Wetlands最新文献

Choghakhor is a freshwater permanent International Wetland in SW Iran where rapid agricultural and ecotourism development has changed the face of the landscape. In this study, the possible effect of these activities was assessed on the accumulation of potentially toxic elements (PTEs) in the wetland surface sediment. The concentration of PTEs varied considerably by sampling station in the order of Fe > Mn > As > Ni > Cr > Pb > Zn > Cd and exceeded the ISQG limits for Cd (11.46 mg/kg) and As (59.30 mg/kg). The results of pollution indices -Geoaccumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI) and Potential Ecological Risk Index (RI)- were spatially investigated using an interpolation technique, showing that the wetland is not contaminated nor severely enriched with Cr, Mn and Zn but is exposed to significantly high Cd and As contamination and enrichment levels across its entire area. Based on PLI, the entire wetland area is heavily polluted. The potential ecological risk of the PTEs was found to be considerably high which is a severe threat to the wetland species and its food web. The primary factors contributing to HM contamination in the wetland were recognized as agricultural land development, inappropriate application of phosphate pesticides and fertilizers, and the overuse of gasoline-powered boats for fishing and tourism activities.

The management of mangrove ecosystems faced to serious problem while these ecosystems are among the world’s richest ecosystems and provide a wealth of important services to human well-being. 35% of the areas of mangrove forests has globally been lost in the past two decades and supposed to be reach 60% by 2030. It is urgent to prospect the potential conservation research topics for the better management of mangrove areas. With a view to reducing mangrove degradation rate, this review aims to highlight restoration strategies and governance tenure of mangrove ecosystems in Africa. A total of 101 papers from Africa (31.68%), Asia (46.53%), America (11.85%), Europe (7.10%), and the rest of the world (2.84%) were considered. Indonesia, Thailand and India respectively recorded the top number of publications in Asia whereas Benin and Ghana accounted the higher number in Africa. 71.42% of publications have considered human activities including tree clearance and higher wood used (e.g. salt production activities) as the main mangrove degradation drivers in Africa. 4.80% of papers were found as the highest annual rate of mangrove degradation and less rate was 0.21% obtained in Africa. Many approaches were described for mangrove ecosystems restoration. 61.54% of mangrove governance publications showed that multi-level mangrove governance approach is widely applied. However, many studies suggested that this model of mangrove governance is the source of the resource’s degradation by the lack of a strong regulation. This review could help to set up a good program of mangrove restoration in West Africa.

The ‘Wise-Use Checklist’ was designed to assist people in formulating the ‘Conservation–Utilisation Plans for Wetlands of Importance’ in Taiwanese wetland conservation policy programme. Feedback from the planning teams, however, indicated that the checklist was difficult to use. Therefore, this research employed the perspective of science–policy interface to understand the barriers people were experiencing while implementing the checklist and identify the factors influencing the governance between science and policy in wetland conservation. The study mainly focused on the period from 2013 to 2015, when the wetland conservation policy was transformed into legislation and regulations in Taiwan. Semi-structured interviews were used to understand the thoughts of planners who participated in the formulation of the ‘Conservation–Utilisation Plans for Wetlands of Importance’. The interviews revealed that the main barrier to the planners was the uncertainty produced by perception divergence, technical difficulties, and policy–institutional barriers, rather than the checklist itself. The responses identified tensions and governance issues among the scientists and between the scientists and policymakers with respect to wetland conservation policies. The research yielded two findings in the aspect of the science-policy interfaces themselves, and six areas for discussion in the aspect of governance between wetland scientists and policymakers.

Current knowledge of the microbiota of soda pans of the Carpathian Basin focuses mainly on diatoms. In studying six soda pans in Vojvodina (Serbia), we aimed to gain deeper insights into the diatom community by using not only traditional microscopic analysis but also high-throughput sequencing of the 18S rRNA gene. In addition, this study aimed to evaluate bacterial communities in these soda pans for the first time using the 16S rRNA gene marker. Although similar numbers of diatom taxa were found using both approaches, a significant discrepancy in species composition was found. The genus Nitzschia was one of the most represented and numerous genera according to the morphological and molecular analyses, but with lower diversity according to the molecular data, with the sequences mostly unassigned. Another major discrepancy was noticed with taxon Halamphora veneta, the results of metabarcoding showed high abundance in almost all soda pans, while microscopy detected it as very low. Diverse communities of aerobic and anaerobic bacteria were detected in the studied soda pans, such as Proteobacteria, Bacteroidota, Actinobacteria, Bacillaceae, and Peptoclostridium. According to current knowledge, harsh environmental conditions and habitat homogeneity regulate diatom and bacteria community composition and enable the survival of taxa with predominantly high ecophysiological plasticity. Finally, uncovering the structure of the microbial community as the first phase in developing an efficient tool to assess the ecological status of these fragile ecosystems is an essential step towards their conservation.

Wetlands are under increasing pressure from threatening processes. Efforts to protect and monitor wetlands are hampered without datasets capturing the extent, type, and condition. The purpose of this study is to map the distribution of wetland type, vegetation type and vegetation condition for wetlands in the Northern Jarrah Forest region, Western Australia. A random forest algorithm implemented via Google Earth Engine (GEE) was used to classify wetlands and vegetation condition using satellite imagery, topographic indices, and soil mapping. Wetland type was classified using a hierarchical approach incorporating increasing level of detail. Wetland type was mapped as system type from the Interim Australian National Aquatic Ecosystem (ANAE) Classification framework and at hydroperiod level, with overall accuracy of 83% and 82% respectively. Vegetation type was mapped with an accuracy of 78.3%. Mapping of vegetation condition using the Vegetation Assets, States and Transitions (VAST) framework achieved an overall accuracy of 79.6%. Results show that wetlands occur in greater concentration as narrow seasonally waterlogged sites in the west, more sparsely and seasonally inundated sites in the northeast, and as broad seasonally waterlogged sites in the southeast of the study area. Wetland degradation determined through vegetation condition is concentrated in the east, and highest in seasonally waterlogged wetlands. Overall, the wetlands mapping framework implemented in this study can be used by land managers and other interested parties seeking to identify threatened and high conservation value wetlands in other areas.

More than 100 tidal marsh creation projects were constructed throughout the Fraser River Estuary, British Columbia, Canada from the 1980s to present. Past studies described and evaluated many of these projects and found varied success, but the underlying factors that determine project outcomes remain uncertain. Combining field sampling, spatial analysis, and statistical modeling of plant communities, we aim to address this knowledge gap by asking what factors influence the resilience of created marshes, as measured by (1) persistence of marsh vegetation, (2) native species dominance, and (3) species richness. We observed marsh recession in 40 of the 78 projects visited, representing 23,666 m² (9.3%) of the 254,357 m² of created marsh surveyed. Increases in mean site elevation had a negative effect on percent recessed area, while sites in the north branch of the river and sites further upriver were more prone to recession. From field observations and data interpretation we suggest that wake erosion and Canada Goose (Branta canadensis) herbivory may be drivers behind these losses and warrant further investigation. Dominance of native species declined with distance upriver, though invasive cattail (Typha angustifolia, T. × glauca) defied this trend, dominating outer estuary sites, particularly closed embayments, when present. Native and non-native richness shared similar patterns and were comparable between reference and created marshes, increasing on average with elevation and distance upriver. These findings offer insight into how site design and location influence the outcome of marsh creation projects, and the challenges presented by stressors and environmental change in estuaries.

Planting hardwood trees on retired marginal agricultural land is one of the main strategies used to restore forested wetlands. Evaluating effectiveness of wetland restoration requires efficient monitoring to evaluate recovery trajectories and desired conditions. Recent advancements in unmanned aerial system (UAS) technologies have prompted wide-scale adoption of UAS platforms in providing a range of ecological data. In this study, we examined the use of UAS Structure from Motion (SfM) derived point clouds in estimating tree density, canopy height, and percent canopy cover for bottomland hardwood plantations within four wetland reserve easements. Using a local maxima approach for individual tree detection produced plantation level estimates with mean absolute errors of 150 trees per hectare, 0.5 m, and 18.4% for tree density, canopy height, and percent canopy cover, respectively. At the plot level, UAS-derived tree counts (r = 0.53, p < 0.01) and canopy height (r = 0.57, p < 0.01) were significantly correlated with ground-based estimates. We demonstrate that UAS-SfM is a viable method of assessing bottomland hardwood plantations for applications that require precision levels congruent with the mean absolute errors reported here. The accuracy of tree density estimates was reliant upon specific local maxima window parameters relative to stand conditions. Therefore, acquisition of leaf-off and leaf-on imagery may allow for better individual tree detection and subsequently more accurate tree density and other structural attributes.

The flood-controlled Okavango Delta in Botswana is an endoreic alluvial fan system developing within the arid to semi-arid Kalahari Desert. The Delta sustains a unique association of ecosystems, from rivers to floodplains, riverine forests to savanna forests. This complex environment is nearly pristine from anthropic activity but its preservation, especially in the face of global change, requires a detailed understanding of the functioning and evolution of its ecosystems. In this work we describe extensive tree dieback in the savanna forest of southern Chiefs Island, the largest permanently emerged island of the Delta. While tree dieback is generally linked to drought, extreme temperatures, fire or increased biotic attacks, we suggest that the destruction in the years 2009–2012 of the Acacia sp. and Colophospernum mopane dominated forest unexpectedly results from drowning through soil water logging associated to a series of successive exceptional floods and abundant rainfall seasons. This result highlights the necessity of transdisciplinary studies in understanding the autogenic functioning of the Delta as a prerequisite to describe the effects of global change.

For decades, federal protections were extended to wetlands adjacent to “waters of the US” by the Clean Water Act. In its Sackett v. EPA ruling, however, the US Supreme Court redefined the meaning of “adjacent,” eliminating protections to wetlands without a continuous surface connection to these waters (i.e., geographically isolated wetlands, GIWs). Yet it remains unclear how this continuous surface test will work in reality, where ecological connectivity often extends beyond physical connectivity. Here, we calculate the number of US wetlands that could be considered geographically isolated depending upon the distance threshold used to define isolation (ranging from 1 m to 100 m from the nearest hydrological feature). Overall, we estimate that 27–45% of wetlands, at minimum, could be considered geographically isolated using this range of distance thresholds. Over 3 million wetlands are within 1–100 m of the nearest hydrological feature, making them most vulnerable to losing prior protections from the Clean Water Act. The Midwest and Northeast have the largest share of potential GIWs within this range. Freshwater emergent wetlands and forested/shrub wetlands make up the majority of these vulnerable wetlands, though this varies by state. Roughly 47% of these wetlands are located in states without state-level protections for GIWs. Our analysis highlights the heterogeneity of risk to wetlands across the country and the scale of the uncertainty imposed by the updated Sackett definition. State-level protections that are robust to changes in federal protections are urgently needed to secure the country’s wetlands from further pollution and destruction.

Small mammals are important, albeit often overlooked, fauna in wetland restoration projects. However, it is essential to evaluate factors that influence small mammal community metrics in restored wetlands to maximize wetland restoration effectiveness. Previous studies found that vegetation differed as restored wetlands aged and that wetland age may play a role in the presence of amphibians and birds. Therefore, we assessed whether wetland age influenced small mammals. We also evaluated 17 environmental factors in restored wetlands that could influence small mammal communities in these wetlands. To assess and evaluate the effects of age and environmental factors on the small mammal community, we appraised 14 restored wetlands in West Virginia, USA, in the summers of 2020 and 2021 for small mammal community metrics, specifically relative abundance, diversity, richness, and evenness. We captured six species of small mammals: deer mice (Peromyscus maniculatus), white-footed mice (Peromyscus leucopus), meadow voles (Microtus pennsylvanicus), meadow jumping mice (Zapus hudsonius), northern short-tailed shrews (Blarina brevicauda), and eastern chipmunks (Tamias striatus). We found that the relative abundance of deer mice, white-footed mice, and meadow voles decreased with wetland age. However, both species diversity and evenness increased with wetland age. Wetland size influenced the relative abundance of white-footed mice, meadow jumping mice, and all small mammals combined. Although the relative abundance of white-footed mice and total small mammals decreased with wetland size, the relative abundance of meadow jumping mice increased with wetland size. Wetland managers should consider wetland age and size when designing wetlands to facilitate small mammal communities.