China's farmland landscape fragmentation follows a distinct evolutionary tendency along the spatial gradient “central urban areas → urban–rural transitional areas → rural areas”, because of its ...binary structure comprising urban and rural areas. This study explores the evolution of this spatiotemporal trend and its dynamic mechanisms in the case of Changzhou City. A landscape analysis model is constructed for farmland landscape fragmentation analysis at the pixel level, and a gradient analysis model is used for farmland landscape evolution analysis along the spatial gradient “urban → transitional → and rural areas”. During the study period, the net switching-in rates of edge patch farmland and discrete patch farmland were 4.58% and 3.63%, respectively, and farmland landscape tended to be somewhat structurally fragmented in the context of Changzhou's traditional agricultural environment. Nevertheless, contiguous farmland, dominated by core and edge farmland, still accounts for 82.53% of the total farmland area. Consequently, the farmland landscape remains relatively stable. In a non-farming environment, however, the net switching-out rate of core farmland reached 17.39%, and the total quantity of core farmland decreased significantly. Gradient analysis revealed that the core evolutionary driver for Changzhou's farmland landscape lies in policy factors relating to land utilisation and management, accounting for up to 79.7% and 60% of evolution in the farmland landscape within central urban areas and rural areas, respectively. Basic farmland preservation areas and spatial regulation of construction land positively affects farmland landscape fragmentation changes. Consequently, it is of great significance to formulate differentiated farmland management policies, and to place strict restrictions on the occupation of farmland resources for urban construction.
•We explored the spatiotemporal evolution of Farmland landscape fragmentation from the perspective of urban-rural difference.•Landscape analysis model at city scale was developed to describe landscape pattern change.•Gradient analysis was used to identify drivers of farmland landscape evolution.•The need for farmland conservation policies and planned urban growth is emphasized.
•A farmland landscape structure classification model is developed to perform landscape analysis at national scale.•How farmland landscape structure changes affect the potential productivity of the ...farmland system is verified.•The potential productivity of the farmland system significantly decreased from the interior edge to the exterior edge.•Farmland conservation policies are designed based on the spatial optimum allocation of natural and human landscapes.
Farmland landscape systems are crucial to sustainable agriculture, but they can readily be disturbed by non-agricultural activities. However, the conclusion that agricultural landscape system would affect farmland productivity remains uncertain and lacks quantitative evidence. To construct a healthy farmland ecosystem to avoid farmland fragmentation and support a sustainable agricultural production, we built a structural classification model for the farmland landscape system to analyse spatiotemporal evolutionary trends in China's farmland landscape system at the pixel level. Then, long-term grain yield monitored by stations and potential productivity of farmland calculated using a global agro-ecological zone (GAEZ) model were applied to explore the relationship between agriculture production and farmland landscape system variations. The results showed that China's farmland landscape tends to be fragmented. Model analyses showed that the fragmentation of farmland will cause an average 55.33 % cumulative decline in potential farmland productivity and that fragmentation of core farmland landscape will cause a 0.85 % decline in potential productivity. Based on these findings, we offer a farmland protection strategy based on the spatial optimum allocation of natural and human landscapes.
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•We propose a cost-effective multi-zoning approach with multiple management zones for ESs management.•It enhances the co-benefits of compatible ESs and reduces the trade-offs of ...incompatible ESs.•Integrating ESs with socioeconomic costs to prioritize the spatial allocation of management zones.•Systematic conservation planning for ESs is urgent for sustainable development.
Integrating ecosystem services (ESs) into the land spatial planning can provide innovative insights for coordinating the spatial conflict between ecological protection and economic development so as to promoting regional sustainable development. However, current studies mostly focus on spatial identification and optimization of ecological protection areas to enable the maintenance of specific ESs, while ignoring human development needs and their impact on ecological protection. For this reason, based on the systematic conservation planning theory, this study proposed a cost-effective multi-zoning method with multiple management zones subject to corresponding management requirements of conservation or development to achieve the sustainable maintenance of multiple ESs that are compatible or incompatible. An empirical study of the Yangtze River Economic Belt (YREB) demonstrates how this systematic multi-zoning approach may be utilized to combine five ESs and three conservation costs to prioritize the spatial distribution of management zones under different management strategies. Our findings revealed significant differences in the spatial scale and priority of various management zones determined by the spatial characteristics of the ESs and the conservation costs associated with different management strategies or scenarios. Among all scenarios, scenario 4 allows for the simultaneous achievement of protection goals for all selected ESs with minimal spaces of management zones. Further conclude that the more flexible multi-zone configuration strategy can increase the opportunities to enhance the co‐benefits of compatible ESs by allocating its conservation targets to the same function zone, and reduces the trade-offs between incompatible ESs by avoiding the allocation of conservation targets in the same function zone. This method and relevant results can provide decision-making support for the land-use sustainable management and holistic land spatial planning of the YREB.
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•We propose a delineation framework of ecological redline areas at river basin scale.•Social needs have strong effects on ecosystem services and ecological redline areas ...delineation.•The identified ecological redline areas exhibit improved connectivity and integrity.•Countermeasures to improve the implementation of protection policies are suggested.
China’s river basin ecosystems are facing serious environmental and structural fragmentation problems. However, there are no complete ecological redlines specifically for watershed ecological conservation. This study considers the Xiangjiang River Basin (XJRB) to propose a framework delineating the ecological redline area (ERA) on a watershed scale and highlights policy recommendations. It combines several evaluating indicators for coupling the response mechanism between human demand and ecological protection. Overall, the water supply in the XJRB meets the social demand. However, water supply in some places, such as the core area of Changsha Zhuzhou Xiangtan Urban Agglomeration and the Hengyang urban area, is still insufficient. This study considers ecosystem service functions, ecological sensitivities, and social needs and estimates the ERA of the XJRB to be 36,057 km2, accounting for 38% of the total watershed. The key ecological functional areas account for 60% of the total redline area and are concentrated in the upper reaches. Compared with the current method conducted at the national and administrative level, the redline area defined in this study by the sub-basin scale exhibits better connectivity and integrity. Moreover, the study can help ensure an accurate placement of the ecological redline while also providing an important reference for redline delineation of other river basins.
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•We analyzed the farmland fragmentation in a developed area with rapid urbanization of China.•The theories of ecology were cited to the driving forces analysis.•We analyzed the ...driving forces from multiple scales and different spatial angles.•Policy is the key factor to prevent farmland loss and fragmentation.
The purpose of this study was to analyze the spatial and temporal patterns of farmland loss and fragmentation and to explore factors that may influence that loss and fragmentation. The study examined changes to farmland in a context of rapid urbanization in Changzhou City, China. It also examined farmland changes in the suburban areas outside the city and in the exurban regions. Time series data from 2004 to 2011 were used to conduct spatial analysis using landscape indices and to perform a redundancy analysis. The results found that farmland was steadily declining during the study period. Farmland also became increasingly fragmented and it moved from low elevation and a gentle slope terrain to higher elevation and a steep slope terrain while its center of gravity generally moved northward. China’s farmland protection policy, agricultural production level, and terrain conditions contributed most to farmland loss and fragmentation in the city. Farmland loss and fragmentation in the suburbs and exurbs were influenced mostly by prime farmland area, total population, and per capita net income of rural residents. To control farmland loss and fragmentation, laws regarding its conversion to built-up environments should be enforced. China’s overall land-use plan and laws of farmland protection are presently the best ways to effectively protect farmland loss and fragmentation.
In addition to land cover change (LCC), land use intensity change (LUIC) is another dominant pathway through which anthropogenic activities influence regional climate. Although the climatic effects ...of LCC have been investigated extensively, little is currently known about the effects of LUIC. In this study, we assess land use and cover change in China over the last three decades in terms of LCC and LUIC and investigate their climatic effects using the observation minus reanalysis method. Results indicate that nearly half of the stations have experienced LUIC, and the climatic response of these stations exhibit different or even opposite signals compared to those that have experienced LCC. With regard to LCC, it is found that urbanized stations generally exert a warming effect on local temperatures, whereas cropland expansion is likely to introduce a cooling effect. In the case of LUIC, the present study demonstrates that the intensification of grassland tends to lead to warming because of the decreased albedo. However, a cooling effect from the enhanced evapotranspiration (ET) dominates local temperature variations in intensified cropland stations. The absence of correlations between albedo/ET and land management changes in urban stations illustrates the inherent complexity of local climate change. The findings of the present study provide a deeper understanding of land–atmospheric interactions and could guide future land-use planning and management to achieve potential climatic benefits.
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•We mapped Chinese land system from the perspective of nature, humanity and ecology.•A set of 24 indicators representing the multi-attributes of land were complied.•The ...Self-Organizing Map algorithm was adopted to derive land system types for China.•Our results facilitate a better understanding of human environment interactions.
Land is an integrated and complex system consisting of multiple natural and anthropogenic elements. The long-term exploitation and utilization of land resources by humans have transformed the terrestrial surface of the Earth and profoundly impacted the spatial patterns of regional land use and land cover. Land use/cover (LULC) data have been extensively used to monitor regional land changes and contribute to land use policy making. However, these products objectively reflect only the current coverage and biophysical attributes of the terrestrial surface but fail to characterize the multiple functions and attributes of the human-environment system (HES). In this study, we present an integrated land system classification for representing the regional HES based on multisource datasets that characterize the attributes of land use and management, biodiversity conservation and cultural landscapes. Then, 40 land system types (LSTs) in China were identified using the self-organizing map (SOM) algorithm. According to the land system map, we found significant east–west differentiation in land use intensity, with high-intensive LSTs occurring mostly in eastern provinces and natural and seminatural LSTs dominating in central and western regions. The multifunctional LSTs that host food production, biodiversity conservation and cultural heritage were estimated to cover 32% of the terrestrial area in China. In summary, our results can provide a basis for regional land assessment and help identify the pressures on and threats to the eco-environment. Mapping regional land systems facilitates an in-depth understanding of human-environment interactions at the landscape level and serves as a useful tool in terms of forging sustainable land use strategies.
Precipitation is critical for maintaining the stability of an ecosystem, especially in arid regions. This study primarily focuses on climatic changes during present (from 1985 to 2005) and future ...(from 2040 to 2059) periods in Xinjiang, Northwest China. In this study, the Weather Research and Forecasting model is implemented in Xinjiang to efficiently predict the future climate. Moreover, the National Climate Research Center Community Climate System Model version 4 is employed for the mid-21
st
century under representative concentration pathways 4.5 and 8.5 (RCP4.5 and RCP8.5, respectively). Our results indicate that the amount of annual precipitation will increase in the future under RCP4.5 and RCP8.5 in Xinjiang, especially in mountainous areas. The increase in precipitation is predicted to be much smaller under RCP8.5 than under RCP4.5, except in Southern Xinjiang. Moreover, the increasing precipitation predicted in Xinjiang implies that the current humid and warm conditions will persist, thereby further indicating that Xinjiang is still currently suffering from a dry climate. The largest increase in seasonal precipitation is predicted to occur in spring and summer in Tianshan and Northern Xinjiang, whereas this phenomenon is predicted to occur in spring and winter in Southern Xinjiang. In addition, it is predicted that daily heavy precipitation events will occur more frequently in various subregions of Xinjiang, although light rain events will remain dominant. Finally, the relative humidity is closely related to the changes in annual and seasonal precipitation.
In this paper, a fast back-projection (BP) synthetic aperture radar (SAR) imaging algorithm based on wavenumber spectrum fusion is proposed for high maneuvering platforms with high squint angles and ...high dive angles. When the platforms have nonlinear trajectory errors, the trajectory errors will introduce significant spectrum displacement, which varies with the target position. If the influence of trajectory error is not considered, the trajectory’s deviation from the ideal SAR imaging geometry will degrade the focusing performance. The dive angle will further enlarge the influence on SAR focusing. In this paper, the center function of the spatially variable sub-aperture wavenumber spectrum is derived, firstly, which is the basis for reasonably setting the oversampling rate. Then, the accurate spectrum fusion method is proposed, which is efficiently implemented by fast Fourier transform (FFT) and circular shifting. The proposed algorithm is called high-squint and high-dive accelerated factorized back-projection (HSHD-AFBP). Compared to the commonly used spectrum fusion method, HSHD-AFBP not only improves the imaging quality, but also expands the image width. Finally, the effectiveness of the proposed algorithm is verified by simulation data.
The model-based polarimetric synthetic aperture radar (PolSAR) target decomposition decodes the scattering mechanism of the target by analyzing the essential scattering components. This paper ...presents a new general three-component scattering power decomposition method by establishing optimization problems. It is known that the existing three-component decomposition method prioritizes the contribution of volume scattering, which often leads to volume scattering energy overestimation and may make double-bounce scattering and odd-bounce scattering component power negative. In this paper, a full parameter optimization method based on the remainder matrix is proposed, where all the elements of the coherency matrix will be taken into account including the remaining T13 component. The optimization is achieved with no priority order by solving the problem using semi-definite programming (SDP) based on the Schur complement theory. By doing so, the problem of volume scattering energy overestimation and negative powers will be avoided. The performance of the proposed approach is demonstrated and evaluated with AIRSAR and GF-3 PolSAR data sets. The experimental results show that by using the proposed method, the power contributions of volume scattering in two sets of data were reduced by at least 2.6% and 3.7% respectively, compared to traditional methods. And the appearance of negative power of double-bounce scattering and odd-bounce scattering are also avoided compared with those of the existing three-component decomposition.
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