Wetlands最新文献

The accelerated eutrophication rate of (sub)tropical lakes is a major environmental problem. Constructed wetlands are considered as an effective method to purify water bodies. However, the removal rate of nitrogen (N), phosphorus (P) and other nutrients by wetland vegetation is quite different, and the continuous observation of plants and water ecosystems is required. In this study, the growth curves of two subtropical wetland plants, Phragmites australis and Zizania caduciflora, and their absorption effects on N and P in constructed wetlands were studied. The results showed that the growth curves of the two wetland plants were similar, reaching the biomass peak in July to August, and the cumulative absorption of N and P by plants had the same trend with the change of biomass. The N and P concentration of plants reached the peak in March to April, with higher concentration in Phragmites australis than that of Zizania caduciflora. At the end of the growing season, i.e. around October 20, the accumulated absorption of N and P by plants reached the maximum, which was the optimal time for harvest of subtropical wetland plants. Thereafter, the residues of plant litter entered the water, causing the recovery of N and P concentration in the water body, therefore affected the purification function of wetland. There is a strong correlation between the water purification efficiency and plant growth. With the increase of biomass, N and P accumulation in Phragmites australis and Zizania caduciflora, the N, P content and chemical oxygen demand (COD) in the water of wetland showed a significant decreasing trend. The removal rates of N, P, COD and suspended substance (SS) in the constructed wetlands with Phragmites australis and Zizania caduciflora as the main plants were 95%, 96%, 82% and 86%, respectively. In general, the purification capacity of Phragmites australis is slightly higher than that of Zizania caduciflora and precipitation had positive effects on the pollutants concentration of wetland water. The results provide scientific basis for plant selection and management of subtropical constructed wetlands.

Oxbow wetlands have been restored in the Midwestern United States to provide habitat for wetland-dependent species and to sequester contaminants originating from agricultural activities. Intensive agriculture may have adverse impacts on oxbow functions, especially if wetlands receive water inputs from subsurface drainage systems (e.g., tile drainage). To explore the influence of tile drainage on oxbow wetland communities, we quantified relationships between physical and biotic variables in 12 Iowa, USA oxbows over a two-year period (June to August 2019–2020). Six oxbows received direct water inputs from tile drainage (multipurpose oxbows), whereas remaining sites did not (non-tiled oxbows). In each oxbow, we measured physical variables and documented taxonomic composition, diversity, and abundance of macrophytes, macroinvertebrates, and fishes. Although water temperature was lower in multipurpose oxbows, values for other physical variables (e.g., turbidity, conductivity, and total dissolved solids) were similar across sites. No significant difference was detected for any biotic variable between oxbow types. In total, we observed 44 invertebrate taxa in both oxbow types with an average richness of 18.6 in non-tiled oxbows and 17.5 in tile-fed oxbows. We sampled 35 fish species, with an average richness across sampling dates of 8.2 in non-tiled oxbows and 11.4 in multipurpose oxbows. A total of 2682 Topeka shiners were found in both non-tiled and multipurpose oxbows. Non-metric multidimensional scaling revealed that potential physical determinants of macrophyte, invertebrate, and fish abundance were unrelated to tile drainage. Tile drainage had negligible impacts on coarse physical characteristics, taxa richness (fish and macroinvertebrates) and abundance (fish and macroinvertebrates).

Urban wetlands constitute a pivotal element within urban ecosystems. The implementation of ecologically sound wetland design methods can foster their biodiversity while augmenting overall ecosystem services. This study investigated three urban wetlands—Xixi, Tongjian Lake, and Qingshan Lake wetlands as the core, fringe, and suburban areas, respectively, of Hangzhou in Zhejiang Province, China. The plant species composition of these wetlands was quantified and 33 ecological design methods were accessed across the values of water quality protection, shoreline maintenance, ecological facilities, and plant diversity. Employing structural equation modeling, design methods significantly influencing plant diversity were identified. Key findings reveal: (1) variances in plant species and design methods occurred across wetlands, with the Xixi Wetland in the urban core displaying higher biodiversity; (2) four design methods—ecological conservation measures, rain gardens, complex plant community structure, and increased hydrophytic species populations—significantly impacted wetland plant diversity; (3) divergent pathways of design methods can be used to improve plant diversity in different urban wetlands; and (4) rational ecological design enhances plant diversity but may have time-limited effects, necessitating ongoing management to be effective. It is crucial that land managers ensure urban wetland protection occurs amidst urbanization using carefully tailored land use planning and management while considering wetland functions and characteristics. This research underscores the importance of employing ecological design methods strategically for sustaining and maximizing the benefits of ecosystem services that urban wetlands can provide.

Drivers of shrub primary production and associated landscape impacts of encroachment are well known in drylands but have not been thoroughly studied in mesic and coastal habitats. The native, nitrogen-fixing shrub, Morella cerifera, has expanded into coastal grassland along the US Atlantic coast due to warming temperatures, but impacts on ecosystem function are not well known. Annual net primary production (ANPP) of Morella cerifera and key environmental drivers were measured long-term (1990 – 2007) across a chronosequence of shrub age on a mid-Atlantic barrier island. Soil and groundwater nutrients were compared with un-encroached grassland soil to evaluate impacts of vegetation on nutrient dynamics. Shrub ANPP declined with age at the same rate among all thickets, but there was variability from year to year. When climate variables were included in models, shrub age, precipitation, and freshwater table depth were consistent predictors of ANPP. Water table depth decreased over time, reducing ANPP. This may be due to rising sea-level, as well as to feedbacks with shrub age and evapotranspiration. Soil N and C increased with shrub age and were higher than adjacent grassland sites; however, there was a significant loss of N and C to groundwater. Our results demonstrate that drivers influencing the encroachment of shrubs in this coastal system (i.e., warming temperature) are not as important in predicting shrub primary production. Rather, interactions between shrub age and hydrological properties impact ANPP, contributing to coastal carbon storage.

Long-term data sets documenting temporal changes in vegetation communities are uncommon, yet imperative for understanding trends and triggering potential conservation management interventions. For example, decreasing species diversity and increasing non-native species abundance may be indicative of decreasing community stability. We explored long-term plant community change over a 40-year period through the contribution of data collected in 2019 to two historical datasets collected in 1979 and 1999 to evaluate decadal changes in plant community biodiversity in a tidal freshwater marsh in the Fraser River Estuary in British Columbia, Canada. We found that plant assemblages were characterized by similar indicator species, but most other indicator species changed, and that overall α-diversity decreased while β-diversity increased. Further, we found evidence for plant assemblage homogenization through the increased abundance of invasive species such as yellow flag iris (Iris pseudacorus), and reed canary grass (Phalaris arundinacea). These observations may inform concepts of habitat stability in the absence of direct anthropogenic disturbance, and corroborate globally observed trends of native species loss and non-native species encroachment. Our results indicate that within the Fraser River Estuary, active threat management may be necessary in areas of conservation concern in order to prevent further native species biodiversity loss.

Coastal wetlands are crucial ecosystems at the interface between land and sea. In the context of economic development and urbanization, these wetlands face challenges such as reduction in area and fragmentation. Ecological networks can connect fragmented habitats, creating corridors for material, information, and energy transmission. This is vital for maintaining biological and landscape diversity and ensuring the healthy development of ecosystems. However, there is currently no research on the ecological networks in the Hebei-Tianjin coastal wetlands. In this study, the morphological spatial pattern analysis method is employed to identify wetlands sources, while the minimum cumulative resistance model is used to extract potential ecological corridors. By combining these with existing river corridors, the ecological network of coastal wetlands in Hebei and Tianjin is constructed, and regional network characteristics are analyzed. Critical areas of ecological protection and restoration are determined, including important ecological corridors, ecological pinch points, and ecological breakpoints. The results showed that: (1) The ecological network of Hebei-Tianjin coastal wetlands consisted of 38 ecological sources, 171 potential ecological corridors, and 399 river corridors, with a total area of 851.31 km². (2) Key ecological protection and restoration areas were proposed, including 35 crucial potential wetlands ecological corridors, 343 ecological pinch points, and 99 ecological breakpoints. Targeted restoration of these critical areas could significantly improve the connectivity of wetlands ecological networks. (3) At present, priority should be given to protecting critical ecological corridors and existing river corridors with high similarity to potential ecological corridors. The findings of this study can provide a scientific basis for the network construction and protection of Hebei-Tianjin coastal wetlands.

The present systematic literature review (SLR) synthesized the literature on mangrove litterfall production and decomposition from studies published between 1985 and 2023 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Key questions about biophysical, chemical, and anthropogenic/societal factors influencing nutrient cycling via litterfall production and decomposition in mangrove forests were addressed. The SLR included 332 peer-reviewed original and review articles from the ScienceDirect, PubMed, and Google Scholar databases. The United States of America had the highest relative count (RC, 31.32%), followed by Japan (8.79%) and Indonesia (8.24%), and the lowest RCs were found in Bangladesh, Kenya, Philippines, and Thailand. We showed the increasing trend on these topics and discussed the milestones to enhance our understanding of litterfall production and decomposition processes and inform future research endeavors in the context of climate change. A positive trajectory for understanding litterfall production and decomposition for effective decision-making and management strategies towards mangrove conservation and sustainable use is also discussed. Ten-year research prospects were also identified, including studies on impacts of pollution, habitat degradation, climate change, and other destructive human activities. The trend in studies about mangrove litterfall production and decomposition suggests the growing recognition of mangroves’ ecological and societal importance. Future advancements can be made to better understand the biophysical, chemical, and anthropogenic factors influencing litterfall production and decomposition through the identified future research directions. Finally, the findings of the present review are relevant to supporting effective conservation and management strategies for mangroves in a changing climate.

Emerging contaminants (EC) are the modern age chemicals that are new to the environment. It includes pharmaceuticals & personal care products (PPCPs), pesticides, hormones, artificial sweeteners, industrial chemicals, microplastics, newly discovered microbes and many other manmade chemicals. These chemicals are harmful and having negative impacts on human being and other life forms. Existing treatment systems are ineffective in treating the EC and the treated effluent act as source of pollution to the water bodies. Considering the requirement of new technologies that can remove EC, the Constructed wetlands (CWs) are getting popular and can be a valid option for the treatment of EC. In this context application of macrophytes in CW have increased the removal performance of constructed wetland system. Growing macrophytes in CW have augmented the removal of EC from these systems. In different studies macrophytes supported the removal process of EC in CW and a removal efficiency up to 97% was achieved. This review summarizes the direct and indirect roles of macrophytes in CW in the treatment of EC. Also, it evaluates the success of CW technology, in treating EC, its limitation, and future perspective. The direct role of macrophytes include precipitation on root surface, absorption, and degradation of EC by these plants. Growth of macrophytes in CWs facilitates the uptake EC by the absorption and detoxify them in their cell with the help of enzymatic and hormonal activity which supports the removal of EC in wetland system. Indirect impacts, which appear to be more significant than direct effects, include increased removal of EC through better rhizospheric microbial activity and exudate secretions, which enhances the removal by four times. Thus, this review emphasizes combined application of CW and aquatic macrophytes which augmented the performance of CW for the treatment of EC.

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Acreman et al. (Wetlands 42:63, 2022) reviewed evidence for ecological damage to the Doñana wetlands (UNESCO World Heritage Site [WHS] and Ramsar site), Spain, associated with intensification of groundwater use, particularly for agriculture. Acreman et al. presented a multistep methodology for evidence-based risk assessment that involves identification of conservation issues, and a systematic review of scientific evidence for ecological damage and its causes. However, they involved few local scientists, used a questionable methodology in stakeholder selection and involvement, used a flawed conceptual framework, and an incomplete literature review. We propose improvements to their methodology. They overlooked or misinterpreted key evidence, and underestimated the impacts that abstraction for irrigation for red fruits (mainly strawberries), rice and other crops has had on Doñana and its biodiversity. They reported groundwater level depletion of up to 10 m in the deep aquifer, but wrongly concluded that there is no evidence for impacts on the natural marsh ecosystem, the dune ponds or the ecotone. Groundwater drawdowns are actually up to 20 m, and have inverted the formerly ascending vertical hydraulic gradient in discharge areas. Phreatic levels have been lowered from 0.5 to 2 m in some areas. Groundwater abstraction has caused multiple ecological impacts to temporary ponds and marshes in the WHS, as well as to terrestrial vegetation, and should be urgently reduced. Furthermore, Acreman et al. focused on groundwater quantity while overlooking the importance of severe impacts on quality of both surface and groundwater, intimately connected to the use of agrochemicals for irrigated crops.

The Nagoya Daruma pond frog Pelophylax porosus brevipodus (formerly Rana porosa brevipoda) requires a wet environment year-round, but such habitats have generally been lost due to improved rice paddy drainage such that the frog populations have been decreasing. There have been attempts to create permanent pools in rice paddy areas to help the populations recover, but the basic life history patterns and population dynamics in both environments have not been well studied. We captured frogs in rice paddies and adjacent biotopes. Using capture–mark–recapture data with 816 marked individuals, we compared frog demographics and population structure using a Jolly–Seber POPAN model. Constructed biotopes had conditions favoring long-term persistence. For example, biotopes had larger frogs of both sexes than rice paddies. The ratio of juveniles to adults was lower in biotopes than rice paddies. By contrast, rice paddies were an important habitat for breeding and producing new frogs. The two habitats complemented each other to support the local frog population. Because P. p. brevipodus is now exclusively distributed in rice paddy areas, the creation of permanent pools is a feasible way to improve habitat quality, especially in modernized rice paddy areas with few permanent lentic habitats.