"Wetlands"

Giblin, Shawn M.;Houser, Jeffrey N.;Sullivan, John F.;Langrehr, Heidi A.;Rogala, James T.;Campbell, Benjamin D.

doi: 10.1007/s13157-013-0508-8pmid: N/A

Abstract Duckweed and other free-floating plants (FFP) can form dense surface mats that affect ecosystem condition and processes, and can impair public use of aquatic resources. FFP obtain their nutrients from the water column, and the formation of dense FFP mats can be a consequence and indicator of river eutrophication. We conducted two complementary surveys of diverse aquatic areas of the Upper Mississippi River as an in situ approach for estimating thresholds in the response of FFP abundance to nutrient concentration and physical conditions in a large, floodplain river. Local regression analysis was used to estimate thresholds in the relations between FFP abundance and phosphorus (P) concentration (0.167 mg l−1), nitrogen (N) concentration (0.808 mg l−1), water velocity (0.095 m s−1), and aquatic macrophyte abundance (65 % cover). FFP tissue concentrations suggested P limitation was more likely in spring, N limitation was more likely in late summer, and N limitation was most likely in backwaters with minimal hydraulic connection to the channel. The thresholds estimated here, along with observed patterns in nutrient limitation, provide river scientists and managers with criteria to consider when attempting to modify FFP abundance in off-channel areas of large river systems.

Li, Wei;Cui, Lijuan;Zhang, Yan;Zhang, Manyin;Zhao, Xinsheng;Wang, Yifei

doi: 10.1007/s13157-013-0509-7pmid: N/A

Abstract A horizontal subsurface flow constructed wetland (HSSF-CW) was constructed to improve the water quality of an artificial lake in Beijing wildlife rescue and rehabilitation center, Beijing, China. Multiple Regression Analysis (MRA) and Artificial Neural Networks (ANNs) including Multilayer Perceptron (MLP) and Radial Basis Function (RBF) were used to model the treatment performance of total phosphorus (TP). In order to increase the model efficiency, input parameters were selected as influent TP concentration, hydraulic retention time, wastewater temperature, month of the year, porosity, area, precipitation and evapotranspiration based on the methods of principal component analysis (PCA) and redundancy analysis (RDA). Genetic algorithm and cross-validation were utilized to find the optimal network architecture and parameters for ANNs. The overall performance of the models was validated using different datasets from the case study spanning 3 years. The results implied that modeling using adequate but crucial parameters can provide an efficient and robust tool for predicting performance. By comparing the three models in terms of model fitness when applied to the prediction, ANNs seemed to be more efficient than MRA in modeling of the areal TP removal and RBF (R2: 0.829, p = 0.000) produced the most accuracy and efficiency indicating strong potential for modeling the TP treatment processes in HSSF-CW systems.

Hossain, Mahmood;Siddique, Mohammad Raqibul Hasan;Abdullah, S. M. Rubaiot;Saha, Sanjoy;Ghosh, Dinesh Chandra;Rahman, Md. Saidur;Limon, Sharif Hasan

doi: 10.1007/s13157-013-0510-1pmid: N/A

Abstract Release of nutrients and organic matter from mangrove litter during the leaching and decomposition processes play an important role in the biogeochemical cycling in mangrove ecosystems. Mass loss and nutrient dynamics associated with leaching and microbial decomposition of leaf litter of Heritiera fomes, Excoecaria agallocha, Ceriops decandra and Xylocarpus mekongensis were studied in the Sundarbans. The initial mass of H. fomes, E. agallocha, C. decandra and X. mekongensis leaf litter was significantly decreased to 11 %, 18 %, 21 % and 19 % respectively after 168 h of leaching process. Irrespectively, mass loss due to the microbial decomposition was higher for E. agallocha (97 %) followed by X. mekongensis (74 %), C. decandra (44 %) and H. fomes (42 %) after 7 months. Highest amount of N (3.29 mg/g) was released from leaf litter of C. decandra and the highest amount of P (1.69 mg/g) and K (16.36 mg/g) was released from E. agallocha. Comparatively higher amount of N (6.36 mg/g), P (2.68 mg/g) and K (16.41 mg/g) was released from the leaf litter of E. agallocha than others. Our results are useful for estimating the total flux of nutrients of mangrove forest ecosystem, especially where the studied mangrove species occur abundantly.

Davenport, Tara;Bart, David;Carpenter, Quentin

doi: 10.1007/s13157-013-0511-0pmid: N/A

Abstract The potential for land-use legacies to alter current wetland macrophyte communities and edaphic conditions are underexplored. Here we present results of a study describing associations among these factors in southern Wisconsin fens. Plant-community composition, hydrology, and nutrient availability data were recorded from 1) fens that had been plowed, 2) fens that have never been plowed, and 3) fens with plowed and never-plowed areas. Plowed fens had: 1) lower total species richness, 2) higher invasive species richness, 2) lower native graminoid richness, 3) lower shrub richness, 4) lower root-zone volumetric water content, and 5) higher available N and P then never-plowed fens. Most of these same relationships held when comparing plowed and never-plowed areas of the same fen. Non-metric Multidimensional Scaling revealed that the most important community gradient separates graminoid- and fen-specialist-rich communities from those dominated by invasive species. This gradient also separated plowed from never plowed plots. Accordingly, we believe that a history of plowing has fundamentally altered biotic and, potentially, abiotic conditions, with real consequences for wetland management and restoration.

Jeanson, Matthieu;Anthony, Edward J.;Dolique, Franck;Cremades, Caroline

doi: 10.1007/s13157-014-0512-7pmid: N/A

Abstract The Island of Mayotte, in the Indian Ocean, is characterized by a highly diversified shoreline comprising numerous mangrove zones set within a vast coral reef and lagoon complex. An analysis of aerial photographs covering the period from 1950 to 2011 shows marked variability in the evolution of these mangroves and clear spatial differences in the dynamics of these communities over the 60-year period of analysis. The northern part of the island shows stability or a slight increase in mangrove area whereas the southern and western shores of the island have been characterized by a clear regression in mangroves. The total surface area of mangroves on Mayotte (7.03 km2 in 2011) has diminished overall by about 5 %, a relatively moderate figure relative to the world context of increasing diminution of mangrove area. The pattern of evolution of mangroves in Mayotte is explained jointly by development pressures on the coast and spatial variability in mangrove recovery determined by hydrological conditions and exposure to waves on this reef-fringed island. Mayotte Island acquired the status of a French administrative department in 2011 subject to both French and European Community legislation on the environment. In consequence, mangroves are now much better protected from future urbanization.

Castro-Morales, Luz M.;Quintana-Ascencio, Pedro F.;Fauth, John E.;Ponzio, Kimberli J.;Hall, Dianne L.

doi: 10.1007/s13157-014-0513-6pmid: N/A

Abstract In recent decades, invasive shrubs have replaced herbaceous wetlands in many parts of the world. In Florida, the native shrub Salix caroliniana Michx. (Carolina willow) expanded its distribution throughout the upper St. Johns River, replacing herbaceous marshes with willow swamps. To identify ways to prevent its expansion, we experimentally tested the effects of watering regime, temperature, substrate, and seed source on willow germination and seedling survival. In growth chamber experiments, germination and survival were most affected by watering regime and were greatest in saturated, organic soils. Survival decreased with soil inundation and on drier, sandy soils. Variable texture and nutrient content in native soils had no differential effect on germination or survivability of willow. Time of seed production, seed source, and delay in watering significantly affected germination. Seed germination occurred quickly after being sown. However, seed viability declined just as quickly. Whenever a soil held sufficient water, especially through capillarity, seeds of Carolina willow germinated and survived well. Seasonal manipulation of water levels to flood marshes during seed-fall and to inundate willow seedlings provides managers with an effective strategy for reducing establishment of Carolina willow.

Adame, Maria Fernanda;Teutli, Claudia;Santini, Nadia S.;Caamal, Juan P.;Zaldívar-Jiménez, Arturo;Hernández, Raquel;Herrera-Silveira, Jorge A.

doi: 10.1007/s13157-014-0514-5pmid: N/A

Abstract Root production influences a range of belowground processes, such as soil accretion, carbon sequestration and nutrient acquisition. Here, we measured biomass and root production of mangroves surrounding a karstic oligotrophic lagoon that spans a nutrient and salinity gradient. We also measured forest structure and soil physicochemical conditions (salinity, bulk density, carbon, nitrogen (N) and phosphorus (P)) in order to determine factors associated with root production. We tested the following hypotheses: 1) root biomass and production increase at low soil P and N in order to maximize resource utilization, and 2) root biomass and production increase with high interstitial salinity. Root biomass (947–3,040 g m−2) and production (0.46–1.85 g m−2 day−1) increased where soil P and interstitial salinity were relatively high. Thus, we rejected the first hypothesis and confirmed the second. The larger root fraction (5–20 mm) was the major contributor to root biomass and production. Our findings suggest that root production and thus capacity for belowground carbon storage in karstic regions, where P is often limiting, is greater where interstitial salinity and P are higher. This contrasts with past assessments indicating that P-deficiency stimulates root growth, suggesting wide variation in belowground responses in mangroves.

Liu, Ha Trieu Hung;Wang, Peier;Tu, Xiao Xia;Yang, Jifang;Asmus, Ragnhild;Asmus, Harald

doi: 10.1007/s13157-014-0515-4pmid: N/A

Abstract This study focuses on the macrobenthic community of an unvegetated mudflat and that of a Schoenoplectus triqueter (synonym: Scirpus triqueter) marsh in the Southern Bank of the Hangzhou Bay, China. Samples were collected between April 2010 and January 2011 in order to evaluate possible effects of seasonality on the species composition for each habitat. Twenty-three species were found in each habitat, with higher crustacean and insect richness in the vegetated area, compared to a higher number of polychaete and mollusc species observed in the mudflat area. The highest macrofaunal abundance was recorded in summer whilst the lowest was registered in autumn. Heteromastus filiformis and Laternula marilina were the main contributors to the high abundance in the Hangzhou Bay. The results show higher mean macrobenthic abundances in the S. triqueter marsh (1,707 ind/m2 ± 1,669 SD) compared to that of the mudflat area (1,172 ind/m2 ± 1,115 SD). However, the highest mean biomass was found in the mudflat habitat (0.73 g/m2 ± 0.84 SD as opposed to 0.64 g/m2 ± 0.59 SD from the S. triqueter marsh) indicating the occurrence of larger specimens. Multivariate analyses indicate significant differences in the species composition between both habitats, confirming the importance of habitat structure on macrofaunal assemblages.

Potter, Christopher;Melack, John M.;Engle, Diana

doi: 10.1007/s13157-014-0516-3pmid: N/A

Abstract A new process-based simulation model to estimate methane emissions from Amazon floodplain ecosystems is described and evaluated in comparison to independent measurements of methane fluxes. The model’s three major components are 1) types of wetland vegetation and the changes in water level, temperature and dissolved oxygen of flooded areas, 2) plant production, biomass accumulation, and litterfall decay in soils and sediments, and 3) methane production and transport pathways through the water column and into the atmosphere. Ecological and limnological data from Lake Calado, a well-studied site in the central Amazon basin, were used to develop the model. One set of model simulations were generated for floating macrophytes. Predicted rates of CH4 emission to the atmosphere by all simulated transfer pathways were typically in the range of 0.25 to 0.33 g C m−2 day−1. Simulated CH4 emissions from flooded forests were predicted to be around 0.25 g m−2 day−1, nearly all by ebullition. These rates compare favorably to rates measured in Amazon floodplain habitats.

Rampi, Lian P.;Knight, Joseph F.;Lenhart, Christian F.

doi: 10.1007/s13157-014-0517-2pmid: N/A

Abstract Topography has been traditionally used as a surrogate to model spatial patterns of water distribution and variation of hydrological conditions. In this study, we investigated the use of light detection and ranging (lidar) data to derive two Single Flow Direction (SFD) and five Multiple Flow Direction (MFD) algorithms in the application of the compound topographic index (CTI) for mapping wetlands. The CTI is defined here as ln [(α)/(tan (β)], where α represents the local upslope contributing area and β represents the local slope gradient. We evaluated the following flow direction algorithms: D8, Rho8, DEMON, D-∞ MD-∞, Mass Flux, and FD8 in three ecoregions in Minnesota. Numerous studies have found that MFD algorithms better represent the spatial distribution of water compared to SFD algorithms. CTI maps were compared to field collected and image interpreted reference data using traditional remote sensing accuracy estimators. Overall accuracy results for the majority of CTI based algorithms were in the range of 81–92 %, with low errors of wetland omission. The results of this study provide evidence that 1) wetlands can be accurately identified using a lidar derived CTI, and 2) MFD algorithms should be preferred over SFD algorithms in most cases for mapping wetlands.