Synergizing economic growth and carbon emission reduction in China: A path to coupling the MFLP and PLUS models for optimizing the territorial spatial functional pattern.

Carbon emissions caused by economic growth are the main cause of global warming, but controlling economic growth to reduce carbon emissions does not meet China's conditions. Therefore, how to synergize economic growth and carbon emission reduction is not only a sustainable development issue for China, but also significant for mitigating global warming. The territorial spatial functional pattern (TSFP) is the spatial carrier for coordinating economic development and carbon emissions, but how to establish the TSFP of synergizing economic growth and carbon emission reduction remains unresolved. We propose a decision framework for optimizing TSFP coupled with the multi-objective fuzzy linear programming and the patch-generating land use simulation model, to provide a new path to synergize economic growth and carbon emission reduction in China. To confirm the reliability, we took Qionglai City as the demonstration. The results found a significant spatiotemporal coupling between TSFP and the synergistic states between economic growth and carbon emission reduction (q ≥ 0.8220), which resolves the theoretical uncertainty about synergizing economic growth and carbon emission reduction through the path of TSFP optimization. The urban space of Qionglai City in 2025 and 2030 obtained by the decision framework was 6497.57 hm2 and 6628.72 hm2 respectively, distributed in the central and eastern regions; the rural space was 60,132.92 hm2 and 56,084.97 hm2, concentrated in the east, with a few located in the west; and the ecological space was 71,072.52 hm2 and 74,998.31 hm2, mainly located in the western and southeastern areas. Compared with the TSFP in 2020, the carbon emission intensity of the TSFP obtained by the decision framework was reduced by 0.7 and 4.7 tons/million yuan, respectively, and realized the synergy between economic growth and carbon emission reduction (decoupling index was 0.25 and 0.21). Further confirming that TSFP optimization is an effective way to synergize economic growth and carbon emission reduction, which can provide policy implications for coordinating economic growth and carbon emissions for China and even similar developing countries.

CH4 and CO2 emissions in water networks of rice cultivation regions.

Rice cultivation regions have a high density of open water networks to meet the requirements of rice growth and production. These open water networks have a significant risk of carbon (C) emissions due to agricultural production, but the C emissions from these waters are not clearly recorded in previous studies. Therefore, this study aimed to explore the pattern and internal mechanism of methane (CH4) and carbon dioxide (CO2) emissions from multiple types of waters (i.e., river, fish pond, reservoir, and ditch) in a typical rice cultivation region in southwestern China. The annual CH4 and CO2 fluxes were higher in the downstream river (2.79-94.89 and 39.39-1699.98 mg m-2 h-1) and ditch (8.80-74.99 and 123.43-542.65 mg m-2 h-1, respectively) and lower in the reservoir (-0.67 to 3.45 and -239.15 to 141.50 mg m-2 h-1) (P < 0.05). The monthly trends of CH4 and CO2 fluxes from the middle river and ditch were driven by interactive reactions of rice cultivation practices and precipitation. In contrast, the emission patterns of CH4 and CO2 from the lower river, upper river, and fish pond were mainly driven by domestic sewage discharge, precipitation, and aquaculture practices, respectively. This study suggested that river and ditch were more sensitive to C emissions than other waters, and the rice production period was the critical period for controlling C emission. Although rice paddy soils yield more cumulative emissions of CH4, water networks in rice cultivation regions were possible hotspots for C emissions due to the higher emission intensities, which were largely overlooked before. Thus, it is necessary to refine and promote practices to better mitigate C emissions from waters in rice cultivation regions in the future.

Ecological spatial intensive use optimization modeling with framework of cellular automata for coordinating ecological protection and economic development.

With the exposure of excessive intensive use of urban and agricultural space, the optimization of intensive use of ecological space provides a new way to coordinate the global problem of spatial conflict between ecological protection and economic development. However, the coupling accuracy of the existing structure-spatial coupling optimization model is low, which cannot provide method support for the optimization of intensive use of ecological space. To solve this problem, we propose a new model of ecological spatial intensive use optimization (ESIUO) based on the non-stationarity of the Markov state transition probability of the dominant ecosystem service functions (DESFs) and their suitability, and with the help of the framework of cellular automata (CA). We took Qionglai City as an empirical study area, and compared the results of this model with those of CA-Markov and CLUE-S models with the same parameters. The results show that: (i) The quantitative structure corresponding to the spatial layout of each dominant ecosystem service function (DESF) optimized by the ESIUO model has the smallest relative error (δk≤0.04%) with the optimal quantitative structure. (ii) The layout of DESFs optimized by the ESIUO model maximizes the supply capacity of ecosystem services. The minimum matching degree between the distribution of each DESF and the high-value area of its suitability is 92.06 %, and the spatial distribution is more compact, and the comprehensive effect of spatial layout is the best. Further analysis confirmed that the model can establish the spatial layout of DESFs that can realize the high precision coupling with the optimal quantitative structure of DESFs in terms of quantitative structure, and can support the construction of the layout of intensive use of ecological space to alleviate the pressure of non-ecological space expansion in these areas, and then provide a new way to coordinate ecological protection and economic development.

Construction of a Territorial Space Classification System Based on Spatiotemporal Heterogeneity of Land Use and Its Superior Territorial Space Functions and Their Dynamic Coupling: Case Study on Qionglai City of Sichuan Province, China.

Territorial space classification (TSC) provides the basis for establishing systems of national territory spatial planning (NTSP) and supervising their implementation in China, thus has important theoretical and application significance. Most of the current TSC research is related to land use/land cover classification, ignoring the connection of the NTSP policies and systems, failing to consider the spatiotemporal heterogeneity of land use superior territorial space functions (TSFs) and the dynamic coupling between land use and its superior TSFs on the result of TSC. In this study, we integrated the factors influencing the connection of NTSP policies and systems and established a theoretical framework system of TSC from the perspective of spatial form and functional use. By integrating the q-statistic method with spatiotemporal geographical analysis, we propose a method to construct a TSC system for Qionglai City of Sichuan Province in China based on the spatiotemporal heterogeneity of land use superior TSFs and the dynamic coupling between land use and its superior TSFs. It makes up for the deficiency of directly taking land use/land cover classification as TSC and solves the problems of ignoring the spatiotemporal heterogeneity of land use superior TSFs and the dynamic coupling between land use and its superior TSFs. Using this method, we found that the TSC of Qionglai City consists of 3, 7, and 14 first-, second-, and third-level space types, respectively. The key findings from this study are that land use superior TSFs show spatiotemporal heterogeneity in Qionglai, and coupling effects in spatial distribution were noted between land use types and their superior TSFs, as was temporal heterogeneity in the coupling degree and the structure of the TSFs corresponding to the land use types, which show obvious dynamics and non-stationarity of the functional structure. These findings confirm the necessity of considering the spatiotemporal heterogeneity of land use superior TSFs and the dynamic coupling between land use and its superior TSFs in TSC. This method of establishing a TSC system can be used to address a number of NTSP and management issues, and three examples are provided here: (a) zoning of urban, agricultural, and ecological space; (b) use planning of production, living and ecological space; (c) delimitation of urban development boundary, permanent basic farmland protection redline, and ecological protection redline.

Contribution of atmospheric N deposition to riverine N load in a forest-dominated watershed through field monitoring for three years.

Increased atmospheric nitrogen (N) deposition significantly impacts N cycling in freshwater ecosystems. Relative to lakes, the importance of N deposition in riverine N load is less studied. Thus, this study monitored N deposition and riverine N load for three years and then used the export coefficient model to explore N deposition's contribution to riverine N load in a forest-dominated watershed. It is found that the annual export of total N (TN) deposition could explain 17.4%-19.2% of riverine TN load. The contribution of TN deposition to riverine TN load was significantly higher (P < 0.05) during the crop production period (recorded as CPP, lasting from June to September, 22.7%) than the non-crop production period (Non-CPP, 13.8%). The application of chemical fertilizer and manure and the high precipitation were assumed as the primary reason for the increased N deposition and increased riverine TN load during CPP. This study shows that inland plain agriculture practices might considerably influence the nearby forest-dominated watershed, and it is necessary to develop sustainable agriculture programs for reducing riverine N load.

Emission of CO2 and CH4 from a multi-ditches system in rice cultivation region: Flux, temporal-spatial variation and effect factors.

Man-made multi-level ditches system is designed to irrigate, drain and collect runoff from surrounding fields. It is not only the conduit of water and field carbon, but also the linear-like wetland with complex carbon cycling. However, the contribution of ditches system to CO2 and CH4 emission has rarely been assessed. To understand the emission pattern of CO2 and CH4 from ditches, this study investigated the emission fluxes of CO2 and CH4 in a three-level ditches system in Chengdu Plain, China. The results showed that the emission of CO2 and CH4 ranged from 70.38 to 950.40 mg C m-2 h-1 and 6.51-74.99 mg C m-2 h-1, respectively, and was higher in spring and summer than other seasons in all ditches (P < 0.05). On the other hand, the emission of CO2 and CH4 increased along with the decreasing ditches size. Besides, it is found that the precipitation, water table depth and water DO concentration might contribute to the emission of CO2, while CH4 was possibly influenced by precipitation, water table depth, temperature, water DO and DOC concentration. Moreover, it is suggested that terrestrial external input and in-situ metabolism might be the main sources of C emission, and in-situ source might largely contribute to CH4 emission. To reduce the C emission, it is necessary to improve fertilization and irrigation methods, limit soil pollutants transferring into ditches, and frequently dredge sediments in future.