Shallow lake is one of the most important freshwater ecosystems for human being. With the increasing of lake eutrophication, people pay more attention to shallow lakes, and have tried different ecological models to predict lake water quality. PCLake model is specifically used for accurate prediction of pollution trend in shallow lakes. The principle of PCLake model and its application are briefly introduced. The application research of PCLake model is elaborated from different perspectives, including regime shift, climate change and lake management. In addition, different lake ecosystem models are compared, such as CAEDYM model, LakeWeb model, MIKE 21 model, CE-QUAL-W2 model, and WASP model. Based on the case studies and analysis of different models, the applicability and limitations of the PCLake model are explored and its future development is predicted, so as to provide a comprehensive and systematic reference for the research of PCLake model in shallow lakes.

Restructuring rural settlement space from the perspective of ecological protection is the main method of constructing the ecologically livable village and strengthening the community of life which is composed of mountains, rivers, forests, paddy field, lakes and grass. Taking Rongchang District of Chongqing Municipality as an example, the spatial differentiation characteristics of rural settlements were analyzed, the ecological protection pattern was constructed based on the model of minimum cumulative resistance and the theory of landscape ecology. According to the impact of the rural settlements on the ecological protection, rural settlements were divided into different types and spatial restructuring strategies were proposed. The results show that the rural settlements in Rongchang District had significant spatial differences. The rural settlements are characterized by scattered layout, large number, small scale, and near water sources. The current distribution of rural settlements is disadvantageous to ecological environment protection. According to the ecological protection theory, the existing rural settlements were divided into four types:to be restructured, to be expanded with certain limits, to be constructed moderately, and to be developed vastly. The corresponding reconstruction strategies have been proposed accordingly, based on the actual situation of rural areas and the position of regional ecological function. The research results would be useful for theoretical support and decision-making process towards the ecological and livable rural settlements in hilly areas.

Rural settlements research is a key part of rural geography studies and is one of the contents of the implementation of the "Rural Revitalization Strategy" of the 19th CPC National Congress. Based on the data of rural settlements in the period from 1980 to 2015, landscape index and GIS spatial analysis methods are used to explore the scale, shape, aggregation/fragmentation characteristics and evolution model of rural settlements in four sub-regions of Guangdong Province and Pearl River Delta, Eastern, Western and Northern Guangdong since the reform and opening-up. Results show firstly that the rural settlement area in Guangdong Province accounts for 2. 3%-2. 8% of the total land area of Guangdong Province in terms of scale characteristics from 1980 to 2015. The ranking in the order of sub-areas' size are the Pearl River Delta > Western > Northern > Eastern Guangdong. According to the proportion of each region, however, the order is Western > Eastern Guangdong > the Pearl River Delta > Northern Guangdong. The average area (14. 4-21. 9 m²) and scale variability (Patch Area Standard Deviation:144. 7) of rural settlements in Western Guangdong are the largest, followed by Eastern Guangdong and the Pearl River Delta. The northern Guangdong has the smallest patch (10. 5-11. 1 m²) and ignorable change. Secondly, the index value of patch shape in the Western Guangdong and Pearl River Delta region is larger and more complex than that in the Eastern and Northern Guangdong in terms of shape characteristics. Small change has been observed in the Land Shape Index curve of the rural settlement in Eastern and Northern Guangdong and the Pearl River Delta, while that of Western Guangdong is obviously declining. Thirdly, the Euclidean Nearest Neighbor Index was less than 1 in terms of aggregation/fragmentation characteristics from 1980 to 2015. The dynamic variation range was not obvious which indicates the rural agglomeration distribution in Guangdong Province and the four sub-regions. Finally, the spatial density distribution of rural settlements presents a pattern of "dense in the east and west wings, sparse in the north and central areas". The above results reveal that using multiple landscape indexes from different perspectives can effectively reveal the characteristics of different aspects of landscape space. The implementation of "rural revitalization" needs further deepen on the impact of physical geography, community economy and rural culture on the spatial characteristics of rural settlements, and strengthen the research on the guiding mechanism of government decisionmaking on the number, shape and spatial distribution characteristics of rural settlements.

Terrain factors not only control the distribution patterns of land use but also have important impact on regional ecological construction and sustainable land use. Taking Yongtai County of Fujian Province as an example, three terrain factors (elevation, slope, and terrain relief) were selected to explore the account for the driving factors of terrain factors on land use pattern in the hilly area of Zhejiang and Fujian provinces. Results show that:(1) the residence area, industrial, mining and traffic areas, cultivated land, garden plot and water area are preferentially distributed in the areas with elevations less than 500 m and slopes less than 25°. In these areas, the above mentioned five types of lands should be rationally arranged due to fierce competitions among the land types. Forestry areas and grassland are mainly distributed in ecologically fragile areas with elevations greater than 750 m and slopes greater than 35°. Ecological conservation should be considered for these two types of lands. (2) There are complex patchs and high heterogeneity in hills and valley plains, which have been affected by human activities. In the hilly mountain and marginal mountainous areas, the patches are regular shape with strong connectivity due to the dominant position of the natural ecosystem. Pearson correlation analysis show a significant correlation between terrain factors and landscape pattern metrics. (3) For developing and utilizing land resources in mountainous and hilly areas, there are important spatial restrictions. To achieve sustainable land use in these areas, it is necessary to arrange reasonably and harmonically in accordance with the distribution rules of different types of land and terrain conditions.

Research on the coordination relationship between natural resource value accounting and social economic development is an important technical means to measure whether a region can achieve sustainable development goals or not. Based on the value accounting system in Shenzhen natural resources balance sheet, the value of Shenzhen natural resources was calculated by using the land use data interpreted from remote sensing images in 2007, 2011 and 2016, and the coordinated development between natural resources and social economy was quantitatively analyzed by using the green economy coordination index (GEI). The results show that:(1) From 2007 to 2016, the area of various natural resources in Shenzhen City decreased by 144. 53 km², with an average annual decline of 1. 00%. (2) In the past 10 years, the total value of natural resources in Shenzhen City has decreased by 56. 195 billion yuan, and the total value of forest land and water bodies accounted for 71. 43% of the total value of natural resources in Shenzhen City. (3) The value of intangible assets of Shenzhen natural resources is much higher than that of physical assets, and the value of intangible assets accounted for 94. 68%. In the value of physical assets, land value accounted for the highest proportion. In the value of intangible assets, carbon fixation and oxygen release and climate regulation were the main contributors. (4) From 2007 to 2016, the coordinated development level of Shenzhen's green economy was in a state of low conflict, but showing a gradual improvement trend.

The objective of this study is to investigate the impacts of underlying surface conditions, i. e., discharged sewage from various sources, runoff paths, and soil background TN and TP contents on the ammonia nitrogen (NH₃), total phosphorus (TP) and permanganate index (I_Mn) loads. The hydrology and transport and transformation processes of the non-point source pollutions at the Fujiang River Basin were simulated with a SWAT model in which the parameters were calibrated by the SWAT-Cup. The global sensitivities of underlying surface condition parameters were evaluated using the Sobol indexes. The Nash-Sutcliffe coefficient, the relative root mean square error, the relative deviation, and the relative total error were used to evaluate the model performance and the results show that the simulated flow rates and NPS loads were accurate. The variation of the NPS pollution loads increased as more pollution discharged into rivers under various underlying surface conditions. The NPS loads were mainly affected by the landscape and the slope length in hills dominated by the natural forests, whereas the NPS loads decreased with the proportion of agricultural land area due to the modulation capacity of the agricultural lands to the runoff. The Sobol sensitivity analysis results demonstrate that flow paths had the most important first-order and total-order effect on the simulated flow and NPS loads. The sensitivity indices of the total phosphorus and the permanganate index were the lowest and the highest, respectively, among three NPS pollutions. Strengthening the control and adjustment ability of the runoff process has the most significant effect on the controlling of non-point source pollution in the Fujiang River Basin.

Farming non-point source pollution is one of the main sources of water pollution in lakes. However, little research has been done on the driving force of farming non-point source pollution. In order to study the driving forces of nonpoint source pollution in farming industry in Xingyun Lake Basin, the amount of fertilizer loss from farming industry in 2005, 2010 and 2015 was calculated by the loss coefficient method, and the influencing factors was analyzed by multiple linear regression. The results show that:(1) The proportion of agricultural population in the total population, the proportion of cultivated land, the farming area of economic crops and fruit trees, the ratio of sowing area of economic crops and grain crops, and the output value of the first industry are positively correlated with the amount of chemical fertilizer loss. The sown area of grain crops, non-agricultural income per capita, and environmental protection investment index are all negatively related to the amount of chemical fertilizer loss. (2) The farming area of economic crops and fruit trees, the ratio of sowing area of economic crops to grain crops and the amount of chemical fertilizer loss are the highest, which are all greater than 0. 9. Therefore, the decisive factor of planting non-point source pollution is planting structure in Xingyun Lake Basin.

The voluntariness of households to take part in the eco-compensation programs will largely affect the outputs of these programs. The factors influencing the household voluntariness to take part in two eco-compensation programs, i. e. the Sloping Land Conversion Program (SLCP) and Public Benefit Forest Compensation Program (PBFC) were studied. The study is based on a 615-households interview with questionnaires in Pingbian and Xichou, Yunnan Province. The results of the study show that household motivation and program attractiveness are vital for household voluntariness. In the SLCP, 84. 4% of households voluntarily took part in the program while 15. 6% of households were not voluntary. The positive factors to influence household voluntariness in the SLCP are trust in neighbours and village leaders, experiences of off-farm jobs, compensation rate, expected policy outcome and understanding to the policy. Age and number of household labors are the negative factors. In the PBFC, 36% of households were voluntary to take part in the program while 64% of households were not voluntary. The positive factors to influence household voluntariness in the PBFC are trust in neighbours and village leaders, compensation rate, expected policy outcome, understanding to the policy. This study implies that SLCP and PBFC could be better implemented with preferable outcomes if policy advocacy is enhanced, compensation rate is raised appropriately, and non-farm job opportunities are created.

In recent years, the integration of the Beijing-Tianjin-Hebei ecological environment has been difficult, which has affected the integration of Beijing-Tianjin-Hebei. The ecological compensation mechanism is one of the economic means to effectively protect the regional ecological environment. By interpreting the Landsat TM remote sensing images of 2000, 2008, 2013 and 2018 in Dingxing County of Baoding City, the changes of land types in Dingxing County was analyzed from 2000 to 2018, and the value of county's ecological service functions and the loss of development rights were calculated. The scope of ecological compensation standards was discussed. On this basis, how the region compensates the county, and how the county compensates the ecological protector were further discussed. The county's ecological compensation mechanism was established. The results show that due to the development and utilization of land, the value of ecosystem services in Dingxing County had been reduced from 861. 17 million yuan to 813. 19 million yuan, and the loss of development rights being 672. 74 million yuan, that is, the ecological compensation range of Dingxing County was 672. 74 million-813. 19 million yuan. The county's ecological compensation mechanism was to grasp the principle of "who protects, who benefits and compensated" and "equal rights and responsibilities", and the region should provide financial compensation, policy compensation, and technical compensation to the county. The county should combine the policies of the times with the townships and enterprises, environmental NGOs, farmers and herdsmen compensated to form "hematopoietic" compensation for "reasonable distribution, key attention, and social participation", thereby improving the operationality of the county's ecological compensation mechanism in the process of Beijing-Tianjin-Hebei integration.

Solidago canadensis is one of the most destructive invasive plants in Eastern China and it is also the notorious exotic weed in forest plantations. In order to understand the invasion of Solidago canadensis in different plantation communities, five plantation communities (Metasequoia lyptostroboides, Koelreuteria paniculata, Cinnamomum camphora, Firmiana platanifolia and Bischofia polycarpa) at Chongming Island in Shanghai were selected to investigate its invasion and distribution in these communities. The results show that the important values of Solidago canadensis in these five communities were ranked as:Bischofia polycarpa > Koelreuteria paniculata > Cinnamomum camphora > Firmiana platanifolia > Metasequoia lyptostroboides. After the evaluation of the niche of herbaceous plants in these communities, the niche breadth and niche overlap of Solidago canadensis were in the rank as:Bischofia polycarpa > Firmiana platanifolia > Cinnamomum camphora > Koelreuteria paniculata > Metasequoia lyptostroboides. It has been observed that the higher the tree density in these communities, the less invasion of Solidago canadensis. The results provided implications for controlling this invasive plant.

In nature reserve, monitoring habitat quality changes by remote sensing technology is of great significance to regional ecological protection policies making. Taking the Yuanjiangyuan Nature Reserve in Guizhou Province as an example, combining Fragstats 4. 2 with InVEST 3. 4. 4 software, land use changes and landscape patterns were analyzed based on Landsat-5 TM images, Landsat-7 ETM+ images and Landsat-8 OLI images from 1990 to 2018. Then, the habitat quality changes were explored and validity of the functional zoning was assessed. Finally, habitat quality improvement affected by ecological protection scenarios was simulated. Results showed that:from 1990 to 2018, forest, constructed land and wetland in nature reserve increased, while grassland, other types and cultivated land decreased. The land transformation of reserve mainly occurred from grassland to forest, cultivated land to forest and cultivated land to grassland. As integrated degree of land use increased, the impact of human activities was gradually increasing. The integrated degree of land use was in the order of the core area < buffer area < pilot area during the past 29 years. The clumpy of cultivated land and the patch density of artificial land increased in reserve. Increase of landscape advantage of patch connectivity led to decrease of the fragmentation. Forest patch controlled landscape pattern. The average habitat quality showed a fluctuating increase trend from 1990 to 2018, which increased by 8. 64% than those in 1990. The average habitat quality was in the order of the core area > buffer area > pilot area in the past 29 years. The trend of habitat quality improvement was greater than that of degradation in nature reserves. Under the ecological protection scenario, the average habitat quality of the reserve increased from 0. 88 to 0. 90. The implementation of Green for Grain plan and the increase of human activities were the main reasons for the changes of the habitat quality.

To explore the relationship between physical and chemical properties of grassland surface soil and altitude in the Xarxili Nature Reserve, 15 representative grassland surface soil samples were acquired from different altitudes in the protected area and the physical and chemical properties of the soil samples were quantitatively analyzed by field investigation and laboratory tests. The results show that there were significant differences (P<0. 05) in soil physical property indices in the grassland surface at different altitudes. Soil bulk density, saturated moisture content, natural water content, and porosity content were significantly correlated with altitude (P<0. 01), and soil bulk weight decreased gradually with the increasing of altitudes, having a minimum value of 0. 91 g·cm^-3 at 2 142. 24 m. There were also significant differences in chemical indices of the grassland surface soil at different altitudes (P<0. 05). The variation ranges of soil organic matter, total nitrogen, and total phosphorus mass fractions were 3. 72%-11. 98%, 1. 25%-3. 25%, and 0. 121%-0. 159%, respectively, all increasing with the increase of altitude. The maximum values were observed at the altitude of 2 142. 24 m. However, the pH value changed in the opposite direction. The physical and chemical properties of grassland surface soil varied with different altitudes with the best at the altitude of 2 142. 24 m and the worst at the altitude of 835. 23 m. For different soil types, the physical and chemical properties of grassland surface soil comprehensively manifest in the order of black calcium soil > chestnut soil > brown calcium soil.

The effect of water exchange purpose and water quality status on frequency of water exchange (FWE) in pond aquaculture was investigated. Through the interview investigation processed in Jiangsu Province between July and August from 2015 to 2018, the information of water exchange came from 57 farmers raising Chinese mitten crab (Eriocheir sinensis) was collected. The five types of primary purpose that drive farmers to make water exchange during that season were:compensating the evaporation (without drainage), avoiding hypoxia, routine farming management, preventing disease and improving water quality, which accounted for 47%, 16%, 11%, 11% and 16%, respectively. Water exchange (with drainage) of 19% of farmer seems unnecessary according to the water quality. It was found that FWE to avoid hypoxia or improve water quality was significantly higher than the other three conditions (P<0. 05). FWE was negatively correlated with the fequency of artificial aeration (r=-0. 177, P<0. 1). 111 water quality samples from 64 common fish ponds were obtained through field monitoring in Suzhou and Yancheng City, and the results show that the average ρ (DO), pH, ρ (TN), ρ (NH₄⁺-N), ρ (TP), ρ (PO₄^3--P), COD_Mn, ρ (chlorophyll a) were (8. 3±2. 7) mg·L^-1, 8. 1±0. 5, (4. 3±2. 2) mg·L^-1, (1. 0±1. 0) mg·L^-1, (0. 56±0. 56) mg·L^-1, (0. 29±0. 37) mg·L^-1, (12±5) mg·L^-1, (133±12) μg·L^-1, respectively, and the average FWE was (0. 87±2. 10) times·month^-1. The water quality and FWE varied greatly among different ponds. FWE was negatively correlated with ρ (DO) and pH (P<0. 01), and positively correlated with temperature, ρ (NH₄⁺-N), ρ (TP) and ρ (PO₄^3--P) (P<0. 01). FWE was influenced by both water exchange purpose and water quality status, which could be reduced by strengthening artificial aeration.

In order to understand how ecological ditches, same in depth (1. 30 m) and different in constructions (grass, fillers, grass and fillers), can reduce main agricultural non-point source (NPS) pollutants under the same condition, pollutants removal efficiency were evaluated under dynamic inflow concentration[ρ (NH₄⁺-N)=0. 17-1. 23 mg·L^-1, ρ (TN)=0. 86-6. 13 mg·L^-1, ρ (TP)=0. 11-0. 24 mg·L^-1 and ρ (SS)=24. 0-70. 0 mg·L^-1]. And the effects of practical application of ecological ditch were also analyzed. Results show that, all the three kind of ecological ditches were quite high in NPS pollutants removal efficiency (>50%), regardless of the difference in construction. Ditch with grass and fillers had the highest pollutant removal efficiency. The mean ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), total phosphorus (TP) and suspended substance (SS) removal rates of the ditch were all higher than 70%, and with relatively high stability. The concentrations of TN and TP in the ditch were decreased exponentially along with distance. In simulated rainfall runoff experiment, the final TN removal effect of the actual 110 m ecological ditch was higher under the low inflow TN concentration, while TP removal effect was higher under the high inflow TP concentration. This research is expected to be of great practical guiding significance to the control of agricultural NPS pollution.

The ability and purification efficiency of different modified kaolins for phosphate adsorption in livestock and poultry wastewater were detected. Batch adsorption experiment and dynamic column adsorption experiment were used to evaluate the cost-benefit of kaolin used in the purification of phosphate-containing livestock and poultry wastewater. The results show that different modification treatments could significantly improve the adsorption performance of kaolin on phosphate, but there are some differences between the different modification methods. For hydrochloric acid modification, with the increase of acid dosage, the adsorption capacity of modified kaolin to phosphate has gradually increased. When the heating temperature was lower than 500℃, the adsorption performance of kaolin increased gradually with the temperature, and could be increased by about 3 times. When the calcination temperature was 500~600℃, the adsorption capacity kept no change with the increase of temperature, then when the temperature was higher than 600℃, it showed a downward trend. The saturation adsorption of phosphate on layered double hydroxide-modified kaolin is significantly higher than that of 500℃ thermally modified kaolin. However, on comprehensive consideration of modification cost, residual solution concentration, adsorption capacity, removal rate and other purification effects, in the treatment of 20 mg·L^-1 phosphate-containing livestock and poultry wastewater or so, adsorption performance of 500℃ thermally modified kaolin is the best, and the cost is lowest and the cost-benefit ratio is the highest, which is about 1421 mg P·yuan^-1.

Sichuan Province has a great variety in topography, which has significant influences on regional climate distribution. Based on the data of monthly air temperature of 144 meteorological stations in Sichuan Province, seven interpolation methods including spline (SP), inverse distance weighting (IDW), ordinary kriging (OK), spline function method considering elevation effect (SPE), inverse distance weighing considering elevation effect (IDWE), ordinary kriging considering elevation effect (OKE) and multivariable linear regression method (MRM) were applied in current study to spatialize the monthly temperature. Meanwhile, the cross validation method was used to evaluate the accuracy of seven interpolation methods. The results show that the monthly temperature in Sichuan Province was significantly correlated with altitude, and correlation coefficient changed seasonally, with greater change in summer than in winter. The average temperature of each month decreased with the increase of altitude, and lapse rate of summer was greater than that of winter. The lapse rate for different months varied from 0. 308 to 0. 443℃·hm^-1. The interpolation methods considering elevation effect achieved better accuracy than that without considering elevation effect. Among four interpolation methods considering elevation effect, MRM had the best accuracy, followed by IDWE and OKE, and SPE had the worst accuracy.

Amphibian are declining worldwide, and it is an urgent task to accurately and rapidly assess the population size of amphibian through monitoring program. This study employed an estimation method to assess the breeding population size of amphibian, which includes surveys at breeding sites and PIT (passive integrated transponder) mark-recapture method. This method provides accurate population size based on short-term mark-recapture data and capture-mark-recapture model for that open populations. The method also offers several advantages:surveys at breeding sites overcome the difficulty that individual distribution is not concentrated at non-breeding seasons. Also, it can avoid the fluctuation of population size in different seasons. Based on the superiority of PIT marker in individual identification, the population size of amphibians can be evaluated quickly and accurately by several times recapture. This model was applied to a five-day capture-mark-recapture data set of toad (Bufo gargarizans) in Laohegou Nature Reserve of Pingwu County, Sichuan Province, and the population size was estimated. This method provides a simple and effective method for amphibian population monitoring, which is of great value to the assessment of rare species.