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VCR/LTER Project Description version: 2.0

See instructions for details on specific fields. Send finished copy via 
email to jporter@lternet.edu or send floppy disk to LTER Office.


>>Project ID:: MMB9201

>>Date Submitted (MM/DD/YY):: 04/01/92

>>Descriptive title (3 lines max.)::  Continuous monitoring of surficial water
     table dynamics, pore water salinity, soil sulfides and redox
     potential along transects of steep to gradual slope.

>>Responsible PIs:: Mark M. Brinson, Robert R. Christian 

>>Student(s)/ technician(s)::  Joseph I. Hmieleski

>>LTER core topic(s) (Y or N)::

>>>>Primary Productivity:: Y

>>>>Trophic Structure::

>>>>Organic Matter:: Y

>>>>Nutrient Movements::

>>>>Disturbance:: Y

>>>>Other (specify)::

>>Study site description:: Brownsville Marsh, Phillips Creek
tributaries to upland forest.

>>Expected project duration (number of growing seasons):: 1

>>Sampling (put Y after all that apply)::

>>>>Harvest::

>>>>Coring:: Y

>>>>Pumping::

>>>>Topographic Survey::

>>>>Trapping:: 

>>>>Collecting::

>>>>Aerial/remote sensing::  

>>>>Other (specify):: Wells

>>Method/location of sample/voucher/core preservation::

>>Keywords (separated by commas):: water table, high marsh, marsh-upland
      continuum, groundwater wells, redox potential, soil
      sulfides, controls of ecosystem processes.

>>Study purpose and goals::        
Hydroperiod and salinity are known to determine species
composition and ecosystem structure along the continuum of marsh
to upland.  Hydroperiod also influences biogeochemical processes
some of which have the effect of producing toxic substances in
soil under anaerobic conditions.  Sulfides are toxic to
vegetation and should be expected to be decreasing along the
continuum toward the upland.  Hydrology, marsh slope, and the
effects of soil stressors are not well documented.  By
characterizing potential stressors (e.g., sulfides, salinity,
hydroperiod, redox potential) along the marsh-upland continuum,
we can begin to identify the relationship of slope and hydrology,
and the effects on vegetation.

>>Experimental/ sampling/ collecting methods:: 
Surficial water table dynamics will be
continuously monitored using Type-F Stevens water level
recorders located in the vicinity of high marsh-upland
transition zone T-1, T-2 (see attached map).  Water level
recorders will be referenced to absolute elevations and to
shallow groundwater wells in the surrounding hydrologic
unit. Charts will be changed at 1 to 4 week intervals.
Marsh surface elevation will be determined in the vicinity
of the recorder.  Plant communities along the transition
will be evaluated.  Interstitial soil sulfides and redox
potential will be monitored.

      Surveys will be conducted to establish elevations in the
areas representative of the water level recorders (see attached
map). Leveling will entail the use of surveyor's automatic level,
a stadia rod, and accessory equipment.  Groundwater wells will be
monitored for depth to water table and salinity.  Soil redox
potential will be determined.  Wells with porous bottoms will be
monitored with a sulfide probe for interstitial soil sulfide
levels along T-1 and T-2.

>>Impact of sampling on site integrity:: 
      The impact of this study on the site will occur mainly
during installation of wells.  Inevitable trampling will be
concentrated along a minimal number of trails as long as they do
not deteriorate in a way that may have long-term effects on the
marsh.


>>Other information:: 
21.  RELATED PROJECT ACTIVITIES:  Environmental monitoring and
      Brownsville-based projects.

22.  REQUIREMENTS FOR NEW REMOTELY-SENSED IMAGERY:  Brownsville
      marsh - as available.

23.  SHORT AND LONG-TERM PRODUCTS:  These data will be available
to projects being conducted in the Brownsville marsh.  Hydrologic
comparisons may be made with Hog Island marsh data.  Masters
thesis and publications are anticipated.

24.  KEY REFERENCES AND REFERENCES TO PREVIOUS VCR/LTER PROJECTS:

Morris, J.T., B. Kjerfve, and J.M. Dean.  1990.  Dependence of
     estuarine productivity on anomalies in mean sea level.
     Limnology and Oceanography 35:926-930.

Patterson, C.S., and I.A. Mendelssohn.  1991.  A comparison of
     physicochemical variables across plant zones in a
     mangal/salt marsh community in Louisiana.  Wetlands 11:139.


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