|
BIOLOGICAL REPORT 90(3)
<br />Cut. The removal of vegetation by cutting, thinning,
<br />or mowing is a management action to maintain or en-
<br />courage growth of desirable plant species.
<br />Fertilization (Fert). Fertilization includes the applica-
<br />tion of chemical fertilizers, hormones, rooting agents, or
<br />commercial growth regulators. For the purposes of this
<br />data base, it does not include topsoil, peat, or organic
<br />matter; these are entered under Soil.
<br />Fire. Prescribed burning may be used as a management
<br />tool in wetland creation, restoration, or maintenance.
<br />Stabilization (Stabil). Stabilization denotes the use of
<br />riprap, wave breaks, or mesh to stabilize streambanks,
<br />shorelines, or substrate, or to reduce wave energy or
<br />stress. It includes containment structures or materials
<br />(e.g., hay bales for containing spoil), concrete revet-
<br />ments, bulkheads, gabions, sod, and burlap for the sta-
<br />bilization of planted areas.
<br />Contaminants (Contam). In some cases, the removal
<br />of existing contaminants (or contaminant sources) is
<br />part of a wetland creation or restoration project. Water
<br />quality improvements and site recovery following a
<br />major pollution event (e.g., an oil spill) are included.
<br />This key word also denotes the presence at the wetland
<br />site of specific contaminants that may affect creation or
<br />restoration activities or responses, such as excessive
<br />acidity caused by acid precipitation.
<br />Model. This key word describes the use of explicit
<br />spatial or temporal models (e.g., simulation, optimiza-
<br />tion, vegetation mapping) for planning, designing, or
<br />evaluating wetland creation or restoration projects. It
<br />includes the use of aerial imagery for the analysis of
<br />community types.
<br />Lab. Lab refers to laboratory or small plot experiments
<br />under controlled conditions. It includes the evaluation of
<br />the effects of salinity, temperature, water depth, turbidity,
<br />and similar conditions on plant growth; demonstration of
<br />vegetative culture techniques; analysis of vegetative toler-
<br />ance or adaptation to low oxygen supply or ammonia; and
<br />determination of the viability, germination, and storage
<br />requirements of seeds.
<br />According to the wetland creation and restoration
<br />projects in the WCR data base, the most frequently
<br />employed actions are landforming and planting (Fig. 6).
<br />About one-fifth of the data base records deal with
<br />dredged materials or gravel-mined sites. Contaminated
<br />sites were treated in 263 (24%) of the data base records.
<br />Of these, 43% were concerned with the use of wetlands
<br />for treatment of wastewater, acid mine waste, urban
<br />runoff, coal mine wastewater, and stormwater runoff;
<br />several records discussed the use of lime as a treatment
<br />for acid conditions and the effects of liming on biotic
<br />systems; 8% contained information about heavy metals
<br />in wetland systems (including uptake by plants) and
<br />subsequent effects; 9% discussed cleanup of oil pollu-
<br />tion and its effects on vegetation and coastal systems;
<br />and 1.5% discussed pesticides in wetland systems. Of
<br />the 263 records, just over one-third (37%) addressed
<br />general pollution problems such as phosphorus re-
<br />moval, nutrients, eutrophic conditions, salinity, and.ef-
<br />fluent in wetland systems.
<br />Wetland Type
<br />This field describes the subject wetland using National
<br />Wetland Inventory codes (Cowardin et al. 1979) in a
<br />system-subsystem- Class-subclass format (Table 3). All
<br />records contain an entry for wetland type. For general or
<br />overview articles or reports, all five systems are listed. The
<br />term riparian ("ripar" in the data base) has been added
<br />to this field even though it is not part of the system
<br />(Cowardin et al. 1979).
<br />Of the 1,100 records in the data base, 68% listed
<br />freshwater wetland types and 46% listed saltwater types;
<br />many contained multiple wetland type listings.
<br />Time
<br />Time is the maximum period reported for a particu-
<br />lar study, rounded off to the nearest year. For example,
<br />13 months would be entered as 1 year; 2 years, 7 months
<br />would be entered as 3 years. All periods less than 1 year
<br />are recorded as 1 year. A "0" entry indicates that no
<br />period was specified in the report or article, that the
<br />project was in the preliminary or planning stages of
<br />development, or that period was not applicable.
<br />Of the 1,100 records in the data base, 42% have a zero
<br />in the time field, 38% deal with studies of 1-2 years'
<br />duration (Group 1), and only 7% contain information
<br />from studies that lasted 10 or more years (Group 2;
<br />Fig. 7). Groups 1 and 2 had the same proportion of
<br />freshwater and saltwater wetlands. Group 2 had a sig-
<br />nificantly higher percentage of the key words Erosion,
<br />Habitat, and Incidental. Group 2 had twice the percent-
<br />age of waterfowl-related studies, a slightly higher per-
<br />centage of hydrology studies, and a much higher per-
<br />centage (eight times greater) of studies that attempted
<br />to evaluate project success than Group 1. Group 1 had
<br />a slightly higher percentage of chemical studies, twice
<br />as high a percentage of water quality studies, and small
<br />percentages for four fields that did not appear at all
<br />under Group 2: amphibians, reptiles, human use, and
<br />shellfish. The remaining percentages for key words used
<br />in both groups were very close.
<br />Quantification
<br />A "Y" indicates that quantitative results are reported
<br />for one or more response variables. An "N" indicates
|