DOCSLIB.ORG

Integrated Shoreline Guidance

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Integrated Shoreline Guidance Integrated Shoreline Guidance May 2020 Center for Coastal Resources Management Virginia Institute of Marine Science William & Mary Adapted from Recommendations for Revisions to the Wetlands Guidelines This report is adapted and updated from the following: Recommendations for Revisions to the Wetlands Guidelines, 2008 And Sand Dunes and Beaches in Virginia: Science and Management, 2009 These reports were funded, in part, by Virginia Coastal Zone Management Program at the Department of Environmental Quality through Grant #NAO5NOS4191180 and #NA07NOS4190178 of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, under the Coastal Zone Management Act of 1972, as amended. Table of Contents Table of Contents ......................................................................................................................... 3 Section 1: Introduction ................................................................................................................. 4 Section 2: Definitions .................................................................................................................. 6 Tidal Wetlands: Vegetated ....................................................................................................... 6 Tidal Wetlands: Nonvegetated ................................................................................................. 6 Beach ........................................................................................................................................ 6 Coastal primary sand dune ....................................................................................................... 6 Water Dependent ...................................................................................................................... 7 Section 3: Tidal Shorelines in the Ecosystem .............................................................................. 8 Shoreline Ecosystem Services .............................................................................................. 9 Tidal Wetland Services to Shoreline Ecosystems .............................................................. 10 Coastal Primary Sand Dune and Beach Services to Shoreline Ecosystems ....................... 11 Section 4: Tidal Shoreline Classification ................................................................................... 12 General Distribution of Tidal Wetlands ................................................................................. 12 Tidal Shoreline Classification ................................................................................................ 16 Wetlands ............................................................................................................................. 16 Beach/ Sandy Intertidal ...................................................................................................... 19 Dunes .................................................................................................................................. 19 Section 5: Criteria for project review ......................................................................................... 20 General Criteria ...................................................................................................................... 20 Required Information ............................................................................................................. 20 Specific Criteria ...................................................................................................................... 22 1. Shoreline Protection ....................................................................................................... 22 2. Residential, Commercial & Accessory Structures ......................................................... 25 3. Dune leveling and relocation .......................................................................................... 26 4. Dredging ......................................................................................................................... 26 5. Channeling into Uplands and Marshes ........................................................................... 27 6. Stormwater Facilities and Best Management Practices (BMPs) .................................... 27 7. Marinas ........................................................................................................................... 27 8. Drainage and Mosquito Ditching ................................................................................... 27 9. Utility Crossings ............................................................................................................. 27 10. Aquaculture .................................................................................................................. 28 11. Temporary Impacts ....................................................................................................... 28 12. Flooding and Sea Level Rise ........................................................................................ 28 13. Wetland, Beach or Dune Restoration ........................................................................... 29 Section 6: Glossary ..................................................................................................................... 30 Section 1: Introduction The purpose of this document is to update the Tidal Wetlands and Coastal Primary Sand Dune and Beaches Guidelines. Originally adopted by the Virginia Marine Resources Commission (VMRC or Commission) in 1974, the Wetlands Guidelines were formally amended to include non-vegetated wetlands in 1982. The Wetlands Mitigation-Compensation Policy first adopted in 1989 was added to the Guidelines when they were reprinted in 1993. The most recent change to tidal wetlands guidance was an update to the Mitigation- Compensation Policy in 2005. These later amendments were critical changes to the Guidelines that focused on the addition of new information and policy while the original content and construct of the guidelines remain largely unchanged. There are close to 300,000 acres of tidal wetlands in Virginia found along shores of the Chesapeake Bay and its tributaries, as well as Back Bay, and the coastal bays and inlets of the Atlantic Coast. The greater share of these is found in the broad, expansive marshes on the seaside of the Eastern Shore and the remaining wetlands line the shores of Virginia’s creeks and rivers. These same shores have and continue to provide access to commerce and trade and are an increasingly popular choice for residential living. Years of human impact have resulted in wetland losses and adverse impacts on wetland functions that have diminished the resource and adversely affected the role of wetlands in the ecosystem. In 2011, the Commonwealth adopted a policy to identify living shorelines are the preferred approach to tidal shoreline erosion. In 2020, legislation was passed to mandate that the Commission shall permit only living shoreline approaches to shoreline management unless the best available science shows that such approaches are not suitable. Additional policy changes to promote living shorelines in Virginia include the provision for a real property tax exemption for living shorelines and that living shorelines projects are not to be assessed as an “improvement” for real property taxes, a low interest loan program through the Virginia Water Facilities Revolving Fund, and the additional of living shorelines to the approved practices for Virginia Conservation Assistance Program cost share. Living shorelines are also eligible for sediment, nitrogen and phosphorus load reduction credits as an approved Best Management Practice of the Chesapeake Bay Program. The Commonwealth of Virginia has committed to a policy of no-net-loss of wetlands, tidal and nontidal. For tidal wetlands, the Wetlands Mitigation-Compensation Policy provides criteria for mitigation and compensation for all direct permitted tidal wetlands losses. As a Chesapeake Bay signatory partner, Virginia has also committed to a Bay goal for tidal and nontidal wetlands for the creation or restoration of 85,000 acres and the enhancement of 150,000 acres largely to occur in agricultural lands. The scientific understanding of the role of tidal wetlands and the connection between and among shoreline habitats; wetlands and riparian lands and subaqueous lands, has continued to evolve and improve. The science shows important interactions between these habitats with the greatest benefits when the resources are in a natural condition with uninterrupted connectivity across and along the shoreline. This understanding requires resource management decisions that are based upon a systems-based perspective rather than an individual resource. Tidal wetlands, adjacent nontidal wetlands, beaches and dunes are subject to changes in extant and location as a result of relative sea level rise. These resources are dependent upon specific elevations relative to tides, availability of sediment and resource specific processes. With rising sea level, the persistence of the habitats is limited by the capacity move vertically upward through sediment capture and plant process and to move horizontally by migrating into the adjacent landscape. Wetlands, beaches and dunes are adversely impacted directly and indirectly by actions taken along and near the shoreline. The placement of a structure in, or landward of the resource, prevents landward migration, or retreat, of the features.
Load more

Recommended publications
  • Bulletin / New York State Museum
    Juncaceae (Rush Family) of New York State Steven E. Clemants New York Natural Heritage Program LIBRARY JUL 2 3 1990 NEW YORK BOTANICAL GARDEN Contributions to a Flora of New York State VII Richard S. Mitchell, Editor Bulletin No. 475 New York State Museum The University of the State of New York THE STATE EDUCATION DEPARTMENT Albany, New York 12230 NEW YORK THE STATE OF LEARNING Digitized by the Internet Archive in 2017 with funding from IMLS LG-70-15-0138-15 https://archive.org/details/bulletinnewyorks4751 newy Juncaceae (Rush Family) of New York State Steven E. Clemants New York Natural Heritage Program Contributions to a Flora of New York State VII Richard S. Mitchell, Editor 1990 Bulletin No. 475 New York State Museum The University of the State of New York THE STATE EDUCATION DEPARTMENT Albany, New York 12230 THE UNIVERSITY OF THE STATE OF NEW YORK Regents of The University Martin C. Barell, Chancellor, B.A., I. A., LL.B Muttontown R. Carlos Carballada, Vice Chancellor , B.S Rochester Willard A. Genrich, LL.B Buffalo Emlyn 1. Griffith, A. B., J.D Rome Jorge L. Batista, B. A., J.D Bronx Laura Bradley Chodos, B.A., M.A Vischer Ferry Louise P. Matteoni, B.A., M.A., Ph.D Bayside J. Edward Meyer, B.A., LL.B Chappaqua Floyd S. Linton, A.B., M.A., M.P.A Miller Place Mimi Levin Lieber, B.A., M.A Manhattan Shirley C. Brown, B.A., M.A., Ph.D Albany Norma Gluck, B.A., M.S.W Manhattan James W.
    [Show full text]
  • A Guide on Common, Herbaceous, Hydrophytic Vegetation of Southern Texas
    United States Department of Agriculture Natural Resources Conservation Service Technical Note No: TX-PM-20-02 July 2020 A Guide on Common, Herbaceous, Hydrophytic Vegetation of Southern Texas Plant Materials Technical Note Horsetail Background: Wetlands are those lands that have saturated soils, shallow standing water or flooding during at least a portion of the growing season. These sites have soils that are saturated for at least two consecutive weeks during the growing season and support a distinct vegetation type adapted for life in saturated soil conditions. Purpose: The purpose of this Technical Note is to provide information on the use of some common wetland plants of southern Texas. The list includes plants found along the Guadalupe River around Tivoli southward to the Rio Grande River floodplain. It is not intended to be a comprehensive treatment of the wetland flora of this region. Rather it is intended to introduce to the reader the many common wetland plant species that occur in south Texas. The guide is broken down into four categories: wildlife habitat, shoreline erosion control, water quality improvement and landscaping. Each species has a brief description of its identifying features, notes on its ecology or habitat, use and its National Wetlands Inventory (NWI) assessment. For more detailed information we suggest referring to our listed references. All pictures came from the USDA Plants Data Base or the E. “Kika” de la Garza Plant Materials Center. Plants for wildlife habitat: The plants listed in this section are primarily for waterbird and waterfowl habitat as well as for fish nursery and spawning areas.
    [Show full text]
  • Herbaceous Tidal Wetland Communities of Maryland's
    HERBACEOUS TIDAL WETLAND COMMUNITIES OF MARYLAND’S EASTERN SHORE 30 June 2001 HERBACEOUS TIDAL WETLAND COMMUNITIES OF MARYLAND’S EASTERN SHORE: Identification, Assessment and Monitoring Report Submitted To: The United States Environmental Protection Agency Clean Water Act 1998 State Wetlands Protection Development Grant Program Report Submitted By: Jason W. Harrison for The Biodiversity Program Maryland Department of Natural Resources Wildlife and Heritage Division 30 June 2001 [U.S. EPA Reference Wetland Natural Communities of Maryland’s Herbaceous Tidal Wetlands Grant # CD993724] Maryland Herbaceous Tidal Wetlands Vegetation Classification / Description and Reference Sites FINAL REPORT TABLE OF CONTENTS Acknowledgements.....................................................................................................................3 Introduction.................................................................................................................................5 Purpose .......................................................................................................................................8 Methods ......................................................................................................................................9 Landscape Analysis .........................................................................................................9 Spatial Distribution of Vegetation: Implications for Sampling Design..............................9 Field Surveys.................................................................................................................10
    [Show full text]
  • Responses of Tidal Freshwater and Brackish Marsh Macrophytes to Pulses of Saline Water Simulating Sea Level Rise and Reduced Discharge
    Wetlands (2018) 38:885–891 https://doi.org/10.1007/s13157-018-1037-2 ORIGINAL RESEARCH Responses of Tidal Freshwater and Brackish Marsh Macrophytes to Pulses of Saline Water Simulating Sea Level Rise and Reduced Discharge Fan Li1 & Steven C. Pennings1 Received: 7 June 2017 /Accepted: 16 April 2018 /Published online: 25 April 2018 # Society of Wetland Scientists 2018 Abstract Coastal low-salinity marshes are increasingly experiencing periodic to extended periods of elevated salinities due to the com- bined effects of sea level rise and altered hydrological and climatic conditions. However, we lack the ability to predict detailed vegetation responses, especially for saline pulses that are more realistic in nature than permanent saline presses. In this study, we exposed common freshwater and brackish plants to different durations (1–31 days per month for 3 months) of saline water (salinity of 5). We found that Zizaniopsis miliacea was more tolerant to salinity than the other two freshwater species, Polygonum hydropiperoides and Pontederia cordata. We also found that Zizaniopsis miliacea belowground and total biomass appeared to increase with salinity pulses up to 16 days in length, although this relationship was quite variable. Brackish plants, Spartina cynosuroides, Schoenoplectus americanus and Juncus roemerianus, were unaffected by the experimental treatments. Our ex- periment did not evaluate how competitive interactions would further affect responses to salinity but our results suggest the hypothesis that short pulses of saline water will increase the cover of Zizaniopsis miliacea and decrease the cover of Polygonum hydropiperoides and Pontederia cordata in tidal freshwater marshes, thereby reducing diversity without necessarily affecting total plant biomass.
    [Show full text]
  • CPR Juncus Roemerianus
    Black Needlerush Juncus roemerianus Propagation Guide Scientific Name Wetland Indicator Category Juncus roemerianus Scheele OBL Common Name Growth Form Black Needlerush Emergent rhizomatous perennial Group forming dense stands Monocotyledon Habitat Family Saline or brackish marsh Juncaceae Juncus roemerianus 1 Seed Collection Observe inflorescence development of Juncus roemerianus in the field. The development of the inflorescence starts as a red ring around the base of a new leaf from late January to late February (Eleuterius and Caldwell 1984). As the leaf grows the ring will move upward and the inflorescence matures. In coastal Mississippi and along the northern Gulf of Mexico the flowers usually mature and the dark brown seeds are ready for collecting in late April to early May (Eleuterius 1978); however, this may vary from year to year depending on weather conditions. The flowers of Juncus roemerianus are gynodioecious (some individuals having bisexual flowers and some having only female flowers). The J. roemerianus inflorescence is dark brown in color, and found 0.5-12" (1–30 cm) below the tip of the sharp pointed bract that looks like a continuation of the stem. There is only one inflorescence per plant and it is composed of erect branches with clusters of two to six flowers at the tips of the branchlets. The mature fruit is a shiny dark-brown three-sided capsule, which contains numerous very small 0.012" (<0.3mm) diameter seeds. The seeds are mature and ready for collecting when the inflorescence is gently shaken or tapped and the seeds are released from the capsules. The seeds can be harvested by cutting the stems above (to remove the sharp bract tip) and below the inflorescence and placing them into plastic bags.
    [Show full text]
  • Juncus Roemerianus Production and Decomposition Along Gradients of Salinity and Hydroperiod
    MARINE ECOLOGY PROGRESS SERIES Published December 15 Mar. Ecol. Prog. Ser. Juncus roemerianus production and decomposition along gradients of salinity and hydroperiod Robert R. Christian, Wade L. Bryant Jr*,Mark M. Brinson Department of Biology, East Carolina University. Greenville, North Carolina 27858, USA ABSTRACT: Juncus roemerianus Scheele, the black needlerush, dominates much of an irregularly flooded salt marsh at the Cedar Island National Wildhfe Refuge, North Carolina, USA. We examined its dynamics of growth, senescence, and decomposition along a 1.6 km transect into the marsh over salinity and hydroperiod gradients passing successively through 3 distinct vegetational zones. Little difference was noted among zones in any of the dynamic aspects examined. Aerial, annual net primary production of J. roernerianus averaged 812 g dry mass m-2. This rate is comparable to that of J. roemerianusin other North Carolina marshes. Measured parameters for production estimates were production-to-biomass ratio, frequency of replacement of growing leaves (number of times per year in which leaf cohorts grow to maximum height), and standing crop of growing leaves. Only the latter parameter revealed statistically significant change with distance into the marsh with the most inner zone having the least biomass of leaves. Senescence of leaves progressed similarly along the transect, as did decomposition. A lack of dominance by J. roemerianus in the inner zone may be a consequence of competitive advantages of other species in an environment of lower salinity and shorter hydroperiod. On average, Juncus roemerianus leaves grow for 259 d and senesce for 312 d. The rate of decomposition of standing dead leaves is slow (-0.25 F-').Thus it would not be uncommon for a leaf to remain standing for several years.
    [Show full text]
  • Flower Morphology and Plant Types Within <I>Juncus Roemerianus</I>
    FLOWER MORPHOLOGY AND PLANT TYPES WITHIN JUNCUS ROEMERlANUS LIONEL N. ELEUTERIUS Gulf Coast Research Laboratory Ocean Springs, Mississippi 39564 ABSTRACT Two plant forms were found to occur within funcus roemerianus, one consistently producing perfect flowers and the other producing pistillate flowers. Staminate flowers were not found. Pistillate flowers have aborted stamens. Rhizomes bearing inflorescences and transplants were dug out and used in the study. These observations serve to clarify previous incon- sistent descriptions of floral morphology. INTRODUCTION funcus roemerianus Scheele is a rhizomatous perennial which occurs in salt marsh from New Jersey to northern Florida on the Atlantic Coast and from south Florida to Texas along the Gulf Coast of the United States. In Mississippi, the species dominates approximately 96% (61,000 acres) of the coastal marsh and contributes significantly to estuarine productivity (Eleuterius 1972). During a recent autecological study of funcus roemerianus detailed investigations of flowers and corresponding plant types were included (Eleuterius, In preparation). It is apparent that some confusion exists in the literature regarding flower type and distribution within the species. Scheele (1849) first described and named f uncus roemerianus from plants bearing perfect flowers collected on Mustang Island at Galveston, Texas. Engelmann (1868) stated that he found "a rare form of J. roe- merianus where both circles of stamens were suppressed or rather under- developed and in a rudimentary state so that those plants become unisexual." He also noted that J. roemerianus was the only species of Juncus in which occasionally unisexual specimens occur. Corresponding male plants were not seen, but he suggested that they may exist.
    [Show full text]
  • Juncaceae - the Rush Family
    JUNCACEAE - THE RUSH FAMILY Juncaceae: Genera: Juncus (22) and Luzula (2) Mostly freshwater wetlands (except J. roemerianus) 10 species are common or frequent: Juncus roemerianus Juncus effusus Juncus megacephalus Juncus marginatus Juncus scirpoides Juncus dichotomous Juncus repens Juncus elliottii Juncus paludosus Juncus polycephalus Credit: floridagrasses.org Credit: John R. Gwaltney Morphological Features: • Cespitose or rhizomatous • Leaves 3-ranked, mostly terete (round) and septate, a few species have flat leaves • Culm (stems) pithy • Nodes without joints • Inflorescence an open or congested; lateral or terminal; panicles or heads • Sheaths fused or overlapping • Fruit is a three-part capsule containing many seeds Credit: Hilton Pond Center Credit: floridagrasses.org JUNCACEAE - Rushes Common Rushes: 1. Juncus effusus: Usually 1m tall or so. flowers appearing lateral, sheaths lacking blades. Often found growing in depressional areas within pastures. 2. Juncus marginatus: flowers borne in glomerate clusters, blades are flat, not septate. Capsule abruptly tapered. This species is extremely variable. 3. Juncus scirpoides: flowers borne in congested, headlike lobed clusters. Leaves round, sheath closed. Found across a wide range of habitats. 4. Juncus megacephalus: Flowers borne in congested, headlike spherical clusters. Leaves round, sheath closed. 5. Juncus paludosus: is an endemic first identified in Florida in 2008. Superficially similar to J. polycephalus, but more closely related to J. megacephalus. Distinguished form the former
    [Show full text]
  • Native Plants of Coastal Louisiana Introduction: Acknowledgements
    Native Plants of Coastal Louisiana Introduction: Acknowledgements: Funding for this guide was administered by The purpose of this guide is to help users the Environmental Protection Agency (EPA) identify common native plants of Louisiana’s Environmental Justice Program. Suggestions Coastal Zone. This guide does not include for improving this guide should be addressed all plants found on our barrier islands, along to the Bayou Land RC&D Program Director, our beaches or within our coastal marshes. Jennifer Roberts, Bayou Land RC&D, P.O. Box Rather this guide provides a cursory 6281, Metairie, LA 70009-6281. introduction to common native species that are adapted for life along our dynamic coast. The authors would like to thank Allen Native These plants provide valuable habitat to Ventures, the USDA – Natural Resources coastal and estuarine communities and play a Conservation Service (NRCS), the Crescent critical role in shoreline stabilization. Soil and Water Conservation District (SWCD), This guide and companion course have been the Lafourche Terrebonne Soil and Water developed and designed to serve as a tool Conservation District, the Plaquemines Soil for local communities. By equipping local and Water Conservation District, and the community members with the knowledge NRCS Plant Materials Program for their and understanding of our coastal plant guidance and input in developing this Native communities that may have been affected by Coastal Plant Guide as well as for their the Deepwater Horizon Oil Spill. This effort assistance in the development and delivery of is the first in a series of initiatives aimed the initial series of coastal plant identification at building a collaborative, open-access, workshops.
    [Show full text]
  • The Biology of Limonium Carolinianum (Walt.) Britt. (Plumbaginaceae) in Coastal Wetlands
    International Biology Review The Biology of Limonium carolinianum (Walt.) Britt. (Plumbaginaceae) in Coastal Wetlands Richard Stalter*, Robert I. Lonard**, and Frank W. Judd** *Department of Biological ABSTRACT Sciences, St. John’s University, 8000 Utopia Limonium carolinianum (Walt.) Britt. is a New World humid Parkway, Queens, NY 11439 continental, temperate, subtropical, and tropical maritime taxon. It is a long-lived perennial that is found in wet sand **Department of Biology, and clay mineral soils. This species is a salt tolerant halophyte The University of Texas – Rio where salinity values approach 30 parts per thousand. Grande Valley, Edinburg, TX Reproduction is primarily vegetative. However, seed 78539 production is estimated at 1,000 to 10,000 per individual plant. Also known as sea lavender, it has been suggested as a Corresponding Author: species that can be used for re-vegetation efforts. Dr. Richard Stalter Inflorescences of this species are often harvested for dried ([email protected]) floral arrangements. Keywords: Sea lavender, morphology, habitats, communities, population ecology, physiological ecology, economic values. Copyright 2016 KEI Journals. All rights reserved 1 International Biology Review INTRODUCTION statice. The following taxonomic description has been derived from Correll and Correll The genus Limonium (Plumbaginaceae) 1972; Flora of North America Editorial includes about 300 to 350 species, and is Committee 2005; Hamilton 1997; Lehman primarily represented in maritime or in arid 2013; Luteyn 1976, 1990; and Radford et al. environments in the northern hemisphere 1968. (Correll and Correll 1972; Mabberley 1997). Eight species have been reported in North Limonium carolinianum has a woody taproot America including four species that have typical of dicots that extend up to 30.5 cm escaped from cultivation in California (Flora below the soil surface (R.
    [Show full text]
  • Patterning Emergent Marsh Vegetation Assemblages in Coastal Louisiana, USA, with Unsupervised Artificial Neural Networks
    Received: 22 June 2018 | Revised: 7 December 2018 | Accepted: 14 December 2018 DOI: 10.1111/avsc.12425 RESEARCH ARTICLE Applied Vegetation Science Patterning emergent marsh vegetation assemblages in coastal Louisiana, USA, with unsupervised artificial neural networks Gregg A. Snedden U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, Louisiana Abstract Questions: Are self- organizing maps (SOMs) useful for patterning coastal wetland Correspondence Gregg A. Snedden, U.S. Geological Survey, vegetation communities? Do SOMs provide robust alternatives to traditional classifi- Wetland and Aquatic Research Center, 700 cation methods, particularly when underlying species response functions are un- Cajundome Blvd, Lafayette, LA 70506, USA. Email: [email protected] known or difficult to approximate, or when a need exists to continuously classify new samples obtained under ongoing long- term ecosystem monitoring programs as they Funding information This study was funded in part by the U.S. become available? Geological Survey and the Coastal Wetlands Location: Coastal Louisiana, USA. Planning, Protection and Restoration Act, Coastwide Reference Monitoring System. Methods: A SOM was trained from in- situ observations of 559 vegetation species relative cover data from 2,526 samples collected over 8 years at 343 locations across Co-ordinating Editor: Hannes Feilhauer coastal Louisiana. Hierarchical cluster analysis was applied to the SOM output to delineate vegetation community types, and indicator species analysis was conducted. Salinity and flood duration were compared across the delineated community types. Results: The SOM patterned the 2,526 training samples into 260 output neurons, which were further clustered into eleven community types. Clear gradients in salinity and flood duration existed among the community types, and geographic zonation of the communities was evident across the landscape.
    [Show full text]
  • ABSTRACT JERNIGAN, LEON STACY, JR. Factors Influencing The
    ABSTRACT JERNIGAN, LEON STACY, JR. Factors Influencing the Distributional Patterns of Juncus roemerianus in Two North Carolina Salt Marshes. (Under the direction of ERNEST D. SENECA). Zonation of salt marsh vegetation as it relates to physical and edaphic factors was examined at two Juncus roemerianus marshes along the North Carolina coast. Other objectives were to determine leaf longevity and to compare leaf density, biomass, and regrowth of Juncus at the two marshes. Juncus was found to tolerate broad fluctuations of salinity, tidal inundation, and redox potential. Soil pH and salinity did not appear to influence vegetational zonation. Tidal and groundwater influence were important because of their effect on sediment saturation. Measurements of redox potentials indicated that Juncus sediments were generally less reduced (55 mY) than Spartina alterniflora (-112 mY) sediments. The upper I <km portion of the root zones of both species was also approximately 50 m V less reduced than the lower 3<km portion. Higher levels of phosphorus found in the Spartina zone sediments was related to duration of inundation. Other nutrient differences found between zones at each marsh can be attributed to the differences in tidal regime. Juncus sediments were found to be coarser than those of Spartina. The most important factor affecting vegetational zonation appeared to be sediment saturation and its influence on other factors. Clip plot data indicate that the two marshes were similar in productivity. Redipping data showed the marsh with the lower salinities produced twice as much Juncus biomass and density data showed that it had 12% more stems than that of the higher salinity marsh.
    [Show full text]