Against the background of China’s advocating ecological civilisation construction, an urgent task and a major challenge are to identify key places for ecological protection and restoration and then propose optimisation strategies for future land use, especially in the Pearl River Delta (PRD), one of the regions in China that has the highest urbanisation level. In this study, we find the key places by constructing ecological security patterns and proposing optimisation strategies for future land use by analysing land-use status. We also propose a source identification method based on the resistance distance principle. Results show that forty-six sources were mainly distributed in the mountainous areas surrounding PRD but were less distributed along both sides of the Pearl River estuary. The difference in the spatial distribution of sources is remarkable. Eighty-four corridors generally had spider-like shapes. In the central plain of PRD, corridors were relatively long and narrow. Ninety pinch points were concentrated on existing rivers. Three barriers were located in the corridors between adjacent sources. Two artificial corridors were proposed to be established, which can improve the ecological network connectivity. The method for extracting sources based on the resistance distance principle is proven to be advantageous for improving the integrity of source extraction results and making ecological security patterns more reasonable.

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Construction of Ecological Security Patterns Based on Circuit Theory under the Resistance Distance Principle

In order to achieve low carbon transformation and green development in agriculture, we analyzed the effects of different types of socialized services on agricultural carbon emissions based on provincial panel data from 2010 to 2020 in China. We further analyzed the possible ways for agricultural social services to reduce the intensity of agricultural carbon emissions with the help of mediating effect model. The results show that socialized services can provide basic services, production and operation services, financial services, and circulation services for the agricultural production chain, which can significantly reduce the agricultural carbon emissions intensity. The results of the intermediation effect suggest that socialized services can break the labor constraint by promoting the scale effect, and thus reduce the agricultural carbon emissions intensity. However, the mediation effect of technology diffusion is not significant. The reason is that although the diffusion of agricultural technology can improve the efficiency of resource utilization, the diffusion of technology also leads to the use of elements such as high concentrations of chemicals and heavy agricultural tools which may increase carbon emissions. In addition, the effect of socialized services on reducing agricultural carbon emissions intensity shows obvious spatial heterogeneity, with the reduction gradually increasing from coastal to inland provinces and from eastern to western regions.

https://www.frontiersin.org/articles/10.3389/fenvs.2022.1039760/pdf

Can socialized services reduce agricultural carbon emissions in the context of appropriate scale land management?

Shifts of ammonia-oxidation process along salinity gradient in an estuarine wetland

Peatlands serve numerous functions, with one of the main ones being the retention of nutrients, including mineral nitrogen. A field study in organic soils was carried out in the Mazurian Lake District situated in north-eastern Poland (53°37′50′ N, 20°28′51′ E). In the test peat soils, the rate of organic nitrogen compound mineralization varied significantly depending on the season. The dynamics of the organic matter mineralization process were most strongly influenced by the soil use and the season. The mineral N release was higher in organic soil under intensively used grassland. In this soil, much more mineral nitrogen was released during the summer and spring periods. The dominant form in the organic nitrogen compound mineralization processes was N-NO3. The highest dynamics of the organic nitrogen compound mineralization were noted at a soil moisture content ranging from 57% to 59%. The interdependence of the soil moisture content and the rate of organic nitrogen compound mineralization fluctuated over the study period, with an increase in spring and a decrease in summer. A correlation was demonstrated between the nitrate form content in the peat soils under intensive cultivation and the nitrate-nitrogen concentration in groundwater, while no correlation was demonstrated between the N-NO3 content in the soils under a forest and the N-NO3 concentration in the groundwater of these soils. The results provide the basis for the conclusion that the land use type (forest, grassland), which determines the morphological structure of organic soils, affects the intensity of the infiltration of different mineral nitrogen forms.

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Dynamics of Organic Nitrogen Compound Mineralization in Organic Soils under Grassland, and the Mineral N Concentration in Groundwater (A Case Study of the Mazurian Lake District, Poland)

Linking trophic state with the eco-hydrological state of dam-induced floodplain wetland in Barind Tract

The largest blue-green infrastructures in industrialized, urbanized and developed regions in China are often multiuse wetlands, located just outside growing urban centers. These areas have multiple development pressures while providing environmental, economic, and social benefits to the local and regional populations. Given the limited information available about the tradeoffs in ecosystem services with respect to competing wetland uses, wetland managers and provincial decision makers face challenges in regulating the use of these important landscapes. In the present study, measurements made by citizen scientists were used to support a comparative study of water quality and wetland functions in two large multiuse wetlands, comparing areas of natural wetland vegetation, tourism-based wetland management and wetland agriculture. The study sites, the Nansha and Tianfu wetlands, are located in two of the most urbanized areas of China: the lower Yangtze River and Pearl River catchments, respectively. Our results indicated that the capacity of wetlands to mitigate water quality is closely related to the quality of the surrounding waters and hydrological conditions. Agricultural areas in both wetlands provided the lowest sediment and nutrient retention. The results show that the delivery of supporting ecosystem services is strongly influenced by the location and use of the wetland. Furthermore, we show that citizen scientist-acquired data can provide fundamental information on quantifying these ecosystem services, providing needed information to wetland park managers and provincial wetland administrators.

Qian Wang

Papers

Comparing Wetland Ecosystems Service Provision under Different Management Approaches: Two Cases Study of Tianfu Wetland and Nansha Wetland in China