Wetlands Ecology and Management最新文献

Due to their coastal location, mangrove ecosystems are especially susceptible to various human-caused disturbances. These disturbances can result in a loss of original mangrove cover, a decline in biodiversity, and a degradation of their ecological functions. This study examines a restored mangrove area within the Barão de Mauá Natural Municipal Park (PNMBM) in Guanabara Bay, Brazil, two decades after the initiation of a restoration project. We used a multidisciplinary approach, combining remote sensing analyses, assessment of the vegetation structure, and genetic diversity analysis to evaluate this restored mangrove forest. Remote sensing data demonstrated high Normalized Difference Vegetation Index values following the restoration project’s completion, indicating the revegetation’s success. Exploring the structure of the new forest, we found Laguncularia racemosa to be the most abundant species, with a higher density and dominance for adults and seedlings. Conversely, Avicennia schaueriana was the least abundant in all areas, indicating a need for species enrichment. Planting age affected the forest structure, suggesting the capacity of this mangrove to achieve a natural maturity state. There was a genetic erosion in L. racemosa individuals, both adults and seedlings and low diversity was observed in A. schaueriana individuals. The PNMBM mangrove forest has shown remarkable resilience in maintaining its vegetation cover after restoration despite previous deforestation cycles. Moreover, as a young mangrove forest, it will continue to go through successional stages naturally. The loss of genetic diversity could be a concern for long-term survival, highlighting the need for genetic management. Integrating remote sensing, phytosociology, and genetic diversity analyses provided a comprehensive and detailed view of the park’s restoration outcome. These results should be used as guidelines for future interventions outlined in this work and can help ensure the resilience and sustainability of any restored mangrove.

Many different approaches to classify wetlands at regional and global levels have been proposed, but their use of different classification parameters complicates comparisons of the results. Moreover, none of the international approaches cover global wetland variety with respect to size and environmental conditions. A comparison shows that hydrology is the only parameter that can be used for a hierarchic classification on a global scale. In the approach presented herein, differentiation between coastal, inland and anthropogenic wetlands is proposed. The use of higher classification units (systems, subsystems, orders, suborders and classes) is based on hydrological parameters. Wetlands are separated into small, simply structured types treated by all classification systems, and large wetscapes that, due to their complexity, are not. However, wetscapes represent well-defined landscape units, many of which are the focus of international organizations involved in wetland protection. They have to be treated using a holistic approach given the many interactions of their ecological subunits, their role in regional economies, their targeting by legislation and their value to humans. Considering the large gaps in knowledge about wetlands at a global scale, the new approach is a powerful tool for its classification, because it is flexible enough to include additional classification units, as required. Local classification systems can eliminate higher categories, which do not occur in their regions. Classification at lower rankings (functional units, subclasses, macrohabitats) can be introduced using additional classification parameters such as vegetation, soils and water chemistry. Examples from Brazil are provided.

Wetlands in East Africa are important for providing ecosystem services and for conserving biodiversity. They are also suitable and increasingly used for agriculture. Between cropping cycles, spontaneous vegetation regrows on fallow plots. We hypothesize that recovery is affected by hydro-edaphic conditions and the duration of the fallow period. Land use intensification reduces fallow durations. A multi-year field study investigated the dynamics, biodiversity, and potential uses of fallow vegetation species after a disturbance event in an inland valley wetland in Central Uganda. The wetland was stratified into three hydrological positions along a gradient comprising the valley fringe, the mid-valley, and the riparian zone. In each zone, biomass was removed, and the soil was tilled, simulating a common disturbance event. Subsequently, four plots of 4 × 4 m size were delineated in each zone. Vegetation regrowth was subsequently monitored over a period of two years. We recorded and analyzed changes in aboveground live biomass, abundance of selected plant species, taxonomic and functional composition, and evenness during a 27-months recovery phase. While annual species dominated the vegetation initially, these were gradually replaced by herbaceous perennials, and eventually by tall reeds and woody plants, constituting three successional stages. The dynamics were similar, but species composition differed across the positions. At all successional stages, we observed the presence of useful wild plants, but also invasive species such as Mimosa pigra were recorded. While temporary fallows are important for biodiversity in tropical wetlands, such successions cannot substitute for the functions and services provided by natural vegetation and may promote invasive species.

The use of variables from different spatial scales has been recommended to increase the explanatory power of environmental models that seek to explain community structure. In this study, using electrofishing data, we tested the relative importance of local (stream habitat characteristics) and landscape (percentage cover of pasture, agriculture, natural vegetation, and water bodies) variables on the structure of fish communities in 13 streams located in veredas, which are small wetlands in the Brazilian savannahs. We used ordination methods to reduce the dimensionality of the environmental data matrices and used the first two axes from these analyses as explanatory variables in variation partitioning models. In these models, we also used the geographic coordinates of the sampling sites to control for spatial effects. The matrix of species abundance by site was our response variable. We found that only local and spatial variables significantly explained the structure of fish communities in wetlands streams. These results suggest that the effect of landscape variables should occur mainly when the variation in land use is more pronounced (when streams are distributed over watersheds with markedly contrasting land uses). Local variables, such as macrophytes, coarse woody debris, and leaf litter were the main predictors in our study, indicating the importance of habitat structure on fish communities. We emphasise that the small wetlands of the Cerrado biome are of great value for biodiversity conservation and are currently highly threatened by human activities. Currently, deforestation for the development of agriculture and livestock activities is the main threat to these ecosystems.

Invasions of floodplains and riparian areas by alien woody species replacing predominantly herbaceous indigenous vegetation have altered the hydrological and ecosystem functioning in catchments. Although existing studies have examined changes in river flows following the establishment or clearing of alien woody vegetation, our understanding of impacts on soil water content and groundwater remains poor. Limited process knowledge restricts our capacity to reliably model and predict the impacts of land cover changes. As such, this work compared temporal variations in soil water content (SWC) and groundwater levels at three locations with different vegetation types: black wattle (Acacia mearnsii) trees, palmiet (Prionium serratum), and grass (dominated by Pennisetum clandestinum spp), within a floodplain site in the Kromme Catchment in the Eastern Cape Province of South Africa. Soil water content and shallow groundwater levels (< 4 m below ground) were monitored from August 2017 to December 2019 using soil moisture probes and piezometers. Rainfall, vegetation type and antecedent conditions were identified as the major factors controlling observed responses. On average, soil water content and water retention were significantly higher (p < 0.05) at the palmiet site, whilst the wattle site had the lowest SWC among the three sites. Shallow groundwater levels were also higher at the palmiet and grass sites and lowest at the wattle site. Results showed the negative impacts of black wattle trees on SWC and groundwater levels. These results are crucial for improved quantitative predictive capacity which would allow for better catchment management, for example, informing water supply planning and guiding restoration programs focusing on alien plant clearing.

The large diversity of ecosystem services provided by natural wetlands has been underestimated by decision-making authorities in Brazil, posing a threat to sustainable development. The intensive land use practices and increased water usage in the country are the main forces driving the degradation and depletion of small wetlands. The aim of this study was to assess the spatiotemporal changes in geographically isolated wetlands (GIWs) in the Paulista Peripheral Depression in São Paulo State, considering the intensification of land use and land cover (LULC) and the role of local governance in protecting water resources in these environments. Remote sensing imagery and climate data were utilized to analyze the spatial‒temporal changes in GIWs. The effectiveness of local governance policies in addressing wetland protection concerns was also evaluated. The findings indicate that the intensification of LULC has negative impacts on GIWs, leading to their depletion or degradation. Additionally, GIWs are outside the scope of regulatory protection at the federal, state, and local levels. This lack of protection contributes to the vulnerability of wetland resources, poses risks to local ecological benefits, and exacerbates social-environmental issues such as water scarcity.

The paper describes the process of restoration of a portion of wetlands in the Ararat Plain of Armenia and the associated changes in the richness and abundance of breeding and migratory waterbirds. During 2019, a total of 1.61 ha of wetlands were restored in Khor Virap Sanctuary, a candidate Emerald Site, a Ramsar Site, and an international stopover point, protected under the African-Eurasian Waterbird Agreement. The design of the wetlands was developed considering the nesting and foraging requirements of various breeding and migratory waterbird species. Monitoring of the birds before and after the intervention (in 2017–2019 and 2020–2021) showed that the fauna of breeding birds changed from 38 to 55 species and the fauna of migratory species changed from 31 to 61 species. The conservation value of the area increased as the number of species included in the IUCN Red List increased from 0 to 1 for breeding birds and from 0 to 4 for migratory ones, in the Red Book of Animals of Armenia from 1 to 3 and from 5 to 19, and in Resolution 6 of Bern Convention from 5 to 12 and from 6 to 22 respectively. The fauna of waders is underrepresented, though, most probably due to a lack of mudflats. The success of the intervention justifies the continuation of wetland restoration on the rest of Khor Virap Sanctuary (almost 50 ha) and beyond it. It is also suggested to review the design of the wetlands to make them more suitable for a wider variety of waterbirds, including waders.

Transitional areas provide many benefits and advantages for several species according to shifts in environmental conditions. Because mangrove crabs (U. cordatus) seem to benefit from the ecotone between mangrove (M) and estuarine várzea (V) forests on Marajó Island, eastern Amazon coast, we investigated whether crab population structure varies in response to shifts in vegetation and fishing pressures. Generalized linear models revealed that crabs are larger and heavier at Furo do Saco (FS), where estuarine várzea trees dominate the landscape, and have higher density and biomass at Praia do Goiabal (PG), where the landscape is dominated by mangrove trees. Multivariate models also indicated that the distance between villages and crabbing sites turns transition zones into difficult access for crabbers and shelters for larger and more commercially profitable resources. The combined analysis of both biotic (crab and vegetation) and fishery variables highlighted the role of transition zones as a key environment for demographic maintenance and species conservation, guaranteeing the natural stocks and other ecological advantages for the sustainable fishery of mangrove crabs for future generations.

Mangroves are highly susceptible to oil exposure. Oil spills cause long-lasting mangrove loss, threatening their conservation and ecosystem services worldwide. This study aimed to explore the impacts of the Gulf War oil spill, which occurred between August 1990 and February 1991, on mangrove vegetation in the Persian Gulf and Oman Sea regions (Nayband, Qheshm, Bandar-Abbas, Sirik, Jask, Gabrik and Govatre mangroves). We utilized remote sensing technologies to investigate the potential changes in mangrove area and health in response to the oil spill. The analysis of historical Landsat-derived Normalized Difference Vegetation Index (NDVI) data revealed significant degradation in the Nayband, Qheshm and Bandar-Abbas mangrove, which were closest to the contamination source. Results indicated that the oil spill degrades the mangroves around 17.7 ha with poor or moderate greenness and health condition in Nayband mangrove site (Bidkhoon and Basatin). The analysis in Qheshm mangroves revealed that the oil spill had a notable effect on mangroves in Classes 2 and 3, causing them to transition into Class 1, which represents weaker mangroves in terms of health and greenness. Also, the Bandar-Abbas mangrove area experienced a significant decline across all classes around 25%, or 129 hectares. These mangroves experienced greater reductions in overall area as well as declines in vegetation health. In contrast, the mangroves along the northern coast of the Oman Sea showed no evidence of area reduction due to oil contamination. Landward mangroves in Iran, which have lower NDVI values and higher oil concentrations in the sediment, are most susceptible to being lost due to oil spills. These mangroves have revealed their resilience and ability to undergo rapid recovery within 5 years after the Gulf war because the Iranian coastal mangrove areas were largely untouched and undeveloped, which provided a favorable environment. Additionally, the high temperatures and intense solar radiation in the region created a suitable condition for the degradation of the oil, further contributing to the mangroves’ recovery. This highlights the need for improved monitoring and conservation efforts to protect mangrove habitats, which are critical for supporting coastal communities and the broader environment.

Wetlands in the Oil Sands Region of Alberta are vulnerable to direct and indirect effects of human development including land disturbance, hydrologic alteration, and addition of contaminants. Nineteen wetlands in the Athabasca Oil Sands Region were monitored over a five-year period to evaluate differences in water quality and benthic invertebrate composition between sites near to and further afield from surface mining operations. Concentrations of dissolved sulphate, dissolved iron, total dibenzothiophenes and specific conductance were significantly higher in wetlands near to surface mining operations. In addition, beta diversity of wetland invertebrates was higher in wetlands further afield of the industrial centre. Drivers of benthic assemblage differences among sites include specific conductance and pH. Conductance was positively correlated with Caenidae (Ephemeroptera) abundance and pH was negatively correlated with abundance of Naididae (Annelida).