Wetlands最新文献

Sorption processes at the soil-water interface are observed to be rapid and dominant pathways of dissolved organic carbon (DOC) exchange. However, kinetics data for sorption in any ecosystem are sparse, and specifically non-existent for temperate tidal marshes. In this study, sorption rate kinetics experiments were designed to constrain new formulations of a sediment flux model coded to include explicit sorption between soil organic carbon and DOC pools. Batch incubations for marsh soil samples from Taskinas Creek (VA, USA) and Jug Bay Wetlands Sanctuary (MD, USA) were performed anaerobically under four sets of initial conditions: permutations of two salinities (0, 35) and two DOC concentrations (0 mg L^-1, 275 mg L^-1). Rates were measured at seven time points over 24 h. These results are the first DOC sorption kinetics data for tidal marsh soils, revealing that 76% of total sorption occurred within 15 min. The results also revealed higher capacity for adsorption under high DOC concentrations and salinity, with differences in magnitude between soil types. Numerical models simulating processes from these experiments provided a range of rates by fitting linear first order and non-linear ordinary differential equations to the kinetic change in DOC concentration curves over time. The outputs suggested that introducing soil adsorption capacity improved model fits across all cases. These results provide a deeper understanding of the biogeochemical controls on sorption kinetics and suggest that it is crucial to incorporate sorption processes into sediment flux models to accurately represent DOC fluxes from tidal marshes.

The cultivation of flooding-tolerant grasses on wet or rewetted peatlands is a priority in climate change mitigation, balancing the trade-off between atmospheric decarbonisation and biomass production. However, effects of management intensities on greenhouse gas (GHG) emissions and the global warming potential (GWP) are widely unknown. This study assessed whether intensities of two and five annual harvest occurrences at fertilisation rates of 200 kg nitrogen ha^− 1 yr^− 1 affects GHG exchange dynamics compared to a ‘nature scenario’ with neither harvest nor fertilisation. Fluxes of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), using opaque and transparent chambers, were measured on a wet fen peatland with a mean water table depth of -10 cm below soil surface. Overall, no treatment effect was found on biomass yields and GHG emissions. Annual cumulative CH₄ emissions were low, ranging between 0.3 and 0.5 t CO₂-C eq ha^− 1 yr^− 1. Contrary to this, emissions of N₂O were high, ranging between 1.1 and 1.5 t CO₂-C eq ha^− 1 yr^− 1. For magnitudes of CH₄ and N₂O, soil moisture conditions and electrical peat properties were critical proxies. Atmospheric uptake of CO₂ by net ecosystem exchange was higher for the treatments with management. However, this benefit was offset by the export of carbon in biomass compared to the treatment without management. In conclusion, the results highlighted a near-equal GWP in the range of 10.5–11.5 t CO₂-C eq t ha^− 1 yr^− 1 for all treatments irrespectively of management. In a climate context, a restoration scenario but also intensive paludiculture practices were equal land-use options.

Optimizing the level of groundwater presents a viable strategy for mitigating the greenhouse gas (GHG) emissions associated with the cultivation of peatlands. This study investigated the impact of soil hydrological conditions on carbon dioxide (CO₂) and methane (CH₄) emissions. The CO₂ and CH₄ emissions from bare soil were continuously measured using an automated chamber system throughout the growing seasons from 2021 to 2023 at a boreal cultivated peat soil site. Annual CO₂ emissions from soil respiration averaged to 21,600 kg ha^-1 (April-November) corresponding to carbon (C) loss of 5890 kg ha^-1. The CO₂ emissions were highly temperature dependent. Lowering the groundwater level (GWL) was found to increase the CO₂ emissions nearly linearly. The soil functioned as a CH₄ sink for the majority of the growing season, and the total sink corresponded to 27 and 20 kg ha^-1 yr^-1 CO₂ equivalent in 2022 and 2023, respectively. The CH₄ emissions occurred generally when soil water content (SWC) exceeded 0.6 m³ m^-3 and when GWL was at the depth of less than 30 cm from soil surface. For optimal climate efficiency the mitigation measures must be implemented during the mid-growing season, and the water table should be brought close to the soil surface. Potentially, this can hamper the operation of machinery on the field and reduce the harvested yield. Thus, comprehensive cost-benefit analysis is necessary before adopting a raised water table level in large-scale crop production.

Four representative halophytes, Tamarix chinensis (Tc), Phragmites australis (Pa), Suaeda salsa (Ss), and Spartina alterniflora (Sa), in the Yellow River Estuary wetland were selected to clarify the root disturbance on soil nutrient elements, salt ions, and their stoichiometric ratios. The results showed that the average total organic carbon (TOC) content of Tc, Pa, Ss, and Sa in the rhizosphere (RS) group was 5.19, 2.15, 2.05, and 2.14 times higher than those in the non-rhizosphere (CK) group, respectively. The total nitrogen (TN) content of Tc in the RS group was about 3.44 times that of the CK group. The average soil salinity reduced by 41.35%, due to the root disturbance of Tc. Soil ions, including K⁺, Ca²⁺, Mg²⁺, Na⁺, Cl^-, and SO₄^2- reduced by 33.86-62.86%. The root disturbance of Pa reduced soil salinity and soil ions by 35.47% and 16.93%-46.85%, respectively. However, the root disturbance effects in Sa and Ss were not obvious. The disturbance of roots played a crustal role in affecting the spatial heterogeneity of soil properties in the coastal wetlands above the intertidal zone (Tc and Pa), but its effect was greatly weakened below the intertidal zone (Sa and Ss). These findings are important for understanding how halophytes can impact soil nutrient levels and salt concentrations in coastal wetlands, which is crucial for effective management and restoration.

Wildfires and deforestation are severe threats to global ecosystems. In Brazil, Cerrado (a tropical savanna) and Pantanal (a tropical wetland) biomes have undergone several changes over the years due to anthropic actions. Both deforestation in Cerrado biome and wildfires in Pantanal have increased lately. Some studies argue that both processes could be related, but there is a scarcity of quantitative analysis evaluating that. In this context, making use of machine learning techniques and temporal data obtained by Remote Sensing in the period 2000–2020, this study aimed to identify the interactions between Cerrado land use and land cover change in native vegetation and wildfires incidence in Pantanal. Our results corroborate that and show that wildfires in Pantanal were directly linked to large-scale and commodities agriculture conversion in Cerrado, as well as native vegetation loss and hydrological changes in Pantanal.

Urban rivers face sustained anthropogenic pressures limiting biodiversity. Yet, urban waterways such as the Detroit River are important habitat in supporting regional diversity. The Detroit River is a Great Lakes Area of Concern where conservation and restoration efforts prioritize improved biological and habitat integrity in the connecting channel. This study explores benthic macroinvertebrate in submerged aquatic vegetation across five mainstem channel wetlands and two tributary sites of the Canadian wetlands to describe spatial patterns and diversity. We first examine inter-wetland differences between five mainstem wetlands by hierarchical cluster analysis, NMDS and PERMANOVA, identifying two mainstem groups: one comprising of two middle reach wetlands (Detroit River Marshes and Grass Island), the second showed similarities among wetlands across all reaches (Turkey Creek, River Canard and Peche Island). The latter groupings shared similar habitat characteristics, deeper and finer grain-sizes, and functional feeding group characteristics - low abundances of shredders. Second objective, we perform an intra-wetland comparison for Turkey Creek and River Canard to analyze for differences along tributaries. At neither River Canard nor Turkey Creek we observed significant tributary influence on mainstem communities but had found the Turkey Creek tributary communities significantly differed from the channel communities. Diversity metrics and Hilsenhoff Biotic Index illustrate strained benthic communities across the river. We had also found water quality to be consistently moderately degraded. Our findings differ from prior analyses within emergent vegetation that indicate variable water quality conditions between mainstem and tributary and non-impaired macroinvertebrate communities.

Wetlands serve as unique habitats that can support high biodiversity. Large-scale loss of wetland habitats can threaten important linkages between lake and wetland habitats that could affect diversity and growth of aquatic organisms. In this study, we compare prey diversity and abundance as well as Walleye (Sander vitreus) diets and condition in a large glacial lake (Lake Kampeska, South Dakota) with a connected wetland to better understand seasonal changes in the benefits provided by each habitat. We examined seasonal differences (spring, summer, and fall) through two years (summer 2021 through fall 2022) between the habitats using prey fish catch per unit effort, richness, Shannon diversity, and Bray–Curtis dissimilarity as well as Walleye relative weight, percent of empty stomachs, diet weight, stomach fullness, diet energy, and diet taxa importance. The prey fish community was more diverse and abundant in the wetland, and Walleye consumed more prey (by weight) in the wetland during all seasons except spring. Wetland reconnection can be a tool for managers to improve water quality while providing seasonal habitat needs for fish. Additionally, the diversity of prey resources provided by wetlands, many of which are unique, support resilience in the face of ecological change. Protection of wetlands may be critical for maintaining healthy and resilient fisheries into the future.

The success of the D-Day landings during World War II was significantly influenced by the detailed reconnaissance and scientific analysis of coastal substrate, particularly peatlands, by Allied wetland scientists. This paper examines the critical role of wetland science in ensuring the feasibility of the Normandy invasion. Initial geological intelligence raised concerns about the stability of the beaches due to extensive peat deposits underlying the Normandy coast. To address uncertainties, the Combined Operations Pilotage Parties (COPP) conducted covert beach surveys, collecting substrate samples crucial for operational planning. These missions, undertaken under challenging conditions, identified suitable landing areas by analysing sediment composition and bearing capacities. The success of D-Day was, in part, attributed to the insights provided by wetland scientists, who highlighted the significance of substrate properties in operational success. Their contributions underscored the interdisciplinary nature of wartime planning, integrating scientific expertise with military strategy. This study illuminates the often-overlooked role of wetland science in pivotal historical events, emphasising its influence on strategic decision-making and operational outcomes during one of the 20th century’s defining battles.

The conversion of organic matter by extracellular enzymes can reveal important insights into carbon and nutrient cycling. The activity and stoichiometry of hydrolytic extracellular enzymes were investigated to assess the effects of vegetation cover and sediment characteristics on microbial-enzyme-mediated decomposition in coastal ecosystems. Extracellular enzyme activity (EEA) was quantified across transects extending from mangrove to tidal flat habitats in two New Zealand coastal ecosystems that differ in mud content (sandy: Hobson Bay, muddy: Snells Beach). We determined the activity of five key hydrolyzing enzymes: β-glucosidase (hydrolyzes cellulose to glucose); β-N-acetylglucosaminidase (catalyzes the terminal reaction in chitin degradation); alkaline phosphatase (releases soluble inorganic phosphate groups from organophosphates); β-D-cellobiohydrolase (hydrolyzes cellulose to generate cellobiose); and β-xylosidase (catalyzes hemicellulose). All enzymes involved in C acquisition and in N and P cycling had higher activity at the muddy site. No habitat differences in EEA were observed at the sandy site, whereas EEA was lower in the non-vegetated habitats for some enzymes at the muddy site. Models of microbial metabolic limitations highlighted that most habitats at both muddy and sandy sites were predominately C and P limited. The EEA in these coastal wetlands was generally lower than has been reported for other terrestrial, freshwater, and estuarine ecosystems, with values often one to two orders of magnitude lower than other wetland studies. These results can be used to advance our understanding of the biogeochemical processes underpinning the response of coastal ecosystems to land-derived nutrient and sediment inputs.

In Japan, abandonment of rice fields has rapidly increased, resulting in biodiversity loss. Fallow field biotopes are attractive measures for compensating wetland species habitats in paddy environments. However, effective management practices of fallow field biotopes for biodiversity conservation are largely unknown, especially for lentic aquatic insects (Odonata, Hemiptera, and Coleoptera). We conducted field experiments in abandoned rice terraces in western Hyogo Prefecture, central Japan. We plowed and flooded nine abandoned paddy fields and divided them into three types: paddy fields, biotopes, and mixed fields. We also surveyed irrigation ponds. To assess the function of the four habitat types, we examined how species richness, abundance, and community composition of aquatic insects differed among habitat types. Aquatic insect assemblages in biotopes differed from paddy fields and ponds and resembled that in a mixed field. The effects of environmental factors on the abundance and species richness of aquatic insects differ according to their order or life stages. The abundance of aquatic insects increased with surface area. The abundance of Odonata nymphs increased with water depth, whereas that of Hemiptera nymphs and Coleoptera larvae decreased. The abundance of Odonata nymphs and Hemiptera adults increased with increasing vegetation cover, whereas the species richness of aquatic insects decreased. Thus, it is important to prevent high vegetation cover by plowing and create a water depth gradient for creating habitats for multiple taxa. We suggest that creating or maintaining mosaic habitats, including paddy fields, biotopes, and ponds could enhance aquatic insect diversity in abandoned rice terraces.