Emergent Wetland Research Articles

Estimating methane emissions using vegetation mapping in the taiga–tundra boundary of a north-eastern Siberian lowland

Taiga–tundra boundary ecosystems are affected by climate change. Methane (CH4) emissions in taiga–tundra boundary ecosystems have sparsely been evaluated from local to regional scales. We linked in situ CH4 fluxes (2009–2016) with vegetation cover, and scaled these findings to estimate CH4 emissions at a local scale (10 × 10 km) using high-resolution satellite images in an ecosystem on permafrost (Indigirka lowland, north-eastern Siberia). We defined nine vegetation classes, containing 71 species, of which 16 were dominant. Distribution patterns were affected by microtopographic height, thaw depth and soil moisture. The Indigirka lowland was covered by willow-dominated dense shrubland and cotton-sedge-dominated wetlands with sparse larch forests. In situ CH4 emissions were high in wetlands. Lakes and rivers were CH4 sources, while forest floors were mostly neutral in terms of CH4 emission. Estimated local CH4 emissions (37 mg m−2 d−1) were higher than those reported in similar studies. Our results indicate that: (i) sedge and emergent wetland ecosystems act as hot spots for CH4 emissions, and (ii) sparse tree coverage does not regulate local CH4 emissions and balance. Thus, larch growth and distribution, which are expected to change with climate, do not contribute to decreasing local CH4 emissions.

Linking people to coastal habitats: A meta-analysis of final ecosystem goods and services on the coast

Coastal ecosystem goods and services (EGS) have steadily gained traction in the scientific literature over the last few decades, providing a wealth of information about underlying coastal habitat dependencies. This meta-analysis summarizes relationships between coastal habitats and final ecosystem goods and services (FEGS) users. Through a “weight of evidence” approach synthesizing information from published literature, we assessed habitat classes most relevant to coastal users. Approximately 2800 coastal EGS journal articles were identified by online search engines, of which 16% addressed linkages between specific coastal habitats and FEGS users, and were retained for subsequent analysis. Recreational (83%) and industrial (35%) users were most cited in literature, with experiential-users/hikers and commercial fishermen most prominent in each category, respectively. Recreational users were linked to the widest diversity of coastal habitat subclasses (i.e., 22 of 26). Whereas, mangroves and emergent wetlands were most relevant for property owners. We urge EGS studies to continue surveying local users and identifying habitat dependencies, as these steps are important precursors for developing appropriate coastal FEGS metrics and facilitating local valuation. In addition, understanding how habitats contribute to human well-being may assist communities in prioritizing restoration and evaluating development scenarios in the context of future ecosystem service delivery.

Inland wetlands mapping and vulnerability assessment using an integrated geographic information system and remote sensing techniques

The understanding of inland wetlands’ distribution and their level of vulnerability is important to enhance management and conservation efforts. The aim of the study was to map inland wetlands and assess their distribution pattern and vulnerability to natural and human disturbances such as climate change (temperature increase) and human activities by the year 2080. Inland wetland types i.e. forested/shrub, emergent and open water bodies were classified and mapped using maximum likelihood standard algorithm. The spatial distribution pattern of inland wetlands was examined using average nearest neighbor analysis. A weighted geospatial vulnerability analysis was developed using variables such as roads, land cover/ land use (developed and agricultural areas) and climate data (temperature) to predict potentially vulnerable inland wetland types. Inland wetlands were successfully classified and mapped with overall accuracy of about 73 percent. Clustered spatial distribution pattern was found among all inland wetland types with varied degree of clustering. The study found about 13 percent of open water bodies, 11 percent of forested/shrub and 7 percent of emergent wetlands potentially most vulnerable to human and natural stressors. This information could be used to improve wetland planning and management by wetland managers and other stakeholders.

Spatial and Temporal Changes in Emergent Marsh and Associated Marsh Birds of the Lower Mobile-Tensaw River Delta in Alabama, USA

Sea-level rise, suppression of natural disturbances, and human development of coastal lands have influenced the capacity of tidal marshes to maintain quality habitat for wildlife, including coastal marsh birds. This study targeted the oligohaline marshes of the lower Mobile-Tensaw River Delta, Alabama, USA with the objective of assessing landcover and marsh bird distributional changes relative to two sampling periods, 2004 and 2015. We employed analysis of aerial imagery and standardized marsh bird surveys to derive information on the densities of common gallinule (Gallinula galeata), king rail (Rallus elegans), and least bittern (Ixobrychus exilis) during each sampling period. A gradient of land change was apparent where the northernmost and the southeastern portions of the study area lost land from 2006 to 2013 while the extent of emergent marsh wetland increased in the south and decreased in the north. Average densities of all three birds declined between survey periods (common gallinule 15%, king rail 50%, least bittern 38%). Changes in the distributions of these marsh birds reflected change in landform and emergent marsh habitat. This study reveals that tidal wetlands and associated communities do not change through linear processes. Rather, coastal wetlands may show distinct patterns surrounding areas of accretion, and loss.

Integrating Drone Imagery into High Resolution Satellite Remote Sensing Assessments of Estuarine Environments

Very high-resolution satellite imagery (≤5 m resolution) has become available on a spatial and temporal scale appropriate for dynamic wetland management and conservation across large areas. Estuarine wetlands have the potential to be mapped at a detailed habitat scale with a frequency that allows immediate monitoring after storms, in response to human disturbances, and in the face of sea-level rise. Yet mapping requires significant fieldwork to run modern classification algorithms and estuarine environments can be difficult to access and are environmentally sensitive. Recent advances in unoccupied aircraft systems (UAS, or drones), coupled with their increased availability, present a solution. UAS can cover a study site with ultra-high resolution (<5 cm) imagery allowing visual validation. In this study we used UAS imagery to assist training a Support Vector Machine to classify WorldView-3 and RapidEye satellite imagery of the Rachel Carson Reserve in North Carolina, USA. UAS and field-based accuracy assessments were employed for comparison across validation methods. We created and examined an array of indices and layers including texture, NDVI, and a LiDAR DEM. Our results demonstrate classification accuracy on par with previous extensive fieldwork campaigns (93% UAS and 93% field for WorldView-3; 92% UAS and 87% field for RapidEye). Examining change between 2004 and 2017, we found drastic shoreline change but general stability of emergent wetlands. Both WorldView-3 and RapidEye were found to be valuable sources of imagery for habitat classification with the main tradeoff being WorldView’s fine spatial resolution versus RapidEye’s temporal frequency. We conclude that UAS can be highly effective in training and validating satellite imagery.

Temporal (1970–2016) changes in human pressures and wetland response in the St. Lawrence River (Québec, Canada)

Temporal changes (1970–2016) in St. Lawrence River wetlands were assessed between Cornwall and Québec (≈400 km) to assess wetland response to cumulative anthropogenic pressures in the watershed. Emergent wetlands area and biomass of submerged aquatic vegetation (SAV) were contrasted among five regions subjected to sharply different water level/discharge regime (stabilized, semi-natural, tidal), nutrient concentrations and shoreline use (rural to urbanized). Between 1970 and 2016, over the growing season (April–Sept.), St. Lawrence River mean water level at Sorel dropped by ≈1 m and mean water temperature increased by ≈3 °C. Reductions in phosphorus concentrations (by ≈2-fold) were observed over time both in water and in SAV tissues, in phase with improvements of urban wastewater treatment and P-reduction in upstream Lake Ontario. Nitrate concentrations in water increased and SAV biomass decreased between the 1970s and 2008 in the downstream regions of Lake Saint-Pierre and fluvial corridor subjected to the cumulative impacts from urban centers and intensively farmed watersheds. Over the 1970–2010 period, dropping water levels yielded slightly increasing wetland areas, owing to the downslope colonization of emergent and submerged plants. In urbanized regions, emergent wetlands shifted towards drier assemblages dominated by invasive reed species. Encroachment of wetlands by agriculture accounted for most wetland losses in rural Lake Saint-Pierre, which holds the single largest area (197 km2) of continuous wetland habitat of the entire watershed. Our results highlight the strong response of riverine wetlands to a wide range of human pressures, including dropping water levels, changing nutrient concentrations, rising population and intensifying agriculture.

A Unifying Approach to Classifying Wetlands in the Ontonagon River Basin, Michigan, Using Multi-temporal Landsat-8 OLI Imagery

Accurate spatial information is critical to the assessment and protection of wetlands in the context of human intervention and global climate change. However, it is challenging to map and monitor wetland vegetation classes with satisfactory results because of their highly seasonal dynamics, spatial heterogeneity, and spectral similarity. This paper examines the effectiveness of various classification approaches commonly employed in wetland mapping, including the support vector machine (SVM) algorithm, maximum likelihood classifier (MLC), classification and regression tree (CART) and other remote sensing indices, by using multi-temporal Landsat-8 Operational Land Imager (OLI) spectral data and end-member fraction data as well as terrain data. These different mapping approaches were compared in the Ontonagon River drainage basin in upper Michigan, USA, where easily-confused wetland types such as forested wetland, palustrine scrub/shrub wetland, and palustrine emergent wetland are extensively distributed. The results show that multi-temporal data sets can reduce the classification omission caused by the highly seasonal dynamic of wetlands. The spatial heterogeneity can partly be characterized by using end-member fraction maps. Classification of the fraction maps had better results than that using the original spectral data, which implies that the selection of data inputs could be more important than the selection of classifiers. While each algorithm has its own capability of discriminating specific wetland types, CART showed relatively better classification results than the others due to its compatibility and lack of assumptions about data normal distribution. Finally, the authors developed a decision tree method (called DTM), which adopted the satisfactory resultant classification of specific wetland types using MLC and SVM classification, to update the wetland map of Ontonagon River Basin with acceptable accuracy (overall accuracy of 89% and kappa coefficients of 0.89).

A comparison of airborne hyperspectral-based classifications of emergent wetland vegetation at Lake Balaton, Hungary

ABSTRACTEarth observation has rapidly evolved into a state-of-the-art technology providing new capabilities and a wide variety of sensors; nevertheless, it is still a challenge for practitioners external to a specialized community of experts to select the appropriate sensor, define the imaging mode requirements, and select the optimal classifier or retrieval method for the task at hand. Especially in wetland mapping, studies have relied largely on vegetation indices and hyperspectral data to capture vegetation attributes. In this study, we investigate the capabilities of a concurrently acquired very high spatial resolution airborne hyperspectral and lidar data set at the peak of aquatic vegetation growth in a nature reserve at Lake Balaton, Hungary. The aim was to examine to what degree the different remote-sensing information sources (i.e. visible and near-infrared hyperspectral, vegetation indices and lidar) are contributing to an accurate aquatic vegetation map. The results indicate that de-noised hyperspectral information in the visible and very near-infrared bands (400–1000 nm) is performing most accurately. Inclusion of lidar information, hyperspectral infrared bands (1000–2500 nm), or extracted vegetation indices does not improve the classification accuracy. Experimental results with algorithmic comparisons show that in most cases, the Support Vector Machine classifier provides a better accuracy than the Maximum Likelihood.

Checklist of bees (Hymenoptera: Apoidea) from managed emergent wetlands in the lower Mississippi Alluvial Valley of Arkansas.

BackgroundHere we present the results from a two-year bee survey conducted on 18 managed emergent wetlands in the lower Mississippi Alluvial Valley of Arkansas, USA. Sample methods included pan traps, sweep netting and blue-vane traps. We document 83 bee species and morphospecies in 5 families and 31 genera, of which 37 species represent first published state records for Arkansas. The majority of species were opportunistic wetland species; only a small number were wetland-dependent species or species largely restricted to alluvial plains.New informationWe present new distributional records for bee species not previously recorded in managed emergent wetlands and report specimens of thirty-seven species for which no published Arkansas records exist, expanding the known ranges of Ceratina cockerelli, Diadasia enavata, Lasioglossum creberrimum, Svastra cressonii and Dieunomia triangulifera. We also distinguish opportunistic wetland bee species from wetland-dependent and alluvial plain-restricted species.

The paleoecology of Pleistocene birds from Middle Bed II, at Olduvai Gorge, Tanzania, and the environmental context of the Oldowan-Acheulean transition

Fossil bird data (community composition and taphonomic profiles) are used here to infer the environmental context of the Oldowan-Acheulean transitional period at Olduvai Gorge, Tanzania. This is the first comprehensive report on the Middle Bed II avifauna and includes fossils excavated by the Olduvai Geochronology and Archaeology Project (OGAP) and recently rediscovered fossils collected by Mary Leakey. Crane, ibis, darter, owl, raptor, crow, and vulture are reported from Bed II for the first time. The presence of these taxa, absent earlier in this Bed, point to a general opening and drying of the landscape with grassland and open woodland expansion. Taxa associated with dense, emergent wetland vegetation, such as dabbling ducks and rails, are uncommon and less diverse than earlier in Bed II. This suggests more mature wetlands with clearer waters. Cormorants continue to be common, but are less diverse. Cormorants and other roosting taxa provide evidence of trees in the area. Compared to lowermost Bed II, the Middle to Upper Bed II landscape is interpreted here as more open and drier (but not necessarily more arid), with matured wetlands, scattered trees, and a greater expansion of grasslands.

The tensile root strength of five emergent coastal macrophytes

The root biomass of emergent macrophytes in coastal wetlands is essential for anchorage and erosion protection. The tensile root strength of these plants is an important component in determining the strength of coastal wetland soils. We made 1449 tensile strength measurements of roots <1.5 mm in diameter for five species of emergent wetland macrophytes (Spartina alterniflora, S.patens, Panicum hemitomon, Schoenoplectus americanus, and Sagittaria lancifolia) collected from six sites in three coastal estuaries. An analysis of variance revealed that the tensile root strength of dead and live roots for all species decreased with depth and that dead roots were stronger than live roots of the same diameter (p < 0.05). There was low variation in the mean tensile root strength among all sites. The S. alterniflora dead roots from the Barataria Basin site, however, were stronger than those from the Lake Pontchartrain site and the S. patens live and dead roots collected from Breton Sound were stronger than those from a nearby site in the same watershed. Wetland root samples exposed to partially-treated sewage effluent were considerably smaller than roots collected from the nearby reference wetland. Further investigation is warranted to ascertain the nature of the factors that causing these variations in tensile root strength with depth, between live and dead roots and with nutrient exposure

Hydrological Conditions Affect the Interspecific Interaction between Two Emergent Wetland Species.

Hydrological conditions determine the distribution of plant species in wetlands, where conditions such as water depth and hydrological fluctuations are expected to affect the interspecific interactions among emergent wetland species. To test such effects, we conducted a greenhouse experiment with three treatment categories, interspecific interaction (mixed culture or monoculture), water depth (10 or 30 cm depth), and hydrological fluctuation (static or fluctuating water level), and two common emergent wetland plant species, Scirpus planiculumis Fr. (Cyperaceae) and Phragmites australis var. baiyangdiansis (Gramineae). An increase in the water depth significantly restrained the growth of both S. planiculumis and P. australis, while hydrological fluctuations did not obviously alter the growth of either species. In addition, both water depth and hydrological fluctuations significantly affected the interspecific interaction between these two wetland species. P. australis benefited from interspecific interaction under increasing water depth and hydrological fluctuations, and the RII values were clearly positive for plants grown at a water depth that fluctuated around 30 cm. The results may have some implications for understanding how S. planiculumis and P. australis, as well as wetland communities, respond to the natural variation or human modification of hydrological conditions.

On Factors Influencing Air‐Water Gas Exchange in Emergent Wetlands

AbstractKnowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographic or limnological settings are inappropriate under conditions found in wetlands. Here six measurements of gas transfer velocities are made with SF6 tracer release experiments in three different years in the Everglades, a subtropical peatland with surface water flowing through emergent vegetation. The experiments were conducted under different flow conditions and with different amounts of emergent vegetation to determine the influence of wind, rain, water flow, waterside thermal convection, and vegetation on air‐water gas exchange in wetlands. Measured gas transfer velocities under the different conditions ranged from 1.1 cm h−1 during baseline conditions to 3.2 cm h−1 when rain and water flow rates were high. Commonly used wind speed/gas exchange relationships would overestimate the gas transfer velocity by a factor of 1.2 to 6.8. Gas exchange due to thermal convection was relatively constant and accounted for 14 to 51% of the total measured gas exchange. Differences in rain and water flow among the different years were responsible for the variability in gas exchange, with flow accounting for 37 to 77% of the gas exchange, and rain responsible for up to 40%.

Modeling the effects of thiamethoxam on Midwestern farm ponds and emergent wetlands.

Potential toxic effects of thiamethoxam on nontarget organisms and the community structure of a generic Midwestern farm pond and emergent wetland were assessed using 2 versions of the comprehensive aquatic system model: CASMGFP , a generic farm pond model, and CASMGWL , a generic wetland model. The CASMGFP and CASMGWL are integrated bioenergetics-based and habitat quality models that describe the daily biomass values of selected producer and consumer populations representative of generalized Midwestern farm ponds and emergent wetlands. The CASMGFP demonstrated the ability to reproduce values of population biomass reported for Midwestern (and other) pond ecosystems; the CASMGWL provided a similar modeling capability for Midwestern emergent wetlands. Lethal and sublethal effects of thiamethoxam were modeled as extrapolations of laboratory toxicity assays using the CASMGFP and the CASMGWL . Time series of daily environmental concentrations of thiamethoxam constructed for 6 regional pesticide applications across the United States failed to produce any calculated impacts on modeled population biomass or changes in community structure of modeled trophic guilds in the CASMGFP or the CASMGWL . However, evaluation of systematically increased daily concentrations demonstrated the ability of both models to simulate direct and indirect toxic effects of this pesticide. The present model study suggests that process-based food web/ecosystem models can be used to characterize the potential ecological effects of thiamethoxam on generalized farm pond and emergent wetland ecosystems. Environ Toxicol Chem 2018;37:738-754. © 2017 SETAC.

Parallelized, Aerobic, Single Carbon-Source Enrichments from Different Natural Environments Contain Divergent Microbial Communities.

Microbial communities that inhabit environments such as soil can contain thousands of distinct taxa, yet little is known about how this diversity is maintained in response to environmental perturbations such as changes in the availability of carbon. By utilizing aerobic substrate arrays to examine the effect of carbon amendment on microbial communities taken from six distinct environments (soil from a temperate prairie and forest, tropical forest soil, subalpine forest soil, and surface water and soil from a palustrine emergent wetland), we examined how carbon amendment and inoculum source shape the composition of the community in each enrichment. Dilute subsamples from each environment were used to inoculate 96-well microtiter plates containing triplicate wells amended with one of 31 carbon sources from six different classes of organic compounds (phenols, polymers, carbohydrates, carboxylic acids, amines, amino acids). After incubating each well aerobically in the dark for 72 h, we analyzed the composition of the microbial communities on the substrate arrays as well as the initial inocula by sequencing 16S rRNA gene amplicons using the Illumina MiSeq platform. Comparisons of alpha and beta diversity in these systems showed that, while the composition of the communities that grow to inhabit the wells in each substrate array diverges sharply from that of the original community in the inoculum, these enrichment communities are still strongly affected by the inoculum source. We found most enrichments were dominated by one or several OTUs most closely related to aerobes or facultative anaerobes from the Proteobacteria (e.g., Pseudomonas, Burkholderia, and Ralstonia) or Bacteroidetes (e.g., Chryseobacterium). Comparisons within each substrate array based on the class of carbon source further show that the communities inhabiting wells amended with a carbohydrate differ significantly from those enriched with a phenolic compound. Selection therefore seems to play a role in shaping the communities in the substrate arrays, although some stochasticity is also seen whereby several replicate wells within a single substrate array display strongly divergent community compositions. Overall, the use of highly parallel substrate arrays offers a promising path forward to study the response of microbial communities to perturbations in a changing environment.

Surrounding land cover types as predictors of palustrine wetland vegetation quality in conterminous USA

The loss of wetland habitats and their often-unique biological communities is a major environmental concern. We examined vegetation data obtained from 380 wetlands sampled in a statistical survey of wetlands in the USA. Our goal was to identify which surrounding land cover types best predict two indices of vegetation quality in wetlands at the regional scale. We considered palustrine wetlands in four regions (Coastal Plains, North Central East, Interior Plains, and West) in which the dominant vegetation was emergent, forested, or scrub-shrub. For each wetland, we calculated weighted proportions of eight land cover types surrounding the area in which vegetation was assessed, in four zones radiating from the edge of the assessment area to 2km. Using Akaike's Information Criterion, we determined the best 1-, 2- and 3-predictor models of the two indices, using the weighted proportions of the land cover types as potential predictors. Mean values of the two indices were generally higher in the North Central East and Coastal Plains than the other regions for forested and emergent wetlands. In nearly all cases, the best predictors of the indices were not the dominant surrounding land cover types. Overall, proportions of forest (positive effect) and agriculture (negative effect) surrounding the assessment area were the best predictors of the two indices. One or both of these variables were included as predictors in 65 of the 72 models supported by the data. Wetlands surrounding the assessment area had a positive effect on the indices, and ranked third (33%) among the predictors included in supported models. Development had a negative effect on the indices and was included in only 28% of supported models. These results can be used to develop regional management plans for wetlands, such as creating forest buffers around wetlands, or to conserve zones between wetlands to increase habitat connectivity.

First reports of turtle tracks from the Williams Fork Formation (‘Mesaverde’ Group), Upper Cretaceous (Campanian) of western Colorado

Tetrapod footprints from the coal-bearing, Upper Cretaceous beds of Colorado, Wyoming and Utah, loosely known as the “Mesaverde” Group, have been reported and collected, mostly for Utah and Colorado institutions since the 1920s. However, it has only been in recent decades that the track assemblages have been reexamined in any detail. The results of such work indicate that the assemblages are more diverse than hitherto recognized. Here we report the first assemblages of turtle tracks that come from an important locality in the Williams Fork Formation in western Colorado, which also yields diverse dinosaur tracks. Collectively the turtle track-dominated assemblages reveal more than 150 swim tracks registered on a total surface area of ∼3 m2, indicating a density of ∼50 tracks/m2, and a fauna in which turtles were a significant component. The swim tracks mostly show strong preferred orientations suggesting the influence of directional currents. The co-occurrence of turtle tracks swim tracks and dinosaur tracks in the local facies indicates a mosaic of subaqueous and emergent wetland substrates consistent with the interpretation of these track-rich, coal- and plant-rich sequences as swampy, coastal plain habitats. Current evidence suggests these Upper Cretaceous tracks are typically larger than those known from the ‘mid’ and Lower Cretaceous in North America and elsewhere. Thus, the Williams Fork paleoenvironments may have represented settings conducive to habitation by large turtles.

Biotic homogenization of regional wetland plant communities within short time‐scales in the presence of an aggressive invader

Abstract Biotic homogenization (BH), a process by which β‐diversity erodes, represents a severe threat to biodiversity. Wetland plant communities may be especially susceptible to BH; however, this process has rarely been quantified and represents just one of many possible outcomes of compositional change. Likewise, few studies have used more than two timepoints to investigate BH as a dynamic temporal process. To address these issues, we quantified changes in β‐diversity amongst 48 herbaceous emergent wetlands across a landscape over four timepoints from 1997 to 2015. Pairwise occurrence‐ and abundance‐based dissimilarity metrics were used to quantify β‐diversity. Nonmetric multidimensional scaling was used to map these changes in compositional similarity through time, and repeated measures ANOVA via randomization was used to test for a significant effect of time on β‐diversity. Results indicated that herbaceous emergent wetlands homogenized in Illinois over 15 years due to the increased presence and abundance of Phalaris arundinacea and the decline of several other species. Temporal dynamics of β‐diversity differed between occurrence‐ and abundance‐based analyses. Synthesis. Using both presence–absence and abundance data to investigate BH helped avoid underestimating the impact of BH on β‐diversity, and drew attention to different temporal dynamics in β‐diversity at these two resolutions of community structure. This study highlights challenges associated with investigating BH, such as problems documenting the process where homogenization is not occurring in every site in a region, or where sites are converging towards more than one homogenized state. Incorporating concepts like alternative stable states may be helpful in resolving these issues, and present a more realistic picture of ecological change.

Remote Sensing for Wetland Mapping and Historical Change Detection at the Nisqually River Delta

Coastal wetlands are important ecosystems for carbon storage and coastal resilience to climate change and sea-level rise. As such, changes in wetland habitat types can also impact ecosystem functions. Our goal was to quantify historical vegetation change within the Nisqually River watershed relevant to carbon storage, wildlife habitat, and wetland sustainability, and identify watershed-scale anthropogenic and hydrodynamic drivers of these changes. To achieve this, we produced time-series classifications of habitat, photosynthetic pathway functional types and species in the Nisqually River Delta for the years 1957, 1980, and 2015. Using an object-oriented approach, we performed a hierarchical classification on historical and current imagery to identify change within the watershed and wetland ecosystems. We found a 188.4 ha (79%) increase in emergent marsh wetland within the Nisqually River Delta between 1957 and 2015 as a result of restoration efforts that occurred in several phases through 2009. Despite these wetland gains, a total of 83.1 ha (35%) of marsh was lost between 1957 and 2015, particularly in areas near the Nisqually River mouth due to erosion and shifting river channels, resulting in a net wetland gain of 105.4 ha (44%). We found the trajectory of wetland recovery coincided with previous studies, demonstrating the role of remote sensing for historical wetland change detection as well as future coastal wetland monitoring.

Mallard survival, movements, and habitat use during autumn in Illinois

ABSTRACTThe Illinois River Valley (IRV) in central Illinois, USA, provides migratory stopover habitat for millions of waterfowl during autumn and spring in the Mississippi Flyway. Mallards (Anas platyrhynchos) are the most abundant species of waterfowl during autumn migration and the most harvested duck in Illinois. We investigated mallard migration ecology in central Illinois, USA, to address information needs of biologists and managers in the Upper Mississippi River and Great Lake Region Joint Venture and Illinois Department of Natural Resources. Our objectives were to document daily movements and identify factors affecting inter‐wetland movements, investigate lengths of foraging flights, assess home range size during stopover, describe habitat use and identify factors associated with wetland use, estimate survival and cause specific mortality, and evaluate proportional use of refuges and areas open to hunting in and nearby the IRV by mallards. We employed standard radio‐telemetry techniques to achieve our objectives during autumns and early winters 2009 and 2010 (n = 86 F and 56 M mallards). The mean movement distance between locations collected on consecutive days was 2,822 ± 120 (SE) m (n = 1,862; max. = 56,966 m) across age, sex, and months. Female mallards (n = 35) traveled 2,708 ± 191 m during evening foraging flights (n = 145) to agricultural fields and emergent marshes. Mean home range size (95% minimum convex polygon) was 21,306 ± 1,925 ha across sex and age classes (n = 81 mallards). We documented 43 mortalities of 142 radio‐marked mallards (2009: 28.2%; 2010: 32.3%) with 85.0% and 69.6% of deaths attributed to hunting in 2009 and 2010, respectively. Body condition, hunting period, age, year, minimum daily temperature, and daily movement distance were important variables affecting survival, but differences were most pronounced for year and hunting period. Overall survival was greater in 2010 (Ŝi = 0.62) than 2009 (Ŝi = 0.39) and daily survival rates were 0.8% and 0.4% greater during closed than open hunting periods in 2009 and 2010, respectively. Mallards used open water most frequently across years (49.4% daily locations), followed by corn (dryland, flooded, standing, or harvested; 16.3%), herbaceous (10.6%), woody (10.5%), and other wetlands and upland cover types. Use of areas closed to hunting was low (18.7%) and most diurnal locations of mallards occurred in wetlands open to hunting (81.3%; i.e., not designated as refuge by statute). Similar to diurnal habitat use, female mallards returning from evening foraging flights (n = 138) used areas open to hunting (81.9%) more than refuges (18.1%). Refuges that were primarily composed of open water received low use by autumn‐migrating mallards in the IRV. Restoration or rehabilitation of moist‐soil and emergent wetlands within statutory refuges protected from unnatural flood regimes may improve foraging habitat quality and increase survival for mallards and other ducks during migration. © 2017 The Wildlife Society.