Wetland Edge Research Articles

Films Floating on Water Surface: Coupled Redox Cycling of Iron Species (Fe(III)/Fe(II)) at Soil/Water and Water/Air Interfaces

Naturally occurring Fe(III) films with rainbow reflection iridescence have been observed floating on the water surface of various spots covered with shallow water (e.g., edges of wetlands and creeks, standing water over soils). This natural phenomenon has become a scenic attraction and stimulated much curiosity. We pursued an experimental inquiry aimed at probing this interesting, curious natural wonder. As the first critical task, floating Fe(III) films were successfully generated in an assessable, controllable setting in our laboratory. This enabled us to establish this phenomenon reproducibly under controlled conditions and characterize the phenomenon over the entire span of the formation and transformation of the Fe(III) films. Our film generation method requires a few things: fresh soil (source for Fe(III) and microbes), glucose (energy source), and water in a container. The floating Fe(III) films as observed in the field occurred in ~1–3 day(s) on the water surface of the inundated soil mixed with the sugar. The Fe(III) films then grew from initial very thin, colorless, somewhat transparent films with rainbow reflection iridescence to colored thicker films and then to orange/orange-red/red crusts over the time. A comprehensive mechanistic picture was formulated to depict the formation of the Fe(III) films. Several sequential processes are operative. First, the Fe(III) (oxides, oxyhydroxides) in the soil is reduced to Fe(II) by the Fe(III)-reducing microbes during their anerobic respiration with Fe(III) as the electron (e−) acceptor after depletion of dissolved O2 in the water as a result of aerobic microbial respiration with O2 as the e− acceptor. The Fe(II), being soluble, then diffuses to the water surface where it is oxidized to Fe(III). Subsequently, the Fe(III) hydrolyzes and various Fe(III) hydrolysis products polymerize to stabilize. A polymeric model was created to account for the Fe(III) film transformation. The Fe(III) films are considered to transform from the dimers and trimers and linear polymers of Fe(OH)3 to Fe(III) polymer sheets (e.g., Fe(OH)3, FeOOH), to 3D Fe(III) polymers, and eventually to Fe2O3 colloid particles. This floating Fe(III) film phenomenon boasts an environmental chemical drama of redox cycling of Fe(III)/Fe(II) at soil/water and water/air interfaces coupled with Fe(II) transport from the inundated soil to the water surface followed by ultimate mineralization of the Fe(III) polymers. Our Fe(III) film generation method can be readily scaled up to supply Fe(III) films of rich varieties in thickness, size, morphology, and structure over the entire span of various stages of their formation and transformation as desired for various uses. This setup offers a platform needed for further controlled studies on the kinetics, mechanism, and process of abiotic and biotic nature involved in the Fe(III) film phenomenon and for exploration of versatile roles of the Fe(III) films as nanofilms in Fe(III)/Fe(II)-surface catalyzed chemical and photochemical reactions involving various natural and synthetic compounds.

How hydrological components of urban blue space influence the thermal milieu?

Present study examines the possible improvement of thermal discomfort mitigation. Unlike prior researches, which focused primarily on cooling effects of urban blue space, this study, instead of physical presence of blue space considers its hydrological components. The aim of the study is to better understand the role hydrological components like water consistency depth etc. In temperature regulation. The work uses field surveys and modeling to demonstrate how these hydrological factors influence the cooling effect of blue space, providing insights on urban thermal management. To fulfill the purpose, spatial association of hydrological components blue space with its thermal environment and cooling effects was assessed. The control of hydrological components on the surrounding air temperature was examined by conducting case studies. Resultsreveals greater hydro-duration, deeper water, and higher Water Presence Frequency (WPF) produce greater cooling effects. The study demonstrates a favorable correlation between hydrological richness and temperature reduction. The study also analyzes how land use and wetland size affect temperature, emphasizing the significance of hydrological conservation and restoration for successful temperature mitigation. Due to their hydrology, larger wetlands are able to moderate temperature to some extent, whereas smaller, fragmented wetlands being hydrologically poor are not so influential in this regard.With these results, the present study reaches beyond to the general understanding regarding the cooling effects of the urban blue spaces. While the previous studies primarily focused on estimating the cooling effect of urban blue space, the current one shows its synchronization with the hydrological characteristics. Novelty also entrusts here, through the modeling and field survey current study demonstrates deeper and consistent water coverage in the urban blue space for maximum period of a year pronounces the cooling effect. In addition, in this cooling effect, the role of land use which is a strong determinant of many aspects of the urban environment is also highlighted. Since all these findings define specific hydrological feature, the study has several practical implications. Mare restoration of urban blue space is not enough to mitigate the thermal discomfort. In order to optimize the cooling effect, the conservation of the hydrological richness is essential. The hydrological richness of the smaller wetlands and the edge of the larger wetlands is to be improved. The connection of these wetlands with the adjacent mighty may strengthen the hydrology. The vegetation was found to promote the cooling effect whereas shorter building helped in spreading the cooling effect. Such finding drives to incorporate the blue space with the green infrastructure along with restricting the building height atleast at the edge of the blue space.

Farm management and landscape context shape plant diversity at wetland edges in the Prairie Pothole Region of Canada.

Evaluating the impacts of farming systems on biodiversity is increasingly important given the need to stem biodiversity loss, decrease fossil fuel dependency, and maintain ecosystem services benefiting farmers. We recorded woody and herbaceous plant species diversity, composition, and abundance in 43 wetland-adjacent prairie remnants beside crop fields managed using conventional, minimum tillage, organic, or perennial cover (wildlife-friendly) land management in the Prairie Pothole Region. We used a hierarchical framework to estimate diversity at regional and local scales (gamma, alpha), and how these are related through species turnover (beta diversity). We tested the expectation that gamma richness/evenness and beta diversity of all plants would be higher in remnants adjacent to perennial cover and organic fields than in conventional and minimum tillage fields. We expected the same findings for plants providing ecosystem services (bee-pollinated species) and disservices (introduced species). We predicted similar relative effects of land management on alpha diversity, but with the expectation that the benefits of organic farming would decrease with increasing grassland in surrounding landscapes. Gamma richness and evenness of all plants were highest for perennial cover, followed by minimum tillage, organic, and conventional sites. Bee-pollinated species followed a similar pattern for richness, but for evenness organic farming came second, after perennial cover sites, followed by minimum tillage and conventional. For introduced species, organic sites had the highest gamma richness and evenness. Grassland amount moderated the effect of land management type on all plants and bee-pollinated plant richness, but not as expected. The richness of organic sites increased with the amount of grassland in the surrounding landscape. Conversely, for conventional sites, richness increased as the amount of grassland in the landscape declined. Our results are consistent with the expectation that adopting wildlife-friendly land management practices can benefit biodiversity at regional and local scales, in particular the use of perennial cover to benefit plant diversity at regional scales. At more local extents, organic farming increased plant richness, but only when sufficient grassland was available in the surrounding landscape; organic farms also had the highest beta diversity for all plants and bee-pollinated plants. Maintaining native cover in agroecosystems, in addition to low-intensity farming practices, could sustain plant biodiversity and facilitate important ecosystem services.

Survival of northern pintail ducklings in grasslands and croplands: implications for fall‐seeded cereals

AbstractSpecies‐specific management strategies have been implemented to address persistently low continental populations of several duck species, including the northern pintail (Anas acuta). In the Canadian Prairie Pothole Region (PPR), addressing threats from spring‐seeded cereals on pintail productivity may provide sufficient gains to recover populations. Research on pintail duckling ecology has revealed that duckling survival may be greater in grassland‐dominated landscapes than in annual cropland‐dominated landscapes, possibly limiting the benefits of fall‐seeded cropping practices. Winter wheat crops increase nest success and may assist nesting pintail populations through provision of nesting refuges from spring tillage operations, earlier hatch, and greater nest densities compared to traditional spring‐seeded cereal crops. Yet inadequate duckling survival may reduce these benefits. Our principal objective was to examine if pintail reproductive success in winter wheat in cropland‐dominated landscapes was comparable to grassland‐dominated landscapes or, alternatively, if duckling survival rates in cropland‐dominated landscapes offset the gains of greater nesting success in winter wheat. We captured and radio‐marked 104 nesting female pintails in grasslands and croplands of southern Saskatchewan, during 2011–2012. We modeled cumulative survival to 30 days post hatch in relation to landscape composition and land cover type, specifically, the influence of nesting in fall‐seeded crops. Predicted 30‐day survival for ducklings hatched in perennial cover (40.8% [85% CI = 40.0–44.6%]) in grassland‐dominated landscapes and winter wheat (38.2% [32.0–44.4%]) in cropland‐dominated landscapes was more than double survival of ducklings hatched in spring‐seeded cropland (16.9% [12.6–21.6%]) in cropland‐dominated landscapes. Ducklings moving through local environments with more perennial cover and seasonal wetlands, but less wetland edge, had increased survival. The benefit of greater nest survival in winter wheat was not completely superseded by reduced duckling survival for broods raised in intensive agricultural landscapes. The retention of grassland landscapes and expansion and promotion of fall‐seeded crops in cropland‐dominated landscapes can benefit northern pintails across broad regions of the PPR.

Water depth influences survival and predator-specific patterns of nest loss in three secretive marsh bird species.

Wetlands have become increasingly rare in the United States, negatively influencing wetland-dependent birds, and many remaining wetlands are intensively managed through seasonal dewatering mimicking historic flood pulses during spring and summer. However, water around nests may provide protection from terrestrial predators, and lowering water levels during the breeding season of wetland birds may increase predation risk and exacerbate marsh bird population declines. Understanding interactions between water depth, nesting marsh birds, and nest predators is critical to aid managers in developing a multi-species management approach in emergent wetlands. During the 2020 and 2021 breeding seasons, we examined nest survival of 148 marsh bird nests (American Coot, Fulica americana, n = 1; Common Gallinule, Gallinula galeata, n = 64; and Least Bittern; Ixobrychus exilis, n = 83) and installed cameras at 78 nests to identify predators at a large, restored floodplain wetland in Illinois where the primary management technique is seasonal water removal to stimulate germination of moist soil plants. We found nest predation of, and abandonment by, Least Bittern and Common Gallinule were related to shallower water, and early season, high volume dewatering. Least Bitterns nested more commonly along wetland edges and nests farther from the shore were more likely to survive. Similarly, we found mammalian depredation of nests and nest abandonment decreased when deeper water was present around nests. Alternatively, snake predation was observed earlier in the year prior to water removal from inundated emergent vegetation. Our results demonstrate water depth may be an important deterrent of nest predators, especially mammals, during the breeding season. Further, we recommend managers delay dewatering until after the nesting season at sites where management for conservation-priority marsh birds is a focus.

Wetland cover in agricultural landscapes is positively associated with bumblebee abundance

Abstract Conversion of land for agricultural use is a leading driver of global biodiversity loss. Natural and semi‐natural lands within agricultural landscapes are targeted for protection because they provide habitat for many organisms. Pothole (or kettle) wetlands occur across the Northern Hemisphere and are a focus for conservation both because of their location within agriculturally intensive landscapes and their importance to vertebrates, especially migratory birds. Recent evidence suggests that wetlands may also be an important habitat for arthropods, including insects that provide ecosystem services. To understand how insects associate with wetlands and landscape features, we examine the relationship between bumblebees (Bombus), and wetland area, cropland area and wetland perimeter‐area ratio. We found that wetland area is significantly positively associated with the occurrence and abundance of the species studied. We also found that the relationship between bumblebees and wetland perimeter‐area ratio varied across the growing season. This suggests that the importance of wetland edge as a foraging habitat varies across the season. These results show the utility of wetlands to bees, though their resources are likely not being used uniformly by all bumblebee species or across the entire growing season. Our results also suggest that pothole wetlands in agricultural landscapes are likely to support biodiversity, and their conservation contributes to overall ecosystem health and function.

Impact of Artisanal Gold Mining on Wetland Health in Buhweju District, Southwestern Uganda

Wetland degradation due to anthropogenic activities including artisanal gold mining is widely common in Uganda, and this affects vegetation health status if not controlled. However, the use of the Normalised Difference Vegetation Index (NDVI) to determine the health status of wetlands is rare. In this study, remote sensing techniques with the use of spatial-temporal Normalised Difference Vegetation Index (NDVI) were used for the wetlands in Bitsya Subcounty, Buhweju district (noted for artisanal gold mining with the use of mercury) to determine the wetland health status for the period between 2012-2021. This was for the purposes of identifying target areas for intervention and developing appropriate, location-specific intervention options. 7 images of 30 * 30 m and 3 images of 10 * 10 m respectively, ortho-rectified, cloud-free Landsat and Sentinel images obtained from the USGS archive were analysed. The results showed that the high NDVI value (0.775) was detected in the year 2019 and the low NDVI value (0.068) was detected in the year 2017. The NDVI maps showed low values mostly in the middle of the wetland where artisanal gold mining was mostly taking place, indicating a huge decline in the wetland health status as compared to other wetland edges noticed with high NDVI. The results from the study suggest that the wetland policies in the study area could not be effectively implemented and this reduces the vegetation health status, threatening the functionality of the wetland and as well as loss of the free natural goods and services derived from them. This necessitates the development of wetland restoration campaigns. However, failure to implement the wetland policies may have an ecosystem impact on the wetland micro and macro-organisms, soil nutrients, and water quality as well as a decline in vegetation health

VESSEL WAKE INDUCED DYNAMICS IN A SHALLOW-BAY ENVIRONMENT

Ship wakes generated by large deep-draft vessels as well as those generated by smaller barges have the potential to cause significant compounding erosion and sedi-mentation issues, especially along high-traffic waterways. Yet, long-term in situ measurements of the actual hydro-dynamics initiated by ship wakes are rare. These data, however, are needed to optimize the design of erosion mitigation structures, to plan dredging efforts, to validate numerical modeling efforts, and to establish a basis from which the erosion and sedimentation potential of projected ship traffic can be estimated. This study is intended to help close some of these existing knowledge gaps through detailed analyses of measured velocity, water free-surface elevation change, and suspended sediment concentration caused by wind waves and ship wakes in the shallow-bay environment of Galveston Bay, Texas (GBT). In addition, numerical modeling efforts are being presented using the Boussinesq-type wave model FUNWAVE-TVD (Shi et al., 2012) to simulate individual vessel wake hydrodynamics and sediment-related dynamics and interactions with the local bathymetry and wetland edges based on the collected field data.

The Quebrada Negra wetland study: An approach to understand plant diversity, hydrology, and hydrogeology of high‐Andean wetlands

AbstractHigh‐Andean peatlands are high‐altitude wetland ecosystems found throughout the arid central Andes of South America. They form through the establishment of specialized grasses and cushion sedges that are well‐adapted to cold temperatures, in areas where groundwater emerges. The Silala River is a groundwater‐fed high‐Andean fluvial system, which emerges in various springs that generate wetlands, the Cajones and Orientales (Bolivia), the river's headwater sources, and the Quebrada Negra (Chile) being the most important. This article reviews detailed monitoring undertaken in the undisturbed Quebrada Negra wetland to provide insights into wetland processes, and to compare its functioning to that of the Bolivian wetlands, which were channelized a century ago. Vegetation composition was found to be similar among the three wetlands, and their spatiotemporal vegetation cover distribution showed strong seasonal and interannual variability. The channelized Bolivian wetlands have the highest annual actual evapotranspiration values (~700 mm, due to their higher vegetation vigor), as estimated using remote sensing, ~10% greater than that obtained in the undisturbed Quebrada Negra wetland. For the Quebrada Negra wetland, groundwater monitoring revealed that hydraulic head contours are consistent with the topography, although water sources to the wetland are complex to identify. While significant groundwater inflows arise at the wetland edges, upwelling and downwelling conditions are observed at various locations within the wetland, similar to other high‐Andean wetlands. The observations suggest that while the underlying groundwater discharge sustains the saturated conditions of the wetland, the spatial variability of groundwater inputs results in a negligible impact of channelization on wetland evapotranspiration.This article is categorized under: Water and Life > Stresses and Pressures on Ecosystems Science of Water > Hydrological Processes

Behavior‐specific habitat selection by raccoons in the Prairie Pothole Region of Manitoba

AbstractPatterns of resource selection depend upon an animal's behavioral state. Because management strategies are often crafted from an understanding of animal space use, incorporating behavior explicitly into analyses of resource selection has the potential to improve outcomes. In the Prairie Pothole Region of Manitoba, Canada, raccoons (Procyon lotor) are a nest predator of waterfowl, but it is unclear how raccoons use this landscape during the waterfowl nesting season. Our objective was to use high‐resolution global positioning system (GPS) telemetry to differentiate among behaviors by raccoons and evaluate behavior‐specific habitat selection during the waterfowl nesting season. We collected approximately 32,000 locations from 33 animals during the 2018, 2019, and 2021 nesting seasons, amounting to 632 animal‐night's worth of movement data. We used hidden Markov models (HMM) to fit 4‐state models to the movement trajectories, classified observations into discrete behaviors, and fit behavior‐specific random forest resource selection models to evaluate the relative importance of habitat features on selection. Proximity to a wetland was the most important variable contributing to selection for the resting, foraging, and slow travel states. Probability of use was as high as 95% within or immediately adjacent to a wetland for animals engaged in those behaviors, and our best HMM predicted increasing probability of switching from resting or foraging to directed travel with increasing distance from a wetland edge. Human‐use sites were also important to foraging animals, suggesting raccoons subsidize their diet with anthropogenic food resources during spring and summer. These results illuminate the complexity of habitat selection by a waterfowl predator in this patchy landscape, allowing managers to develop effective conservation strategies (e.g., wetland prioritization and conservation, elimination of anthropogenic subsidies) where raccoons are having a disproportionate effect during the waterfowl nesting season.

Preliminary evidence of upland plant encroachment in high‐elevation wetlands of Volcanoes National Park, Rwanda

AbstractWetland ecosystems are increasingly altered by anthropogenic activities, with upland plant encroachment as one possible outcome. Here, we present preliminary evidence that encroachment by herbaceous and woody upland species is ongoing in five small Afromontane wetlands straddling high elevations (~2600–3400 m a.s.l.) in Volcanoes National Park (Rwanda). Although encroachment seems to commence at wetland edges it reaches waterlogged soils at wetland centres. This evidence of the spread of upland plants in these wetlands should be followed by additional research efforts focused on possible causes and consequences of this encroachment as well as the exploration of potential management and mitigation efforts.

Vegetation productivity of the Lake Poyang Wetland in the post Three Gorges Dam era

三峡运行以来,气候变化与人类活动共同驱动了鄱阳湖水文情势的急剧变化,并对其湿地植被产生了显著影响,但当前研究尚未系统量化鄱阳湖湿地植被在此条件下的演变规律与趋势。因此,本研究以增强型植被指数EVI(enhanced vegetation index)的时段最高值作为表征湿地植被生产力的代用指标,定量揭示了后三峡工程时代鄱阳湖湿地植被生产力的气候态特征及其变化,包括变化的量级、显著性及阶段性。结果表明:(1)2000-2020年,鄱阳湖湿地植被EVI最高值在全年及春、秋两季分别为0.37、0.30和0.33,入湖河流三角洲及碟形洼地边滩是其生产力中心;春季EVI最高值在此区域高于秋季,而在湖心区低于秋季。(2)三峡运行后的湿地植被生产力变化在全年及春、秋两季均有极大空间异质性,在湖心深泓线附近显著增加,而在入湖河流三角洲及湿地边缘下降。春季EVI增长区域面积占比极大(84.2%),而秋季增长区面积占比较小(71.2%),即有较大面积区域EVI在秋季下降(38.8%)。(3)三峡运行后,鄱阳湖湿地植被生产力中心经历了原位增长、空间扩张以及湖心向转移3个阶段,最终完成了由支流三角洲向湖心区的转移。从总体来看,鄱阳湖湿地植被生产力在全年及春、秋季均呈增长趋势,增速分别为0.0035、0.0049和0.0028 EVI/a。本研究量化了后三峡工程时代的鄱阳湖湿地植被生产力变化,为该区域进一步的综合管理提供了数据支撑。;Since the operation of the Three Gorges Dam (TGD), the superposition of human activities and climate change has dramatically changed hydrological regimes of the Lake Poyang. These changes significantly affected the structure and function of the surrounding wetland ecosystems. However, vegetation variations in the Lake Poyang Wetland under this changing condition has not yet been systematically quantified. Hence, this study took the maximum EVI (enhanced vegetation index) as a proxy index to characterize vegetation productivity of the Lake Poyang Wetland, aiming to quantitatively reveal its changes in the post TGD era. The results show that: (1) During 2000 to 2020, the regional averaged maximum EVI of the wetland was 0.37, 0.30 and 0.33 in the whole year, spring, and autumn, respectively. River deltas of the lake tributaries and the dished depressions in the wetland were generally with higher EVI values compared to other areas, thus regarding as high productivity center of the wetland. In springs, the maximum EVI in the productivity center was higher than that in autumn, whereas it was lower than that in autumn in other areas with low EVI values such as the center of the lake. (2) Changes of vegetation productivity had great spatial heterogeneity for all the periods including the whole year, springs, and autumns. The maximum EVI values increased significantly in the central of the wetland (surrounding the thalweg), while the maximum EVI values decreased in river deltas of lake tributaries and wetland edge. The areas with increasing EVI values in spring accounted for about 84.2% of the whole wetland, while the area with increasing EVI in autumn accounted merely 71.2% of the wetland. That is, there was still a large proportion of the wetland with decreasing EVI in autumn (38.8%). (3) After TGD, the high productivity center of the wetland experienced three stages: in-situ growth, spatial expansion and towards lake center transfer, thus moved from river deltas to lake center areas. Overall, the maximum EVIs of the wetland showed an increasing trend, with a rate of 0.0035, 0.0049, and 0.0028 EVI/year for the annual, spring and autumn, respectively. The findings systematically quantified vegetation productivity changes of the Lake Poyang Wetland in the post TGD era. It also provided a scientific basis for proposing water resource management strategies to maintain the stability of wetland ecosystem.

Notes on the nesting and foraging behaviours of the Common Coot Fulica atra in the wetlands of Viluppuram District, Tamil Nadu, India

The nesting and foraging behaviours of the Common Coot Fulica atra were studied in the wetlands of Viluppuram District, Tamil Nadu during the breeding season. A total of 4,054 individuals of Common Coot including 467 juveniles and 1,327 nests were enumerated. Of the 1,327 nests, 1,191 were built on Ipomoea carnea vegetation and 136 on open water. The birds used twigs of Ipomoea carnea and various parts of eight other plant species as nest material. The nests were elliptical in shape, with flattened upper surfaces containing nest cup and a ramp-like structure each. 49.96 % of nests were found within 50 m distance from the edge of wetlands. A total of 16 plant species were identified as food sources including five algal species, such as Aphanothece stagnina, Spirogyra irregularis, Chara flaccida, C. vulgaris, and C. zeylanica. The Common Coots maintained strict territory during the breeding season and no other water birds were observed in the vicinity of their nesting and foraging sites. Even after completion of the breeding season, sporadic nesting was observed by a few pairs till June 2022.

Living on the edge: How traits of ecosystem engineers drive bio-physical interactions at coastal wetland edges

Salt marshes and mangrove forests provide critical ecosystem services such as reduced sediment erosion and increased hydrodynamic buffering. Sediment transport and hydrodynamics can be influenced by specific functional traits of the plants (for example, flexibility vs. rigidity) and community traits (for example, spatial density). While there is a growing body of literature on plant trait and hydrodynamic interactions, direct comparative studies of sediment transport and scour development in and around intertidal wetland edges are scarce. In this study we systematically compared the effects of plant traits on sediment budgets around the lateral edges of intertidal wetlands under controlled hydrodynamic and sedimentary conditions using full scale vegetation mimics with contrasting flexibilities and densities. Experiments were carried out in a large-scale flume, using two spatial densities each of flexible and rigid vegetation mimics. We measured unconsolidated sedimentary bed-level changes in experimental runs using waves only, currents only, and waves combined with currents. Both mimic types dampened the energy of the incoming flow, highlighting the role of rigid and flexible aquatic vegetation in providing coastal protection. The rigid vegetation mimics’ lateral edge experienced larger velocities, more energetic turbulence, and local scour around individual stems. Scour around stems could influence the lateral expansion of the rigid vegetation ecosystem by reducing sediment stability and thus decreasing seedling establishment success. The flexible plant mimics produced lower turbulence at their leading edge, which resulted in sediment being deposited over a shorter distance into the patch than in the rigid mimics. Decreased vegetation density caused reduced sediment erosion at the leading edge and less sediment accumulation within the vegetation patches for both the rigid and flexible mimics. The hydrodynamic and sedimentary processes identified for both ecosystems are linked to different feedbacks. A positive feedback was identified in which vegetation attenuates hydrodynamic energy allowing sediment accumulation within the patch. A negative feedback was identified where large velocities caused flow divergence and erosion outside of the vegetation, and would therefore compromise its lateral expansion. High densities of rigid vegetation enhance this negative feedback. Lower density flexible vegetation, however, combined with less energetic hydrodynamic conditions facilitate the expansion of vegetation patches as they cause less flow divergence and therefore less erosion. The strong flow divergence observed in the rigid vegetation cases highlight their importance for buffering hydrodynamics but at the cost of increased erosion within the front end of patches and along their lateral edges.

Prairie wetlands as sources or sinks of nitrous oxide: Effects of land use and hydrology

National and global greenhouse gas (GHG) budgets are continually being refined as data become available. Primary sources of the potent GHG nitrous oxide (N2O) include agricultural soil management and burning of fossil fuels, but comprehensive N2O budgets also incorporate less prominent factors such as wetlands. Freshwater wetland GHG flux estimates, however, have high uncertainty, and wetlands have been identified as both sources and sinks. Here, we analyzed a regional database of >26,000 N2O chamber flux measurements sampled across >150 wetlands from the Prairie Pothole Region (PPR) in the Great Plains of North America. Our goal was to identify important land use and hydrologic drivers of N2O flux to help reduce uncertainty in N2O models, and to incorporate these drivers into an upscaled estimate of wetland N2O emissions from the U.S. portion of the PPR. Within individual wetlands, exposed soils with no standing water, such as along wetland edges, were hotspots that accounted for greater than 90% of wetland N2O emissions. In contrast wet (i.e., ponded) areas had minimal or negative N2O flux. N2O flux from wetlands nested within croplands (16.3–17.3 μg N2O m−2 hr−1) was, in some instances, nearly double that from wetlands within grasslands (9.2–14.4 μg N2O m−2 h−1). We estimated that seasonal N2O flux from PPR wetlands equated to roughly 0.2% (1.04 Tg CO2 equivalents) of the U.S. N2O budget (c. 2019). Overall, even though PPR wetlands are a small net source of N2O to the atmosphere, their emissions are negligible relative to agricultural soil management. Policy and management to restore wetland hydrology and surrounding uplands from cropland to grasslands can reduce landscape N2O fluxes. Future activities focused on wetland N2O flux would benefit from inclusion of adjacent land use and hydrologic factors, as well as from incorporation of temporally dynamic ponded wetland areas.

Habitat preferences of adult Canada Jays (Perisoreus canadensis) during the post-breeding period in Algonquin Provincial Park, Ontario, Canada

Habitat preferences in animals are often examined during the breeding period when individuals are easier to observe. However, habitat use may change once young become independent and if resource availability shifts with seasonality. While Canada Jays ( Perisoreus canadensis (Linnaeus, 1766)) in Algonquin Provincial Park, Ontario, Canada, have been studied for several decades, there is no information on habitat use outside of the fall and late-winter nesting period, where they primarily used conifer forests. Using radio telemetry and resource selection functions comparing used versus available habitats, we estimated home-range size and habitat preferences of 12 adult Canada Jays ( n = 334 locations) in the spring and summer. Mean (±SD) home-range size from minimum convex polygons was 84 (±48 ha) and ranged from 35 to 201 ha. Canada Jays strongly preferred forest–wetland edges, showed a weak preference for coniferous forests, a corresponding weak avoidance of shade-tolerant hardwood forests, and used mixed forest and wetlands in proportion to their availability. Our results suggest that, while adult Canada Jays use multiple types of habitat during the post-breeding period, they also key into forest–wetland edges, likely to take advantage of emergent prey while remaining near forested areas to maximize protection from predators.

HABITAT USE AND WINTER SITE FIDELITY OF LINCOLN’S SPARROW (MELOSPIZA LINCOLNII) IN THE LOWER RIO GRANDE VALLEY OF TEXAS

HABITAT USE AND WINTER SITE FIDELITY OF LINCOLN’S SPARROW (<i>MELOSPIZA LINCOLNII</i>) IN THE LOWER RIO GRANDE VALLEY OF TEXAS

Seaside Recreation Ground: A Multi-Proxy Palaeoenvironmental Investigation on the Coastal Edge of the Willingdon Levels, Eastbourne, East Sussex, UK

ABSTRACT The Willingdon Levels hold some of the best-preserved prehistoric archaeological and palaeoenvironmental remains in south-east England. This study aims to characterise the previously unexplored coastal limits of the Willingdon Peat and compare the chronology with known sites. The degree of anthropogenic influence on vegetation cover in prehistory is of significant interest to archaeologists, and this paper aims to strengthen the case for human-induced landscape alteration surrounding the Willingdon Levels in the Bronze Age. Lithological, palynological, entomological, ostracod, foraminifera, diatom and radiocarbon analyses were applied to a sequence of deposits at Seaside Recreation Ground. This paper palaeoenvironmentally reconstructs the coastal edge of the Willingdon wetland and proposes a timing for the main period of peat initiation that occurred across the Levels. A decline in woodland taxa and the presence of cereal pollen allude to human presence in the landscape. The results have contributed to the Willingdon Levels modelling project.

Ecohydrological costs and benefits of common carp, the dominant species in a `novel' tropical lake ecosystem

'Novel ecosystem' is a concept which was introduced in the 21st Century to describe ecosystems heavily modified by humans, about 15 years after 'ecohydrology' had been introduced as concept within UNESCO IHP, to facilitate the sustainable management of aquatic ecosystems by humans and about 5 years after the concept of IHP 'Demonstration Sites' had been introduced to promote ecohydrological principles globally. The tropical African Lake Naivasha became a DS initially to demonstrate the importance of papyrus-dominated wetland edges for nutrient and climate control in an aquatic ecosystem driven by regional hydrological instability, but it already represented a ‘novel’ ecosystem.This paper critically examines the consequences of the aquatic food web restructuring by the major alien species, common carp (Cyprinus carpio L.) – whose arrival is directly an ecological consequence of hydrological instability. Carp were first recorded in Lake Naivasha in 2001 and reached dominance in the commercial fishery by 2003. The costs and benefits of its dominance are shown by comparing aspects of the ecosystem state before and after arrival. These were hypothesized and tested by comparing data in 2012-4 with data gathered in the 1990s using the same methodologies. Carp have filled a previously vacant benthivorous niche. The species achieved moderate density but has not caused ecological disruption. Overall, carp has been a positive contributor to the local community. More intensive management strategies, better post-harvest processing and new marketing techniques need to be developed to enhance financial gain.

Natural vegetation regeneration from soil seed banks in the cultivated edges of Sudd wetlands in Juba, Southern Sudan

Soil seed banks are important for regeneration of degraded wetlands ecosystems. The Sudd wetlands of Juba city have long been encroached for crop cultivation. Seedling germination was monitored in a greenhouse to establish possible natural regeneration in Mindiari, Rejaf and Roton wetlands in the Sudd. Sixty-four species germinated from the soil seed bank of which 12.5% were dominated by Cyperus difformis and Typha capensis. The findings showed that median wetland species richness in Mindiari was 1.5 (interquartile range = 0.75?3.5), Rejaf 2.5 (interquartile range = 1.0 ? 4.0), Roton 3 (interquartile range = 1.0 ? 5.0) while median Shannon-Wiener diversity was 1.5 (1.14 ?1.73), 1.43 (1.01?1.66), 1.15 (0.98?1.67) for Mindiari, Rejaf and Roton respectively. Both the median seed species richness and diversity were not significantly different among the study wetlands. The median of seed density (56.1) was significantly higher in Roton than in Mindiari (36.7) and Rejaf (29.4) wetlands. The NMDS results showed that species composition of Mindiari and Rejaf was different from Roton. It is concluded that growing crops in wetlands did not influence species richness and diversity but it reduced seed density and altered species composition. Although wetland species were not significantly different in the three-wetland categories, dominance of canopy species belonging to Typhaceae and Cyperaceae indicates that these species are resilient to cultivation and could facilitate natural regeneration of cultivated wetlands edges of the Sudd region in Juba. Further research should examine effect of cultivation duration and flooding regimes on soil seed bank species richness, diversity, and density and composition.