly reflected in stalk flow and penetrating rain. Canopy interception accounts for a small proportion. And both leaf area index and rainfall intensity have an important effect on rainfall redistribution.

Abstract:[Objective] The dynamic change trend and main influencing factors of land degradation in Qinghai Province was analyzed, in order to provide a theoretical basis for ecological environment construction projects and the prevention of land degradation.[Methods] ANUSPLIN interpolation, trend analysis, Hurst index and residual analysis were employed, and the rainfall use efficiency (RUE) was used as the indicator to monitor land degradation.[Results] ① The spatial distribution of RUE and normalized difference vegetation index (NDVI) in Qinghai Province was mainly lower in the northwest and higher in the southeast. The main RUE in the west was less than 0.004, accounting for 40.77%, and NDVI in the northwest was less than 0.75, accounting for 38%. ② Land degradation of Qinghai Province in 1999-2006, 2006-2012, and 2012-2018 accounted for 5.16%, 4.25%, and 14.57%, respectively, which was mainly shifted from the middle and west to the northwest. ③ Temperature, sunshine hours, and average wind speed were significantly positively correlated with RUE, accounting for 64%, 91%, and 73%, and 24%, 61% and 32% of them passed the significance test. The negative interference of human activities on RUE accounted for 55%.[Conclusion] Land degradation in Qinghai Province in 1999-2018 decreased initially and then increased, with a weak sustainability. The influencing factors leading to the reduction of land degradation area in Qinghai Province are mainly sunshine hours, average wind speed and temperature, and human activities were also a major factor affecting land degradation.

Abstract:[Objective] The flood disaster in small watershed of island areas was simulated, in order to provide technical support for the subsequent development and construction of island areas and the smooth development of flood prevention and drainage management.[Methods] Taking Zhujiajian Island in Zhoushan City of Zhejiang Province as the research object, MIKE was used to establish a one-dimensional river network model, a two-dimensional hydrodynamic model and a coupling MIKE FLOOD model based on the data of design rainstorm, and the design and check tide level. The inundated area and the inundated water depth of the study area, the water level of the main river section, and the inundated duration of the key study area under these two schemes were compared and discussed.[Results] Compared with Scheme 1 (94 rainfall + measured tide level) under the condition of designed rainstorm and tide level, the inundated area of Scheme 2 (94 rainfall + extreme tide level) under the condition of design rainstorm and check tide level was larger and the maximum inundated water depth of the latter was deeper at the relatively high water level.[Conclusion] The flood control ability of Zhujiajian watershed caused by rainstorm is weak because of the large gradient ratio of rivers, the short confluence time, poor regulation and storage capacity. Especially when the rainstorm suffers astronomical spring tide, the disaster degree of the study area will be more serious.

Abstract:[Objective] The effects of plant root system on freeze-thaw damage in seasonal-frozen highway slope were explored, in order to provide basis for plant selection of slope protection project.[Methods] The characteristics of soil and plant roots on highway slope in seasonal freezing area were investigated, effects of plant on freeze-thaw cycle were discussed by comparative analysis.[Results] The resistances of three plants to freeze-thaw damage were showed as follows:Robinia pseudoacacia > Lespedeza bicolor > Amorpha fruticose. Plant roots affected the process of freeze-thaw destruction by regulating soil physical properties and constituting soil-root structure. The existence of roots regulated soil moisture content and thus reduced the probability of soil settlement or crack.[Conclusion] Plants with deeper vertical root and wider root distribution were recommended to prevent freeze-thaw damage on highway slope in seasonal frozen area.

Abstract:[Objective] The change characteristics of soil nutrients and ecological stoichiometry ratio before and after the change of land use pattern were explored, in order to provide scientific basis for agricultural production and ecological restorations in loess hilly area.[Methods] Three kinds of sample plots, namely, conversion of slope cropland to level terrace (terrace), return the grain plots to forestry (forest land) and terrace walnut garden (garden), were selected as research objects in Chakou small watershed in Yonghe County of Shaanxi Province. Taking the existing slope cropland as the reference substance, the spatio-temporal contrast method was used to compare the contents of C, N, P, K and ecological stoichiometry ratio of 0-20 cm and 20-40 cm soil before and after the change of land use patterns.[Results] ① After the implementation of various ecological restoration measures, the content of soil C and N elements increased significantly. The soil organic C content of 0-40 cm in terrace, forest land and garden land was 1.38, 2.44 and 1.09 times of that in the slope cropland, and the TN content was 1.76, 2.66 and 1.68 times of that in sloping land, respectively. The increment of P and K elements was not obvious, and the forest land immobilized C and N elements were more obviously than the other two modes of land use. ② The limiting elements of the soil were C and N through the analysis of ecological stoichiometry ratio of soil nutrients. ③ There was a stable coupling relationship between soil nutrients and ecological stoichiometry ratio of the watershed, and the coupling relationship between C and N was the most significant and played an important role in the stability between each element and the ecological stoichiometry ratio.[Conclusion] The three land use patterns effectively changed the total nutrient content of soil and the ecological stoichiometry ratio, which was beneficial to the ecological protection and vegetation restoration in the watershed.

Abstract:[Objective] Identifying priority watershed for soil and water conservation is a premise for the watershed planning. The purpose of this study was to determine the scale effect of identifying the priority watershed.[Methods] Taking Hechuan District, Chongqing Ciyt as an example, the comprehensive indexes was calculated by using the proportion of soil and water loss area, the proportion of land use and the average slope of the basin for identifying the priority watershed. The scale changes from level Ⅰ (with watershed area ranged from 50 to 300 km²), level Ⅱ (10~50 km²), level Ⅲ (1~10 km²), level Ⅳ (0.1~1 km²) and level Ⅴ (0.01~0.1 km²).[Results] The watershed scale had obvious effect on the identification of priority watershed. The distribution of priority watershed derived from level Ⅳ and Ⅴ was more similar to that of soil erosion area derived from soil erosion map in the Hechuan District. The average percentage area of soil loss, the mean proportion of cropland and mining land, and average slope gradient of the priority watersheds from the level Ⅳ and Ⅴ were clearly greater than those from the other levels.[Conclusion] The number of the priority watershed from the level Ⅳ was less than that from the level Ⅴ. The level Ⅳ was the best watershed scale for identifying the priority watersheds. It will aid in the management and planning of the priority watershed based on the level Ⅳ watershed.

Abstract:[Objective] The purpose of this work is to improve the accuracy of interpretation of land use and soil and water conservation measures from high-resolution images and analyze the regional representativeness of interpretation results in typical regions of the Pan-Third Pole.[Methods] Totally, 9, 18 and 15 sampling units were selected respectively in Tibet of China, Chiang Rai in Thailand and Pothohar Plateau of Pakistan for field surveys in the period of 2018-2019.The results of the field surveys of land use were taken as the references. The interpretation accuracy of land use and soil and water conservation measures based on Google Earth images was analyzed using confusion matrix and land use change transition matrix. The regional representativeness of the interpretation results was analyzed by comparing the land use structure obtained to the reference data sets.[Results] ① The accuracy of land use interpretation in the three typical sample areas was high with the overall classification accuracies being all above 80%, and the average kappa coefficients of 0.74, 0.75 and 0.82 respectively; ② The interpretation results for soil and water conservation measures in the three typical sample areas were found to be quite satisfactory compared with the field survey results; ③ The results of remote sensing interpretations of land use structure based on sampling showed a high similarity with the GLC 30 m and GLC 10 m data sets.[Conclusion] The results of land use interpretations and soil and water conservation measures based on high-resolution images are consistent with the results of field survey, and conform to the land use structure of the reference data sets. Thus, the results of remote sensing interpretation of sampling units can express the macro feature structure of land use very well.

Abstract:[Objective] The spatial and temporal variation of soil water under the low impact development measures in Guyuan City of Ningxia Hui Autonomous Region was analyzed, in order to provide scientific reference for the low impact development and construction of sponge city and the construction of the relevant standards and norms for the effective utilization of water resources.[Methods] Three low impact development measures, namely, grassland, aquatic grass ditch and sunken green land were selected, to study the spatial-temporal changes and stability characteristics of soil water storage at different depths. And the changes of soil moisture under different measures of low impact development measures in dry and wet seasons, different rainfall and freeze-thaw conditions were analyzed.[Results] ① The soil water storage capacity of grassland, aquatic grass ditch and sunken green land was 101.96, 27.22 and 97.33 mm respectively all through the year, was 107.37, 29.46 and 101.03 mm respectively in rainy seasons, and was 67.6, 20.66 and 69.34 mm respectively in dry seasons. The variation coefficient of soil water storage under various low impact development measures was between 26.01% and 76.37%, all of which belonged to moderate variation. ② Under rainstorm conditions, the replenishment amount of grassland, aquatic grass ditch and sunken green land was 63.68, 14.84 and 66.49 mm, respectively. Under light rain conditions, the soil replenishment of grassland, aqueduct grass ditch and sunken green land was 3.94, 1.71 and 1.26 mm, respectively. ③ During the freeze-thaw period, the freezing-thawing capacity of grassland, aquatic grass ditch and sunken green land was 111.16, 75.73 and 46.9 mm, respectively. Low temperature and freeze-thaw were mainly concentrated in 0-10 cm soil layer. ④ The annual, rainy, dry, heavy rain and freeze-thaw replenishment of the study area were 1 691.31, 1 766.46, 1 216.31, 1 121.8 and 699.67 m³, respectively.[Conclusion] The potential of soil water recharge under the low-impact development measures is great. And the improvement of structure, filler and vegetation cover of different low impact development measures should be considered to improve the water storage of LID measures.

Abstract:[Objective] The performance of farmland consolidation project and its influencing factors from the perspectives of farmers was analyzed, in order to provide a basis for improving the performance level of farmland consolidation project.[Methods] Factor analysis, importance-performance analysis (IPA) methods, obstacle degree model and questionnaire survey were used to diagnose the performance and its influencing factors of farmland consolidation project.[Results] From the perspectives of farmers, the performance of farmland consolidation project was explained by the factors of final management and maintenance satisfaction, the early stage satisfaction, social benefit satisfaction, ecological benefit satisfaction, economic benefit satisfaction and construction satisfaction. The measurement value of farmland consolidation project performance was 3.742 1, which was in the level of good, and the project result performance level was higher than the process performance level. The important factors impacting project performance level mainly included the supply of funds for the final management and maintenance satisfaction, the improvement degree of later management and maintenance measures, the system of later management and maintenance, the clarity degree of later management and maintenance, the consultation with farmers' opinions in the stage of planning, the adoption degree of farmers' opinions in the stage of the decision making, the adoption degree of farmers' opinions in the stage of planning, the consultation with farmers' opinions in the stage of the decision making, biodiversity conservation, agricultural scale production, and production cost reduction.[Conclusion] The performance level of farmland consolidation project can be effectively enhanced by futher strengthening the later management maintenance, improving the farmers' effective participation, promoting the ecological construction of farmland consolidation, and carrying out the appropriate scale operation of agriculture combined with farmland consolidation.

Abstract:[Objective] The land subsidence in Shanghai City was verified and predicted, in order to provide reference for scientific regulations of underground construction and groundwater exploitation.[Methods] Based on monitoring data of groundwater extraction volumes, land subsidence and layered deformation of soils, the correlations between land subsidence and groundwater exploitation, deformation of soils layers were investigated. Based on the characteristics and causes of land subsidence in Shanghai City, a polynomial distribution lag model (PDL model) was established, considering groundwater extraction volumes and deformation of aquifer Ⅳ.[Results] ① There was a high positive correlation between cumulative groundwater exploitation, cumulative layered deformation of aquifer Ⅳ and cumulative land subsidence. However, due to the creep of sand and slow water release from aquitards, lagging effect existed between land subsidence and groundwater extraction volumes as well as layered deformation of aquifer Ⅳ. ② Calculated results using PDL were accurate with small relative error and better fitting effect when verifying land subsidence. ③ Based on the current groundwater extraction and recharge pattern and layered deformation of aquifer Ⅳ, the prediction showed that slight ground lift would occur in 2019-2024.[Conclusion] There is a high correlation between land subsidence and groundwater extraction volumes and soil deformation in Shanghai City, and controlling groundwater exploitation can effectively alleviate land subsidence.

Abstract:[Objective] Mulching effects of different organic materials on evaporation and soil moisture content were studied to identify the best material for moisture retention.[Methods] The simulated evaporation analyses were conducted with garden waste in various particle sizes (M₁:0~1 cm, M₂:1~3 cm, M₃:3~5 cm). In addition the barrel control experiments were carried out with M₂, wood chips (M₄), and bark (M₅).[Results] Garden waste in various particle sizes could reduce daily evaporation of soil moisture. After 14 days of continuous evaporation, the cumulative evaporation capacity of M₂ (1~3 cm in size), M₁ (0~1 cm), M₃ (3~5 cm) and CK (control) were 193.0, 269.5, 304.0 and 1 037.0 g, respectively, which were 81.4%, 74.0% and 70.7% lower than those of CK. The soil moisture content of different layers were increased by covering with different organic materials, except for the rainy season, which were wood chips (M₄), bark (M₅) and garden waste (M₂) from high to low. The annual change of soil moisture content under various mulching layers showed a similar bimodal trend, with a low soil moisture content in the period from April to May while a high soil moisture content in the period from June to August. The annual average of soil moisture content within the 0-40 cm soil layer of M₄, M₅, M₂ and CK were 32.9%, 30.3%, 27.4%, and 26.8%, respectively.[Conclusion] Wood chips are the best materials for moisture conservation, followed by bark and garden waste.

Abstract:[Objective] Two kinds of municipal solid waste, shield decement and Cinnamomum camphora branch, were disposed and utilized to the maximum at the same time, in order to promote the application of landscaping waste and urban shield sludge recycling products.[Methods] The products of shield decement and Cinnamomum camphora branch compost were treated with a proportion of 25:1, 30:1, 20:1, 25:1, respectively. Proportion (quality ratio) was used to prepare grade 1 and grade 2 lawn planting soil and grade 1 and grade 2 flower bed planting soil. The degradation characteristics of AES during composting and the nutrient element content of composting fermentation products and pot experiments were then investigated.[Results] The compost products of decement and composting of Cinnamomum camphora branches with the ratios of 25:1, 30:1, 20:1 and 25:1 (mass ratio) for 20 d met the requirements of grade Ⅰ and Ⅱ lawn planting soil and grade Ⅰ and Ⅱ flower bed planting soil in "green planting soil CJ/T340-2016". Co-composting significantly promoted the degradation of AES, which was the main pollutant in shield decement, and the content of AES surfactant in the products after 20 days of compost decreased by more than 75.24%. The results of pot experiment showed that the germination rate of Manila seeds planted in primary and secondary turf soil was 92% and 86%, respectively. The survival rate of transplanted azalea in first-grade and second-grade flower bed soil was 100%.[Conclusion] The composting product of Cinnamomum camphora branch mixed with shield demulsification is not only beneficial to the environment friendly disposal of shield demulsification, but also can be reused after composting, promotes the degradation of AES in shield demulsification mud, and reduces the harm of AES in shield demulsification to the environment.

Abstract:[Objective] This paper aims to explore the non-point source pollution in Hongfeng Lake reserve and the relationship with it water quality, and understand the current status of non-point source pollution land, in order to provide the scientific evidence to prevent the non-point source pollution.[Methods] The total nitrogen (TN) and total phosphorus (TP) pollution load of Hongfeng Lake was studied by improved export coefficient model (IECM).[Results] The non-point source pollution emissions of TN and TP in 2016 were 863.78 t and 77.14 t respectively, and the non-point source pollution emissions of TN calculated by the empirical coefficient was 701.19 t, TP was 232.99 t, and the improved output coefficient model incorporated terrain factors increased accuracy greatly. In 2016, TN and TP of non-point source emissions accounted for 73.54% and 82.54% of the total pollution load. Compared with the non-point source pollution load in 2008, TN and TP accounted for 27.03% and 19.69%, respectively, but the water quality was generally Class Ⅱ.[Conclusion] At present, non-point source pollution is the main source of pollution of Hongfeng Lake, but it has little impact on water quality.

Abstract:[Objective] The effects of adding green manure straw and attapulgite soil on the soil structure and carbon and nitrogen content of the fluvo-aquic soil of the old Yellow River course were studies, in order to provide a theoretical reference for scientific evaluation of attapulgite soil for the sustainable development of farmland soil health and the utilization of green manure straw.[Methods] We set up 6 treatments:control (CK), broad bean straw 10 g/kg (B), ryegrass straw 10 g/kg (R), attapulgite 16 g/kg (A), attapulgite broad bean straw (AB) and attapulgite combined with ryegrass straw (AR), and analyzed the effects of treatments by SPSS statistics and Origin.[Result] After 120 days of indoor cultivation, we found that adding green manure straw and attapulgite soil could improve soil structure and increase carbon and nitrogen content, in which A and AB treatments mainly increased the content of large aggregates (>0.25 mm), and AR treatments mainly increased the content of micro-aggregates (0.053~0.25 mm). Compared with CK, A, AB, and AR treatments reduced the soil three-phase structure distance by 50.8% to 55.6%, and increased soil water holding capacity by 16.0% to 19.2%. The increase of soil organic carbon and total nitrogen with single application of green manure straw and single attapulgite soil was 0.38~1.99 g/kg and 0.12~0.49 g/kg. The combined application of the two fertilizers could greatly improve soil organic carbon, total nitrogen and microbial biomass nitrogen than single application of green manure. The increase rate was 0.86~3.23 g/kg, 0.29~0.44 g/kg and 0.3~21.6 mg/kg higher than that of single application of green manure, respectively. The combined effect on broad bean was better than that of ryegrass.[Conclusion] Combined application can take full advantages of easy decomposition of straw, rich nutrients, and large specific surface area of attapulgite, which has great advantages in improving soil structure, mitigating nutrient release, and enhancing soil solid nutrient capacity. Among them, proportion of 10 g/kg of broad bean straw 10 and 16 g/kg of attapulgite had the best effect in improving the soil sandy structure and increasing soil carbon and nitrogen content in the old course of the Yellw River.

Abstract:[Objective] The effects of substrate water content and super absorbent polymer on the water potential, water use efficiency and transpiration rate of Platycladus orientalis were studied, in order to provide theoretical basis and technical support for the application of super absorbent polymer in vegetation reconstruction and ecological restoration of lead-zinc tailings ponds in areas with different rainfall.[Methods] The test used a quadratic general rotation combination design. The measured indicators included the water potential, net photosynthetic rate, transpiration rate, and water use efficiency of the annual Platycladus orientalis. A regression model between the water potential(ψ) of the leaf, the water use efficiency (WUE), transpiration rate (T_r) and the concentration of super absorbent polymer and substrate water content was fitted.[Results] ① The main effect sequence of the regression model of water potential and transpiration rate was:substrate water content > concentration of super absorbent polymer; the main effect sequence for the regression model of water use efficiency was:concentration of super absorbent polymer > substrate water content. ② When the water potential reached the highest point, the concentration of super absorbent polymer applied was 0.1%, the substrate water content was 19.73%; when the water use efficiency was highest, the concentration of super absorbent polymer applied was 0.1%, the substrate water content is 7.89%; when the transpiration rate was the minimum optimal, the concentration of super absorbent polymer applied was 1%, and the substrate water content was 7.89%.[Conclusion] Low super absorbent polymer application amount (0.1%~0.23%) is beneficial to the extraction of water from the modified lead-zinc tailings matrix, which also promotes the fixation of carbon dioxide in the leaves and improves the water use efficiency.

Abstract:[Objective] The water environment quality of Pingzhai Reservoir was evaluated for the core water source project of the first phase of the Qianzhong water diversion project, in order to provide scientific reference for the evaluation and scientific management of the water environment quality of the reservoir.[Methods] This paper selected seven sections of Pingzhai Reservoir for water sampling in January, May and August 2018. Dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen (TN) and ammonia nitrogen (NH₃-N) factors were selected as water quality evaluation index. Based on the combination of analytic hierarchy process and entropy weight method, the weight of each evaluation index was determined, and the water quality of Pingzhai Reservoir was evaluated by Bayesian model.[Results] ① From the combination weight, TN and COD showed great impact on water quality of Pingzhai Reservoir, while DO and NH₃-N showed little impact. ② The water quality of Pingzhai Reservoir was the best in high-flow period, followed by the low-flow period, and then followed by the moderate-flow period. Among the sections, the water quality of reservoir area 1 (KQ1), reservoir area 2 (KQ2) and Nayong river sections (NY) were the worst. ③ TN and COD were the main pollution factors in Pingzhai Reservoir.[Conclusion] The water quality evaluation method based on the combined weighted Bayesian model not only distinguishes the difference of contribution of each evaluation factor to water quality, but also evaluates the water quality accurately. Overall, the water quality of Pingzhai Reservoir meets the corresponding requirements of water function zoning in Guizhou Province.

Abstract:[Objective] The effects of land use conditions on farmland quality, and the balance of quantity and quality of farmland occupied and replenished in increasing urban construction land and reducing rural residential areas project were scientifically evaluated, in order to provide technical support for the scientific promotion of the work.[Methods] Taking Dujianyan City of Sichuan Province as a study area, referring to the existing achievements of cultivated land quality evaluation, the project was simulated. And the balance relationship model and achievability prediction model for the quantity and quality of farmland were contructed and used to evaluate the balance of farmland occupation and compensation.[Results] The balance discriminant value of the quantity and quality of the occupied and replenished farmland in the study area was -11.82%, which indicated that the simulation project had not achieved the balance of the quantity and quality of the farmland. The balance achievability prediction value of the quantity and quality of the occupied and replenished farmland was 1.42, which indicated that the quantity and quality of farmland supplemented by the simulation project had the potential to reach the comprehensive level of the quantity and quality of the occupied farmland.[Conclusion] The models constructed in this paper can realize the rapid analysis and discrimination of the comprehensive balance of the quantity and quality of the farmland and the improvement potential in project of increasing urban construction land and reducing rural residential areas.

Abstract:[Objective] The spatial distribution and reasonable sampling of soil moisture content in potato field were studied, in order to provide scientific proof for precision irrigation system under the condition of large sprinkler irrigation.[Methods] A total of 116 sample points was selected in a 34 hm² farmland by the combination of fixed and random sampling. The soil moisture content of 0-20 cm and 20-40 cm depth was measured respectively. The traditional statistics combined with geostatistics were used to analyze the characteristic of the spatial distribution of soil moisture content and the reasonable sampling number.[Results] The soil water content at 0-20 cm depth before and after irrigation ranged from 7.61% to 13.79%, the soil water content at 20-40 cm depth before and after irrigation was ranged from 8.71% to 16.12%. The overall variation coefficient of soil moisture content was 16.47%~28.55%, showing a moderate variability, and the variation of soil water content at 20-40 cm depth was slightly higher than that of the surface layer. The soil moisture content of potato at different times in successive two years showed a moderate spatial correlation, and the spatial variation of soil moisture content was influenced by random factors and structural factors. The distribution of soil moisture in the field was patchy, and soil mositure in the late irrigation period was more disordered than that before irrigation. According to geostatistics, the number of reasonable sampling in the field was 87.[Conclusion] Under the condition of large-scale sprinkler irrigation, the soil moisture content of potato field shows a moderate variability, and both geostatistics and traditional statistics methods are suitable for determining the optimal sampling number of soil moisture content in the potato field.

Abstract:[Objective] The temporal and spatial evolution of vegetation coverage change from 2000 to 2018 was analyzed, and the response mechanism of vegetation coverage to climate change was clarified in Gansu section of the Yellow River basin, in order to provide scientific basis for the coordinated and sustainable development of ecological environment and social economy in this region and for the further implementation of ecological environment protection, construction and restoration.[Methods] Based on the MODIS NDVI data and meteorological data from 2000 to 2018, linear regression and correlation analysis method was used to analyze the temporal and spatial variation of vegetation coverage and its relationship with climate factors in Gansu section of the Yellow River basin.[Results] The vegetation coverage was decreasing from southwest to northeast in the past 19 years, and Gannan Prefecture had the best vegetation cover. The improved area of vegetation coverage accounted for 36.64%, which was mainly distributed in the north of Lanzhou, Linxia Prefecture, Dingxi City, Qingyang City, Pingliang City and the south of Tianshui City, while the degraded area accounted for 4.2%, which was mainly concentrated in Gannan Prefecture. The vegetation coverage in the study area showed a trend of continuous increase before 2013 and then decreased in fluctuation afterward, but it was increasing as a whole. Pingliang City was the fastest growing city, with an average annual growth rate of 0.96 per year. The vegetation coverage was sensitive to precipitation change in the study area, which showed a significant positive correlation with precipitation.[Conclusion] The spatial difference of vegetation cover in the study area was obvious. The vegetation was mainly improved from 2000 to 2018. Precipitation is a favorable factor affecting the improvement of vegetation, and the improvement of precipitation is very important for the construction and restoration of ecological environment in the study area.

Abstract:[Objective] The impacts of sloping land conversion program (SLCP) on grain production were studied, in order to provide a scientific basis for the further development of SLCP.[Methods] This paper investigated the temporal and spatial changes of cultivated land and grain production by taking 117 counties in Shanxi Province as research units, based on the land use data and socio-economic statistics in 1990, 2000, 2005, 2010 and 2015. And the production function was used to analyze the impact of SLCP on grain production.[Results] ① The effect of SLCP to the key ecological environment control areas in Shanxi Province was remarkable. The spatial distribution of cultivated land converted to forest land and grassland was more obvious in the hilly and gully region of the Loess Plateau. ② Over the past 15 years, the total grain output and the grain yield per unit area in Shanxi Province showed an overall upward trend. The total grain output and the grain yield per unit area in key conversion counties were increased to a certain extent, and the increasing rate of grain yield per unit area was higher than the average level of the whole province. ③ SLCP showed a significant positive impact on the total grain output and the grain yield per unit area.[Conclusion] At the provincial level, SLCP will not have a negative impact on grain production. Instead, it will promote the intensive production of agriculture and other ways to improve the level of grain per unit area, and then promote the increase of grain production.

Abstract:[Objective] The dynamic changes of vegetation on the Loess Plateau and its response to extreme climate were studied, in order to provide scientific basis for mitigating and adapting to climate anomaly.[Methods] Based on the remote sensing data and meteorological date from 1982 to 2017, the study used Mann-Kendall trend test and correlation analysis method to analyze temporal and spatial changes of vegetation in Loess Plateau and its response to extreme climate.[Results] NDVI exhibited a significant increasing trend with an annual rate of 0.37% (p<0.01) from 1982 to 2017, and increased from northwest to southeast on the Loess Plateau. As for the change of extreme climate, the variation trend of extreme temperature was relatively consistent. The extreme high temperature events showed a significant increasing trend, and the extreme low temperature events showed an extremely significant downward trend. However, the extreme precipitation index did not change significantly. The correlation analysis between extreme climate index and NDVI showed that the interannual variation of NDVI was significantly correlated with extreme temperature index FD₀, TMAX_mean, TMIN_mean, TN_10p, TN_90p, TR₂₀ and SU25 (p<0.01). There was no significant correlation between NDVI changes and extreme precipitation index in all seasons. However, NDVI showed a significant correlation with extreme temperature index, moreover, the correlation of spring and summer was higher than that autumn and winter. On the monthly scale, NDVI was significantly correlated with extreme precipitation index (RX_1day, RX_5day) and extreme temperature index (TMAX_mean, TMIN_mean, TN_90p, TX_x, TN_n) (p<0.01). The correlation between NDVI and extreme temperature index TMAX_mean, TN_10p, TN_90p and TX_x a lag of one month was greater than that current month, a lag of two months and a lag of three months.[Conclusion] The NDVI showed a significant increasing trend. The interannual and monthly NDVI changes were correlated with the extreme temperature index, and both showed a significant correlation with the extreme precipitation index. Moreover, the response of vegetation cover change in the Loess Plateau region to extreme climate has a certain lag.

Abstract:[Objective] The characteristics of the drought and flood in the Weihe River basin and their influencing factors under climate change were studied, in order to provide scientific support for regional water resources planning and management, ecological environment construction and maintenance, climate prediction, and disaster prevention and mitigation.[Methods] We used historical data during 1800-2017 to establish the drought and flood sequence, and the wavelet transform, sliding t-test, rolling correlation and other methods to study the flood/drought characteristics of the Weihe River for more than 200 years. And the possible causes of droughts and floods were explored.[Results] The frequency of mild droughts was the highest, while the frequency of major floods was the lowest in the past 200 years. In the first hundred years, the upper reaches of the river was dominated by drought, and the lower reaches was dominated by floods. The next 100 years were opposite to the previous ones. The fluctuations of drought and flood in the middle reaches were less. The first main period of drought and flood change was 18 years for the upstream, 62 years for the midstream, and 10 years for the downstream. Most of them were small and medium cycles. The consistency between the sliding correlation coefficient and the decrease of ENSO variance was obtained, indicating the remote correlation mechanism between the drought/flood of Weihe River and ENSO. There was a teleconnection between the drought/flood sequence and ENSO. The analysis of drought and flood period and precipitation showed that the changes of sunspot and flood period were similar in short period.[Conclusion] The mutation of drought and flood in Weihe River has a high inheritance, which is closely related to climate and environmental change. Besides, more attention should be paid to disaster prevention when the number of sunspots is low.

Abstract:[Objective] The impacts of targeted poverty alleviation policies on the happiness index of farmers in soil erosion areas were studied, in order to provide a scientific reference for sustainable development in poverty area.[Methods] The assessment index system of farmers' happiness index at Shuangbai County of Yunan Province was established, and entropy method and weighted summation model were used to evaluate the farmers' happiness index under the influence of targeted poverty alleviation policies.[Results] Per capita disposable income, marriage satisfaction and ecological environment satisfaction were the top there among the farmers' happiness index evaluation indicators. Most of farmers had a higher degree of recognition for targeted poverty alleviation, with an average satisfaction of 67.55 points. However, there were significant differences in the perception of policy among farmers. The satisfaction of income increase and decrease, policy consequence, and policy promotion were the key factors affecting the overall satisfaction of farmers in Shuangbai County with regard to targeted poverty alleviation policies. The average happiness index of farmers in Shuangbai County was 65.64 points, and the difference in happiness index of farmers in each township was relatively small, which maintained between 59~71 points.[Conclusion] In the future, farmers' happiness improvement and poverty alleviation should be regarded as the key breakthrough point in Shuangbai County, and targeted poverty alleviation policies would promote sustainable development in poverty area.

Abstract:[Objective] The impacts of farmland consolidation policies on farmers' livelihood strategies were studied, in order to provide references and basis for the government land department to formulate a sound farmland management policies.[Methods] A sustainable livelihood framework model was constructed for farmers in the context of farmland improvement, and multiple linear regression model was used to analyze the impact of farmland improvement on farmers' livelihood strategies.[Results] ① There was no change in the human capital of the farmer households after the rural land consolidation, the natural capital and social capital had a slight change, and the physical capital and financial capital showed a significant increase. ② To some extent, the implementation of rural land consolidation would promote the transformation of farmers' livelihood strategies from traditional agriculture to modern agriculture, and the production and manufacturing livelihood activities would be decreased, while the service-related livelihood activities would be increased significantly.[Conclusion] The implementation of farmland consolidation policy will change the influencing factors of farmers' choice of related livelihood activities in modern agriculture, manufacturing and service industries. After farmland consolidation, the quantity and quality of cultivated land are still significant influencing factors for farmers to choose traditional agriculture.

Abstract:[Objective] The habitat quality and habitat degradation in the Qilian Mountains was explored, in order to reveal the extent of human activities affecting the ecological environment of the Qilian Mountains and to provide scientific references for the ecological environmental protection and development in the region.[Methods] The land use and landscape pattern changes in the Qilian Mountains in the past 35 years based on the national 1:100 000 land use data since 1970s, and then the InVEST model was used to evaluate the evolution in habitat quality.[Results] ① Grassland and unused land were the most important land use types in the study area, followed by forest land, cultivated land, waters, urban and rural construction land. Among them, changes of grassland and urban and rural construction land were more severe, the former was reduced firstly and then increased, while the latter continued to increase. ② In temporal scale, with the change of land use type, the habitat quality of Qilian Mountain area gradually improved from the deterioration, and the habitat quality was the best in 2015. ③ At spatial scale, both of the habitat quality and habitat degradation degree in the Qilian Mountains were high in the east and low in the west.[Conclusion] Superior natural conditions result in higher habitat quality, and higher intensity of human activities are responsible for habitat degradation.

Abstract:[Objective] Taking Xinzhou City of Shanxi Province as an example, the pre-warning of ecological security in energy-ecological recombination region was discussed, in order to provide a basis for regional ecological protection planning and high-quality development.[Methods] Based on the pressure-state-response conceptual model framework, 21 indexes were selected from population, resources, economy, environment and ecological elements to establish the ecological security early warning and evaluation index system in energy-ecological recombination region. Entropy method was used to determine the weights and analyze the ecological security pre-warning in Xinzhou City from 2000 to 2018.[Results] ① In 2018, the comprehensive pre-warning values of 14 counties in Xinzhou City ranged from 0.356 2 to 0.587 0, with the average value of 0.491 2. The pre-warning level was within the range of medium to light, among which Xinfu District, Dingxiang County, Wutai County, Fanshi County and Jingle County were in the state of medium pre-warning level. The remaining seven counties were in the state of light pre-warning level. The overall ecological security of Xinzhou City was not optimistic because of its low ecological security level. ② From 2000 to 2018, the ecological security pre-warning values of Xinzhou City showed a slow upward trend. The number of counties with medium and light alarm level decreased, while the number of counties with light alarm level increased.[Conclusion] The ecological security in the research area presented unbalanced in space. The overall warning situation tended to be improved due to the decreasing pressure on economy, resources and environment in the system.

Abstract:[Objective] Based on topography and socioeconomic factors, the temporal and spatial differences and the cause of land cover change in Guangdong Province were studied, in order to provide a basis for the sustainable use of land resources.[Methods] Based on the land cover, topographic and socioeconomic data, we quantified the spatial and temporal variations of land cover change in Guangdong Province from 1992 to 2015. The causes of land cover change were analyzed using the land use dynamic degree, land use transfer matrix and the grey correlation analysis.[Results] Land cover change in Guangdong Province could be divided into two stages with the year of 2000 as the turning point. During the first stage (1992-2000), the area of cultivated land increased significantly and the construction land increased slowly. During the second stage (2000-2015), the cultivated land decreased while the construction land expanded rapidly. In areas with low elevation and gentle slope, land cover changes were mainly from cultivated land to construction land, while in areas with medium slope, it was mainly from forest land to cultivated land. In comparison, the land cover change caused by social and economic factors showed time difference, and many factors drove the land cover change in Guangdong Province. However, for different land cover types, the correlation degree of driving factors was different in the early and later stages, and the change of land cover was the result of multiple factors driving superposition.[Conclusion] The topographic feature is responsible for the spatial variation of land cover change, while the socioeconomic development plays a dominant role in temporal variation of land cover change in Guangdong Province.

Abstract:[Objective] The relationship between livelihood capital and livelihood strategies of farmers in karst rocky desertification areas was explored, and the impact factors of livelihood strategies was identified, in order to provide theoretical basis for promoting the optimal choice of livelihood strategies of farmers in the region.[Methods] Based on the framework of sustainable livelihood analysis, the livelihood capital of farmers in the Guanling-Zhenfeng Huajiang rocky desertification comprehensive demonstration zone of Guizhou Province was calculated. The multiple logistic regression model was used to analyze the livelihood strategies of different farmers to explore the relationship between the livelihood capital and livelihood strategies of farmers in the area.[Results] ① The human capital index of farmers in Huajiang demonstration zone was the highest, and the physical capital and natural capital indexes were lower. ② The farmers in the demonstration area were mainly non-agricultural livelihood strategies, mainly concentrated in Cha Eryan village and Xiagu village. ③ Human capital was the main influencing factor in the conversion of farmers' livelihood strategies, and it had a great impact on the conversion of livelihood strategies of both farming, part-farming and non-farming farmers. ④ The increase in non-agricultural income and the number of family laborers was conducive to promoting farmers to choose more diversified livelihood activities. The cultivated land area, the area of returning farmland to forest land, and livestock capital had a negative impact on the conversion of livelihood strategies.[Conclusion] The administrative villages in the Huajiang demonstration zone are limited by natural conditions, and there are some differences in the livelihood capital stock and the choice of livelihood strategies. The improvement of human capital can effectively promote the transformation of farmers' livelihood strategies in the demonstration zone.

Abstract:[Objective] The impacts of land use change on the ecosystem service value of various natural process were studied, in order to provide scientific basis for rational utilization of land resources and ecological security protection of the basin.[Methods] Based on the change of land use transformation, this paper analyzed the change of land use and the change of ecosystem service value in Yongjiang River basin under the influence of human activities from 1980 to 2015.[Results] ① The decrease of cultivated land and the increase of construction land were the main characteristics of land use change in Yongjiang River basin, whose degree of land use is rising. The land use types showed complicated mutual transformation, and the largest transfer area was from the conversion of cultivated land to construction land. ② During the past 35 years, the dynamic degree of land comprehensive utilization was 0.42%. The single dynamic degree of construction land use was the largest, and the reduction of cultivated land area was the greatest. ③ In terms of time, the total value of ecological services in the Yongjiang River basin increased first and then decreased, and increased continuously before 1995, but decreased continuously afterwards. ④ At the spatial level, the total value of ecological services showed a decreasing trend from southwest to northeast.[Conclusion] The transformation of land use in Yongjiang River basin was intense, and the rapid change of land use has aggravated the degradation of ecosystem function.

Abstract:[Objective] The effects of extreme precipitation events on ecosystem carbon flux in different growth periods were studied, in order to provide a theoretical basis for accurately assessing the response mechanism of an artificial coniferous forest ecosystem to extreme weather at Qianyanzhou of Ji'an City, Jiangxi Province.[Methods] The response of carbon flux to changes in environmental factors (net radiation RN, temperature TA, soil water content SWC, and enhanced vegetation index EVI) in the early growth period (April) and flourishing period (June) in 2008 and 2010 were compared.[Results] The net ecosystem productivity (NEP) decreased by 22.87% in April, mainly due to a decrease of 17.36%[GEP, 9.56 g/(m²·d)] in total primary production and 2.84%[RE, 2.86 g/(m²·d)] in ecosystem respiration by 17.36%[GEP, 9.56 g/(m²·d)]. While in June, a decrease of 3.58%[7.17 g/(m²·d)] in GEP and an increase of 12.8%[20.37 g/(m²·d)] in RE, led to a decrease of 65.77%[27.55 g/(m²·d)] in NEP.[Conclusion] The inhibition of RE caused by the reduction of TA at the early growing season was greater than that caused by the increase of soil moisture content, while the increase in soil moisture during the flourishing period would offset the inhibition of cooling on respiration, resulting in greater carbon loss. Therefore, the impacts of carbon flux on extreme climate should also be considered in future studies.