Influence of hydrology and related variables on primary productivity along an environmental gradient in an irregularly flooded brackish marsh / by Paul B. Hook.
| Author/creator | Hook, Paul B. author. |
| Other author | Brinson, Mark M., degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 1988. |
| Description | xi, 234 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The influence of hydrology and related factors on net primary productivity in an irregularly flooded brackish marsh was investigated. Hydrology, salinity, and nitrogen availability were manipulated at three sites along a gradient of hydroperiod, salinity, and pH in Cedar Island Marsh, North Carolina. Hydroperiod, salinity, sulfide concentration, redox potential, pH, biomass accumulation, senescence, and leaf N and P content were quantified. Production decreased from interior to near-estuary sites, but growth of the dominant plant, Juncus roemerianus, did not vary significantly between these extremes. Data support the interpretation that plants at the most flooded, saline site near the estuary are subject to the greatest stresses and are least able to resist additional stresses imposed experimentally, and that plant growth is limited primarily by nearly constant flooding. High porewater sulfide concentration, rather than salinity, is the most likely growth limiting stressor at this site. Limitation of plant growth at intermediate and interior sites is not primarily hydrologic though salinity and factors related to flooding may contribute to low productivities. Nitrogen limitation was demonstrated for the intermediate and interior sites, and leaf nutrient content data suggest that phosphorus may be deficient in the interior and intermediate sites. A greenhouse study documented spatial variation in substrate response to ̌vapotranspiration, including greater desaturation of peat from the marsh interior at equivalent water table drawdown. Response of redox potential to short term water level fluctuations indicated that the aerated zone was typically 6 cm shallower than the water table. Evaluation of long term climatic and tide gauge records revealed regular as well as irregular components in seasonal patterns of flooding and water table drawdown. The principal factors which appear to regulate production and plant community composition are all probably controlled by hydrology on short or long time scales. Hydrologic influences through geomorphic, pedogenic, and material transport processes, as well as through restriction of soil aeration, are important. Applicability of current paradigms of hydrologic control of wetland function is discussed. Functional analogies with tidal salt marshes appear to be more appropriate for levee and near-estuary sites. In the interior, some similarities with freshwater bogs are present. The large size, weak development of open-channel drainage, and low energy. estuarine setting of the marsh may allow development of ecological characteristics not usually recognized for coastal salt marshes. |
| General note | Submitted to the faculty of the Department of Biology. |
| General note | Advisor: Mark M. Brinson |
| Dissertation note | M.S. East Carolina University 1988 |
| Bibliography note | Includes bibliographical references (leaves 202-216). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
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