Wetland Plant Communities Research Articles

Temporal changes in wetland plant communities with decades of cumulative water pollution in two plateau lakes in China’s Yunnan Province

Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteristics of changes in wetland plant communities in two of the largest lakes in Yunnan Province, Dianchi and Erhai lakes. We collected records of native and alien plant communities in the two lakes from literature published from the 1950s to current period. We calculated plant community types and their area in some historical periods when related data were reported, and analyzed the relationship between changes in plant communities and water pollution. In Dianchi Lake, 12 community types of native plant communities, covering over 80% of the surface in the 1950s and 1960s, were reduced to four types covering 2.4% by the late 2000s. Alien plant communities started to appear in the lake in the late 1970s, and have since come to cover 4.9% of the lake surface, thereby becoming dominant. In Erhai Lake, 16 community types of native plant communities, covering 47.1% of the lake surface in the late 1970s, declined to 10 community types, covering 9.3% of the surface, by the late 2000s. Alien plant communities appeared in the middle 1980s, and at present cover 0.7% of the surface area. It was indicated that changes in plant communities were significant related to water eutrophication. The area occupied by native and alien plant communities was, respectively, negatively and positively related to the content of nutrients in water. This showed lacustrine pollution played an important role in native plant loss and alien plant invasion in the two plateau lakes.

Zonation of emergent freshwater macrophytes: Responses to small-scale variation in water depth

Abstract Plant responses to hydrology are central to understanding the structure of wetland plant communities and to informing restoration efforts. The objectives of this study were to examine ecological responses of emergent plant species to water depth in a freshwater wetland in south-central New York (USA) and to test growth responses and associated nutrient relations for emergent species exposed to controlled water depths without interspecific competition in a greenhouse experiment. Field observations quantified the distribution of wetland plants in relation to water depth at Harpur Pond in the Binghamton University Nature Preserve. Presence or absence of plant species was noted in 0.25-m2 quadrats, along 11 transects extending from the upland limit of emergents to their greatest depth in the pond. Ten of the 12 most frequent taxa showed significantly nonrandom distributions (P 0.2 m above the median water level, ...

Water use strategy of Tamarix chinensis during a drought year in the coastal wetlands of the Yellow River Delta, China

Tamarix chinensis, the dominant species of plant communities in the coastal wetlands of the Yellow River Delta, was selected to study the water use strategy of coastal plants at different habitats during a drought year. The Δ18O values for xylem water of T. chinensis were analyzed. Potential contributions by different water sources to T. chinensis were estimated using the IsoSource model. The contributions were analyzed to reveal the adaptation mechanism of T. chinensis to water stress at different habitats. The results showed that the main water sources for T. chinensis during a drought year were soil water and groundwater rather than precipitation. However, the water use strategies of T. chinensis changed significantly with different micro-topographies. For dune crests, 72.6%-95.4% water of T. chinensis came from deeper soil water (40-100 cm) and groundwater. However, near the high tide line, T. chinensis absorbed 40.7%-97.3% of the water from the upper soil (0-40 cm) to avoid the salt stress caused by sea water and shallow groundwater. This provided T. chinensis with a competitive advantage related to water consumption and improved its water use efficiency in the coastal ecosystem, which led to mono-dominant shrub community of T. chinensis in this area.

Wetland restoration by natural succession in abandoned pastures with a degraded soil seed bank

AbstractNatural restoration of historical wetland plant communities in fallow fields with a degraded seed bank has been assumed to be possible only if source populations of the target species are present adjacent to the abandoned fields and a high density of suitable microsites is available. However, few studies have monitored both factors simultaneously and verified this assumption. We hypothesized that plant communities that are similar to historical wetlands, including back marshes, back swamps, and bogs, will reestablish in abandoned pasturelands in cases when (1) gaps for new recruitment emerge, followed by the decline of pastures; and (2) seeds with longevity are supplied from the surrounding remnant plant communities of wetlands. We conducted a survey of vegetation and microsites in pastures, abandoned pastures, and reference wetlands followed by structural equation modeling to verify our hypothesis for the natural restoration of Phragmites australis–Phalaris arundinacea and Alnus japonica–Spiraea salicifolia communities. These communities represent historical back marshes and back swamps along a river. However, our hypothesis was not verified for the natural restoration of Vaccinium oxycoccos–Sphagnum spp. communities, which represent plant communities in historical bogs grown on acidic peat that are maintained by rainfall and fog. Our findings partly support our hypothesis that decline in pastures creates gaps and that cumulative seed dispersal from nearby remnant wetlands allows the original wetland plant communities to regenerate. Further case studies are needed to determine how the natural restoration of bog plant communities occurs.

“Accidental” urban wetlands: ecosystem functions in unexpected places

“Accidental” urban wetlands are formed not through deliberate restoration or management activity, but as a product of land use and water infrastructure decisions by municipalities. Often formed in abandoned industrial, residential, or low‐lying commercial areas, where overland flows from storms and municipal water use accumulate, these ecosystems support wetland soils and plant communities. Research that we have conducted in the northeastern and southwestern US suggests that accidental wetlands are capable of counteracting anthropogenic eutrophication, providing habitats for important ecological communities, fostering biodiversity, and mitigating heat. Because the factors contributing to their formation are ubiquitous, accidental wetland systems are likely pervasive in urban landscapes, accounting for a substantial portion of aquatic habitat extent and influencing nutrient and water cycles within cities. They also provide ecosystem services at a fraction of the cost associated with more traditional environmental management efforts.

Plant traits of propagule banks and standing vegetation reveal flooding alleviates impacts of agriculture on wetland restoration

Summary Restoration of degraded plant communities requires understanding of community assembly processes. Human land use can influence plant community assembly by altering environmental conditions and species’ dispersal patterns. Flooding, including from environmental flows, may counteract land use effects on wetland vegetation. We examined the influence of land use history and flood frequency on the functional composition of wetland plant communities along a regulated river. We applied fourth corner modelling to determine species’ trait‐based responses to flooding and land use by combining data on (i) the occupancy and abundance of species in propagule banks and standing vegetation, (ii) species traits, and (iii) environmental conditions of 22 standing vegetation and 108 soil propagule bank study sites. We used analysis of deviance to test how well each dataset characterised trait–environment interactions, and generalised linear models to identify traits related to species’ responses. The occupancy and abundance of native species in the propagule bank and standing vegetation increased with flood frequency and decreased with duration of agricultural land use. Species in standing vegetation with water‐borne propagule dispersal (hydrochory) showed similar trends. In contrast, species with higher specific leaf area were associated with longer land use duration. Identifying trait‐based differences in the propagule bank and standing vegetation can help disentangle effects of dispersal and environmental filters. The occupancy and abundance of hydrochorous species in standing vegetation were negatively related to land use duration, but hydrochorous species were positively related to land use duration based on their abundance in the propagule bank. This suggests that land use does not limit plant dispersal, but acts as an in situ abiotic filter, limiting species present in standing vegetation. Synthesis and applications. Land use duration and flood frequency have opposite effects on plant community traits in floodplain wetlands of the Macquarie Marshes, Australia. Legacies of agriculture can impede restoration of plant communities. Environmental flows that increase flooding may alleviate these impacts, especially in areas that have been used for agriculture for over 20 years, by providing dispersal and environmental filters that favour native wetland species. More flooding will likely be required to restore floodplains with longer histories of agricultural land use compared to floodplains less impacted by agriculture.

Functional traits, spatial patterns and species associations: what is their combined role in the assembly of wetland plant communities?

Studies of community assembly focus on finding rules that predict which species can become member of a plant community. Within a community, species can be categorized in two ways: functional groups classify species according to their functional traits, whereas generalized guilds group species based on their (co-)occurrence, spatial distribution and abundance patterns. This study searches for community assembly rules by testing for coherence among functional groups and generalized guilds, as well as for correlations between the individual functional traits and assembly features, in two wetland plant communities in South Africa. The classifications of functional groups and generalized guilds were not consistent. However, rhizome internode length was related to fine-scale spatial pattern, suggesting that in systems dominated by clonal species (including wetlands, where recruitment sites are strongly limited) community assembly may be strongly linked to colonization ability. Functional groups do not predict guilds in wetland plant communities, precluding their use as the basis for assembly rules. However, an explicit consideration of clonal strategies and their effect on species’ spatial patterns appears to be important for understanding community assembly in systems dominated by clonal plants.

Future extinction risk of wetland plants is higher from individual patch loss than total area reduction

Quantifying the risk of extinction due to habitat loss is an increasingly urgent task for the design and implementation of effective conservation interventions. Methods based on species- and endemics-area relationships are well developed, but applications to date have concentrated primarily on the fragmentation of formerly continuous habitats such as forests and woodlands. Applying these area-based methods to predict extinction risk in habitat types occurring naturally as spatially discrete patches has been largely ignored. We address this knowledge gap using a network of seasonally connected wetlands. We modelled the risk of extinction associated with native wetland plant communities under two alternative scenarios: the loss of (i) entire wetlands (patch loss) versus (ii) an equivalent area distributed across the wetlands (area loss). Patch-loss scenarios resulted in more than twice the number of species going extinct than the equivalent loss of area. Extinction due to patch loss was highest when wetlands were removed in increasing size order (smallest to largest) – a plausible scenario arising from forecast climatic drying in the region. Small wetlands contained >16% of endemic species in only <5% of wetland area, largely explaining this result. Extinction risk associated with naturally occurring habitat patches depends on the distribution of regionally endemic species; where this is not solely a function of habitat area, the loss of small patches can represent higher risk than an equivalent reduction in total habitat area across the network.

Effects of flooding regime on wetland plant growth and species dominance in a mesocosm experiment

Flooding regimes are a primary influence on the wetland plant community. Human-induced disturbance often changes the duration and frequency of flooding in wetlands, and has a marked influence on wetland plant composition and viability. Comprehensive studies of the environmental thresholds of wetland plants are required for the development of proper practices for wetland management and restoration after hydrological disturbance. This study provides a quantitative assessment of the establishment, growth, and community shifts in dominance of three emergent plant species (Scirpus tabernaemontani, Typha orientalis, and Zizania latifolia) typical of South Korean wetlands, under five hydrological regimes (waterlogged, low-level standing water, high-level standing water, intensive periodic flooding, and intermittent flooding) over four growing seasons. A mesocosm experiment was conducted in the campus of Seoul National University, South Korea. The number and biomass of shoots of Z. latifolia responded positively to increased water level and flooding frequency, while that of the other plants did not. Zizania latifolia outcompeted S. tabernaemontani and T. orientalis irrespective of hydrological regime. This study suggests that Z. latifolia can outcompete the other two macrophytes in the field. This study will improve our ability to predict the dynamics of wetland vegetation and so facilitate the formulation of wetland management and restoration strategies.

Macroclimatic change expected to transform coastal wetland ecosystems this century

Research into the impacts of climate change on coastal wetlands has tended to focus on sea-level rise. Now modelling of Gulf of Mexico wetland plant community responses to climate change projects transformative ecological changes this century. Coastal wetlands, existing at the interface between land and sea, are highly vulnerable to climate change1,2,3. Macroclimate (for example, temperature and precipitation regimes) greatly influences coastal wetland ecosystem structure and function4,5. However, research on climate change impacts in coastal wetlands has concentrated primarily on sea-level rise and largely ignored macroclimatic drivers, despite their power to transform plant community structure6,7,8,9,10,11,12 and modify ecosystem goods and services5,13. Here, we model wetland plant community structure based on macroclimate using field data collected across broad temperature and precipitation gradients along the northern Gulf of Mexico coast. Our analyses quantify strongly nonlinear temperature thresholds regulating the potential for marsh-to-mangrove conversion. We also identify precipitation thresholds for dominance by various functional groups, including succulent plants and unvegetated mudflats. Macroclimate-driven shifts in foundation plant species abundance will have large effects on certain ecosystem goods and services5,14,15,16. Based on current and projected climatic conditions, we project that transformative ecological changes are probable throughout the region this century, even under conservative climate scenarios. Coastal wetland ecosystems are functionally similar worldwide, so changes in this region are indicative of potential future changes in climatically similar regions globally.

Effects of wetland vegetation on soil microbial composition: A case study in Tumen River Basin, Northeast China

Hydrology plays a dominant role in wetland plant distribution and microbial composition, but few studies explicitly attempted to relate the linkage between wetland vegetation and microbial community. The present study consisted of five wetland plant communities along three adjacent flood gradients zones (zone 1 dominated by Carex appendiculat, zone 2 dominated by Eleocharis ovate, and zone 3 dominated by Phragmites australis/Bidens pilosa/Calamagrostis angustifolia, which formed separate, monoculture patches). Gram negative and arbuscular mycorrhizal fungal phospholipid fatty acid (PLFA) are more abundant in the site with short flooding period (zone 3) than in the site with long flooding period (zone 1), and they are also different in the P. australis, B. spilosa and C. angustifolia of zone 3. Principle Component Analysis (PCA) showed that the flooding period could explain 92.4% of variance in microbial composition. Redundancy Analysis (RDA) showed that available nitrogen (AN), total nitrogen (TN) and soil organic matter (SOM) could explain the 79.5% of variance in microbial composition among E. ovata, P. australis, B. pilosa and C. angustifolia. Results demonstrated that flooding period was the main factor in driving the microbial composition and plant-derived resources could influence soil microbial composition in the seasonally flooded zones.

Effect of changes in groundwater levels on selected wetland plant communities

Effect of changes in groundwater levels on selected wetland plant communities

Sandhill Fen, an initial trial for wetland species assembly on in-pit substrates: lessons after three years

Open-pit mining of oil sands removes wetland plant communities from the landscape. Sandhill Watershed, located on Syncrude Canada’s oil sands lease, is the first reclamation of a complex watershed that includes a 17 ha central wetland designed to develop into a rich fen. Here we sample the vegetation after three years. Of the 124 plant species recorded, 48% are peat-forming species, including 24 bryophyte species. We identified, using ordination techniques, four plant assemblages that vary in abundance of peat-forming plants. Each assemblage occurs in a spatially distinct area of Sandhill Fen, forming vegetation zones that are closely associated with height of water table. The plant assemblage distributed in the wettest areas has abundant marsh species. The assemblages in the driest areas of the fen have large numbers of upland and weed species and few species characteristic of fens. In between is a species assemblage with an abundance of species characteristic of natural peat-forming habitats. Two key findings are: water levels control spatial distributions of species assemblages, and non-peat-forming plant species are abundant and a concern for the establishment of peat-forming wetlands. Future designs should include plans for a number of interconnected site types such as marshes, fens, and riparian areas.

A Simple Harmonic Model for FAPAR Temporal Dynamics in the Wetlands of the Volga-Akhtuba Floodplain

The paper reports a technique used to construct a reference time series for the fraction of absorbed photosynthetically-active radiation (FAPAR) based on remotely-sensed data in the largest Russian arid wetland territory. For the arid Volga-Akhtuba wetlands, FAPAR appears to be an informative spectral index for estimating plant cover health and its seasonal and annual dynamics. Since FAPAR algorithms are developed for multiple satellite sensors, all FAPAR-based models are suggested to be universal and useful for future studies and long-term monitoring of plant cover, particularly in wetlands. The model developed in the present work for FAPAR temporal dynamics clearly reflects the field-observed seasonal and annual changes of plant cover in the Volga-Akhtuba floodplain wetlands. Various types of wetland plant communities were categorized by the specific parameters of the model seasonal vegetation curve. In addition, the values derived from the model function allow quantitative estimation of wetland plant cover health. This information is particularly important for the Volga-Akhtuba floodplain, because its hydrological regime is regulated by the Volzhskaya hydropower plant. The ecosystem is extremely fragile and sensitive to human impact, and wetland plant cover health is a key indicator of regulatory efficiency. The present study is another step towards developing a methodology focused on arid wetland vegetation monitoring and conservation of its biodiversity and natural conditions.

Variant restoration trajectories for wetland plant communities on a channelized floodplain

AbstractRestoration efforts are typically based on an assumption that reestablishment of altered determinants of ecological structure and function will lead to a predictable reestablishment of populations and reassembly of communities. Dechannelization and reestablishment of natural hydrologic regimes provide the basis for the ongoing restoration of the Kissimmee River in Central Florida, United States. The expected reestablishment of historically dominant broadleaf marsh (BLM) and buttonbush shrub (BB) communities was evaluated over a 10‐year period following implementation of the first phase of the restoration project. Plant species composition and cover were assessed during dry (spring) and wet (summer) season sampling periods at five sites on the restored floodplain, and four “control” sites on the channelized floodplain. Mean daily stage data from nearby gauges indicated hydroperiods and depths on the reflooded floodplain were within the range of historic hydrologic conditions that selected for BLM and BB communities on the pre‐channelization floodplain. After reflooding, pasture grass and upland shrub communities rapidly transitioned to a fluid mix of obligate and facultative wetland species. Although signature BLM and BB species, Sagittaria lancifolia (bulltongue arrowhead), Pontederia cordata (pickerel weed), and Cephalanthus occidentalis (buttonbush), recolonized all study sites, the expected reestablishment of dominant cover of these species did not occur. Results indicate that restoration of BLM and BB communities has been impeded by deep flood pulse disturbances, establishment of invasive wetland grasses, and mineralized soil characteristics of the drained floodplain.

The Response of Wetland Plant Communities to Disturbance: Alleviation through Symmetric Disturbance and Facilitation

ABSTRACT The study pays attention to disturbances in early successional communities of wetland vegetation. We conducted artificial disturbances in a community of Suaeda salsa and Phragmites australis in the Yellow River Delta (China). Eight types of disturbances combining mowing treatments with species treatments were applied. Removal of the standing litters of P. australis or not was defined as mowing treatments, and removal of two species solo or both was defined as species treatments. We sampled 80 quadrats from the treatments plots at different intervals after the disturbance to investigate plant height, abundance, aboveground biomass, the distance between plants to reflect the effect of disturbance on composition, structure, productivity, and function of the plant communities. The strategies of seedling emergence and height growth differed as the canopy changed. Biomass contribution of different species, combined with disturbance intensity, was the main factors that affected the productivity. Homogen...

A Middle Pennsylvanian macrofloral assemblage from wetland deposits in Indiana (Illinois Basin): a taxonomic contribution with biostratigraphic, paleobiogeographic, and paleoecologic implications

AbstractTaxonomic analysis is provided for a Middle Pennsylvanian macrofloral assemblage collected from clastic wetland deposits in Clay County, Indiana, on the eastern margin of the Illinois Basin. Adpressed plant fossils were recovered from four distinct beds in the lowermost Staunton Formation, positioned above the Minshall Coal (uppermost Brazil Formation), part of a succession deposited near the Atokan-Desmoinesian boundary. The assemblage of 22 fossil-taxa is dominated by pteridosperms (includingNeuropteris flexuosa,Macroneuropteris scheuchzeri,Alethopteris densinervosa,Neuropteris ovata,Eusphenopteris neuropteroides, andNeuropteris missouriensis) with lesser cordaitaleans (Cordaitesspp. indet.) and sphenopsids (particularlySphenophyllum cuneifolium). Lycopsids are uncommon, and ferns are rare. In contrast, the microfloral assemblage from the Minshall Coal and overlying clastic units is dominated by lycopsid and tree fern spores. Comparisons with established biozonation schemes yield different ages depending on the regional biostratigraphic framework used: (1) latest Bolsovian (Radiizonates difformisBiozone, American microfloras); (2) latest Bolsovian or earliest Asturian (‘Neuropteris’ rarinervisBiozone, Appalachian Basin macrofloras); or (3) earliest Asturian (Linopteris obliquaBiozone, European macrofloras). The placement and correlation of the Bolsovian-Asturian and Atokan-Desmoinesian boundaries, which have traditionally been equated by palynology, are evaluated in the context of this discordance. Several revised stratigraphic scenarios are proposed for this interval in the Illinois Basin, which is being increasingly recognized as a time of significant environmental change throughout Euramerica. Homotaxial comparisons with European macrofloral assemblages indicate that, of the 18 biological taxa recorded, between 14 and 17 (78–94%) also are common in coeval wetland deposits in Europe. The similarities exemplify the spatial conservatism and low diversity of wetland plant communities over vast areas of tropical Euramerica, a manifestation of the intrinsically stressful conditions that characterize such habitats, and indicates that neither the Laurentian Shield nor the Appalachian-Variscan Mountains were an insurmountable barrier to plant dispersal during the Middle Pennsylvanian.

Feral swine damage to globally imperiled wetland plant communities in a significant biodiversity hotspot in Florida

We studied rooting damage during five-years of feral swine control at Avon Park Air Force Range, a significant botanical biodiversity hotspot in peninsular Florida with many globally imperiled plant species and communities. While control reduced swine abundance, remaining animals consistently rooted the 49 studied sites in both middle-dry season (MDS) and late-dry season (LDS) each year. At each study site, we measured rooting with sub-meter accuracy. Neither total nor proportional area rooted differed in either season, across study years, or among plant community types: herbaceous seepage slopes, wet pine savannas, wet grasslands. The proportion of sites with damage during MDS was at least 25 % less than pre-control baseline. During LDS, the proportion of sites with damage increased over years but remained below the initial 2 years’ MDS results. Fresh rooting frequency (rooting <1 week-old) across sites dropped precipitously from baseline and remained low for MDS. Fresh rooting frequency among sites during LDS was lower than MDS for all but year two of the study. Canopied habitat <50 m from a study site almost guaranteed rooting at the site each observation period. We propose actions for protecting wetlands, integrating swine control into other compatible land use practices, and improving swine control efficacy. While we measured damage amounts at each site very accurately, our approach of also considering frequency of rooting and frequency of fresh rooting across sites offers low-labor means to broadly assess swine damage and control efficacy at large geographic scales because in-field measurements of damage amounts are not needed.

Impacts of climate change on submerged and emergent wetland plants

Submerged and emergent wetland plant communities are evaluated for their response to global climate change (GCC), focusing on seagrasses, submerged freshwater plants, tidal marsh plants, freshwater marsh plants and mangroves. Similarities and differences are assessed in plant community responses to temperature increase, CO2 increase, greater UV-B exposure, sea level rise and other expected environmental alterations associated with GCC. Responses to most climate change variables are more similar within submerged plant communities, marine or freshwater, than between submerged vs. emergent plant communities. The submerged plants are most affected by temperature increases and indirect impacts on water clarity. Emergent plant communities (marshes and mangroves) respond most directly to climate change related hydrological alterations. Wetland plant communities overall appear to be adversely impacted by all climate change variables, with the exception of increased CO2 in the atmosphere and the oceans, which in most cases increases photosynthesis. Effects of GCC on all these communities have already been seen with many others predicted, including: shifts in species composition, shifts in range and distribution, and declines in plant species richness. Other effects are associated with specific community types, e.g., salt marsh habitat lost to mangrove incursion, and decreases in submerged macrophyte coverage in lakes and estuaries, exacerbated by eutrophication. Sea level rise poses threats to all aquatic plant community types in the vicinity of the oceans, and changes in weather patterns and salinity will affect many. Overall, losses are likely in all these wetland plant communities yet their species can adapt to GCC to some degree if well managed and protected.

Soil seed banks and their implications for wetland restoration along the Nongjiang River, Northeastern China

Soil seed banks provide seeds for the redevelopment of plant communities in wetlands. They can be important components of the ecological restoration of farmed wetlands, particularly if the seeds can survive periods of cultivation. We assessed if key structural dominant wetland plant species were present as seeds in farmed sedge meadows in northeastern China. We conducted a germination experiment in a greenhouse to compare the seed banks of four natural sedge meadows and four adjacent farmed fields along the Nongjiang River under drained and flooded conditions. We further conducted vegetation surveys in four natural sedge meadows. Sedges (Carex species) and the grass Calamagrostis angustifolia dominated plant communities in the natural sedge meadows. Many important sedge meadow species (>30 species, e.g., Calamogrostis angustifolia and Potamogeton crispus) survived cultivation as seeds. Farmed fields converted from sedge meadows are nearly devoid of dominant Carex species, including two keystone tussock-forming species, Carex appendiculata and Carex meyeriana. Species of various life history types require either drawdown (emergent, e.g., Carex lasiocarpa and Calamogrostis angustifolia) or flooding (submerged, e.g., Potamogeton crispus and Ceratophyllum demersum) for successful germination. The structure of the seed bank was related to experimental water regime, and the field environments of latitude, number of years farmed, and field water depth based on Nonmetric Multidimensional Scaling (NMDS) analysis. Our study indicated that, although certain critical components of the vegetation are not retained in seed banks, which made it difficult to replicate historic habitat via natural recolonization, the seed banks of farmed sedge meadows could still contribute toward the restoration of novel wetland vegetation assemblages under suitable environmental conditions. Carex reestablishment could rely upon artificial introduction if necessary.