Identifying loss threshold and migration trajectory in the management of Suaeda salsa wetland under coastal squeeze.

The coastal salt marsh wetland is mainly located in the tidal area where sea and land are intertwined, which has the functions of promoting silt and consolidating beach, wave reduction and disaster reduction, and is an ecological barrier against erosion in the coastal zone, which has important ecological value. Nevertheless, owing to the intricate nature of wetland species formation mechanisms and community distribution patterns, the impact of coastal squeeze on Suaeda salsa wetlands loss may not exhibit a linear relationship, necessitating further elucidation of the specific processes involved. Precisely understanding the extent to which coastal squeeze affects the threshold of loss in the Suaeda salsa wetland holds immense importance in safeguarding the distinctive red beach landscape. Furthermore, it represents a pivotal scientific challenge that necessitates resolution in the management of coastal wetlands for their protection and restoration. Hence, drawing upon the theoretical framework concerning the impact of coastal squeeze on the degradation of coastal Suaeda salsa wetland, this study employs the representative silty coastal region of China's northern Liaodong Bay as a case study to conduct empirical investigation. The research integrates Landsat imagery and digital elevation data, and incorporates spatial autocorrelation, elastic coefficient analysis, and barycenter model analysis to examine the threshold of degradation and spatial variations of Suaeda salsa wetland in response to coastal squeeze. The results show that: (1) The risk intensity of coastal squeeze in the study area exhibited a pattern of initial decline followed by an increase from 1995 to 2020, with the highest risk areas predominantly located in the development zone on the eastern bank of the Liao River Estuary. (2) There was a positive correlation between the growth of the coastal squeeze index and the loss of the Suaeda salsa wetland. When the proportion of area in which the coastal squeeze deteriorates reached 43.9%, the Suaeda salsa wetland lose resilience against the impact of coastal squeeze, leading to an intensified rate of loss. (3) Compared with the west side of the Liao River, the critical area of coastal squeeze and the loss barycenter of the Suaeda salsa wetland on the east side of the Liao River have a greater range of changes. The planning and management of coastal ecological restoration necessitates considering the occurrence conditions of the coastal squeeze impact threshold on the loss threshold of wetland and the migration characteristics of the wetland loss area. This approach enables the timely control of coastal squeeze risk intensity in the area and the preservation of wetlands' resistance to external disturbances. Consequently, it holds immense importance for the sustainable development of coastal wetlands.

New insight into blue carbon stocks and natural-human drivers under reclamation history districts for sustainable coastal development: A case study from Liaohe River Delta, China.

Blue carbon is a vital aspect of climate change mitigation, which necessitates the identification of stocks and drivers for implementing mitigation strategies. However, reclamation may be among the most invasive forms, and the question of its influence has not been addressed well in blue carbon research. Therefore, the effects of reclamation on carbon stocks and the interaction of crucial drivers from reclamation time areas (1930s, 1960s, 1990s) were evaluated in the Liaohe River Delta (LRD) and compared with natural reserves (core, buffer, experimental areas). Carbon stocks based on InVEST model were lower than preexisting conditions (1.930 × 106 Mg-1.893 × 106 Mg). One-way Analysis of Variance showed that average carbon stocks accumulated 55 years after reclamation and reached the lowest value (13.19 Mg·ha-1) in 85 years. The interaction analysis of dominant drivers affecting carbon showed the difference between reclaimed areas and reserves regarding potential effect pathways. In the 1930s and 1960s reclamation time areas, crop yield and industrial output determined blue carbon by changing NO3--N and AP. In the 1990s reclamation time area, population density played an important role. In defining the impact of vegetation cover on carbon within the reserves, the distance to the coast and residence were significant factors. This study demonstrated that coastal management practices, such as the size of industry and population control and the balanced fertilization techniques in reclamation areas, maintaining adequate vegetation cover in reserve, played a crucial role in the improvement of blue carbon sinks.

Spatiotemporal assessment of ecosystem services supply-demand relationships to identify ecological management zoning in coastal city Dalian, China.

Integrating ecosystem services supply-demand relationships into ecological management zoning is a hot topic. Most studies have focused on the matching relationship between the supply and demand of ecosystem services. However, the extent to which both are coordinated at different matching levels is ignored, that is, whether ecosystem services supply and demand tend to reinforce each other at high levels or constrain each other at low levels. Therefore, taking Dalian as an example, this study constructed a research framework for ecological management zoning by integrating the matching and coupling coordination relationship of ecosystem services supply-demand. We found that the supply of ecosystem services in Dalian decreased by 23.70% and the demand increased by 22.54% from 2005 to 2019. There was an obvious mismatch and disharmony in the supply and demand of ecosystem services, and the matching and coordination often did not exist simultaneously. Overlay analysis was used to divide Dalian into four ecological management zones: eco-conservation, eco-development, eco-improvement, and eco-restoration zones. This study helped in integrating the matching and coupling coordination relationship of ecosystem services supply-demand into the environmental management system, which has practical significance for the sustainable development of ecosystem services.

Scales and Historical Evolution: Methods to Reveal the Relationships between Ecosystem Service Bundles and Socio-Ecological Drivers-A Case Study of Dalian City, China.

Ecosystem service (ES) bundles can be defined as the temporal and spatial co-occurrence of ESs. ES bundles are jointly driven by socio-ecological factors and form at different scales. However, in recent research, a few studies have analyzed the dynamic evolution and driving mechanisms of ES bundles at different scales. Therefore, this study explored the spatial patterns of six ESs supplied in Dalian (China) from 2005 to 2015 at three spatial scales, determining the distribution and evolution patterns of ES bundles and their responses to socio-ecological driving factors. Our results are as follows: (1) We identified four ES bundles representing ecological conservation, water conservation, ecological depletion, and food supply. The developmental trajectory of each ES bundle could be attributed to the combined effects of environmental conditions and urban expansion. In particular, the water conservation bundle and food supply bundle were changed to the ecological depletion bundle. Given the ongoing urbanization, the conflict between ESs has intensified. (2) The impact of socio-ecological driving factors on ES bundles vary with scale. At three spatial scales, the digital elevation model (DEM) and normalized difference vegetation index (NDVI) had a great impact on ES bundles. Urbanization indicators also strongly explain the spatial distribution of ES bundles at the county and grid scales. The interaction factor detector shows that there is no combination of mutual weakening, indicating that the formation of ES bundles is driven by multiple factors in Dalian. Overall, this study used a more holistic approach to manage the ecosystem by studying the temporal-spatial dynamics of the multiple ESs.

Land use management based on multi-scenario allocation and trade-offs of ecosystem services in Wafangdian County, Liaoning Province, China.

Developing effective methods to coordinate the trade-offs among ecosystem services (ES) is important for achieving inclusive growth and sustainable development, and has been the focus of scholars and ecosystem managers globally. Using remote sensing and geographic information system (GIS) data, our study examined Wafangdian County of Liaoning Province as a case study to reveal the spatiotemporal evolution of four ES (food supply [FS], net primary productivity [NPP], water yield [WY], and soil conservation [SC]) and changes among their interactions. Then, an ordered weighted averaging model was introduced to simulate the optimal scenario of ES allocation. Results showed that: (1) the spatial and temporal changes in ES were significant over 14 years. All ES presented an inverted U-shaped growth curve from 2000-2014. (2) Synergies were observed within provisioning services, and there were trade-offs between provisioning services and regulating services, as well as provisioning services and supporting services. (3) The optimal scenario for Wafangdian was scenario 5 (trade-off coefficient, 0.68). The allocation of FS, NPP, WY, and SC in scenario 5 were 0.187, 0.427, 0.131, and 0.063, respectively. Implementing each ES weight of optimal scenario in land use management contributed to achieving intercoordination of ES. We propose to coordinate land and sea management to restore natural habitats that were expanded into in the high ES area. It is our anticipation that this study could provide a scientific basis for optimizing the allocation of ES and improving land use structure of coastal zones in the future.