•Annual increased of ecosystem resilience in peripheral cities while that in central cities was decreased.•Economic, population, and urbanization growth were negatively correlated with ecosystem ...resilience.•Normalized difference vegetation index showed a positive correlation with ecosystem resilience.
Ecosystem resilience plays a vital role for security and resilience in the urban system which experiences the combined effects of anthropogenic activities and natural disasters. Nonetheless, there is currently no unified indicator for assessing urban resilience. Therefore, this study aims to examine the changes of ecosystem resilience in the Guangdong-Hong Kong-Macao Great Bay Area (GBA) based on land use, using the framework of resistance, adaption, and elasticity. The study's results revealed that between 2000 and 2020, the increase in ecosystem resilience in peripheral GBA cities outpaced the decrease in central cities, leading to a yearly rise in overall ecosystem resilience. Nighttime light (NL), population density (PD), urbanization rate (UR), and the normalized difference vegetation index (NDVI) were the primary driving factors influencing resistance and elasticity resilience in the GBA, thereby shaping overall ecosystem resilience. Findings from the multi-scale geographical weighted regression (MGWR) analysis demonstrated that ecosystem resilience decreased as NL, PD, and UR increased, while it exhibited an increase in areas with higher NDVI. This study contributes to the improvement of urban resilience in cities by providing targeted strategies, expediting the development of resilient cities, and offering theoretical insights for land management, urban planning, and policy formulation.
Biochar is a widely proposed solution for improving degraded soil in coastal wetland ecosystems. However, the impacts of biochar addition on the soil and plant communities in the wetland remains ...largely unknown. In this study, we conducted a greenhouse experiment using soil seed bank from a coastal saline-alkaline wetland. Three types of biochar, including
biochar (JBC),
biochar (SBC) and
biochar (FBC), were added to the saline-alkaline soil at ratios of 1%, 3% and 5% (w/w). Our findings revealed that biochar addition significantly increased soil pH, and increased available potassium (AK) by 3.74% - 170.91%, while reduced soil salinity (expect for 3% SBC and 5%SBC) by 28.08% - 46.93%. Among the different biochar types, the application of 5% FBC was found to be the most effective in increasing nutrients and reducing salinity. Furthermore, biochar addition generally resulted in a decrease of 7.27% - 90.94% in species abundance, 17.26% - 61.21% in community height, 12.28% - 56.42% in stem diameter, 55.34% - 90.11% in total biomass and 29.22% - 78.55% in root tissue density (RTD). In particular, such negative effects was the worst in the SBC samples. However, 3% and 5% SBC increased specific root length (SRL) by 177.89% and 265.65%, and specific root surface area (SRSA) by 477.02% and 286.57%, respectively. The findings suggested that the plant community performance was primarily affected by soil pH, salinity and nutrients levels. Furthermore, biochar addition also influenced species diversity and functional diversity, ultimately affecting ecosystem stability. Therefore, it is important to consider the negative findings indirectly indicate the ecological risks associated with biochar addition in coastal salt-alkaline soils. Furthermore,
was needed to desalt before carbonization to prevent soil salinization when using
biochar, as it is a halophyte.
Vibration induced by marine power devices (MPD) transmitting to the hull structure is one of the most important factors that cause ship vibration and underwater sound radiation. Vibration isolation ...technologies (VIT) are widely applied to reduce the vibration transmission. However, the overweight issue of VIT for marine power devices is a currently challenging engineering problem. The current reserve of lightweight and high-efficiency VIT for MPD and relevant theoretical and design research are seriously insufficient. This article first elaborates the causes of the overweight problem of VIT for MPD: (1) failing to grasp the quantitative law; (2) single vibration suppression mechanism. Then, it systematically sorts out the technical methods and application examples with potential to solve the overweight problem, such as dynamic optimization design, lightweight material method, novel intermediate mass structures, distributed dynamic vibration absorbers (DDVAs), locally resonant structures (LRS), particle damping (PD), quasizero stiffness isolators (QZSI), and active vibration control (AVC) technologies. Finally, the future development of lightweight VIT for MPD is prospected. It can be used as a reference for marine vessel vibration attenuation research and engineering design.
•Waterbird populations have gradually increased over the past 20 years in China’s Bohai Rim.•Five waterbird hotspots were found here.•NDVI, land cover and maximum temperature of the warmest month are ...recognized as major drivers of waterbird change.
In recent years, due to rapid economic development, the Bohai Rim has become a focus of attention. The area has abundant waterbird resources, however, the coastal wetlands in the Bohai Rim are currently under serious threat and waterbird conservation needs to be addressed urgently. Exploring the changes and main driving factors of waterbirds and conducting habitat suitability assessments for waterbirds are of great significance to regional ecology and environmental protection efforts. In this study, during the period of 2002–2021, we recorded the waterbird numbers and species in the Bohai Rim region of China. Then, we quantified the potential suitable habitats and analyzed the driving factors for waterbirds using the MaxEnt model. The results showed that the waterbird richness around the Bohai Rim increased gradually over a 20-year period, and more waterbird species were detected in wetland habitats than in other habitats. Five waterbird hotspot regions require special attention, including the Yellow River Delta Nature Reserve, Beidagang Wetland, Beidaihe National Wetland Park, Liaohe Estuary wetland and Caofeidian Wetland Park. The main driving factors of waterbird changes are the NDVI, land cover and maximum temperature in the warmest month. This study provides a reference and theoretical support for waterbird conservation and rational habitat use.
Considered as an essential measure in the application of soil seed bank (SSB) projects, the mixing of substrate and surface soil can effectively improve soil condition. This research is aimed at ...exploring the diversity characteristics of SSBs and the relationships between SSBs and soil properties.
Canonical correspondence analysis (CCA) was adopted to describe the ordination of SSBs on soil properties' gradients; multiple linear regressions were adopted to analyze the relationship between average growth height and soil properties, density and soil properties.
Experimental groups of mixed substrate (the mixture of organic and inorganic substrates) had high diversity indexes, especially the Shannon-Wiener Index compared with those of single substrate. Meanwhile, a higher number of species and increased density were also noted in those of mixed substrate. The best test group, No.16, had the highest diversity indexes with a Shannon-Wiener of 1.898, Simpson of 0.633 and Pielou of 0.717, and also showed the highest density of 14000 germinants /m2 and 21 species. In addition, an improvement of the soil's chemical and physical properties was noted when the substrates were mixed. The mixed substrate of turfy soil and perlite could effectively enhance the soil moisture content, whilst a mixed substrate of rice husk carbon and vermiculite could improve the content of available potassium (AK) and phosphorus (AP) and strengthen soil fertility. The germinated plants also reflected obvious regularities of ordination on soil factor gradients. Three distinct cluster groups were presented, of which the first cluster was distributed in an area with a relatively higher content of AK and AP; the second cluster was distributed at places with relatively higher soil moisture content; and the third cluster of plants didn't show any obvious relationship with soil physical and chemical properties. Through CCA analysis, AK and AP were considered the most important soil factors to influence the SSB, which was illustrated in regression analysis with a high correlation coefficient when dependent values were growth height and density respectively. The linear regression equations with: growth height = 142.728 - 1.514TC + 30.218AP - 5.083TN + 10.839AK + 1.234mc; density = -68.216 - 4.609TC + 9.566AP - 35.492TN + 19.779AK - 1.591mc.were established by multiple linear regression.
(1) The mixed substrates showed a greater advantage for SSBs than single substrates, both in improving the number of species, density and diversity indexes. (2) The germinated plants reflected an obvious preference to different soil conditions, which different mixed substrates could improve accordingly. (3) AK, AP were important soil factors to influence SSBs, especially in the growth of plants and density.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Maintaining carbon sequestration is becoming increasingly significant and challenging during coastal wetland carbon restoration. To clear the influence of water, nitrogen and salinity on soil organic ...carbon (SOC), indoor incubation experiments were carried out, where soil from wetlands with dominant vegetation of Phragmites australis and Suaeda salsa were sampled and Box-Behnken central composite design was used to maximize SOC. The results indicated that:1) water, nitrogen and salinity altered soil chemical and physical properties, then significantly affect SOC in Phragmites australis wetland, but possessed little impact on Suaeda salsa wetland. 2) Optimal condition was determined with water of − 5.49 cm, salinity of 3.52 ds/m and nitrogen of 13.40 g/m2 for the biggest SOC of 8.6 g/kg in Phragmites australis wetland, whereas in Suaeda salsa wetland, SOC reached out to 8.7 g/kg with water of − 4.09 cm, salinity of 2.51 ds/m and nitrogen of 16.61 g/m2. 3) Nitrogen and water were determining factors on SOC. In Phragmites australis wetland, SOC was substantially influenced by water, nitrogen and its interaction, while in Suaeda salsa wetland, water and nitrogen displayed no direct influence, but its interactive effect worked. 4) Quadratic models were found the most desirable to reveal connections between SOC and three factors (p < 0.05). Our finding could provide support for maintaining soil carbon sink in coastal wetland restoration management.
•Water, nitrogen and salinity could alter soil properties to influence soil organic carbon in Phragmites australis wetland.•The maximum soil carbon organic was optimized by response surface methodology.•Quadratic models were established to reveal relationships between soil organic carbon and three factors.•Nitrogen and water were determining factors, the interaction of nitrogen and water was found significant to influence soil organic carbon.
In order to provide more scientific guidance for wetland bird protection, this study addressed the dynamics of the bird community sorted by ecotypes, classifications and threat categories from 2015 ...to 2019, and non-metric multidimensional scaling analysis, generalized additive models and the Mantel test were used to examine the relationships between bird communities and habitat types. The results showed that: (1) The abundance of birds peaked in 2017 at 88,258 individuals and then declined. Moreover, there was an inverse trend between species richness and abundance of birds, meaning greater abundance is associated with fewer species. (2) Swimming birds were dominant ecotypes and Anseriformes possessed the highest abundance. It was noteworthy that the abundance of critically endangered birds (Aythya baeri and Grus leucogeranus) and the species richness of endangered birds increased. (3) Building land and farmland had dominant impacts on the composition of bird community. Wading birds and birds in Gruiformes were significantly impacted by building land and farmland, and near threatened species were substantially influenced by farmland. Therefore, maintaining good connectivity between protected areas and surrounding areas is one of the best ways to effectively manage biodiversity of the target area. This research may provide a broader insight for coastal wetland bird habitat management and bird diversity preservation.
Coastal reclamation is the gain of land from the sea or coastal wetlands for agricultural purposes, industrial use or port expansions. Large-scale coastal land reclamation can have adverse effects on ...the coastal environment, including loss of marine habitats and deterioration of coastal water quality. In recent decades, coastal land reclamation has occurred extensively to meet the increasing needs of rapid economic development and urbanization in China. The overall objective of this study is to understand the coastal reclamation status of China from 1979 to 2014 and analyzed its driving factors for mitigating negative ecological effects. The data of coastal reclamation were done with the ERDAS Imagine V9.2 platform and ArcGIS software based on remote images including Landsat, SPOT, ZY-2 and ZY-3. Potential driving factors for sea reclamation were selected based on statistics bulletins and the knowledge of experts in coastal management. In order to understand the relationships among possible impact factors and coastal reclamation, the Partial Least-Squares Regression models was constructed. The analysis results indicated that the total area of reclamation was 11162.89 km2 based on remote sensing images between 1979 and 2014. Shandong Province is the largest reclamation area, reaching 2736.54 km2, and the reclamation is mainly concentrated in Zhejiang, Jiangsu and Liaoning, where the reclamation areas were all more than 1000 km2. According to the remote sensing images, there are three coastal reclamation hotspot regions including Bohai bay (in which is located Liaoning, Tianjin and Hebei), Jiangsu province coastal area and Hangzhou bay (in Zhejiang province). A large scale land reclamation plan of more than 5880 km2 has been made by local government and 2469 km2 has approved by the State Council. From the analyzed results, there is a significant collinearity between these indicators, and no significant correlation between the area of reclamation and selected indicators. Economic development and employees in marine industries have weak positive correlation and correspondingly, the area of cultivated land (ACL) had a negative correlation. Because of the weak correlation, there is an assumption that economic development, outcome of coastal reclamation and population growth were not only was the direct driving factor, but also the outcome of coastal reclamation and population growth was not the direct driving indicator. Construction land quota and huge economic returns to local government may be the direct driving factors according to our field investigation. To resolve the contradiction between the need for land and coastal wetland conservation, it is recommended that China should establish a special management agency and coordination mechanisms, reconsidered the implementation of the reclamation plans and projects that have been approved, enhance law enforcement and increase penalties and strengthen public participation in reclamation management.
•The total area of reclamation between 1979 and 2014 was 11162.89 km2.•A large scale land reclamation plan of more than 2469 km2 has been approved.•Economic development not only was the direct driving factor, but also the outcome of the coastal reclamation.•Population growth was not the direct driving indicator.•Construction land quotas and huge economic returns may be the direct driving factors.
The total area of wetlands in China is 53.42 × 106 ha, accounting for 10% of global wetlands and 5.58% of China's territorial area. Wetlands in China are constantly under serious threat from multiple ...influencing factors. A large number of wetlands have been destroyed and degraded since the 1950s. During past decades, China has already recognized the importance of wetland ecosystems and made many efforts in wetland conservation. More than 550 National Wetland Nature Reserves and 100 National Wetland Parks have been established. However, in the context of so much effort being done, the annual wetland disappearance rate is still close to 1%. In this paper, the current status of wetland resources was reviewed, and the impact factors of wetland degradation were discussed. We further discussed the weaknesses of the current management system. Furthermore, some key recommendations for improvement of wetland protection and management for China were given. These recommendations include: improve special laws and regulations regarding wetlands, establish specialized management agencies; strengthen wetlands research and monitoring; and enhance public wetland conservation awareness.
•China has 53.42 × 106 ha of wetlands, accounting for 5.58% of China's territorial area.•The wetlands of China are constantly under serious threat from multiple impact factors.•China wetlands area decreased 3.39 million ha from 2003 to 2013.•The main reasons of wetlands degradation are climate change, pollution, biological resources exploitation and reclamation.•The improvement of wetlands legislation and management systems in China is urgently needed.
Coastal wetland losses in China are globally-relevant issues, as formerly sequestered soil organic carbon is released as CO2 into the atmosphere. Wetland losses also reduce the primary production by ...plants that would otherwise bury carbon in the future. More than 50% of these ecosystems have been lost globally over the last half century, with this number approaching 58% in China. The negotiation of international accords such as the Paris Climate Agreement rely on the accurate assessment of ecosystem-held carbon quantities. Our objective was to provide the first national scale survey of coastal wetland-based carbon in China. The average soil organic carbon stock (Mg SOC ha−1) across all three types of ecosystems was 236.91, with an average of 344.67 for mangroves, 175.14 for seagrass, and 134.37 for salt marshes. The SOC stock was greatest at 30–60 cm of depth in the case of mangroves, as opposed to 0–20 cm of depth for salt marshes. In terms of the carbon content of the standing aboveground and belowground biomass (Mg C ha−1), mangroves contained by far the most with an average of 253.98 and 83.96, respectively. Carbon burial rates, or the annual flux of SOC into the soil column (Mg C ha−1 yr−1), were 2.26 ± 0.39 for mangroves, 1.38 ± 0.38 for seagrass, and 2.18 ± 0.24 for salt marshes. Through our work, we found a total of 48.12–123.95 Tg of C in China's coastal wetlands (down to 1 m of soil column depth), with an annual burial of 0.84 Tg yr−1. We estimate the average annual emissions of CO2 to be on the order of 6.83 Tg CO2 yr−1, due to ongoing and extensive wetland loss and conversion.
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