Wetland Area Research Articles

Methane Emissions From Land and Aquatic Ecosystems in Western Siberia: An Analysis With Methane Biogeochemistry Models

AbstractWestern Siberia contains extensive wetlands and aquatic ecosystems, contributing a significant amount of methane (CH4) emissions to the atmosphere. However, estimates of CH4 fluxes over the region are poorly constrained partly due to the uncertainties from the inundated area data. This study applied two process‐based biogeochemistry models to quantify the emissions from land and aquatic ecosystems over the region within the period 2000–2021 using different inundation datasets. To drive land methane modeling, we use one static wetland map and one dynamic wetland area data set called Wetland Area and Dynamics for Methane Modeling (WAD2M) (2000–2020). To drive lake methane modeling, we use the surface area of aquatic ecosystems from three datasets: (a) HydroLAKES; (b) Global Surface Water (GSW); and (c) surface water inundation from Soil Moisture Active Passive (SMAP) (2016–2021). Using these datasets, we conduct four simulations to compare emissions over the region. We find that the net methane emissions from land using the static wetland map are larger than those using WAD2M. SMAP and GSW estimate larger emissions than HydroLAKES does from aquatic ecosystems. Total emissions over the region range from 4.80 ± 0.43 to 8.29 ± 0.81 Tg CH4/year from 2016 to 2020, which is the intersection period of four simulations. This study is among the first to investigate methane emissions from the whole landscape in the region. Our study highlights the importance of dynamic wetland and aquatic area data in quantifying regional methane emissions.

Long-term spatio-temporal changes of wetlands in Tibetan Plateau and their response to climate change

Understanding the changes of wetlands on the Tibetan Plateau (TP) is important for action to ensure ecosystem resilience in Asia. However, mapping long-term changes of wetlands at high resolutions remains challenging. Here, we quantify the spatio-temporal changes of TP wetlands from 1990 to 2019, by combining Landsat imagery with deep learning to map TP wetlands. The deep learning model combined with transfer learning strategies achieves high classification performance using a few class samples. The validation results show that the user’s accuracy is 95.5% and the producer's accuracy is 90.1% for wetland extraction, satisfying with subsequent analysis of wetland spatio-temporal changes. Based on the wetland extraction model, we have created annual wetland map in the TP for the first time. We find that the areal extent of TP wetlands has increased by 31.2 ± 6.6 % over the past 30 years. The growth is particularly noticeable (by 22.5 ± 6.2 %) during 2015–2019. Spatially, the wetland areal extent on the Qiangtang Plateau (in the inner part of TP and as habitats of various birds and rare wild animals) and the source region of Yangtze River show the largest expansions by 55.3 ± 9.3 % and 44.0 ± 8.9 %, respectively. Such rapid wetland expansions are associated with increasing rainfall and temperature which have heterogeneous influences on wetland changes across the TP. Our findings provide evidence for the impact of climate change on wetland area. The marked wetland changes highlight that climate mitigation is a priority for high-latitude ecosystems.

Contrasting effects of climate change on the invasion risk and biocontrol potential of the invasive Iris pseudacorus L. between Northern and Southern Hemisphere

Iris pseudacorus is both a prized ornamental and an invasive aquatic plant that tends to grow dense monospecific stands, displacing the local vegetation and altering the hydrology of freshwater ecosystems. Originally from Europe, this species has historically invaded North America, China and Japan, and more recently spread through Argentina, South Africa and Australasia, where it is now a target for biological control. Field surveys within its native range have led to the selection of three candidate biocontrol agents. Prioritizing the best candidates for different regions constitutes a critical step, which could save significant time and resources before further cost-intensive experimental studies are conducted. Climate change is seldom taken into consideration in the prioritization process. In this regard, climatic suitability can be used to model the potential distributions of weeds and their candidate agents, both in space and time, thus allowing to identify areas at risk of invasion and predict where agents will be able to establish long-term. Accordingly, the objectives of this work were (i) to predict I. pseudacorus invasions and range shifts in the context of climate change; (ii) to identify wetland areas most at risk of invasion under present and future climatic conditions; and (iii) to prioritize the best suite of candidate biocontrol agents for different invaded ranges, worldwide. To do so, we modelled the present and future (2040–2060) climatic suitability of I. pseudacorus and its candidate agents using the software MaxEnt. Our results highlight a clear distinction between predictions for the Northern and Southern Hemispheres. In North America and eastern Asia, the area climatically suitable for I. pseudacorus is expected to increase and shift northwards. As for its biocontrol agents, very low suitability is predicted across these regions, further decreasing under future climatic conditions. On the other hand, climatically suitable areas for the plant in South America, southern Africa and Australasia are predicted, on average, to reduce in response to climate change. A decrease in climatic suitability is also expected for its candidate biocontrol agents which, however, would still maintain a significant range overlap with their host. These results can be used to prioritize areas most at risk of invasion and identify which combination of candidates could potentially provide the best level of control across different invaded ranges.

Community Validation of Threatened Species in Coastal Wetland Areas of Negros Occidental, Philippines

This research aims to identify threatened bird species in wetland areas and define temporal changes occurring among species based on local observations and experiences. Survey, ethnobiology workshops, key informant interviews and focus group discussions were approaches employed in the collection of primary data from the chosen participants residing in the coastal communities in Central Negros, Philippines. The threatened wetland bird species in these sites are generally perceived as “abundant” as indicated by their perceived common presence. The ten sites also shared two vulnerable species, Egretta eulophotes,locally known as as Tulabong by locals and Anas luzonica called Pato ilahas by the natives. The Numenius madagascariensis is considered endangered and eight near threatened bird species (IUCN Red list), Numenius arquata, Limnodromus semipalmatus, Charadrius peronii, Limosa limosa, Limosa lapponica, Tringa brevipes, Calidris ruficollis and Calidris ferruginea, were validated by locals in almost all of the study sites. However, some threatened species were observed to have disappeared and declined in these areas. An updated list of threatened species found in coastal wetland cities and municipalities in the central area of Negros Occidental was produced that shall serve as basis for crafting relevant programs to properly manage, conserve and develop these wetland areas.

Feeding Habits and Diet Composition of the African Sacred Ibis in Selected Water-Logged Sites in Dar es Salaam, Tanzania

The African Sacred Ibises Threskiornis aethiopicus are generalist birds that feed on many invertebrates and some vertebrates. However, the diet composition of local T. aethiopicus populations in wetland areas in Dar es Salaam Tanzania was unknown. Sacred Ibises from eight water-logged areas in Dar es Salaam City, Tanzania were studied to determine their feeding habits and diet composition using direct observations and molecular analysis of faecal samples. Snails species identified from sites frequented by T. aethiopicus included Lymnaea natalensis (61.62%), Melanoides tuberculatus (20.64%), Bulinus sp. (17.66%) and Anisus sp. (0.08%), while molecular analysis of the birds’ diet revealed presence of mostly non-native invasive molluscs (Physa acuta, Planorbella trivolvis and Radix natalensis), fungus (Candida parapsilosis) and protozoan ciliate (Vorticella striata). There was no significant association between bird and snail abundance (r = 0.2141, p > 0.05, ns) although snail diversity showed strong negative relationship (r = -0.7904, p < 0.05). Our findings indicate that the African Sacred Ibises do not preferentially feed on snails, but do so as part of their broader diet. The results confirm that the African Sacred Ibis is a generalist feeder and therefore, ecological impacts of its feeding strategies particularly on invasive snails should be further investigated.
 Keywords: African Sacred Ibis, feeding, diet, molluscs, generalist

Increasing Physical Fitness in Gender in Wetland Areas Negara Hulu Sungai Selatan District

The purpose of this study was to determine the increase in physical fitness for gender in the wetland area of Negara Hulu Sungai Selatan District. The method used in this study is the pre-experimental method. The purpose of the pre-experiment is to obtain information that is an approximation of the information that can be obtained by the actual experiment in circumstances where it is not possible to control and manipulate all the relevant variables. The design in this study uses The One Group Pretest-Posttest design, which means that a group of subjects is subjected to treatment for a certain period of time, while measurements are made before and after treatment is given and the effect of treatment is measured from the difference between the initial measurement (O1) and the final measurement (O2). The population in this study were women in the wetlands of Negara District, while the sample size was 35 people. The results of the study showed that there was an increase in physical fitness in women in the wetlands of Negara Hulu Sungai Selatan District. The benefits of physical fitness are currently very well recognized by the community, as evidenced by the development of fitness centers and sports activities that are widely held, all of which stem from the pursuit of physical fitness.

Effects of Temporal and Spatial Changes in Wetlands on Regional Carbon Storage in the Naoli River Basin, Sanjiang Plain, China

The Naoli River (NLR) Basin is a crucial distribution area for wetlands in China. Investigating the link between land use changes and carbon storage in this basin is of significant importance for protecting regional ecosystems and promoting the sustainable development of the social economy. This paper uses long-term Landsat satellite images provided on the GEE (Google Earth Engine) platform and the random forest classification algorithm to create spatial distribution maps of land use in the NLR Basin from 1993 to 2022. The study analyzes the dynamic changes in wetlands in the basin over the past 30 years and employs the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model to explore the temporal and spatial evolution characteristics of carbon storage. The results reveal that the wetland area of the NLR Basin showed a downward trend from 1993 to 2022, with a total decrease of 1507.18 hm2 over 30 years. During this period, the carbon storage in the NLR Basin decreased, with a cumulative loss of 1.98 × 107 t, mainly due to the continuous reductions in wetland and forest land. Additionally, the change in carbon storage in the basin has a strong spatial and temporal relationship with the changes in land use/cover area. The total carbon storage is positively associated with the areas of wetland, forest land, and water bodies. The conversion of wetlands into any other land type results in the reduction in carbon storage. These findings can improve our understanding of the spatial and temporal dynamics of wetlands in the NLR Basin over the past 30 years and enable us to analyze the relationship between land use changes and regional carbon storage. The results of this study have great significance for protecting the wetland ecology and regional carbon balance in the NLR Basin.

Landscape Pattern Changes and Climate Response in Nagqu Hangcuo National Wetland Park in the Tibetan Plateau

Wetlands are vital ecosystems in the Tibetan Plateau that play a crucial role in water conservation, flood storage, and biodiversity maintenance. They are sensitive to climate change and typically have high ecological and environmental quality levels due to minimal human disturbance. This study aimed to quantify landscape pattern changes within the Nagqu Hangcuo National Wetland Park (NNWP) and identify the impact of climate on wetland change. Using remote sensing data from six periods (1990, 1995, 2000, 2005, 2010, and 2015), dynamic change analysis, landscape pattern analysis, and correlation analysis were employed to determine the evolutionary features of the wetland landscape and explore their relationship with climatic factors. The results showed that the total wetland area increased from 15.11 km2 in 1990 to 15.23 km2 in 2015. The meadow area increased the most among landscape types, primarily converted from swamps. Over 25 years, the fragmentation of the NNWP’s landscape increased while diversity decreased and its shape became more complex. Meadows were more sensitive to climatic factors than other landscape types, with correlation coefficients between wetland separation and sunshine duration being more significant than other climatic factors. Therefore, it is imperative to monitor landscape pattern changes and the effects of climate change to better protect wetland parks through long-term planning, suitable mechanisms, and advanced technology.

Analysis of the gains and losses of ecosystem service value under land use change and zoning in Qiqihar

Under a background of uncoordinated economic development and the ecological environment, quantifying the ecological effect brought by land resource changes, have become research key and hotspots. To explore land use change and its impact on ecosystem service value (ESV), the land use change analysis method, ecosystem service evaluation model, flow direction analysis model and two-dimensional graph theory clustering method were used to analyze the profit and loss of ESV in Qiqihar in 2010 and 2020 and the division of ecological function areas with counties as units. The results show that: 1) The land use change in Qiqihar city is more obvious, Among them, the area of cultivated land, wetland, construction land and other increases, Woodland, grassland, water area decreased, The changed land area accounts for 30.95% of the total area; 2) The ESV in Qiqihar city increased by 869 million yuan, The sum of the value of cultivated land and wetland exceeded 70.0% of the ESV, is the main source of ESV in Qiqihar city; 3) Not all land-use shifts are conducive to ESV growth. The increase of ESV mainly comes from the flow of cultivated land and grassland to the wetland; Conversion of woodlands, water area, wetlands to other types causes ESV loss, the most loss is the conversion of wetlands to cultivated land; 4) Qiqihar city is divided into the central wetland ecological conservation area, the western characteristic agriculture and dotted wetland ecological function area, and the northeast agricultural ecological environment construction functional area. Three policies were proposed to improve ESV:(1) give play to the radiation role of wetland nature reserves; (2) popularize the black land protection technology model; and (3) prevent and control agricultural non-point source pollution and promote clean agriculture.

Synoptic water isotope surveys to understand the hydrology of large intensively managed catchments

Understanding the hydrology of large catchments has always been a major challenge due to the spatial heterogeneity of climate, geology, topography, soils and land use. However, precise knowledge of water cycling, storage and losses across large scale catchments is required to sustainably meet growing water demands and adjust water management strategies. This study used four large-scale, seasonal synoptic surveys in 2021 to characterize the spatio-temporal patterns of water isotopes (stable water isotopes and radioisotope tritium at natural abundance) to better understand the complex hydrology of the intensively managed 10,000 km2 catchment of the River Spree in Germany. Apart from the upper headwaters, the hydrology of the Spree is heavily regulated by reservoir releases, pumped minewater discharges, extensive wetlands and lakes, water abstractions and urban drainage. Moreover, the catchment is drought-sensitive with potential evapotranspiration (∼800 mm a year) often exceeding annual rainfall (∼600 mm). This is reflected in the isotopic composition of river water: In the steeper, upper headwaters, the river has a “flashy” rainfall-runoff response, with isotopes plotting close to the Global Meteoric Water Line (GMWL) consistent with dominant groundwater sources, but showing more influence by rainfall in winter. However, flows in the midstream parts are complex due to artificially enhanced baseflows and attenuated high flows from extensive reservoir releases and pumped groundwater releases from dewatering of mines. The reservoir waters are isotopically heavier and reflect the effects of open water evaporation. Fractionation effects strengthen downstream as managed wetland areas in the Spreewald and natural lakes further enhance evaporation and attenuate flows. Water abstractions for drinking water and to sustain the Oder-Spree canal reduce flows further. In Berlin, sources of urban runoff and waste water discharges reduce the effects of fractionation, though samples still plot below the meteoric water line. Seasonally, the effects of evaporation in the lower river network are strongest in summer and autumn, though they remain in winter and spring, indicating a large memory effect due to long mean travel times within the river system. Tritium variability along the river reflects inputs of younger and older water in different parts of the river system; though the influence of pumped groundwater means that the mean age of stream water (i.e., time elapsed since rainfall) in the lower river is likely to be >50 years. Climate change, together with increased population and economic growth in Berlin, is likely to increase pressures on the Spree system in future. In the coming years, the anticipated termination of the lignite mining will lead to a reduction in artificial inputs into surface water, which in turn may exacerbate water stress. We demonstrated that longer-term, synoptic isotope studies are valuable in better understanding the hydrology of such complex, large-scale, heavily modified river systems in terms of insights into water sources and mixing processes; thus, providing an evidence base for more sustainable management in the future.

Distribution Patterns and Factors Influencing Relative Abundance of the Alligator Snapping Turtle (Macrochelys temminckii) in Mississippi

Macrochelys temminckii (Alligator Snapping Turtle) was recently proposed as a threatened species under the US Endangered Species Act due to current and projected future declining populations range wide. Despite a presumed statewide distribution in Mississippi, the Alligator Snapping Turtle had been documented in only 32 of 82 counties between 1857 and 2012, thus leaving a substantial gap in our knowledge of this species' distribution. Therefore, we collected credible records from museums, literature, and the general public, as well as directly assessed the current distribution and relative abundance of the Alligator Snapping Turtle in all major river systems (i.e., Pascagoula, Pearl, Tombigbee, and Mississippi river drainages) in Mississippi. From 2017 to 2021, we systematically trapped 77 sites across the state totaling 839 captures of 787 individual Alligator Snapping Turtles over the course of 4750 trap nights. State-wide catch per unit effort (CPUE) averaged 0.177, with the Big Black River (0.348) and Tombigbee River (0.028) drainages having the highest and lowest average CPUE, respectively. In Mississippi, CPUE was positively correlated with greater surrounding wetland area and river size, and negatively correlated with terrain ruggedness. This survey, along with the collaboration of other biologists and the public, verified an additional 189 locality records in 56 counties, with Alligator Snapping Turtle presence reconfirmed at 29 of 30 historical localities. Currently, it appears that there have been no local extirpations of the species in Mississippi, and state-wide CPUE was higher than those of the surrounding states.

Selecting and refining suitable methods of developing digital elevation models to represent geomorphic features and characteristics of smaller wetlands in data-scarce environments

Land surface geomorphology plays an important role in water and sediment dispersal processes in wetlands. For wetland practitioners and researchers to engage with these processes in time and space, they require topographic data in order to derive wetland surface gradient, cross-sectional shape and area, surface and subsurface hydrological connectivity, and hydraulic characteristics. A range of data options, with varying spatial resolutions, are available, ranging from free national and global resources (e.g. contour data and global elevation models) to project-specific high-resolution surveys (e.g. Differential Global Positioning Systems (DGPS), Photogrammetry, Light Detection And Ranging (LiDAR)). Due to the scarcity of high-resolution and high-accuracy data, especially in developing countries, data gathering and processing costs can be significant. This paper presents a commentary on a range of topographic data and processing options for a relatively small (~ 40 ha) floodplain wetland in the Eastern Cape, South Africa. It critically reviews the usefulness and shortfalls of various wetland-related applications ranging from gradient calculations to more detailed hydraulic modelling, and the data resolution required for each application. Free, low-resolution, datasets have a limited representation of geomorphology at this scale due to the relatively low-resolution and large vertical error. Field-based surveys (using survey-grade equipment such as a DGPS) have the benefit of providing accurate terrain results in areas with dense vegetation and surface water, while photogrammetry and LiDAR data are useful to represent the higher resolution morphology across the wetland, despite shortcomings regarding the penetration of dense vegetation and surface water. However, combining DGPS data with LiDAR proves to yield the best model for detailed process modelling for wetlands at the local scale.

Occurrence, distribution, and ecological risk of heavy metals and persistent organic pollutants (OCPs, PCBs, and PAHs) in surface sediments of the Ashtamudi wetland, south-west coast of India

Monitoring heavy metals (HM) and persistent organic pollutants (POP) has become more important recently, as they pose serious threats to tropical aquatic ecosystems. The Ashtamudi wetland a Ramsar Site in the southwest coast of India must be monitored due to the intense urbanisation and anthropogenic activities that occur in the nearby areas of this wetland. This study aims to identify potential sources of POPs (OCPs, PCBs, and PAHs) and HM in the surface sediments of Ashtamudi wetland, as well as to assess their ecological risk. The enrichment factor (EF), contamination factor (CF), degree of contamination (CD),geo-accumulation index (Igeo), pollution load index (PLI), and sediment quality guidelines (SQG) were used as pollution indices. The average concentrations of HM were Iron (39582.52 mg/kg) > manganese (365.92 mg/kg) > Zinc (91.39 mg/kg) > nickel (49.36 mg/kg) > Copper (31.47 mg/kg) > lead (21.21 mg/kg) > Cadmium (0.73 mg/kg). The concentrations of HM detected during the study were on par with or even higher than the other coastal systems. Several areas of the Ashtamudi wetland are extremely enriched and moderately to considerably contaminated with cadmium (EF and CF indices). Nickel exceeds the ERM (Effects Range Median) in some sampling stations. The Ashtamudi wetland has not been seriously contaminated by organochlorine pesticides (2.03 to 2.45 μg/kg) and polychlorinated biphenyls (0.26 to 0.35 μg/kg). Sediments are moderately contaminated with polycyclic aromatic hydrocarbons (202.81–158.23 μg/kg) from urban emission sources of Kollam. These results can be used as a reference point for future research on organic contaminants in Indian wetlands and highlight the need for effective controls of micro pollutants.

Construct the future wetland ecological security pattern with multi-scenario simulation

The construction of wetland ecological security pattern has important guiding significance for balancing urban development and ecological restoration. In this paper, the PLUS model was used to simulate the land use change under the business as usual scenario (BAU), economic development scenario (ED) and expansionary conservation scenario (EC) in 2030. Coupled with the wetland ecological security pattern, four wetland ecological networks were constructed for vertical and horizontal comparative analysis. The optimal network was selected and ecological pinch points and obstacles were identified. The results showed that: (1) The land use change mainly occurred in the main urban area of Haikou. Under BAU and ED scenarios, the area of construction land increased greatly. Under EC scenarios, the overall ecological land in Haikou would expand, but the area of wetland showed a downward trend. (2) In 2030, the overall ecological wetland network will be improved, the number and length of corridors will increase significantly, and the network structure under EC scenario will be more stable. (3) The number and area of ecological pinch points and obstacle points under the EC scenario in 2020 and 2030 increased significantly, and this area should be regarded as a priority area for ecological protection. This study provides a new perspective for ecological protection and restoration, and provides a reference for clarifying the direction of wetland ecological restoration work and formulating urban construction and development policies.

Spatio-temporal sensitivity analysis of the wetland modules of a semi-distributed hydrological model

Hydrological models offer the opportunity to evaluate wetland conservation networks as nature-based solutions to mitigate hydrological extremes. To optimize the replication of a hydrological model response (i.e., stream flows), the models rely on input data (land cover, hydrographic network, soil types, topography, meteorological data) and parameters. However, the effect of parametric uncertainty on the simulated variables and the spatio-temporal variability of this sensitivity are insufficiently documented. This study presents an application of the novel global sensitivity analysis method, the Variogram Analysis of Response Surface, to the isolated and riparian wetland modules of HYDROTEL, a semi-distributed, process-based, deterministic model, on two watersheds located in the province of Quebec, Canada. The analysis accounted for: (i) the spatial variability by assessing the sensitivity at various locations in the watersheds and by compiling sensitivity indices for wetland networks discretized following the Strahler order classification which quantifies the structure of hydrographic networks and (ii) the temporal variability of the sensitivity using the Generalized Global Sensitivity Matrix. The results indicate that the parameters defining the geometry of wetlands (area, depth) are the most sensitive for both isolated and riparian wetlands, and for all Strahler orders. The temporal assessment of sensitivity highlights the seasonal controlling processes, including a peaking sensitivity of the maximum water depth in wetlands during spring snowmelt, whereas the sensitivity of the evapotranspiration parameter increases during summer, but is null during winter. Results also indicate that the parameters of the isolated modules are more sensitive for wetlands located on lower stream order (upstream/headwaters) while those of the riparian modules display a greater sensitivity when wetlands are located on higher Strahler orders (downstream/main channel). These findings deepen our understanding of the impact of wetland features on stream flows and provide guidelines to plan future data acquisition campaigns in wetlandscapes.

The Impact of the Trans-Java Toll Road Development on Spatial Planning in the Northern Region of Java Island: A Study Utilizing NDBI and Google Earth Images

The primary objective of toll roads is to stimulate economic growth. As the pivotal road network on Java Island, the Trans-Java Toll Road has a significant impact on regional development and spatial planning. However, there has been a lack of research focusing on the specific influence of this toll road on spatial planning. Therefore, this study aims to comprehensively examine the spatial and temporal implications of the Trans-Java Toll Road. To achieve this goal, the Normalized Difference Built-Up Index (NDBI) method is employed using satellite imagery. This method is widely recognized for its effectiveness in detecting changes in built-up areas through remote sensing techniques. The calculated NDBI values reveal substantial expansion of built-up areas in the cities and regencies traversed by the Trans-Java Toll Road. Notably, two specific areas with the highest rates of change are investigated: Gresik Regency and Bekasi Regency, where the built-up areas have experienced remarkable growth of over 186.9% and 61.8% respectively over a five-year period. To validate these findings, Google Earth imagery is utilized for two different years, namely 2016 and 2021. The observed changes in these regions are predominantly attributed to the economic growth facilitated by the establishment of industrial areas. Consequently, the expansion of industrial zones and settlements has resulted in a notable reduction in wetland areas and a simultaneous increase in built-up areas.

Horizontal Integrity a Prerequisite for Vertical Stability: Comparison of Elevation Change and the Unvegetated-Vegetated Marsh Ratio Across Southeastern USA Coastal Wetlands

Surface elevation tables (SETs) estimate the vertical resilience of coastal wetlands to sea-level rise (SLR) and other stressors but are limited in their spatial coverage. Conversely, spatially integrative metrics based on remote sensing provide comprehensive spatial coverage of horizontal processes but cannot track elevation trajectory at high resolution. Here, we present a critical advance in reconciling vertical and horizontal dynamics by assessing the relationship between elevation change, relative tidal elevation (Z*), and the unvegetated-vegetated marsh ratio (UVVR) across coastal wetland complexes in the southeastern USA. We first used the UVVR to determine the representativeness of the SET site relative to varying spatial footprints across the complex and found that SET sites generally represent the tidal wetland areas in terms of vegetated cover. There is also overall coherence between positive vertical change and high vegetative cover, but we also identified sites with high vegetative cover and negative vertical change (relative to SLR). The only sites exceeding the pace of SLR have UVVR values below the previously established 0.15 threshold. Some sites are not keeping up with SLR despite having intact marsh plains; this may indicate a risk of submergence with undetectable marsh plain loss, or an imminent transition to future open-water conversion. Aggregation of Z* across the same footprint as the UVVR demonstrates consistent coherence between elevation and vegetative cover, with lower elevation sites having larger UVVR. These results indicate that the UVVR is a suitable initial screening tool: areas above the 0.15 threshold are both horizontally and vertically vulnerable. Furthermore, this comparison suggests that horizontal integrity is a prerequisite for vertical stability: a marsh can only maintain elevation if the plain is intact with minimal unvegetated area.

Spatial mapping of the leaf area index using remote sensing and ground measurements – the Biebrza National Park case study

The purpose of the described research was an attempt to estimate the leaf area index (LAI) parameter describing the structure of the vegetation based on the Landsat 5TM satellite imagery and field measurements made with the use of an optical plant canopy analyzer. The study was carried out in north-eastern Poland in the Biebrza river valley within the boundaries of the Biebrza National Park during the growing season of the year 2007. There were 13 spectral indices given in the literature known to be correlated with the LAI. The highest coefficient of determination and the highest correlation coefficient were obtained for the normalized difference vegetation index (NDVI) and the soil adjusted vegetation index (SAVI) indices for the wetland areas in the Biebrza river valley. The field measurements of the leaf area index and its spatial representation on satellite image show that the vegetation of natural river valleys is characterized by high spatial and seasonal variability. The study of the LAI on such large natural areas that are extensively used also requires knowledge of the methods of land use and the application of individual agrotechnical measures.

Monitoring of drainage system and waterlogging area in the human-induced Ganges-Brahmaputra tidal delta plain of Bangladesh using MNDWI index

Waterlogging is one of the major global problems which affects agro-economic activities around the world. In the coastal areas of Bangladesh, especially the southwestern coast, drainage congestion and waterlogging are very common which makes the area uninhabitable. Therefore, timely checking of drainage systems and surface water, and conveying data on the dynamics of drainages and surface water are important for plan and supervisory processes. The present study took an effort to illustrate the waterlogging and morphological change of the rivers in the southwestern coast of Bangladesh through the Modification Normalized Difference Water Index (MNDWI) values which are valuable indicators for monitoring the water area and land use pattern change. Landsat images (Landsat L8 Oli TIRS, Landsat ETM+, Landsat TM) were used in the research. The study reveals that from 1989 to 2020, the shallow water area (mostly covered with rivers) decreased by ∼14.30 km2 yr−1, whereas the wet-land area (mostly covered with beels and water logging areas) increased by ∼ 67.12 km2 yr−1. The bare land area also increased at a rate of ∼ 36.90 km2 yr−1. On the other hand, the green vegetation decreased at a rate of ∼166.1 km2 yr−1, whereas the moderate green vegetation area increased by ∼ 69.77 km2 yr−1 for the same period. In the coastal zones of Bangladesh, the polders, embankments, upstream dams, etc., enhance more sedimentation within the channels rather than in the nearby tidal plains. As a result, the shallow water area which is mostly covered by rivers is gradually decreasing. Moreover, due to increase in wet-land areas with salinity intrusions which affect the vegetation. Therefore, the green vegetation area is regularly declining due to demolition or conversion to moderate green vegetation. The findings of the research will be supportive for coastal scientists worldwide, policy makers & planners, and finally supportive for sustainable management of the coastal areas including Bangladesh.

Changes in the landscape patterns of Black-necked Crane habitat and its correlation with their individual population numbers during the past 40 years in China.

The landscape pattern of the Black-necked Crane (Grus nigricollis) habitat in China changed at different spatial scales and long-term periods due to natural factors and human activities, and habitat reduction and fragmentation threatened the survival of Black-necked Cranes. The factors driving the habitat landscape pattern and individual population changes of Black-necked Cranes remain to be studied. In this paper, based on remote sensing data of land use from 1980 to 2020, the changes in landscape pattern and fragmentation of the Black-necked Crane habitat in China over 40 years were analyzed from two different spatial scales using the land cover transfer matrix and landscape index. The correlation between landscape and Black-necked Crane individual population was analyzed. The most obvious observations were as follows: (1) Although transformation between landscapes occurred to varying degrees, the area of wetlands and arable land in the breeding and the wintering areas (net) increased significantly from 1980 to 2020. (2) Habitat fragmentation existed in the breeding and the wintering area and was more obvious in the wintering area. (3) The number of individuals of Black-necked Cranes increased period by period, and habitat fragmentation did not inhibit their population growth. (4) The number of individuals of Black-necked Crane was closely related to the wetland and arable land. The increasing area of wetlands and arable and the increasing landscape shape complexity all contributed to the growth of the individual population. The results also suggested that the number of individuals of Black-necked Crane was not threatened by the expanding arable land in China, and they might benefit from arable landscapes. The conservation of Black-necked Cranes should focus on the relationship between individual Black-necked Cranes and arable landscapes, and the conservation of other waterbirds should also focus on the relationship between individual waterbirds and other landscapes.