Wetlands最新文献

This paper presents the first analysis of impacts of COVID-19 on willingness-to-pay for wetland restoration. Two potential effects were identified that may affect willingness-to-pay for wetland restoration and empirically tested using a referendum-style contingent valuation survey that was administered in the midst of the pandemic to measure willingness-to-pay for restoring mangroves and saltmarshes in Tampa Bay, Florida. Results indicate that willingness-to-pay was $2,791 per household during COVID, but it would have been $3,262 if there had not been COVID. These results imply a loss of $3.8 billion in the total value of restoring wetlands in the state of Florida.

Climate change and its variability impact water availability in wetlands, jeopardizing their ecosystems. This study focuses on the Sudd Wetland, Africa’s most extensive and one of the world’s largest tropical wetland systems. We analyzed historical climate data (temperature, rainfall) in the Sudd and its upstream regions to assess climate impacts on the wetland’s health (NDVI) and water conditions (surface water extent, lake height) using spatial and temporal trends. The study unveils distinct seasonal and long-term variations in vegetation and temporal fluctuations in surface water dynamics within the Sudd Wetland. While central areas experienced declining NDVI (vegetation cover), peripheries showed an increase. The wetland gained open water surface area, with a slight rise in permanent water (3%) and a significant increase in seasonal inundations (19%). All monitored water bodies in the Sudd displayed a gradual increase in surface water height. Climate shifts are observed as rising temperatures and increased rainfall trends. Annual and seasonal temperatures rose across the basin, with the January-Feburary season experiencing the most significant increase (~ 1.3 °C). Rainfall trends were mostly flat, except for the south-central and southeastern regions, where a statistically significant increase ranging from 5 mm to 17 mm per year was observed. Conclusive evidence from this paper could be used to assess water policy and management in the region while protecting key parts of the hydrologic cycle.

Wetlands are important ecosystems for mitigating climate change impacts on the environment and society. Most studies focus on how single environmental factors affect those ecosystems, although several environmental factors may change simultaneously. This study focused on nutrient – water level interaction effects on two different but associated wet grassland species Carex acuta and Glyceria maxima. Biomass allocation and root exudates were measured in a full-factorial mesocosm experiment. Species identity and water level mostly determined total alive biomass and the biomass allocation pattern. Root weight ratio generally increased in C. acuta whereas increased rhizome biomass was associated with G. maxima. Furthermore, increased water levels increased relative aboveground biomass allocation with C. acuta having more leaf and G. maxima having more stem biomass. Surprisingly, fertilisation had little impact on total biomass, but decreased relative biomass allocation to the roots and also strongly suppressed root exudation. There is an apparent nutrient dependent shift in the realised hydrological niche of both plants towards drier conditions. C. acuta behaves similar under all water levels without fertilisation, but thrives best under dry conditions when fertilised. Without fertilisation, G. maxima thrives best under flooded conditions (water level ~ 15 cm above soil surface), but does equally well in saturated water conditions (water level ~ soil surface) when fertilised.

In freshwater forested wetlands, bald cypress knees (Taxodium distichum (L.) Rich.) have the potential to emit large amounts of methane (CH₄), but only a few studies have examined their greenhouse gas contribution. In this study, we measured CH₄ fluxes associated with cypress knees across various climate and flooding gradients of the Mississippi River Alluvial Valley in southcentral United States. Greenhouse gases were measured using a portable gas analyzer with a custom-made chamber placed over the knees. We also conducted 3D lidar scans of knees using a smartphone to estimate the surface area and volume of knees. We investigated the following: (1) What parameters influence CH₄ fluxes (i.e., knee height, distance to stream, temperature, relative humidity, water level, precipitation)? and (2) Which type of knee shape measurement (i.e., cone, frustrum, or lidar scan) provides the best fit to model data while maximizing measurement efficiency? We found that knee CH₄ flux rates ranged from − 0.005 to 182 mmol m^− 2 d^− 1. There were positive correlations between CH₄ fluxes, water levels, and temperature, and a negative correlation with knee height. Sites that had been dry for longer periods of time emitted less CH₄ than sites where the soil remained saturated. The frustrum shape produced a knee volume estimate that was within 12% of lidar scans, whereas cone shapes underestimate knee dimensions (-100%). Further research of emissions and fluxes in cypress knees could fill knowledge gaps within the carbon cycle and could represent a major component of wetland CH₄ budgets.

Along with wetland loss, wetland habitat quality degradation is a growing concern that requires immediate attention. The current study aimed to assess the Wetland Habitat Quality State (WHQS) of Rarh region, Murshidabad, West Bengal. WHQS used a total of seventeen metrics, including water quality, hydrology, and landscape composition. Machine learning techniques such as ANN, SVM, RF, BAGGING, and REP-TREE were used to model WHQS. The effectiveness of the models was evaluated using statistical techniques such as the Receiver operating characteristics (ROC) curve. According to machine learning models, 6% of the area fall under very weak habitat quality zones in 1990 which increased by 15%, 26%, 41% in 2000, 2010 and 2020, respectively. Very strong portions of wetland area have been decreased from 32.74% in 1990 to 20.72% in 2020. The current study's findings could provide comprehensive research on the monitoring of habitat quality in wetlands, which will serve as the foundation for developing water resource management plans for the conservation, management, and restoration of wetlands.

Understanding the dynamic patterns of wetlands in the Yellow River basin and promoting connectivity among them are important for the protection and restoration of wetlands in this basin. Although many existing studies effectively optimize the structural characteristics of ecological networks, they often overlook the spatial distribution of the actual landscape to be optimized and the associated ecological risks. This study centers on Maduo County in Qinghai Province, employing the MSPA model and connectivity indices to meticulously analyze the spatial dynamics of wetland alterations and hydrological connectivity over the past two decades. The introduced concept of optimizing the importance index involves the stratification of low-connectivity wetland patches, identified as nodes for optimization. A theoretical assessment of the complexity and connectivity robustness of the river network before and after optimization was performed. Findings reveal: (1) The core area and connectivity of wetlands in Maduo County have exhibited persistent growth. The centroid of wetlands shifted southeastward in both periods, albeit at differing angles. (2) Hydrological connectivity of wetland patches in Maduo County experienced rapid enhancement from 2000 to 2010, maintaining stability from 2010 to 2020. (3) There are 44 nodes to be optimized, with 6, 13, and 25 nodes in levels 1, 2, and 3, respectively. As the number of levels increases, the nodes slated for optimization are more likely to be interconnected within the river network. Post-optimization, both the complexity and connectivity of the river network show improvement. The study will offer fundamental theoretical support for wetland research in the Yellow River Basin.

Wetlands, widely distributed and hotspots of biodiversity, play a crucial role in global biogeochemical cycles and human well-being. However, despite their ecological importance, wetlands worldwide are under threat due to widespread conversion into agricultural fields, leading to changes in hydrology, increased salinity, and more frequent eutrophication. In response to these challenges, constructed wetlands are created to treat agricultural wastewater and mitigate eutrophication. This study aims to assess the effect of natural vs. constructed wetlands on ecosystem functioning (organic matter decomposition of the dominant vegetation: Phragmites australis and Typha angustifolia). We conducted this study in the Ebro River Delta (NE Spain), which represents a deltaic wetland affected by agricultural land-use changes, examining two constructed and two natural wetlands. Our findings indicate that the influence of agricultural runoff on the decomposition process was similar in both types of wetlands, suggesting that freshwater agricultural runoff has a consistent effect on ecosystem functioning, regardless of its origin, natural vs. constructed. Differences in macroinvertebrate communities associated with leaf litter were likely due to specific conductivity but did not impact decomposition rates. The estimated time required to decompose 95% of the T. angustifolia litter produced annually in the studied wetlands ranged from 288 to 856 days. In constructed wetland, this decomposition time exceeded one year, contributing to soil formation and carbon sequestration in wetland ecosystems. Our study suggests that the utilization of constructed wetlands for treating agricultural runoff can aid in mitigating the impacts of agricultural land use in these areas.

Vernal pools—small seasonal wetlands—provide critical breeding habitat for many species but are under-protected in environmental regulation. Because vernal pools are not rare in the northeastern United States, regulatory emphasis is typically placed on protecting “significant” vernal pools yet scientific criteria for determining thresholds for conservation significance remain poorly developed. We used an evidence-based approach to identify thresholds of pool significance based on populations of breeding amphibians in five ecoregions and across urbanization gradients of New York State, where a recent revision to wetland law allows regulation based on amphibian productivity. We combined existing population survey data with new surveys to yield a dataset of 587 pools for estimating statistical distributions of productivity of two indicator species: spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus). Spotted salamander egg mass counts were significantly lower in highly developed landscapes. Larger pools were generally more productive for both species yet no single habitat feature reliably predicted high egg mass counts. Pool incidence and productivity also varied regionally: the Hudson-Mohawk region hosted the most known vernal pools and highest egg mass counts and the Lake Plain region the fewest known pools. Our dataset yielded threshold options for guiding pool protection that varied by the proportion of pools targeted. We suggest a lower standard for protecting pools in high-development areas and that presence of other pool-breeding indicator species could also qualify pools for significance. These recommendations can guide regulators in affording protection critical to small wetland habitats specific to regional and landscape contexts.

The Drift Prairie, in central North America, has been largely converted from grasslands to croplands, but still contains thousands of wetlands used by shorebirds and waterfowl during breeding and migration periods. Consequently, many of the remaining wetlands are situated within cropland where disturbance regimes (i.e., fire, grazing, and water-level dynamics), which occurred naturally prior to agricultural development, have been highly altered by landscape fragmentation from agriculture practices. Currently, smaller wetlands within crop fields are subject to disturbances stemming from agricultural practices (i.e., manipulations), such as burning, disking, harvesting, and mowing. We evaluated vegetation structure of idled (i.e., not recently manipulated by farming practices) and manipulated agricultural wetlands to investigate whether management method or resulting vegetation structure had greater influence on occurrence probabilities and densities of dabbling ducks and shorebirds during spring. All manipulation methods reduced vegetation heights compared to idled wetlands and most manipulations reduced the proportion of vegetation cover in inundated areas. Wetland manipulations generally increased shorebird occurrence compared to idled wetlands, whereas vegetation variables better explained duck occurrence probabilities. Duck occurrence peaked in wetlands with lower vegetation coverage (32%), and duck densities decreased as vegetation coverage increased beyond 10%. While more studies are needed to understand underlying mechanisms driving these outcomes, our results indicate that including periodic disturbances that reduce dense vegetation within wetlands in agricultural fields would increase their use by migrating and breeding shorebirds and dabbling ducks.

The temporal changes in the effect of damming on the hydrological and ecological condition of a river and associated riparian wetland were examined in the present study. Does the degree of hydrologic and ecological alteration decline over time? Hydrological alteration was assessed in reference to the wetland water richness (WWR) modelling in three phases: pre-dam phase (up to 1992), post-dam phase 1 (1993–2012), and phase 2 (2013–2020). Periodicity of river flow at season scale was assessed usingthe wavelet transform model. The degree of ecological alteration was measured using a range of variability approach (RVA) and flow duration curve (FDC). From the analysis, it was revealed that after damming, the monthly flow failure rate increased (70–96%). The eco-deficit in the river was further exacerbated as the temporal distance increased. As a consequence of this, wetland water richness (WWR) maps of different phases exhibited continuous loss in the poor WWR parts. Eco-deficit condition of the wetland became severe in post-dam phase 1 and it was continued but with a lesser rate of increase in the next phase. The findings of this study would have significant implications for ecological flow management in rivers even after damming in order to continue eco-flow in downstream river reach and support riparian wetlands of immense ecosystem values. The study suggests conducting comparable studies with longer post-dam lengths in order to better determine how the effects of damming change over time.