Wetlands Ecology and Management最新文献

Peatlands represent an important part of the landscape of boreal western Canada, occupying some 365,157 km². Sixty-three percent of these are minerogenous fens. Scattered among these fens are landscape features that have unique and distinctive patterns—pools and carpets (flarks) separated by raised linear ‘strings’. These patterned fens harbor rare and uncommon species and serve as habitats for endangered wildlife (e.g., woodland caribou, whooping cranes). In this study, utilizing Google Earth Pro (1) we documented 1083 ribbed fens and 250 reticulate fens in the province of Alberta, Canada; (2) determined the regional variation in patterned fen occurrences; (3) described the various morphological forms of patterned fens; and (4) recognized these as six distinctive peatland site-types. Patterned fens are not randomly arranged on the landscape. Ribbed fens are concentrated on regional high elevational uplands and montane benchlands with morainal deposits, while reticulate fens are more numerous on low elevation plains with glacial-fluvial and glacial-lacustrine deposits. Patterned fens vary along minerotrophic vegetation and chemical gradients and have a complex set of morphological types. To our knowledge, this is the first study that provides base line information on the abundance and distribution of patterned fens in Alberta and associates morphological patterned fen types with environmental or geological characteristics. The digital files and maps provide a permanent record against which future change can be compared.

Understanding sedimentary deposits in wetlands is crucial for their effective management. In this study, we used an integrated approach to estimate the radiocarbon (¹⁴C) chronology, sedimentation rate, and nutrient dynamics of the Khushalsar wetland in the Kashmir Himalaya. A UWITEC gravity corer was used to retrieve a 60 cm sediment core from the wetland. Accelerator mass spectrometer (AMS) facilitated ¹⁴C dating of core sediments revealed that the age of the sediments ranged from 248 ± 30 BP at 15–16 cm depth to 889 ± 27 BP at 59–60 cm depth. The linear increase in ¹⁴C age with depth revealed steady depositional conditions. According to the Constant Rate of Supply model applied to ¹⁴C ages, the sedimentation rate for Khushalsar wetland averaged 0.10 cm per year over the past 829 years, spanning from 1189 to 2018. Physicochemical analysis revealed a high concentration of ionic components in the sediments, wherein the electrical conductivity (EC) ranged from 2230 to 2970 µS cm⁻¹, and organic matter (OM) ranged from 6.6 to 19.8%. The regression model demonstrated significant (p < 0.05) positive and negative associations between the physicochemical parameters. EC explained 91% of the variation in total dissolved solids (TDS) and 89% of the variation in salinity, whereas organic carbon (OC) explained 44% of the variation in nitrogen and 20% of the variation in phosphorus. Depth exhibited a strong positive association with C/N ratio (explaining 17% of the variation) and a negative association with OC, nitrogen, and phosphorus (explaining 59%, 56%, and 50% of the variation, respectively). The study concluded that primary productivity, stormwater runoff, anthropogenic inputs (domestic sewage, raw fecal matter, slaughterhouse wastes), and deforestation in the catchment area are responsible for the increased nutrient concentration and high sedimentation rate in the wetland.

“Ghost cypress”—standing trees killed by increased salinity—indicate sea-level rise (SLR) effects along lower reaches of many coastal plain rivers. Mature cypress can survive indefinitely in permanently flooded sites, but experience mortality at salinities as low as 2 to 3 ppt. Thus, ghost trees in permanently inundated sites can indicate mortality due to increased salinity. Ghost cypress were mapped along the margins of the Neuse River estuary and fluvial-estuarine transition zone (FETZ), along with co-indicators of salinity as a potential cause of death. The distribution was compared with other indicators of upstream propagation of SLR effects; all occurred within a 25 km river reach. Many ghost cypress are consistent with SLR-driven mortality, but in the upper FETZ the co-indicators argue against it, and throughout the study area some ghost cypress lack co-indicators of salinity effects and may have been killed by other factors. The upstream limit of ghost cypress with co-indicators suggesting possible SLR-driven mortality, and the downstream limit of Nyssa aquatica and N. biflora, whose habitats and niches overlap almost entirely with Taxodium except for less salinity tolerance, occur downstream of other indicators of the leading edge of SLR. The furthest upstream is the hydraulic impact of backwater effects on river flow. Downstream, other effects are encountered: a transition from occasionally to frequently flooded wetlands, sedimentary burial of Pleistocene alluvial terraces, and a shift from dominantly mineral floodplain soils to Histosols. The ecological indicators of cypress and tupelo are furthest downstream. Hydraulic (backwater) effects are the leading edge of SLR impacts on the Neuse, trailed by geomorphological, sedimentological, and pedological indicators. Though biota often respond more rapidly to changes than landforms and soils, ecological indicators such as ghost cypress and forest-to-marsh transitions that are salinity dependent are the downstream-most sentinels of sea-level encroachment in rivers.

Reed beds can be managed for commercial or conservation purposes, with effects on its inhabitants. In this paper, we assess the effect of management on the reed bed Coleoptera community by investigating reed beds subject to winter cutting, winter harvest, short-term unmanaged (3 years), and long-term unmanaged (25 years). Using pit fall traps, we collected Coleoptera across a summer season to estimate Coleoptera biomass, abundance, size, richness, diversity, and community composition across the four types of management of reed beds. Cutting and harvest both show to increase Coleoptera biomass compared to unmanaged reed beds, with the highest Coleoptera abundance found in the harvested reed bed. The species richness and diversity, on the other hand, peaked in the long-term unmanaged reed bed. Community composition differed between the different management types, and across time. Species of conservation concern were most abundant in recently managed areas. These results have implications for the conservation of the reed bed Coleoptera community. First, to maintain a high Coleoptera diversity, some areas must be left unmanaged. Secondly, to secure habitats for species of conservation concern as well as boost the Coleoptera biomass, frequent management of other areas is advised. This mosaic management pattern will also create the overall most species rich reed bed, as unique Coleoptera communities were found in each management type.

Wetlands are one of the world’s most threatened ecosystems, yet they provide outsized ecosystem services compared to their global surface area. Africa is experiencing a burgeoning human population, and though border areas receive short-term pulses in transient population growth, borders often create legal and logistical barriers to long-term settlement. This lack of long-term settlement may leave border ecosystems more intact than those in more interior areas. Reptiles and amphibians are considered indicator species and thus can be used to assess the health and resilience of their habitats. We sampled the herpetofauna of three transborder wetland systems in Uganda using time-constrained visual encounter surveys during diurnal and nocturnal activity hours. We then compared the communities of these wetlands using alpha and beta diversity indices and provide baseline population data on these communities. These data will allow for future investigations of the ability of transborder wetlands to act as long-term refugia for herpetofauna, even as human populations continue to increase. Border wetlands may be vital in conserving Africa’s herpetofauna.

Comparisons among vegetated and unvegetated intertidal habitats have led to the paradigm that benthic fauna are more abundant and diverse in the former. Mangroves and their associated saltmarshes are the dominant vegetation type in intertidal zones of the Ajuruteua Peninsula, northern Brazil, however until now, there no studies that investigate the benthic fauna among vegetated and unvegetated intertidal habitats. Therefore, the present study compares the macrobenthic fauna among red mangrove (Rhizophora mangle), saltmarsh (Spartina alterniflora) and adjacent unvegetated sediment (mangrove borders and saltmarsh borders) in the Furo Grande tidal channel in the Caeté estuary, northern Brazil. Overall, vegetated habitats have finer sediments, lower salinities and temperatures and higher organic matter and water content than unvegetated habitats. However, the macrofauna structure among the habitats did not fully correspond to this division, perhaps responding instead to differences among the four habitats in detrital production, tidal inundation frequency, leaf litter processing by crabs and rates of predation. Deposit feeding tubificid oligochaetes and capitellid polychaetes were particularly abundant in the mangrove and at mangrove borders probably due to greater availability of suitably processed detritus.

This paper investigates the origin and geomorphic evolution of Shadow Vlei, a depression wetland located approximately 30 km northwest of Gqeberha, South Africa. The wetland is on sandstone on the African Erosion Surface. The depression wetland has a rim of high-lying ground surrounding a central depression. Fluctuations between wet and dry periods create both highly reducing conditions in soils during wet phases in the depression, and highly oxidising conditions in the depression margin. Under reducing conditions, iron(III) oxides that are insoluble, are reduced to soluble iron(II), which is transported to and trapped in the margins of the depression under oxidising conditions when the water table declines and iron(II) is oxidised to iron(III). There is also a moderate flux of silica from the surface in the centre of the depression to the margins, which is suggested to be associated with maximum alkalinity associated with iron(III) reduction, and decreased alkalinity in the margins associated with iron(II) oxidation. However, the main flux of silica is from the surface in the centre of the depression to depth of greater than 1.5 m, again associated with variations in pH linked to iron-cycling. These reactions have thus caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression, causing swelling. Wetland formation associated with alteration of landform morphology as a consequence of alternating redox conditions represents a novel mechanism that has not yet been described.

Expansion and intensification of agriculture are among the main factors of degradation and systematic loss of wetlands throughout the twentieth century. We analyze the potential occurrence of wetlands in the core area of the temperate Pampas region of South America, recognized for the quality of its pastures and the suitability of its soils for grain production. We mapped the spatial distribution of wetlands in the Province of Buenos Aires based on the analysis and classification of the local soil database at a scale of 1:50,000. Thus, 399 soil series were classified as hydric/non-hydric according to the scope of methods and criteria reviewed. Then we used this information to classify 2211 map units into five categories based on the percentage of hydric and non-hydric soil series: 1—hydric (100% hydric series); 2—predominantly hydric (66–99% hydric series); 3—partially hydric (33–65% hydric series); 4—predominantly non-hydric (1–32% hydric series); and 5—non-hydric (0% hydric series). We estimated wetlands cover about 35% of the province. Wetlands distribution is not uniform, we identified three main landscapes: terrestrial matrix with wetlands, mosaic of wetlands and non-wetlands, and mosaic dominated by wetland patches. Our results provide tools for land management in terms of strategies for a wise use of wetlands and their conservation. Our map shows high values of consistency with the occurrence of wetlands visually identified in high-resolution imagery (Google Earth platform). In such a highly agriculturized landscape, our results indicate a much larger wetland area compared to estimates made with optical remote sensing data classifications.

Wetlands harbour a wide range of vital ecosystems. Hence, mapping wetlands is essential to conserving the ecosystems that depend on them. However, the physical nature of wetlands makes fieldwork difficult and potentially erroneous. This study used multispectral UAV aerial photography to map ten wetland plant species in the Fynbos Biome in the Steenbras Nature Reserve. We developed a methodology that used K-Nearest Neighbour (KNN), Support Vector Machine (SVM), and Random Forest (RF) machine learning algorithms to classify ten wetland plant species using the preselected bands and spectral indices. The study identified Normalized green red difference index (NGRDI), Red Green (RG) index, Green, Log Red Edge (LogRE), Normalized Difference Red-Edge (NDRE), Chlorophyll Index Red-Edge (CIRE), Green Ratio Vegetation Index (GRVI), Normalized Difference Water Index (NDWI), Green Normalized Difference Vegetation Index (GNDVI) and Red as pertinent bands and indices for classifying wetland plant species in the Proteaceae, Iridaceae, Restionaceae, Ericaceae, Asteraceae and Cyperaceae families. The classification had an overall accuracy of 87.4% and kappa accuracy of 0.85. Thus, the findings are pertinent to understanding the spectral characteristics of these endemic species. The study demonstrates the potential for UAV-based remote sensing of these endemic species.

Most of the world’s river-floodplain ecosystems are simultaneously undergoing modifications to their hydrological regimes and experiencing species invasions, making it unclear whether invasive species are the main drivers of ecosystem change or simply responding to changes in the hydrological regime.

We simulated patterns of forest recruitment and succession in a 2500-ha portion of the Upper Mississippi River floodplain with and without removal of invasive Phalaris arundinacea and under two different future 100-year hydrological scenarios: a future maintaining the average flooding conditions of the past 40 years (random) and a future that projects an observed upward 40-year trend in flooding conditions forward (trending). By comparing scenarios that included Phalaris removal and ones that did not, we were able to identify the conditions where Phalaris was the main driver of forest loss vs. the conditions where hydrology was the main driver of forest loss. Areas where Phalaris was the main driver of forest loss had mean annual flood inundation durations that were similar to areas that did not lose forest cover (60–90 growing season days), while areas where flooding was the main driver of forest loss had longer mean inundation durations (102–124 growing season days). In comparison to the random hydrology scenario, the trending scenario produced a decrease in the area over which Phalaris was identified as the main driver of forest loss and an increase in the area over which flood inundation was identified as the main driver of forest loss. Thus, if the observed trends in flooding continue, our model projects an increase in the area over which eradicating Phalaris is unlikely to result in the maintenance of forest cover. We used the Resist-Accept-Direct (RAD) framework to discuss potential management options to resist changes and maintain forest cover where Phalaris is likely to be the main driver of forest loss and to accept or direct changes in areas where forest loss is likely driven by hydrological change.