Effects of endogenous factors on regional land-use carbon emissions based on the Grossman decomposition model: a case study of Zhejiang Province, China.

The impact of land-use change on greenhouse gas emissions has become a core issue in current studies on global change and carbon cycle. However, a comprehensive evaluation of the effects of land-use changes on carbon emissions is very necessary. This paper attempted to apply the Grossman decomposition model to estimate the scale, structural, and management effects of land-use carbon emissions based on final energy consumption by establishing the relationship between the types of land use and carbon emissions in energy consumption. It was shown that land-use carbon emissions increase from 169.5624 million tons in 2000 to 637.0984 million tons in 2010, with an annual average growth rate of 14.15%. Meanwhile, land-use carbon intensity increased from 17.59 t/ha in 2000 to 64.42 t/ha in 2010, with an average annual growth rate of 13.86%. The results indicated that rapid industrialization and urbanization in Zhejiang Province promptly increased urban land and industrial land, which consequently affected land-use extensive emissions. The structural and management effects did not mitigate land-use carbon emissions. By contrast, both factors evidently affected the growth of carbon emissions because of the rigid demands of energy-intensive land-use types and the absence of land management. Results called for the policy implications of optimizing land-use structures and strengthening land-use management.

Managing the supply-demand mismatches and potential flows of ecosystem services from the perspective of regional integration: A case study of Hangzhou, China.

Regional integration is a development strategy that synergizes various components as a whole to maximize overall benefits. The natural heterogeneity and fluidity of ecosystem service (ES) make it a promising target for regional integration. However, the current focus on regional integration was more on the socio-economic factors rather than ecological resources, and the understanding of the supply-demand relationship and potential flow of ecosystem services was still limited. Therefore, we attempted to interpret ecological integration management by linking ES budgets, bundles, and flows in this study. The results showed that the spatial mismatches of ESs supply-demand were observed in all six selected ES types. Most of the ESs deficit regions were concentrated in urban centers, while ES surplus regions were scattered in surrounding rural areas. Multiple heterogeneous ES resources could ideally benefit an additional 0.13-4.84 million people in 9-70 townships through potential ES flows under ecological integration management. Therefore, we connected the service provisioning areas (SPAs) and service beneficiary areas (SBAs) with three types of ES flows and drew the potential provider-beneficiary relationship networks at the townships/bundles scale, demonstrating the interactive relationship of ecological integration within the region. On this basis, we also proposed the applicability matrix of governance tools for the first time according to the type of ES flows, and then put forward the corresponding governance opinions around the two aspects of "improving ES budges within clusters" and "strengthening ES flow among clusters". This study provided an ecological perspective for understanding regional integration, and relevant conclusions can inform environmental policy priorities for sustainable decision-making in urbanized areas.

A growing global threat: Long-term trends show cropland exposure to flooding on the rise.

Flooding is one of the most widespread and catastrophic natural disasters. The exposure of cropland to floods is directly related to the quality of cropland and food security, so it is particularly important to map the spatiotemporal evolution of this exposure, with a specific focus on longer time series and higher resolution scales. This study is the first of its kind to analyse the worldwide spatiotemporal variability of Cropland Exposure to Flooding (CEF) with the 30 m resolution of Global Land Analysis & Discovery (GLAD) dataset during 2000-2019. The findings indicate that: (1) the global CEF area increased by a total of 83,429.50 km2 or 7.75 %, from 2000 to 2019; (2) only North America's CEF showed a downward trend, and the region with the largest increase in CEF was South Asia; (3) the CEF in 23 river basins, including Ganges, Indus, Mississippi, Yangtze, and Danube, accounted for 79.88 % of the global total in 2019P; (4) in 2019P, China had the largest CEF globally, reaching 239,525.07 km2. The fastest growing CEF was India, contributing 16.36 % of the global CEF growth. The CEF of United States experienced a reduction trend; (5) two constructed indicators were used in evaluating the CEF of countries worldwide, and a total of 46 countries are considered to be at the highest level of risk, mainly in Europe and Asia. Based on these conclusions, we carried out a cold/hot spot analysis to reveal the spatial heterogeneity and possible driving factors in this phenomenon, and we offer management suggestions to limit the risks to cropland in the floodplains.

Reveal the severe spatial and temporal patterns of abandoned cropland in China over the past 30 years.

The abandonment phenomenon is familiar in China. It threatens food security and seriously affects the sustainable development of society, the economy, and the natural environment. However, monitoring and mapping abandoned cropland on a large scale remains a challenge because of its complex land-use change process. According to the World Food and Agriculture Organization, cropland not used for agricultural production for more than 5 years is defined as abandoned cropland. This study uses the Landsat high-precision long-time series product to detect cropland nationwide from 1990 to 2019 by using the sliding window method on Google Earth Engine to profile the spatial distribution, intensity, trend, frequency, and recultivation of abandoned cropland. Between 1992 and 2015, the results illustrate that the total area of abandoned cropland in China was 559,170.26 km2, 18.59 % of the cropland area. Excluding the recultivated cropland area, China's abandoned cropland area amounted to 392,156.24 km2, 13.03 % of the total cropland. Cropland abandonment is mainly distributed in the second terrain gradient in midwestern and southwestern regions such as Inner Mongolia and Gansu. It rarely happens in western and eastern coastal areas. A high abandonment rate area usually has high elevation and slope. The light index is negatively correlated with the abandonment rate in suburban areas. This study is the first to map the spatiotemporal distribution of abandoned cropland in China with high precision at 30 m resolution. It provides an important basis for policies regarding the recultivation of abandoned cropland.

Mapping trade-offs among urban fringe land use functions to accurately support spatial planning.

The land use planning and management of urban fringe areas have become major governmental agendas under the background of continuing periurbanization processes. Quantifying land use functions (LUFs) and their interactions as rationales for spatial planning can aid in formulating a more effective and sustainable land use management system. Considering that most of the previous research on LUFs focused on large-scale regions, research on local-scale districts such as urban fringe is still limited. Therefore, the objective of this work is to map the spatial distribution of LUFs and their level of provision around an urban fringe area, so as to identify LUFs synergies and trade-offs in relation to urban expansion and environmental protection planning. To achieve this target, we have proposed an improved LUFs classification system that was suitable for small-scale regions. Fine scale multivariate datasets were used to meet the practical requirements of spatial planning. The urban fringe areas of Binzhou city in China was taken as a case study to quantify and analyze nine kinds of sub-land use functions. The interactions among LUFs and their cold-hot spots were measured through Spearman correlation analysis and bivariate local Moran's I respectively. The results demonstrated a heterogeneous spatial pattern of multiple LUFs and the diverse interactions among them. The social production function presented an obvious regional distribution, the residents' living functions were greatly affected by the radiation of the urban central areas, and the ecological regulation functions were closely related to the land use types. According to the LUFs clustering results, we proposed two spatial planning-zoning schemes based on the land use function and human utilization intensity. The integrative approach and the proposal of functional zones developed in this paper are applicable to provide a new perspective for spatial planning and peri-urban land use management.

Adaptation of soil fungi to heavy metal contamination in paddy fields-a case study in eastern China.

Soil fungi have been widely studied, but the effects of heavy metal contamination at various levels as well as the abundance and diversity of heavy metal tolerant fungi in the contaminated paddy soils are still unknown. The purpose of this study is to analyze the adaptability of fungi at different levels of heavy metal contamination to identify species that have strong adaptability to heavy metals. In this research, the technology of high-throughput sequencing was applied to study fungal communities in severe level (SL), moderate level (ML), light level (LL), and clean level (CL) for soil samples polluted by heavy metal, as well as to analyze the relations between environmental variables and fungal communities. The spearman analysis showed that 6 dominant fungal phyla and 18 dominant fungal genera were significantly correlated with these environmental variables. The α-diversity indexes of the soil fungal community from SL, ML, and CL were, mostly, drastically higher than the LL samples (p < 0.05). Meanwhile, Ascomycota, the main fungal phylum, was spotted to yield a strong tolerance towards heavy metals, especially in ML. The most dominant genera of tolerant fungi in this area, which are Aspergillus, Penicillium, and Fusarium, could absorb and transport the heavy metals with the help of nutrients under certain heavy metal contamination levels. Therefore, this study indicated that some fungi, which have strong biodegradability on heavy metals, can reduce toxicity of heavy metals and create a proper soil environment to grow food crops. Graphical abstract.

Improvement of subsoil physicochemical and microbial properties by short-term fallow practices.

Fallow management can improve the soil nutrients in the topsoil and upper subsoil. However, little is known about the effects of short-term (one year) fallowing with different treatments, such as vegetation and fertilization, on subsoil (20-40 cm) properties. We conducted field trials to explore the changes in subsoil properties in response to such treatments in the Yellow River Delta region in China. Different vegetation and fertilization treatments were applied, and we measured the carbon and nitrogen contents, microbial biomass and microbial community structure in the subsoil. Fallowing without manure resulted in the storage of more total nitrogen (16.38%) than fallowing with manure, and meadow vegetation improved the ammonium nitrogen content (45.71%) relative to spontaneous vegetation. Spontaneous vegetation with manure improved the microbial biomass nitrogen (P < 0.05). Although the impact of short-term fallowing on microbial community structure was low, an effect of management was observed for some genera. Blastopirellula, Lysobacter, and Acidobacteria Gp6 showed significant differences among fallow treatments by the end of the year (P < 0.05). Blastopirellula abundance was related to the microbial biomass nitrogen and nitrogen mineralization rate in the subsoil. Manure retained a high abundance of Lysobacter, which may strengthen soil-borne disease resistance. The response of Acidobacteria Gp6 showed that meadow vegetation without manure may not benefit future crops. Although the treatments did not significantly improve microbial community structure in the one-year period, annual fallowing improved certain subsoil properties and increased the number of functional genera, which may enhance crop productivity in the future.

Comprehensive assessment of paddy soil quality under land consolidation: a novel perspective of microbiology.

Soil quality assessment is an important means to demonstrate how effective land consolidation is. However, the existing assessment system is not sufficient to reflect actual soil quality. So, the purpose of this study is to integrate abiological and biological indicators into a comprehensive assessment to evaluate the paddy soil quality under different land consolidation practices. Soil samples were collected from 35 paddy sites under different land consolidation practices including land merging, land leveling (LL), ditch construction (DC) and application of organic fertilizer (AO). A total of 10 paddy sites were selected under conventional tillage (CT) from non-land consolidation area as a control group in Y county, China. The results indicated that soil organic matter (OM), total nitrogen (TN), available phosphorus, bacterial functional diversity (BFD), bacterial and fungal abundances were significantly improved. Fields under LL, among all the land consolidation practices, might still face the risk of land degradation caused by low TN, OM and microbial diversity. High microbial biomass, BFD and OM were significantly higher in fields under AO in nutrient cycle. According to the results of comprehensive assessment, the samples with severe heavy metal contamination and low microbial diversity were generally concentrated in CT. These results indicated that land consolidation was an efficient technique to improve soil quality and could achieve higher quality of agricultural products.

Determination of potential management zones from soil electrical conductivity, yield and crop data.

One approach to apply precision agriculture to optimize crop production and environmental quality is identifying management zones. In this paper, the variables of soil electrical conductivity (EC) data, cotton yield data and normalized difference vegetation index (NDVI) data in an about 15 ha field in a coastal saline land were selected as data resources, and their spatial variabilities were firstly analyzed and spatial distribution maps constructed with geostatistics technique. Then fuzzy c-means clustering algorithm was used to define management zones, fuzzy performance index (FPI) and normalized classification entropy (NCE) were used to determine the optimal cluster numbers. Finally one-way variance analysis was performed on 224 georeferenced soil and yield sampling points to assess how well the defined management zones reflected the soil properties and productivity level. The results reveal that the optimal number of management zones for the present study area was 3 and the defined management zones provided a better description of soil properties and yield variation. Statistical analyses indicate significant differences between the chemical properties of soil samples and crop yield in each management zone, and management zone 3 presented the highest nutrient level and potential crop productivity, whereas management zone 1 the lowest. Based on these findings, we conclude that fuzzy c-means clustering approach can be used to delineate management zones by using the given three variables in the coastal saline soils, and the defined management zones form an objective basis for targeting soil samples for nutrient analysis and development of site-specific application strategies.

Effects of Short-Term Set-Aside Management Practices on Soil Microorganism and Enzyme Activity in China.

Set-aside farmland can effectively improve the self-rehabilitation of arable soil. Long-term set-asides however cannot satisfy provisionment, therefore the use of short-term set-asides to restore cultivated soil is a better option. Few studies have compared short-term set-aside patterns, and the effects of set-asides on soil microbial community and enzyme enzymes. We analyzed the bacterial structure, microbial biomass carbon/nitrogen and enzyme activity of farmland soil under different set-aside regimes in the Yellow River Delta of China. Bacterial alpha diversity was relatively lower under only irrigation, and farmyard manure applications showed clear advantages. Set-asides should consider their influence on soil organic carbon and nitrogen, which were correlated with microbial community structure. Nitrospira (0.47-1.67%), Acidobacteria Gp6 (8.26-15.91%) and unclassified Burkholderiales (1.50-2.81%) were significantly altered (p < 0.01). Based on functions of these genera, some set-aside patterns led to a relative balance in nitrogen and carbon turnover. Partial treatments showed a deficiency in organic matter. In addition, farmyard manure may lead to the increased consumption of organic matter, with the exception of native plants set-asides. Conventional farming (control group) displayed a significant enzyme activity advantage. Set-aside management practices guided soil microbial communities to different states. Integrated soil microbiota and the content of carbon and nitrogen, native plants with farmyard manure showed an equilibrium state relatively, which would be helpful to improve land quality in the short-term.

Quantification of the effects of management factors on maize (Zea mays L.) and cotton (Gossypium hirsutum L.) residues decomposition rate.

Efforts to quantify management effects on decomposition rate of added substrates to the soil is important especially where such information is to be used for prediction in mathematical or simulation models. Using data from a short-term (60 days) greenhouse simulation study, a procedure for quantifying effects of management on SOM and substrate decomposition is presented. Using microbial growth rate u(q), microbial efficiency in substrate utilization e(q), specific decomposition rates for added plant residues to two contrasting soils, red earth (Ferrasol) and black earth (Acrisol) were estimated. The treatments included straw addition + buried, (T1); straw addition + mineral N (T2); and straw addition + tillage, (T3). Sampling was done every 15 days. Straw decomposition rate was affected by external mineral N sources (Urea 46% N). Addition of an external N source significantly increased decomposition rates. The study could not, however, fully account for the effect of tillage on residues because of the limited effect of the tillage method due to the artificial barrier to mechanical interference supplied by the mesh bags. It is concluded that using few decomposer parameters, decomposition rates and consequently SOM trends in a soil system can be monitored and quantification of the influence of perturbations on decomposition rate of added substrates possible.

[Application of ecosystem service value in land use change research: Bottlenecks and prospects].

In recent years, the application of ecosystem service value in land use change research is a hot topic in many famous international journals. However, policy makers are seldom taking into account the achievements of the related studies in practice. This paper summarized the three main bottlenecks in applying ecosystem service value in land management practices, i. e., the difficulty in measuring the service values, the complexity of driving factors, and the bias of evaluation criteria. Some solutions on the bottlenecks were provided, and the future research directions in China were prospected. It was suggested that in the studies of land use change based on ecosystem service value, it would be more appropriate to adopt comparative analysis method in small scale case studies, especially focusing on the natural ecological resources and the excessive loss of their values.

[Ecological design of ditches in agricultural land consolidation: a review].

Agricultural land consolidation is a strong disturbance to farmland ecosystem. In traditional agricultural land consolidation, the main technical and economic indices for the design of ditches include the convenience for production and transportation, the allocation of water resources, and the improvement of water utilization, but short of ecological consideration, which has already affected the spread of agricultural species, caused the degradation of bio-habitat, and given obvious negative effects on the bio-competition mechanism, buffering and compensation capacity, and insect pests-resistance of farmland ecosystem. This paper summarized the functions of ecological ditches, and introduced the recent progress on the formations and construction designs of ecological ditches, tests of ecological engineering methods, and technologies and methods of choosing correct ecological materials. It was suggested that the future research should focus on the different functional requirements and specifications for different roads and ditches, and the characteristics and habitats of all the organisms and animals should be considered by the designers and constructors. Moreover, a comprehensive design which meets the ecological demands for the ditches' formations, structures, and regulatory sizes should be taken into account to solve the most of the problems listed above.

[Spatiotemporal changes of wetlands in Hangzhou Bay Industrial Belt].

By using RS and GIS techniques, the spatiotemporal changes of wetlands in Hangzhou Bay Industrial Belt, one of the most developed zones in Zhejiang Province, from 1990 to 2005 were studied. There was a frequent conversion between the wetlands and other land use types and between the wetlands themselves, mainly manifested in the conversion between wetland and farmland, and from wetland to construction land and from tidal flat to aquiculture area. The comparative advantage of other land use types and the policy of cultivated land's requisition-compensation balance decided the inherent mechanisms of these spatiotemporal changes. Driven by the aquaculture's comparative advantage to traditional agriculture, large areas of inland farmland and of the tidal flat along the coast of Hangzhou Bay were reclaimed into aquiculture area, and the rapid expansion of construction land, limited land resources, and the implement of cultivated land's requisition-compensation balance policy induced the wetlands being occupied.

[Complexity of land ecosystem].

In recent years, complexity studies has become a new research region and been widely applied in engineering, biology, economy, management, military, police and sociology. In this paper, from the view of complex science, the main complexity characteristics of land ecosystem were described, furthermore, the application of fractal, chaos, and artificial neural network on the complexity of land ecosystem were also discussed.

[Theories and methodologies of engineering designs on sustainable agricultural land consolidation project--a case study of Xuemeiyang land consolidation project in Changtai County, Fujian Province].

The concept and characteristics of engineering designs on sustainable agricultural land consolidation project were discussed in this paper. Principles, basic methods and procedures of engineering designs on agricultural land consolidation project were put forward, which were successfully adopted for designing agricultural land consolidation in Xuemeiyang region of Changtai County, including diversity designs of sustainable land use, engineering designs of soil improvement, roads, ditches, and drains for protecting existent animal environments, and design of ecological shelter-forests in farmland. Moreover, from sustainable economic, ecological and social points, the results of these engineering designs were evaluated based on fouteen important indexes. After carrying out these engineeringdesigns, the eco-environments and agricultural production conditions were significantly improved, and the farm income was increased in planned regions.