A Study of Forest Swamp Mapping in Hani Wetland Integrating Sentinel-1 and Sentinel-2 Satellite Images

As a unique wetland type, forest swamps play an important role in regional carbon cycling and biodiversity conservation. Taking Hani wetland in Jilin province as the research object, we integrated the application of Sentinel-1 radar and Sentinel-2 multispectral images, fully exploited the potential of Sentinel-1 multi-polarization band features and Sentinel-2 red edge index for forest swamp remote sensing identification, and applied the random forest method to realize the extraction of forest swamp distribution information of Hani wetland. The results show that when the optimal number of decision trees for forest swamp information extraction is 1200, the fusion of Sentinel-1VV and VH backscattering coefficient radar band features and Sentinel-2 red-edge band features can significantly improve the extraction accuracy of forest swamp distribution information, and the overall accuracy and Kappa coefficient of forest swamp information extraction in protected areas are as high as 89% and 0.85, respectively. The overall accuracy and Kappa coefficient of forest swamp information extraction in the protected area were 89% and 0.85, respectively. The landscape types of Hani Wetlands of International Importance are diversified, with natural wetlands, artificial wetlands and non-wetland landscape types co-existing. Among the natural wetland types, the forest swamp has the largest area of 27.1 km2, accounting for 11.2% of the total area of the reserve; the river has the smallest area of 0.7 km2, accounting for 0.3% of the total area of the reserve. The forest swamp extraction method provides data support for the sustainable management of Hani wetlands and case guidance for forest swamp mapping in other regions.

Four Years Continuous Monitoring Reveals Different Effects of Urban Constructed Wetlands on Bats

Proactive artificial wetland constructions have been implemented to mitigate the loss of wetlands and their ecosystem services. As wetlands are habitats for bats, short-term (one or two years) studies find that constructed wetlands can immediately increase local bat activity and diversity. However, it is not clear how constructed wetlands affect bats through time while the wetlands are aging. We collected four years of continuous bat acoustic monitoring data at two constructed wetlands in an urban park in Greensboro, NC, USA. We examined bat activity and community composition patterns at these wetlands and compared them with reference sites in the city. With four years of data, we found that the effects of constructed wetlands were both habitat- and species-specific. The wetland in forests significantly increased bat activity, while the wetland in the open grass altered bat community composition. Specifically, in terms of species, we found that over time, constructed wetlands no longer attracted more big brown, silver-haired, or evening bats than control sites while the wetlands aged, highlighting the need to study broadly how each bat species uses natural and artificial wetlands. We emphasize the importance of long-term monitoring and the periodical evaluation of wildlife conservation actions.

Landscape Pattern Evolution Processes and the Driving Forces in the Wetlands of Lake Baiyangdian

The spatiotemporal features of land use changes and the evolution process of landscape pattern from 1980 to 2017 were investigated using historical satellite images from a Landsat Thematic Mapper (TM) for 1980, 1990, 2000, 2005, 2010 and 2017 in the wetlands of Lake Baiyangdian in the North China Plain (NCP). Landscape pattern indices were used to quantify landscape changes in wetlands, and a redundancy analysis (RDA) was conducted to analyze the driving forces and quantitatively explain the effects of human activities and natural changes on wetland fragmentation. The results showed that the total wetland area was 234.4 km2 in 1980 but it decreased by 8.1% at an average decrease rate of 0.5 km2 per year. The dominant transition between land use types was from natural wetlands to artificial wetlands, and wetland conversion to dry land and residential land. The RDA results suggested that agricultural activities and total population were the main driving factors affecting wetland landscape. Additionally, climate change provided a potentially favorable environment for agricultural development, due to the increased temperatures and decreased wind speeds. Additionally, governmental policy changes and dam construction also played the roles in land use changes.

Artificial Wetlands as Breeding Habitats for Shorebirds: A Case Study on Pied Avocets in China’s Largest Saltpan Complex

Artificial wetlands such as coastal saltpans have replaced a number of coastal natural habitats worldwide and may have accommodated specific waterbird populations in the East Asian–Australasian Flyway (EAAF). The role of saltpans in the EAAF as foraging grounds for shorebirds is widely recognized, although their role as breeding grounds for waterbirds is very limited and contradictory. The Nanpu saltpans in northern Bohai Bay, China, are one of the largest saltpan complexes in the world. In this study, we monitored the nesting success (852 nests) of pied avocets (Recurvirostra avosetta) during three breeding seasons (2015, 2016, and 2018) in the Nanpu saltpans. The nest daily survival rate (DSR) was 0.970; hence, nest survival over the 27 exposure days was 44%. The apparent nest success was 51%. Surprisingly, 55% of nests failed during the laying period. Flooding and nest abandonment were the main causes of nest failure during both the laying and incubation periods. We found a strong positive relationship between the DSR and nest age, with nests that approached hatching having a greater probability of survival than freshly started nests. We also found a strong negative relationship between the DSR and precipitation, with the highest DSR observed for nests that experienced no precipitation. The DSR decreased over the course of the 71-days nesting season and followed a linear trend. The DSR was also density dependent and decreased slightly when nests were denser. A literature review showed that nest survival in the Nanpu saltpans was average compared with that of other studies and that nest success in artificial wetlands was significantly higher than that in natural wetlands or both habitats. Nevertheless, nest success decreased with the study date, suggesting that that breeding conditions for the pied avocet are worsening with time. The loss of saltpans could negatively affect the population of avocets and other ground-nesting waterbird species; therefore, conservation actions and research efforts should be strengthened to understand and conserve these functional wetlands for waterbirds.

ArcGIS-mapping to sustainable wastewater management in Greece: siting artificial wetlands systems in a biosystem

<p>In this work, the ArcGIS technology combines analogue and digital geospatial data to derive multiple resolution meshes with a triangulated irregular networks (TINs) approach that serves to integrate the geospatial data such as surface topography, hydro graphic features and land surface characteristics into an adaptive representation of a basin biosystem. The ArcGIS model that has been developed is applied at the municipal level to a small remote settlement with less than 2000 people in Northern Greece. The aim was a site assessment for constructing an artificial wetland (ATW) system as a viable solution to the wastewater management problem and protection of biosystems. This study demonstrates that there are discrepancies in Greece between the existing open geospatial data and on the basis of the results from our study we can conclude that this combination of local maps and geographic information in ArcGIS with a TIN approach increases our knowledge of the physical terrain. It accordingly facilitates the analysis and implementation of action plans by selecting suitable sites for construction of ATW systems in small remote settlements. We moreover discuss problems regarding spatial data quality and scale and provide suggestions for improvement while the desktop classification steps can be easily reproduced for other data-similar countries.</p>

Waterbird habitat loss fringing the Yellow and Bohai seas along the East Asian--Australasian migratory flyway

Natural wetland along the coasts of Yellow and Bohai seas provided key stopover sites for migratory waterbirds. However, these wetlands are facing land loss. Understanding how natural wetlands loss influence habitat is an important step for habitat management. Using species distribution model to report changes in area of suitable habitat, and the effects of natural wetland loss on habitat for 80 waterbird species attributed to four functional categories (shorebird, duck, heron, gull), between 2000 and 2015 in the Yellow and Bohai seas. Of 1794.8 km2 of coastal wetland lost to development between 2000 and 2015, most represented tidal flats converted into aquaculture and salt pan habitat, or for construction. Consequently, habitat for 73 of these 80 species has decreased in area over this time period. Generally, the proportional decline in habitat suitable for species of duck was less than it was shorebirds, herons and gulls. The proportional loss of tidal flat habitat that formerly represented suitable habitat for shorebirds, herons and gulls was also significantly higher than it was for ducks. Because more species of duck exploit aquaculture and salt pan habitat converted from tidal flats than do shorebird, heron and gull species, such conversion of tidal flats pose a greater threat to shorebirds, herons and gulls than they do to ducks. Preventing further reclamation of tidal flats and managing artificial wetlands are priorities for waterbirds conservation, especially for the species ducks.

Evaluation of Heavy Metal Pollutants From Plateau Mines in Wetland Surface Deposits

The Liupanshui Minghu Wetland is a typical artificial urban wetland in a plateau mining region. It is important to identify the sources and potential ecological risks of heavy metal contaminants in its surface sediments to monitor the wetland and the downstream water quality and prevent pollution. In this study, we measured the concentrations of six toxic heavy metals (Pb, Zn, Cr, Cu, Ni, and Cd) in the surface sediments collected from the Liupanshui Minghu Wetland. Further, the geological accumulation indices of heavy metals and their potential ecological risk indices, pollution levels, and associated ecological hazards were evaluated. The average levels of Pb, Zn, Cr, Cu, Ni, and Cd in the superficial sediments were 197, 222, 79.0, 59.1, 68.6, 4.67 mg/kg, respectively. With the exception of Cr, the concentrations of the remaining metals were greater than the background levels in the region. The Statistical analysis indicated a strong correlation between Pb, Zn, Cr, and Cu (p &lt; 0.01). The pollution in the wetland by these elements can be attributed to human activities such as transportation, industrial activity, and agricultural production. Ni and Cd pollution can be attributed to human activities, such as coal mining, and natural phenomena, such as the weathering of mountains and rocks. The geological accumulation indices of Zn, Ni, and Cu indicated low levels of accumulation and minimal contamination. Cd and Pb were moderately enriched, and the levels of Cd and Pb contamination ranged from moderate to high. The potential ecological risk to the Shiyuan region (S) was the highest among the three regions in the wetland park. It was followed by the Longtoutan (L) region, and the potential ecological risk was the lowest in the Erdaoba (E) region. Among the six heavy metals, Cd was the main contributor to pollution in the Minghu Wetland. This study also strives to provide theoretical basis and data support for the prevention and control of heavy metal pollution in artificial wetlands in Alpine mining areas.

Landscape Characteristics and Ecological Risk Assessment Based on Multi-Scenario Simulations: A Case Study of Yancheng Coastal Wetland, China

Carrying out coastal wetland landscape simulations and current and future ecological risk assessments is conducive to formulating policies for coastal wetland landscape planning and promoting the coordinated development of the social economy and ecological environment. This study used the Cellular Automaton (CA)-Markov model to simulate the landscape data of the study area under different scenarios in 2021 and 2025, and built an ecological risk assessment (ERS) index model to analyze the differences of spatio-temporal characteristics of ecological risks. The results showed that: (1) The test accuracy of the CA–Markov model was 0.9562 after passing through the consistency test. The spatial distribution data of landscapes under current utilization scenarios (CUSs), natural development scenarios (NDSs), and ecological protection scenarios (EPSs) were gained through simulations. (2) During 1991–2025, the landscape types of Yancheng coastal wetlands undertake complicated transfers and have vast transfer regions. Under CUSs and NDSs, a large number of natural wetlands are transferred to artificial wetlands. Under EPSs, the area of artificial wetlands declines and artificial wetlands are mainly transferred to natural wetlands. (3) The ecological risk of Yancheng Coastal Wetland increases, accompanied with significant spatial heterogeneity, which is manifested as low in the north area and high in the south area, and there exist some differences between sea areas and land areas. Ecological risk levels transfer violently.