The Ecology of a New England Salt Marsh

Carbon dioxide fluxes reflect plant zonation and belowground biomass in a coastal Marsh

Article

Full-text available

Nov 2016

Coastal wetlands are major global carbon sinks; however, they are heterogeneous and dynamic ecosystems. To characterize spatial and temporal variability in a New England salt marsh, greenhouse gas (GHG) fluxes were compared among major plant-defined zones during growing seasons. Carbon dioxide (CO2) and methane (CH4) fluxes were compared in two mensurative experiments during summer months (2012-2014) that included low marsh (Spartina alterniflora), high marsh (Distichlis spicata and Juncus gerardii-dominated), invasive Phragmites australis zones, and unvegetated ponds. Day-and nighttime fluxes were also contrasted in the native marsh zones. N2O fluxes were measured in parallel with CO2 and CH4 fluxes, but were not found to be significant. To test the relationships of CO2 and CH4 fluxes with several native plant metrics, a multivariate nonlinear model was used. Invasive P. australis zones (-7 to -15 μmol CO2m-2s-1) and S. alterniflora low marsh zones (up to -14 μmol CO2m-2s-1) displayed highest average CO2 uptake rates, while those in the native high marsh zone (less than -2 μmol CO2m-2s-1) were much lower. Unvegetated ponds were typically small sources of CO2 to the atmosphere (<0.5 μmol CO2m-2s-1). Nighttime emissions of CO2 averaged only 35% of daytime uptake in the low marsh zone, but they exceeded daytime CO2 uptake by up to threefold in the native high marsh zone. Based on modeling, belowground biomass was the plant metric most strongly correlated with CO2 fluxes in native marsh zones, while none of the plant variables correlated significantly with CH4 fluxes. Methane fluxes did not vary between day and night and did not significantly offset CO2 uptake in any vegetated marsh zones based on sustained global warming potential calculations. These findings suggest that attention to spatial zonation as well as expanded measurements and modeling of GHG emissions across greater temporal scales will help to improve accuracy of carbon accounting in coastal marshes.

Natural Communities of New Hampshire

Book

Full-text available

Jan 2004

New Hampshire Natural Heritage Bureau and The Nature Conservancy T he New Hampshire Natural Heritage Bureau is located within the NH Department of Resources and Economic Development's Division of Forests and Lands. Primarily an information resource, the bureau finds, tracks, and facilitates the protection of New Hampshire's rare plants and exemplary natural communities. It is not a regulatory agency; instead, the bureau works with landowners and land managers to help them protect New Hampshire's natural heritage and meet their land-use needs. Its mission, as mandated by the Native Plant Protection Act of 1987 (NH RSA 217-A), is to determine protective measures and requirements for the survival of native plant species in the state, to investigate the condition and rarity of plant species, and to distribute information regarding the condition and protection of these species and their habitats. The New Hampshire Natural Heritage Bureau is an excellent source of information on plants and natural communities in New Hampshire, including their ecology and distribution in the state. It maintains the state's only comprehensive database of New Hampshire's exemplary natural communi-ties, exemplary natural community systems, rare plants, and rare animals, including their known locations. Rare wildlife locations are maintained in cooperation with the Nongame and Endangered Wildlife Program at the New Hampshire Fish and Game Department, which has legal authority over all wildlife in the state. The bureau is also a member of the NatureServe network, which connects nearly 80 Natural Heritage Programs throughout the United States, Canada, and several Latin and South American countries. The Nature Conservancy provides ecology staff and other services to the bureau through a cooperative agreement with the state of New Hampshire.

The role of waterlogging in maintaining forb panes in northern New England salt marshes

Article

Jun 2004

Areas of high plant diversity, known as forb pannes, characterize many northern New England salt marshes. These pannes are physically harsh habitats where stress-tolerant forbs escape the competitively dominant clonal turfs. In this paper, we experimentally examine the hypothesis that soil waterlogging maintains forb pannes. Experimentally draining pannes led to the replacement of typical panne vegetation by Spartina patens. After four years, S. patens cover increased by greater than 300% in the drained plots, while in adjacent, unmanipulated controls, its cover remained unchanged. In a second experiment, forb panne elevation was manipulated to either increase or decrease soil drainage. After three years elevated plots were dominated by S. patens, whereas lowered plots were dominated by Spartina alterniflora, with reduced forb densities. Our results demonstrate that forb panne communities are the consequence of poor drainage and waterlogged soils that limit the success of competitively dominant clonal turfs and permit the persistence of panne forbs. These results imply that the extensive ditching of New England salt marshes over the past three centuries to increase the value of marshes for livestock grazing, development, and mosquito control has likely eradicated most of these forb panne habitats.

Assessing Spectral Band, Elevation, and Collection Date Combinations for Classifying Salt Marsh Vegetation with Unoccupied Aerial Vehicle (UAV)-Acquired Imagery

Article

Full-text available

Oct 2023

New England salt marshes provide many services to humans and the environment, but these landscapes are threatened by drivers such as sea level rise. Mapping the distribution of salt marsh plant species can help resource managers better monitor these ecosystems. Because salt marsh species often have spatial distributions that change over horizontal distances of less than a meter, accurately mapping this type of vegetation requires the use of high-spatial-resolution data. Previous work has proven that unoccupied aerial vehicle (UAV)-acquired imagery can provide this level of spatial resolution. However, despite many advances in remote sensing mapping methods over the last few decades, limited research focuses on which spectral band, elevation layer, and acquisition date combinations produce the most accurate species classification mappings from UAV imagery within salt marsh landscapes. Thus, our work classified and assessed various combinations of these characteristics of UAV imagery for mapping the distribution of plant species within these ecosystems. The results revealed that red, green, and near-infrared camera image band composites produced more accurate image classifications than true-color camera-band composites. The addition of an elevation layer within image composites further improved classification accuracies, particularly between species with similar spectral characteristics, such as two forms of dominant salt marsh cord grasses (Spartina alterniflora) that live at different elevations from each other. Finer assessments of misclassifications between other plant species pairs provided us with additional insights into the dynamics of why classification total accuracies differed between assessed image composites. The results also suggest that seasonality can significantly affect classification accuracies. The methods and findings utilized in this study may provide resource managers with increased precision in detecting otherwise subtle changes in vegetation patterns over time that can inform future management strategies.

Do predators have a role to play in wetland ecosystem functioning? An experimental study in New England salt marshes

Article

Full-text available

Jul 2021

The historical ecological paradigm of wetland ecosystems emphasized the role of physical or “bottom-up” factors in maintaining functions and services. However, recent studies have shown that the loss of predators in coastal salt marshes can lead to a significant reduction in wetland extent due to overgrazing of vegetation by herbivores. Such studies indicate that consumers or “top-down” factors may play a much larger role in the maintenance of wetland ecosystems than was previously thought. The objective of this study was to evaluate whether altering top-down control by manipulating the presence of predators can lead to measurable changes in salt marsh ecosystem properties. Between May and August of 2015 and 2016, we established exclosure and enclosure cages within three New England coastal wetland areas and manipulated the presence of green crab predators to assess how they and their fiddler and purple marsh crab prey affect changes in ecosystem properties. Predator presence was associated with changes in soil nitrogen and aboveground biomass at two of the three field sites, though the magnitude and direction of these effects varied from site to site. Further, path analysis results indicate that across field sites, a combination of bottom-up and top-down factors influenced changes in measured variables. These results challenge the growing consensus that consumers have strong effects, indicating instead that predator impacts may be highly context-dependent.

Self‐thinning and size‐dependent flowering of the grass Spartina alterniflora across space and time

Article

Full-text available

Jun 2019
FUNCT ECOL

Plants adjust their size and reproductive effort in response to numerous selection pressures and constraints. The self‐thinning law describes a well‐known trade‐off between size and density. Plants also trade‐off investment into growth vs. sexual reproduction, as described by life‐history theory. We build on past work on plant allometry and life history by examining both self‐thinning and size‐dependent reproduction in a single plant species, the saltmarsh grass Spartina alterniflora, across a wide range of settings: three landscape positions, two habitats and eight sites, across sixteen years. Plants in different landscape positions and years varied tremendously in size and shoot density. However, all this variation could be explained by a single allometric relationship consistent with the self‐thinning law, but with a lower slope. Flowering was size‐dependent, and the size at which plants had a 50% probability of flowering varied among habitat, sites and years. Plants that were stressed reproduced at a smaller size than plants that were growing under good conditions, and this pattern was consistent among habitat, sites and years. Finally, reproductive biomass and the proportion of shoots flowering increased with increasing vegetative size (plant height or shoot biomass). Combining these two patterns, S. alterniflora plants growing high density are small and reproduce at a smaller size than large plants growing at low density. Although there is tremendous spatial and temporal variation in S. alterniflora growth and reproductive patterns, all this variation can be understood as resulting from two simple allometric trade‐offs. Because saltmarsh plants often occur in monospecific stands, they may serve as simple, model systems for studies of plant life history. A free Plain Language Summary can be found within the Supporting Information of this article.

Effects of Herbivory on Arrowgrass: Interactions between Geese, Neighboring Plants, and Abiotic Factors

Article

May 1998

Herbivores may affect plants by removing biomass, altering competitive interactions, and altering the abiotic environment. Changes in the size and quality of forage species and in species composition as a result of herbivory, in turn, affect future herbivory. We investigated the direct and indirect effects of herbivory by Brant Geese (Branta bernicla nigricans) on Triglochin palustris (arrowgrass) in a subarctic salt marsh in southwestern Alaska. In the first experiment, we compared arrowgrass in exclosed plots, unexclosed plots with feces removed, and control plots. In the second experiment, we used a full-factorial design to examine the effects of clipping arrowgrass, clipping neighboring plants, depositing goose feces, and their interactions on arrowgrass size and biomass allocation. In the third experiment, we placed hand-reared goslings on premanipulated plots from the second experiment to examine the effects of arrowgrass size, density, and species composition on the probability of an individual arrowgrass plant being grazed. For unclipped plants, feces deposition resulted in reduced bulb mass, reduced percentage of biomass in bulb and roots, and increased percentage of biomass in leaves, whereas feces deposition had no effect on clipped plants. Clipping neighbors resulted in increased arrowgrass root and stolon mass only for unclipped plants. Feces deposition resulted in increased vegetative reproduction when neighbors were clipped, but had no effect on vegetative reproduction when neighbors were not clipped. Plants in exclosed plots were larger, had greater allocation to leaves, had higher concentrations of C and N, and were more likely to flower than were plants in unexclosed plots. These results indicate an increase in competition for light with neighbor plants under feces deposition, which may be ameliorated by biomass removal of neighbors. Our results predict that an increase in grazing pressure is not necessarily detrimental to arrowgrass, provided that it is accompanied by increases in consumption of neighbor plants. The number of arrowgrass plants completely removed was not related to arrowgrass density, but the number of plants partially grazed increased with arrowgrass density. The probability that an individual arrowgrass plant would be grazed was negatively related to biomass or percent cover of several other species (Potentilla egedei, Chrysanthemum arcticum, Carex spp., Salix spp.). These results suggest that some neighbor species may provide a measure of protection (associational refuge) from herbivory, and that an increase in grazing intensity may have a strong negative effect on arrowgrass populations by reducing this protection and through an increased likelihood of consumption of the arrowgrass remaining after neighbors are removed. We conclude that the way in which we view neighboring plants (as competitors or potential protectors) affects our predictions regarding the effects of changing herbivore populations. Feedbacks from the plant community to herbivores following grazing should be included in studies that aim to extrapolate to the population level the effects of herbivory on individuals.

RAINFOREST EQUIVALENCE–A NEW APPROACH FOR COMPARATIVE ASSESSMENT OF ECOSYSTEM SERVICES OF HABITATS

Article

Full-text available

Jan 2024

Stronger increase of methane emissions from coastal wetlands by non‐native Spartina alterniflora than non‐native Phragmites australis

Article

Full-text available

Oct 2024

Societal Impact Statement The invasive species S. alterniflora and P. australis are fast growing coastal wetland plants sequestering large amounts of carbon in the soil and protect coastlines against erosion and storm surges. In this global analysis, we found that Spartina and Phragmites increase methane but not nitrous oxide emissions, with Phragmites having a lesser effect. The impact of the invasive species on emissions differed greatly among different types of native plant groups, providing valuable information to managers and policymakers during coastal wetland planning and restoration efforts. Further, our estimated net emissions per wetland plant group facilitate regional and national blue carbon estimates. Summary Globally, Spartina alterniflora and Phragmites australis are among the most pervasive invasive plants in coastal wetland ecosystems. Both species sequester large amounts of atmospheric carbon dioxide (CO2) and biogenic carbon in soils but also support production and emission of methane (CH4). In this study, we investigated the magnitude of their net greenhouse gas (GHG) release from invaded and non‐invaded habitats. We conducted a meta‐analysis of GHG fluxes associated with these two species and related soil carbon content and plant biomass in invaded coastal wetlands. Our results show that both invasive species increase CH4 fluxes compared to uninvaded coastal wetlands, but they do not significantly affect CO2 and N2O fluxes. The magnitude of emissions from Spartina and Phragmites differs among native habitats. GHG fluxes, soil carbon and plant biomass of Spartina‐invaded habitats were highest compared to uninvaded mudflats and succulent forb‐dominated wetlands, while being lower compared to uninvaded mangroves (except for CH4). This meta‐analysis highlights the important role of individual plant traits as drivers of change by invasive species on plant‐mediated carbon cycles.

Contributions of Perennial Pepperweed (Lepidium latifolium) Invasion to Rarity of the Endangered Suisun Thistle (Cirsium hydrophilum var. hydrophilum)

Article

Full-text available

Jan 2024

Invasive species exert disproportionate impacts in wetlands and pose particular challenges for rare species persisting at small spatial scales. In the urbanized San Francisco Estuary (SFE), which contains 90% of California’s remaining coastal wetlands, invasive and rare species often co-occur. One narrow endemic taxon, the federally listed Suisun thistle ( Cirsium hydrophilum var. hydrophilum ) is restricted to two or three locations where the invasive perennial pepperweed ( Lepidium latifolium ) has an increasing presence. Perennial pepperweed has invaded salt, brackish, and freshwater wetlands around the SFE, leading to high management concern. In this study, we investigated how perennial pepperweed may contribute to further rarity of the Suisun thistle, by conducting a removal experiment and surveying soil-plant relationships. Removing pepperweed led to a doubling of native species relative cover and an increase in native species richness by an average of one species per plot, positive effects on Suisun thistle cover, number, and reproductive output, and shifts in soil properties. Combined with survey data inside and outside of pepperweed stands, we conclude that pepperweed competes with Suisun thistle via competition for space, nutrients, and light, interferes with the Suisun thistle’s reproductive success, and alters brackish marsh soil physicochemical characteristics to further favor pepperweed. We recommend local control of pepperweed to prevent further loss of Suisun thistle. Further, the wide range of mechanisms by which this invasion may proceed if unchecked should be considered in other settings where rare or uncommon species are at risk from invaders.

Differential Nutrient Uptake by Saltmarsh Plants Is Modified by Increasing Salinity

Article

Full-text available

Jul 2021

In Southern European estuaries and associated salt marshes, the anthropogenic nutrient inputs, together with longer drought periods, are leading to increasing eutrophication and salinization of these coastal ecosystems. In this study, uptake kinetics of ammonium, nitrate, and phosphate by three common plants in Palmones salt marsh (Southern Spain), Sarcocornia perennis ssp. alpini, Atriplex portulacoides, and Arthrocnemum macrostachyum were measured in hydroponic cultures. We also determined how these uptakes could be modified by increasing salinity, adding NaCl to the incubation medium (from 170 to 1,025 mM). Kinetic parameters are analyzed to understand the competition of the three species for nutrient resources under realistic most frequent concentrations in the salt marsh. These results may also be useful to predict the possible changes in the community composition and distribution if trends in environmental changes persist. Atriplex portulacoides showed the highest Vmax for ammonium, the most abundant nutrient in the salt marsh, while the highest affinity for this nutrient was observed in A. macrostachyum. Maximum uptake rates for nitrate were much lower than for ammonium, without significant differences among species. The highest Vmax value for phosphate was observed in A. macrostachyum, whereas A. portulacoides presented the highest affinity for this nutrient. High salinity drastically affected the physiological response of these species, decreasing nutrient uptake. Sarcocornia perennis ssp. alpini and A. macrostachyum were not affected by salinity up to 510 mM NaCl, whereas A. portulacoides notably decreased its uptake capacity at 427 mM and even withered at 1,025 mM NaCl. At current most frequent concentrations of ammonium and phosphate in the salt marsh, S. perennis ssp. alpini is the most favored species, from the nutritional point of view. However, A. portulacoides could enhance its presence if the increasing ammonium load continues, although a simultaneous salinization would negatively affect its nutritional physiology.

Safe Havens Protected Areas for Disaster Risk Reduction and Climate Change Adaptation (Edited by Radhika Murti and Camille Buyck)

Chapter

Jan 2014

Brian Kastl

Mangrove ecosystems provide invaluable protection from climate change impacts and create environments in which communities can build coastal resilience. They are situated at the interface of saltwater and freshwater sources, where the stable flow of sediment and freshwater allows mangrove forests and associated livelihoods to thrive. One of the largest mangrove forests in Southeast Asia is located in Peam Krasaop Wildlife Sanctuary of Koh Kong Province in Cambodia. It is supported by a 4 km The community of Koh Kapik relies on surrounding mangroves for protection from coastal hazards. However, as the barrier beach to the mangroves retreats landwards, fishing villages are becoming increasingly vulnerable to coastal hazards. River sand mining and sea level rise are likely responsible. Forest conservation, initiated by IUCN, would improve the consistent flow of freshwater and sediments from the upstream rivers to the ocean, thereby reducing barrier beach migration and coastal disaster risks. This case study highlights the importance of protected area management that accounts for hydrological connectivity from the upstream watershed to the coast, and it provides further recommendations to protect mangrove-dependent livelihoods from coastal hazards. This research proposes river management strategies that will reduce barrier beach migration and build coastal resilience. It establishes priority zones for rehabilitation on the barrier beach, based on barrier beach migration rates. Coastal features, including spits and un-vegetated beaches within these priority zones are targeted for intervention. Re-vegetation with local plant species will prevent further landward migration of the barrier beach and protect livelihoods. During a provincial workshop and meeting with national government representatives the use of these strategies was discussed. This improved understanding of the highly connected sediment dynamics, coupled with rehabilitation and erosion prevention strategies, offers a pathway to build greater coastal resilience in Peam Krasaop Wildlife Sanctuary. Similar socioecological systems exist throughout the tropics, and lessons learnt from this case study can therefore be examined for application to other mangrove-dependent communities.

Site Fidelity, Philopatry, and Survival of Promiscuous Saltmarsh Sharp-Tailed Sparrows in Rhode Island

Article

Oct 2001

We investigated site fidelity and apparent survival in a promiscuous population of Saltmarsh Sharp-tailed Sparrows (Ammodramus caudacutus) in southern Rhode Island. Based on capture–recapture histories of 446 color-banded sparrows studied from 1993 to 1998 at our primary study site, Galilee, we observed significant variation in apparent survival rates among years, but not between sexes. Return rates of adult males (37.6%) and females (35.6%) were not significantly different during any year. Juveniles exhibited high return rates, ranging from 0 to 44%, with males (61% of returns) more likely to return than females (35%). In addition, we monitored movements of 404 color-banded sparrows at nine satellite marshes in 1997 and 1998, which supported our findings at Galilee and documented intermarsh movements by 10% of all banded birds. Lack of gender-bias in adult dispersal and strong natal philopatry of sparrows in Rhode Island occurs regularly among passerines possessing a variety of mating systems. Despite emancipation from parental and resource defense duties, adult male Saltmarsh Sharp-tailed Sparrows exhibited apparent survival rates similar to adult females. Availability of high-quality breeding habitat, which is patchy and saturated, may be the most important factor limiting dispersal for Saltmarsh Sharp-tailed Sparrows in Rhode Island.

Safe Havens Protected Areas for Disaster Risk Reduction and Climate Change Adaptation Edited by Radhika Murti and Camille Buyck

Article

Full-text available

Aug 2019

Chandra Bhushan Kumar

About IUCN IUCN, International Union for Conservation of Nature, helps the world find pragmatic solutions to our most pressing environment and development challenges. IUCN's work focuses on valuing and conserving nature, ensuring effective and equitable governance of its use, and deploying nature-based solutions to global challenges in climate, food and development. IUCN supports scientific research, manages field projects all over the world, and brings governments, NGOs, the UN and companies together to develop policy, laws and best practice.

Distribution of CSR strategy types in floodplain forest in Aksaz-Karagöl Wetland

Conference Paper

Jun 2018

Introduction: Wetland are very productive and stressful environment. Plant individuals adjust themselves phenologically, physiologically or morphologically to stress. Negative relation between competitive and stress tolerance is one of the most important factor that effecting the distributing of plant distribution and community structuring. In this study, we aimed to determine distribution of CSR (competitive, stress-tolerant, ruderal) strategy types in floodplain forest in Aksaz-Karagöl Wetland. Material and Methods: The present study was carried out between 2015-2017 years. Plant taxa, CSR strategy types and cover percentage of each taxa were identified. Specific leaf area (SLA), canopy height, dry matter content, leaf dry weight, lateral spread, flowering initiation and flowering period were used to determine CSR types. For the field measurements, at least ten individuals of each species were marked, while three individuals were used for leaf characters. Results: 85 plant taxa and 14 different CSR strategy types were identified in floodplain forest. The most abundant CSR types were C, C/CS, CR and C/CR. The cover percentage of these types were 107.7%, 43.1%, 36.9% and 13.3%, respectively. Discussion: According to results, competitive strategies are abundant in floodplain forest. On the other hand, representing of ruderal strategies after competitive ones shows low disturbance in the forest. Presence of the other strategy types could be mean that the forest has functional diversity. Acknowledgement: This study was supported by TUBITAK (The Scientific and Technological Research Council of Turkey, project no. 114O796). Keywords: Floodplain forest, CSR strategies, Aksaz-Karagöl Wetland, Sinop

The role of conservation agreements in disaster risk reduction: the case of Mount Mantalingahan Protected Landscape (MMPL) in the Philippines

Chapter

Full-text available

Jan 2014

As a protected landscape, Mount Mantalingahan’s importance lies in it being a Key Biodiversity Area (KBA) and one of ten Alliance for Zero Extinction (AZE) sites in the Philippines. However, prior to its declaration as a protected landscape, its forest area was not only in danger of mining activities but also of several hazards such as flooding and landslides. The declaration of Mount Mantalingahan as a protected landscape, along with its associated livelihood programmes for the mountain’s inhabitants, allowed for participatory activities that contributed to reduction of flooding and landslide risks in addition to livelihood improvements in three out of five municipalities that are included in the protected landscape. Disaster risk reduction in protected landscapes is best pursued in conjunction with conservation and development objectives. Through several conservation agreements with Conservation International-Philippines (CI-P), local communities in the Mount Mantalingahan Protected Landscape (MMPL) restored and conserved watersheds and, in the process, developed soft skills in managing community forestry enterprises and local water cooperatives.

Competition and salt-marsh plant zonation: Stress tolerators may be dominant competitors

Article

Full-text available

Sep 2001

Although a great deal of research has focused on the effects of nutrient supply on plant competition, few studies have explored how these processes interact with non-resource factors to determine community-level patterns. This study examined how resource competition interacts with physical stress to structure salt-marsh plant communities across a natural gradient in tidal stress. First, nutrient additions at naturally,occurring species borders at zonal and patch boundaries in two Rhode Island (USA) marshes revealed that competitive outcomes were typically reversed when nutrients were abundant. These results, which are consistent with earlier findings in a third southern New England marsh, suggest that a nutrient-dependent competitive hierarchy is a general characteristic of salt marshes in this region. To test whether these shifts in competitive outcomes occur only at naturally occurring species borders or can lead to more significant shifts in zonation patterns, lower marsh species were transplanted into the matrix of each zonal species at higher tidal elevations, and the outcomes of plant competition in fertilized plots and unfertilized plots were compared. Results of this experiment indicate that nutrient effects on the competitive relations of marsh plants were independent of where the interactions took place along the tidal gradient. The stress-tolerant species were consistently the best competitors in fertilized treatments, showing that an increase in nutrient availability can lead to drastic shifts in the distributions of plants across marshes. Finally, a third experiment examined the interaction between nutrient supply and the aboveground and belowground components of plant competition using a reciprocal transplant design coupled with nutrient-addition and neighbor-removal treatments. Results suggest that. competition is primarily belowground under ambient marsh conditions but is aboveground at high nutrient levels. Thus the mechanism underlying the nutrient-dependent competitive hierarchy, may be driven by a trade-off between belowground and aboveground competitive abilities, although the potential interaction between above- and belowground effects was not examined. Together, the results of these experiments suggest that nutrient supplies may significantly affect the competitive dynamics between salt-marsh perennials and their resultant zonation.. across an environmental gradient in tidal stress. The result that stress tolerators can be dominant competitors is not predicted by any current model of plant competition and must be considered in future empirical and theoretical studies.

Adaptation to Climate Change and Disaster Risk Management in the Po River Delta Protected Area

Chapter

Full-text available

Jun 2014

Carolina Collaro

An Ecological Profile of the Narragansett Bay National Estuarine Research Reserve

Book

Full-text available

Jan 2009

Spatial Ecology of Fiddler Crabs, Uca pugnax , in Southern New England Salt Marsh Landscapes: Potential Habitat Expansion in Relation to Salt Marsh Change

Article

Full-text available

Jun 2013

The spatial distribution of the fiddler crab Uca pugnax (Atlantic Marsh Fiddler Crab) in relation to salt marsh patch structure was investigated along the central Connecticut coast of Long Island Sound. Salt marsh landscape structure at the study sites exhibit characteristics consistent with changes noted in other systems along the US Atlantic coast over the last several decades, including significant seaward erosion, encroachment of low-marsh plants into high marsh, changing composition of high-marsh plant patch structure, and marsh dieback and drowning. Our objective was to determine whether the spatial patterns of U. pugnax inhabiting these systems differed from those previously reported for southern New England in light of these characteristics. Densities of crab burrows were highest in low-marsh patches of Spartina alterniflora (Atlantic Smooth Cordgrass) and unvegetated muds along tidal creek banks and mosquito ditches. Seaward-eroding low-marsh areas were generally devoid of live crabs and burrows. Crab-burrow densities varied across the complex patch mosaics in high-marsh areas. Burrow densities were generally low in the extensive short S. alterniflora patches that comprised much of the high-marsh area at several sites. However, high burrow densities, equivalent to low-marsh densities, were found in certain high-marsh patch types and upland transition zones. These included patches of Spartina patens (Marsh Hay Cordgrass), Distichils Spicata (Desert Salt Grass), and mixes of these, and particularly in S. patens patches wholly or partly comprised of hummocks of vegetation surrounded by bare sediment. At several sites, burrow densities were high in upland transition zone patches of Phragmites australis (Common Reed). As such, crab-burrow distributions were highly variable at local, within-marsh system spatial scales. Live U. pugnax were found regularly in all patch types on all marshes. Our results indicate a much broader distribution of U. pugnax at relatively high densities across southern New England marsh landscapes than previously reported. This finding may represent a case of habitat expansion in response to salt marsh change, likely due to sea-level rise and other factors, creating high-marsh habitats in a variety of patch types that can support resident populations of fiddler crabs. Such an expansion of a dominant salt marsh species, which can significantly affect ecosystem dynamics, may potentially increase the complexity of current salt marsh change patterns and dynamics along southern New England coastlines.

Estuarine Habitats of Narragansett Bay

Article

Malia L Schwartz

Does invasion of oligohaline tidal marshes by reed grass, Phragmites australis (Cav.) Trin. Ex Steud., affect the availability of prey resources for the mummichog, Fundulus heteroclitus L.?

Article

Apr 1998
J EXP MAR BIOL ECOL

Reed grass (Phragmites australis (Cav.) Trin. ex Steud.) has invaded large areas of tidal marsh along the lower Connecticut River and often occurs as a monoculture. Tidal marsh invertebrates (snails, amphipods and isopods) were common to abundant in reed grass-dominated regions, as well as in areas covered by typical tidal marsh vegetation at four sampling stations set up along the salinity gradient. This finding suggests that reed grass marshes provide suitable physical habitat and usable food resources for these semiaquatic detritus/algae feeders. Mummichogs (Fundulus heteroclitus L.) were caught on the high marsh during daylight high tides using Breder traps and an analysis of their gut contents was made. When daylight tides were high enough to cover the marsh surface, mummichogs moved up onto the marsh and fed extensively on marsh invertebrates, both in reed grass marshes and reed grass-free marshes. Such foraging appears to represent a direct trophic link between the marshes and adjacent estuarine waters. Even when tides were not high enough to flood the marsh surface, mummichogs moved into the tidal creeks that course through reed grass marshes and largely reed grass-free marshes and foraged there. With respect to macroinvertebrate populations and mummichog foraging, the reed grass marshes appear to be functioning in essentially the same ways as nearby marshes not invaded by this plant, at least in the short term.

Estuarine Vegetation at Rush Ranch Open Space Preserve, San Francisco Bay National Estuarine Research

Article

Full-text available

Dec 2011

The Rush Ranch Open Space Preserve (Rush Ranch) is located at the northwestern edge of the Potrero Hills and includes the largest remaining undiked tidal wetland within the Suisun Marsh region of the San Francisco Estuary. The brackish tidal wetlands grade into the transitional vegetation and undeveloped grasslands of the Potrero Hills, and we describe diverse vegetation that reflects the estuarine position, land use history, and hydrogeomorphic complexity of the site. We present a useful framework for future study of vegetation at this San Francisco Bay National Estuarine Research Reserve site. Rush Ranch includes four major estuarine geomorphic units that are widely distributed in the region and support vegetation: subtidal channel beds, fringing tidal marsh, tidal marsh plain and tidal marsh–terrestrial ecotone. These are distinguished by small variations in hydrology and elevation, as noted and described through field observations and historic vegetation-mapping data. We discuss vegetation within each of these landforms, considering each vegetation community as a function of changing physical environment and biological interactions. Past land use and exotic plant species invasions have substantially altered Rush Ranch's tidal marsh vegetation patterns. Our results indicate 27% of the current estuarine wetland-associated flora at Rush Ranch are exotic species, and several are highly invasive. Despite these influences, Rush Ranch's position in the landscape provides important and increasingly rare habitat linkages between the tidal marsh and upland grasslands, which allows great potential for restoration and enhancement. We present a detailed flora and vegetation analysis by hydrogeomorphic setting to provide an ecological framework for future monitoring, research, and adaptive conservation management at Rush Ranch.

Hydrology, Herbivory, and the Decline of Spartina patens (Alton) Muhl. in Outer Cape Cod Salt Marshes (Massachusetts, U.S.A.)

Article

Full-text available

May 2012

Salt marsh dieback in different regions of the United States exhibits considerable variability in symptoms, processes, and theoretical or proven causes. On Cape Cod (Massachusetts), where losses within the low-marsh zone (elevations below mean high tide, dominated by smooth cordgrass [Spartina alterniflora Loisel.]) have been particularly severe, recent studies suggest that intense grazing pressure from increased abundances of a native, herbivorous, purple marsh crab (Sesarma reticulatum) is to blame. Low-marsh dieback is spatially heterogeneous because it is closely related to the distribution of the crabs' preferred substrate (peat vs. sand or mud). However, vegetation losses have also occurred in the high marsh, which is comprised of mainly saltmeadow cordgrass (Spartina patens [Aiton] Muhl). In contrast to the low marsh, high-marsh losses consistently occur along the seaward-most edge of this zone, suggesting a link with hydrology (flooding frequency). In this study, we attempted to determine the relative contribution of environmental factors and crab herbivory to high-marsh dieback. To do this, we (1) characterized tidal regimes in dieback vs. healthy areas, (2) assessed the extent of herbivory on S. patens using crab-exclosure cages, (3) documented the ability of S. patens to recover from simulated grazing (clipping) in different marshes and in different areas of individual marshes, and (4) estimated densities of S. reticulatum in two high-marsh dieback areas. The results indicate that S. patens losses are likely the result of a combination of Stressors. Flooding frequency and salinities are higher in dieback areas, which impart a higher level of physiological stress. Plants growing there also seem to have a much-reduced capacity to recover from both simulated and actual grazing by the herbivorous crab, S. reticulatum. Continued losses of high-marsh vegetation could eliminate this community from coastal wetlands on Cape Cod, Massachusetts.

Genotypic diversity and trait variance interact to affect marsh plant performance

Article

Mar 2014
J ECOL

Anne Randall Hughes

Intraspecific diversity can have important effects on population, community and ecosystem processes, yet we have little understanding of the relative importance of genetic‐ versus trait‐based measures of intraspecific diversity. I conducted a manipulative field experiment of plant ( Spartina alterniflora ) genotypic diversity and trait diversity to examine their independent and interactive effects on plant performance and community structure. I focused on variation within and among genotypes in plant stem height, a trait that varies substantially across environmental gradients and can be an important predictor of plant competition intensity. Trait and genotypic diversity interactively affected multiple metrics of plant performance. Both stem density and spatial spread increased with genotypic diversity in the low trait diversity combinations, yet there were negligible to weak negative effects in the high trait diversity treatments. Spartina alterniflora percentage cover also varied with genotypic and trait diversity, but not in a clear linear pattern. There were no effects of trait or genotypic diversity on associated macrofauna above‐ground, yet they interactively affected below‐ground measures. Infaunal abundance and sediment oxygen availability mirrored the idiosyncratic response of plant percentage cover. Despite the interactive effects of genotypic and trait diversity, high trait diversity consistently increased plant performance in genotypic monoculture. Synthesis . The effects of intraspecific plant trait diversity on a range of plant and community responses in this study reinforce the premise that functional differences underlie ecological effects of genetic diversity and suggest that readily measured trait variance may serve as a valuable predictor of plant performance.

Ecosystem Restoration and Management: Scientific Principles and Concepts

Article

Full-text available

Jan 1999

Natural disasters and long-term recovery: A baseline study of historical change and habitat structure of Juncus roemerianus marsh at Grand Bay, Mississippi

Article

Full-text available

Jan 2010

Tami Wells

Ecosystem structure and function in a Juncus roemerianus dominated marsh in coastal Mississippi was investigated using remote sensing techniques. Rate of change in land cover types were computed from historical aerial photography (1940 to 2006) of the study area located in Kreole, MS. Baseline biodiversity and vegetation coverage were determined from in situ line intercept vegetation analyses. Post-classification difference maps for intervals between image time periods and baseline parameters were compared using 2006 vegetation transects and a 1 m resolution Digital Ortho Quarter Quadrangle (DOQQ) image as ground-reference. The ancillary photographs and digital imagery were rectified, digitized and interpreted from both analog and digital file formats using a combination of geospatial techniques. A Gaussian normalization technique provided a minimum standard deviation in pixel brightness among 1940, 1985 and 2006 images as compared to other image normalization techniques. Additional investigations were made from images with dates significant to Hurricane Elena (1985) and xxv Hurricane Katrina (2005) storm events in coastal Mississippi. Data collected from Mahalanobis distance supervised image classification and simple value difference maps demonstrated that change in marsh structure did occur between pre and post-storms at the study area in Mississippi. A classification error matrix showed accuracies ranging from 46.80% in the 1940 classification to 91.96% in the 2006 ground reference. The supervised post classification percent change of natural marsh for the Hurricane Elena (1985) imagery was + 5.25% Juncus roemerianus marsh, +2.47% pine hummock, +0.91% open-water, -7.14% salt panne, and +0.34% unclassified. The Hurricane Katrina (January 2004-March 2006) supervised post classification percent change was +13.62% Juncus roemerianus marsh, - 13.3230% pine hummock, -2.90% open-water, +2.61% salt panne, and 0.0% unclassified. The percent change difference map for Hurricane Elena (natural) was 0%, 10.81%, 88.85%, and 0.34% respectfully with a mean of 2.8952% and standard deviation of 1.0683% across all classes. The Hurricane Katrina percent change difference was 0%, 11.68%, 88.32%, and 0% respectively with a mean of 2.8832% and standard deviation of 0.3212 %. The overall pixel change in pre and post storm images from Hurricane Elena were 10.34% of the pixels (2811 m2) and 11.68 % (3175 m2) for Hurricane Katrina.

Marine ecological research in seashore and seafloor systems: Accomplishments and future directions

Article

Mar 2000

Research in seashore and seafloor communities has contributed immensely to the conceptual growth of ecology. Here we summarize some of the most important findings and discuss needs and opportunities for future work. Disproportionately large numbers of the most influential contributions are derived from studies of rocky shores and coral reefs because aspects of these Systems (accessibility) and of their most common species (sessile or weakly motile, high density, short generation time) make them well suited to manipulative experiments. Foremost among the research contributions from seashore and seafloor systems are increased understanding of (1) competition and consumer-prey interactions, (2) trophic cascades and other indirect species interactions, (3) the evolution of defense and resistance in consumer-prey systems, (4) the importance of propagule transport and recruitment variation to adult populations, (5) the impacts of physical disturbance, and (6) the generation and maintenance of species diversity on ecological time scales. We acknowledge the importance of manipulative experiments in the growth of marine ecology, but question whether a strict adherence to this approach will best serve future needs. Some of the most pressing needs for future knowledge are: (1) documenting the complex influences of spatial and temporal scales on ecological processes, (2) identifying the role of large, mobile predators in marine ecosystems, (3) understanding factors limiting marine autotrophs, (4) integrating historical biology and neontology, and (5) appreciating intersystem linkages. Increased attention to conducting arrays of experiments, taking measurements and observations, and documenting change at larger scales of space and time will provide insights that are unattainable by the commonly used methodological protocols. Novel approaches, including (1) evaluating and managing human disturbance for the joint purpose of conservation and learning, (2) developing stronger ties between scientists working in open-ocean and near-shore systems, and (3) developing collaborative projects among scientists in the academic, governmental, and private sectors are required to understand many of these processes.

Comparison of nitrogen cycling in salt marsh zones related to sea-level rise

Article

Full-text available

Oct 2001

Zones in salt marshes can be distinguished by different community and ecosystem properties. As marshes respond to changes in sea level, one might expect alterations in the relative proportions of these zones and, hence, alterations in overall functioning. We used ecological network analysis to assess potential changes in 1 ecosystem function, nitrogen cycling. We constructed nitrogen cycle networks of zones (creekbank, low marsh, and high marsh) for 3 salt marshes on the East Coast of the USA; Great Sippewissett in Massachusetts, Upper Phillips Creek in Virginia, and Sapelo Island in Georgia. The same network structure was applied to all zones, largely using data derived from the literature on the 3 marshes. The factors used to analyze how nitrogen flowed through each zone included how nitrogen imported into the marsh was exported, how imports were related to primary productivity, and how much nitrogen was cycled within the system. Emphasis was placed on identifying patterns across zones that were consistent for all 3 marshes. When precipitation and tidal particulate nitrogen (PN) were the imports, export from active cycling via burial and denitrification significantly increased in importance moving across the marsh from the creekbank to the high marsh. Relative nitrogen cycling also significantly increased from creekbank to high marsh. As the area of the marsh zones decrease or increase in response to sea-level rise, nitrogen dynamics will change as a consequence, If the landscape slope is low allowing the marsh to migrate overland, the high marsh zone will increase in area. Nitrogen cycling as a percentage of total system throughput will increase per unit area averaged over the total marsh. If, however, the marsh stalls because of a steep slope at the upland margin, cycling will decrease on a per unit area basis. If the supply of sediment is great and the marsh progrades toward the sea, nitrogen cycling within the marsh may decrease. Therefore, as relative sea-level rises, the response of a salt marsh's nitrogen cycle will depend on the slope and sediment supply available to the marsh.

Salt Marsh Distribution, Vegetation, and Evolution

Chapter

Apr 2021

Salt marshes are highly dynamic and important ecosystems that dampen impacts of coastal storms and are an integral part of tidal wetland systems, which sequester half of all global marine carbon. They are now being threatened due to sea-level rise, decreased sediment influx, and human encroachment. This book provides a comprehensive review of the latest salt marsh science, investigating their functions and how they are responding to stresses through formation of salt pannes and pools, headward erosion of tidal creeks, marsh-edge erosion, ice-fracturing, and ice-rafted sedimentation. Written by experts in marsh ecology, coastal geomorphology, wetland biology, estuarine hydrodynamics, and coastal sedimentation, it provides a multidisciplinary summary of recent advancements in our knowledge of salt marshes. The future of wetlands and potential deterioration of salt marshes is also considered, providing a go-to reference for graduate students and researchers studying these coastal systems, as well as marsh managers and restoration scientists.

What Is the Role of Ecosystem Engineers in New England Salt Marshes? A Mesocosm Study of the Fiddler Crab and the Purple Marsh Crab

Article

Jan 2019

Alexandria Moore

The services and functions provided by coastal wetlands are numerous and influenced by factors ranging from climate and tidal regime to ecosystem engineers and anthropogenic modifications. In New England salt marshes, fiddler crabs and purple marsh crabs are cooccurring species that are among the most conspicuous burrowing macroinvertebrates in the region. Both are known to influence salt marsh ecosystem functions through their burrowing and feeding behavior, but the ways in which they regulate specific properties, individually and together, is unclear. Using an ex situ mesocosm study, I manipulated the presence of fiddler crabs and purple marsh crabs in order to evaluate their impact on several soil properties and aboveground biomass. Results show that, contrary to previous studies, the fiddler crab had little impact while the purple marsh crab altered soil quality with positive implications for plant growth. This suggests that the purple marsh crab, known to be a voracious consumer of marsh vegetation, may play a much more nuanced role in the maintenance of plant growth than previously thought. Additional ex situ studies should be done to further delineate the impact of these two species.

Scale Mismatch in Marsh Migration Modeling: Opportunities Afforded by μUAS/Drone Mapping

Article

Full-text available

Jun 2017

Scott Graves

Coastal Habitats of the Gulf of Mexico

Chapter

Full-text available

Jun 2017

Urbanization and industrial development pressures have seriously impacted coastal ecosystems, including vegetated intertidal and subtidal marine habitats such as barrier strands and associated wetlands and seagrasses. These ecosystems provide a suite of services including carbon storage, pollution and nutrient abatement, soil formation, fisheries support, and flood and storm protection. Emphasis has been placed on vegetated marine habitats that occur immediately adjacent to the Gulf of Mexico, including barrier islands and beaches, salt marshes and mangroves, seagrasses, intertidal and subtidal flats, and reed marshes at the mouth of the Mississippi River. These habitats, their depositional environments, and the ecology of their dominant flora and fauna are described within the context of major marine and terrestrial ecoregions. The information and analysis in this chapter should better enable effective management and restoration of coastal habitats in the Gulf as environmental change continues to alter their structure and function and reshape their associated biotic assemblages.

Riparian Vegetation Responses: Snatching Defeat from the Jaws of Victory and Vice Versa

Chapter

Jan 1999

The 1996 controlled flood failed to demonstrate five aspects of its primary vegetation-related management goal of removal of near-shore vegetation. First, when compared to pre-flood measurements, total vegetative cover was reduced only 20% and the areal extent of wetland and woodland/shrubland patches was not significantly different from the previous year when measured 6 months after the high flows. There was an immediate effect in terms of burial of some marshy areas under coarse sand, but most of these recovered within 6 months. Second, the controlled flood consistently affected only the lowest vegetation layer (grasses and herbs). Third, there was some effect on soil seed banks; sites lost roughly 45% of the seeds and 30% of the species richness of the pool of readily germinable seeds in the top 10 cm of the soil. Fourth, the loss of surface organic matter (duff) was significant in only 3 of the 9 sites, the other 6 showed no significant differences between years. There was no significant change across all sites. Finally, although there was no consistent effect on germination site quality in terms of mean soil grain sizes, there was a significant homogenization of substrates within and among sites due mostly to the loss or burial of fine sediments in return current channel settings. As documented in other chapters of this volume, the controlled flood was a success administratively and a successful demonstration of other management goals, especially in moving sediment from the channel bottom to high elevation deposits. Further, the flood was also a success in that it provided a relatively consequence-free opportunity to learn about flood hydrographs and vegetation in this system. Our data and those of others in this volume suggest that had the flows been successful in removing plants and reworking the underlying substrate in wetland patches, the recovery of vegetation would have been slowed considerably by the lack of fine, nutrient-rich sediments.

Phytoremediation: A Plant—Microbe-Based Remediation System

Chapter

Jan 1999

Salt marshes: A natural and unnatural history

Article

Jan 2009

Now championed as critical habitats for plants, animals, and people because of the environmental service and protection they provide, salt marshes were once considered unproductive wastelands. Salt Marshes, with an emphasis coastal wetlands in the Atlantic and Gulf regions and the San Francisco Bay area, offers readers a wealth of essential information about a variety of flora and fauna, marshes' ecological importance, consequences of human neglect and overdevelopment, and insight into how these wetlands recover.

Tidal Wetland Vegetation and Ecotone Profiles: The Rush Ranch Open Space Preserve

Chapter

Oct 2012

Rush Ranch includes the largest remaining tidal marsh within Suisun Marsh of the San Francisco estuary. Estuarine geomorphic units frame its diverse wetland vegetation, influenced by estuarine position, land-use history, and the hydrogeomorphic structure of the site. The geomorphic-vegetation units (subtidal channel beds, fringing tidal marsh, tidal marsh plain, and tidal marsh-terrestrial ecotones) are distinguished by variations in hydrology, substrate, and elevation. We consider the vegetation with each landform as a function of past and modern physical processes and biological interactions. Historical land uses and exotic plant invasions have substantially altered Rush Ranch tidal-marsh vegetation and species diversity. Rush Ranch's landscape position provides important and increasingly rare terrestrial ecotones between the tidal marsh and lowland grasslands, providing potential for estuarine transgression with rising sea level.

Coastal Wetland Ecology and Challenges for Environmental Management

Chapter

Feb 2014

Anna R. Armitage

Coastal wetlands are plant communities at the land-sea interface. Two common types of coastal wetlands are salt marshes and mangrove swamps. Marsh vegetation is typically comprised of grasses and shrubs, and mangrove swamps are dominated by trees. Salt marshes are widespread in cooler temperate latitudes, but most mangrove species cannot tolerate freezing temperatures, so they grow in warmer tropical and subtropical latitudes. Salt marshes and mangroves overlap in some subtropical regions; these areas may undergo shifts in foundation plant species composition in response to climate change. The dynamics and ecological consequences of these shifts are important topics for future research. Plants in coastal wetlands are anatomically and physiologically adapted for abiotic stressors including prolonged inundation, which causes soil anoxia, and high salinity. Salt marshes exhibit predictable zonation patterns, where the distribution of species within a site predictably varies with small changes in elevation. These zonation patterns are driven by species-specific adaptations to abiotic stressors and by interspecific competition. Zonation patterns in mangrove swamps are more variable. Coastal wetlands provide a variety of ecosystem services to human communities: wetlands can improve water quality, store nutrients, buffer against erosion and storm surge, and provide nursery habitat for commercially and recreationally important fishery species. Current management issues in coastal wetlands include encroaching suburban and agricultural development, sea level rise, nutrient enrichment and eutrophication from agricultural run-off and treated sewage discharge, and freshwater diversion. The policies regulating development on coastal wetlands are complex and dynamic. Restoration is the most common approach to mitigate for anthropogenic impacts. An understanding of wetland ecology is crucial to making wise decisions concerning the nature and direction of restoration projects.

The role of positive interactions in communities: Lessons from intertidal habitats

Article

Full-text available

Oct 1997

Positive interactions that result from neighbors buffering one another from stressful conditions are predictably important community forces in physically stressful habitats. Here, we examine the generality of this hypothesis in marine intertidal communities. Intertidal communities have historically played a large role in the development of community ecology since they occur across pronounced physical gradients and are easily manipulated. Positive interactions, however, have not been emphasized in studies of intertidal communities. We first review studies of intertidal marsh plant communities that suggest that positive interactions play a dominant role in the structure and dynamics of these common assemblages. We then present the results of an experimental manipulation on New England rocky shores that suggests that group benefits are as important in maintaining the upper intertidal limits of dominant spaceholders on rocky shores as the negative forces of competition and predation are in maintaining lower distributional limits. We conclude by discussing the generality and implications of our results. We argue that biogeographic biases have limited appreciation of the role played by positive interactions in intertidal communities. Most of the work that has formed the foundation of marine intertidal ecology was done in cool temperate habitats, whereas positive interactions driven by the amelioration of thermal or desiccation stresses are likely more important in warmer climates. We further argue that many important positive feedbacks operate at large spatial scales, not conducive to experimental study, and thus have escaped critical attention and general acceptance. We suggest that recognizing the role of positive interactions in communities may be key to understanding population and community processes in physically stressful habitats, many large-scale landscape processes, and uncovering long-suspected linkages between biodiversity and community stability.

Coastal ecosystems in Kouchibouguac National Park: adaptation possibilities for protecting traditional knowledge of a local community

Chapter

Full-text available

Jan 2014

Over the past 50 years, the coastal ecosystem of Kouchibouguac National Park of Canada has become increasingly exposed to climate related events such as sea level rise and storm surges. Salt marshes are an important component of this ecosystem as they contain many traditional medicinal plants for the nearby First Nations. This case study examines the potential challenges facing these plants and the community that relies on them, as well as the possible adaptation solutions, including restoration, monitoring and translocation. The study included field surveys along the coastal marshes of the park, integration of the data with a digital elevation model and climate change scenarios, and talking circles with community members to discuss the implications of the data. The results of the field survey showed that most of the populations of sweetgrass (Hierochloe odorata) and other traditional medicinal species are under threat when storm surges occur. Under the projected scenarios of sea level rise coupled with storm surges, many of these sites would probably not be able to recover, leading to loss of populations. Some of the proposed measures that may also be useful for disaster risk reduction include linking weather forecasting (for storms) with harvest and monitoring periods in order to avoid risks to people, as well as relocation of some populations.

Effects of Environmental Manipulations on Triglochin Palustris: Implications for the Role of Goose Herbivory in Controlling its Distribution

Article

Apr 1996

1 Arrowgrass (Triglochin palustris) is a preferred forage species of geese in the Yukon-Kuskokwim Delta (south-western Alaska) where it is found primarily on slough levees in coastal areas. Geese may affect nutrient availability, interspecific light competition, and salinity. These variables were manipulated in order to identify interactive effects of interspecific competition and abiotic factors on arrowgrass size, biomass allocation and distribution, which are likely to be significant in relation to the effects of herbivory on arrowgrass abundance and distribution. 2 Arrowgrass individuals were transplanted from two slough levee communities to the same two communities and to the adjacent slough margin and wet Carex meadow communities. Geese were excluded and nutrient availability, light competition and salinity levels were manipulated. 3 When light levels were not manipulated, fertilization had a negative effect on plant biomass and allocation to bulbs. Under decreased competition for light, plant biomass of fertilized plants was not significantly different from that of control plants. Fertilization appears to have a negative effect on arrowgrass as a result of increased competition for light. 4 Plants in the slough margin habitat were smallest, had the lowest allocation to leaves and stolons, and the lowest N concentrations and total N mass. Results from the fertilization treatment suggest plants in this community are limited primarily by physical factors. 5 Plants in the Carex wet meadow had higher allocation to leaves than in other communities under unfertilized conditions, but decreased allocation to leaves under fertilization. Plants in this community appear light- and nutrient-limited under unfertilized conditions, and primarily light-limited under fertilization. 6 Our results suggest that the presence of geese may control arrowgrass distribution because (a) faeces deposition has a negative effect on arrowgrass, (b) this negative effect is ameliorated by consumption of neighbours, and (c) the combination of high light competition and highly selective foraging for arrowgrass limit expansion of arrowgrass into the Carex meadow community. These explanations can now be tested.

The role of groundwater flow in controlling the spatial distribution of soil salinity and rooted macrophytes in a southeastern salt marsh, USA

Article

Mar 1998

Groundwater flow is an important factor in governing botanical zonation in the salt marsh at North Inlet, SC. Areas of the marsh adjacent to upland forest are characterized by upward flow of fresh groundwater. This inhibits the infiltration and evapoconcentration of saline tidal water and the development of a habitat for hypersaline-tolerant fugitive species such as Salicornia europaea. Areas of high marsh that are not adjacent to extensive upland forest are characterized by downward gradients in hydraulic head. This allows the infiltration and evapoconcentration of tidal water and the development of hypersaline conditions that are suitable for salt-tolerant fugitives.

Tidal Vegetation: Spatial and temporal Dynamics

Article

Oct 2012

San Francisco Bay and Delta tidal wetlands represent the most intact Mediterranean-climate wetlands in North America, yet only 10 percent survived the twentieth century. Wetland plant communities within the bay, as elsewhere, are structured by gradients in inundation and salinity, as well as competitive and positive interactions, resulting in a predictable pattern of tidal-freshwater, brackish, and salt-marsh systems. Inundation stress creates patterns of plant distribution within tidal wetlands, often with strong patterns of zonation. Plant-species diversity within tidal wetlands varies strongly across salinity gradients, with fewer than twenty species in bay and delta tidal salt marshes and sixty to one hundred species in tidal freshwater wetlands; productivity is also greatest in freshwater and brackish tidal wetlands.

Seasonal variation of fungal biomass in the sediment of a salt marsh in New Brunswick

Article

Full-text available

Jul 1993

In a marsh in New Brunswick, Canada, belowground biomass of Spartina alterniflora consistently exceeded aboveground biomass by a factor of approximately 9. Both values peaked in July. Redox potential of the sediment was negative at all levels tested (2, 6, and 11 cm below surface), and was negatively correlated with depth. Concentrations of ergosterol, a sterol typical of higher fungi, were negatively correlated with redox potential and were highest in roots and rhizomes in July and August, 1-3 cm below the surface. These maxima corresponded to a fungal content of approximately 0.6% per ash-free dry mass of Spartina material. Balsa wood panels buried in anaerobic salt marsh sediment were colonized by fungi within 12 weeks. Eight fungal species isolated from S. alterniflora roots did not grow in the absence of oxygen, but were able to grow downward into an anaerobic medium.

Suppressed recovery of plant community composition and biodiversity on dredged fill of a hurricane-induced inlet through a barrier island

Article

Full-text available

Sep 2013

In September 2003, Hurricane Isabel created an inlet over 500 m wide and 10 m deep that connected the Atlantic Ocean and Pamlico Sound. This breach was subsequently filled with sediments dredged from the adjacent sound. The purpose of this study was to determine if the barrier island terrestrial plant communities were naturally re-establishing through primary succession. In 2006–2008, we compared plant communities, soil carbon and nitrogen, and Aeolian transport of sediments in undisturbed back-dunes, undisturbed shrub thickets, putative back-dunes, and putative shrub thickets. We found that species richness and evenness were low on the filled area relative to adjacent plant communities that had persisted through the storm. Plants on the filled area were almost entirely limited to a band of primarily Spartina patens found at the margin of the sound and there were no signs of establishing the typical zonation of back dune grasses, shrubs, and salt marsh. Evaluation of soil quality suggests that nutrients and organic material are not limiting recovery. Aeolian transport, however, was demonstrably higher across the filled area, where no dense stands of taller plants buffered the airflow. Plant re-establishment is suppressed by wind erosion inhibiting deposition of seeds. Recovery of the site will likely depend on the rhizomatous spread of S. patens from the sound shore. S. patens can then potentially facilitate the colonization of other species by buffering the wind and trapping seeds of other plants. Ironically, this slow recovery may benefit federally threatened bird species that require sparse vegetation for nesting success.

Negative and neutral marsh plant interactions dominate in early life stages and across physical gradients in an Oregon estuary

Article

Feb 2013

Conceptual models and some empirical studies in plant systems show that species interactions can shift from competitive under low stress and high productivity conditions to positive under high stress and low productivity conditions. In this study, we explore the relative strength and direction of marsh plant interactions at early life stages across a stress and productivity gradient in South Slough, Coos Bay, Oregon, USA. Germination and survival of five plant species (Atriplex patula L., Distichlis spicata (L.), Plantago maritima (Lam.) A. Gray, Sarcocornia pacifica (Standl.) A. J. Scott, Triglochin maritimum L.) were examined in the presence and absence of neighboring vegetation at three intertidal levels in each of three marsh sites along an estuarine gradient. We found that many of the interactions measured across these gradients were negative or neutral. The direction of the interactions depended on life stage, with neighboring plants having mostly negative and neutral effects on seed germination, and mostly neutral and rarely positive effects on seedling survival especially at lower intertidal locations. The exception was in the high intertidal at all sites, where competition was common. We found that the intensity of the interactions varied depending on marsh site, intertidal elevation, and plant species identity and that life stage and regional climate may be responsible for the general lack of positive interactions. We suggest that measuring species interactions across complex gradients of physical stress at different life stages can help refine our conceptual models and lead to better predictions of the factors controlling community structure.

Patrones de biomasa de Spartina SPP. en dos marismas costeras de la provincia de Buenos Aires

Thesis

Full-text available

Jan 2010

Gabriela González Trilla

In this thesis allometric models for estimating biomass for both species characteristics of two marshes of the Buenos Aires Province: Spartina densiflora in Mar Chiquita and Spartina alterniflora in Bahia Blanca are generated. A nondestructive method applied to permanent sample plots based on these models was used to determine biomass and primary productivity in the two sites. In addition, spectral profiles at different biomass levels was recorded for both species using a hand held radiometer and regression models relating biomass and synthetic indices derived from hyperspectral data were performed. Finally, these models of biomass were applied to a Landsat TM time seriesdata and were compared with biomass data measured at the field.

A preliminary carbon budget for a part of the Ems estuary: The Dollard

Article

Aug 1977

F.B. Van Es

During 1975, measurements were made to quantify all sources of input of organic matter in the Dollard. This made a comparison possible between in situ primary production, import from natural sources and organic waste discharges in terms of organic carbon. In order to make a carbon budget, mineralization and the amount of organic matter buried in the sediment was also measured. Input of organic carbon was mainly based on primary production on the tidal flats (measured in situ as O2 production, 9.3×106 kg C · year−1), accumulation of suspended matter originating from the North Sea and the River Ems (maximal 37.1×106 kg C · year−1) and discharge of heavily polluted water (33.0×106 kg C · year−1). Input from primary production in the water phase was negligibly low (0.7×106 kg C · year−1). Loss of organic carbon was due to mineralization in the sediment (measured in situ as oxygen consumption, 18.2×106 kg C · year−1), mineralization in the water phase (using the BOD technique, 7.2×106 kg C · year−1) and burying of organic matter in the sediment (9.9·106 kg C · year−1). The loss of dissolved organic matter to the adjacent Waddensea was not measured but must be considerable. Allochthonous detritus was the main source of energy for the food-webs in the Dollard. The role of bacteria as an important source of food for higher organisms in the Dollard is discussed.

Effect of thermal stress on phytoplankton productivity in condenser cooling water

Article

Jan 1973

Spatial Cover of Eight Common Macrophytes and Three Associated Invertebrates in Narragansett Bay and Contiguous Waters, Rhode Island, U.S.A

Article

Jan 1993

Eight macrophyte species and three invertebrate species were surveyed in the intertidal and upper subtidal zones at 54 stations in Narragansett Bay and adjoining waters during one week of spring low tides. The result is an instantaneous estimate in early summer of: 1) the location of these species throughout the estuary, 2) the frequency of stations in which each species was present and 3) the percentage cover of that species at each station. These results were combined with related information from 10 additional stations that were being monitored for quantitative changes in a broader range of species over four seasons. Subtidal Zostera marina (16% frequency) and Laminaria saccharina (20%) were restricted to southern portions of the bay but extended into the East Passage and Sakonnet River. Where these plants were found, they often occupied > 50% cover. Chondrus crispus (78% frequency), Codium fragile (68%), Fucus spp. (72%), Ascophyllum nodosum (25%) and Ulva lactuca (84%) were found throughout the bay. These algae generally occupied < 50% cover. Spartina alterniflora (53% frequency) appeared in mid- to upper sections of the bay, most frequently in Mount Hope Bay; where it occupied up to 100% cover. Of the associated invertebrates, Littorina littorea and Semibalanus balanoides were present at nearly every station (91 and 92% respectively) rarely exceeding 10% cover. In contrast Mytilus edulis appeared throughout the bay with lower frequency (72%) but higher percentage cover (often above 50%). This semiquantitative survey adds to the international data bank on variability within an embayment and provides a data base against which biological changes in the bay may be compared.