Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
Crop & Soil Sciences
Non Technical Summary
Water table levels (saturation periods) in wetlands vary across the wetland and change with soil type and drainage class. These saturation periods have not been determined for most soils, and consequently, hydrologic performance requirements for restored wetlands haven't been well defined. The main objective of this project is to define saturation periods as a percentage of the growing season that restored wetlands should meet for the specific soils used for restoration. Saturation periods of natural wetlands will be determined for selected soil series ranging from very poorly drained organic soils to moderately well drained mineral soils. Data for most soils will come from prior investigations that measured water tables and computed 40 year records of water table data for each soil. Field monitoring of flood plain soils and very poorly drained mineral soils on flats will also be conducted to complete the data base. Saturation periods for restored wetlands will be obtained from the NC Department of Environmental Quality database which has catalogued water table and soils data for 233 restored sites in NC. Sites having soils similar to the natural sites will be identified, visited to assess wetland condition, and to determine soil type at selected well locations. Saturation periods will be compared between the restored and natural sites for a given soil type. Saturation periods for wetlands successfully restored will be proposed for soils in very poorly drained, poorly drained, somewhat poorly drained and moderately well drained classes. These results will allow estimation of saturation periods that restoration sites should meet for all soil types across the region.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
(N/A)
Goals / Objectives
Water table levels (saturation periods) in wetlands vary across the wetland and change with soil type and drainage class. These saturation periods have not been determined for most soils, and consequently, hydrologic performance requirements for restored wetlands haven't been well defined. The main goal of this project is to define saturation periods as a percentage of the growing season that restored wetlands should meet for the specific soils used for restoration.
Project Methods
Procedure: a. Description of project area, including soils, topography, land use/vegetation, climateFour groups of study sites will be selected to complete objectives using both natural and restored wetlands. Each group will represent soil drainage classes in either: very poorly drained, poorly drained, somewhat poorly drained, and moderately well drained soils. The restoration sites will be selected from those managed by the DMS's, and will be restored wetlands. The study sites will be selected after evaluating data from 233 restoration sites using reports currently in the DMS's data base. These reports were reviewed for this proposal to confirm that they contain the necessary information. Sites with detailed water table measurements and rainfall data, which were collected for periods of at least 7 years, will be identified. On-site inspections will then be conducted for each identified project to determine its appropriateness for this study. Natural wetland soils will also be studied. It is expected that most of these will be ones where the project leaders have already collected data and modeled the hydrology.b. Field sampling and measurement design, techniques, and methodsFour plots will be established in each restored wetland along a transect that extends across a wetness gradient (wettest to driest) in the restoration project. Soil in each plot will be described to a depth of 2 m with the assistance of the NRCS regional soil scientist (see letter from USDA State Soil Scientist). Soil samples will be collected in 15 cm depth increments to determine particle size distribution and total organic C. Undisturbed cores (7.6 cm diam. by 7.6 diam. in height) will be collected from major horizons.c. Laboratory analyses Soil particle size analysis will be performed on soil sample by the hydrometer method of Gee and Or (2002). Total soil C will be determined by combustion (Culmo, 1988). These data will be used to confirm that hydric soils are present and to evaluate hydrology field indicators. Undisturbed cores will be used to determine pore size distribution by the method of Dane and Hopmans (2002), and bulk density by the method of Grossman and Reinsch (2002).d. Data analysis i. Determining Wetland Hydrology for Natural SoilsPrevious work has documented longterm hydrology of wetland soils in the very poorly drained, poorly drained, somewhat poorly drained, and moderately well drained soils using a combination of on-site monitoring and simulation models (Caldwell et al., 2012; He et al., 2002,2003). These data will be used to establish the saturation durations of natural soils. Our preliminary assessments of saturation durations for each soil group are shown in Table 1. These will be tested in this project.ii. Determing wetland hydrology of restored sites.The DMS's database of restored wetlands will be reviewed to identify sites that have at least 7 years of water table data and one or more of the soils listed in Table 1. Water table data will be reviewed to determine average saturation durations within 30 cm of the surface for each year.e. Wetland Hydrology RecommendationsFor each soil group shown in Table 1, we expect to establish the saturation periods needed for wetland restoration sites to meet. This will be determined evaluating the natural sites first. The proposed saturation durations will then be compared to those found in restored sites for similar soils. We will adjust the saturation durations to include the restored sites that have been judged to be successfully restored. Guidelines for assessing wetland hydrology at restored sites will be developed.Table 1. Summary of estimated saturation durations for selected soil series in the Coastal Plain region. Soils are categorized by drainage class and then grouped by characteristics related to organic matter content and flooding potential. Examples of the USDA's Soil Taxonomy for each group are shown along with the soil series expected in each group.Soil Drainage ClassSoil GroupAnnualSaturation DurationUSDA Soil ClassificationsSoil Series Examples% of Growing SeasonVery Poorly DrainedOrganic Soils-Deep25HaplosapristsDareOrganic Soils-Shallow20HaplosapristsBelhaven, CroatanMineral Soils12 to 16Humaquepts, Umbraquults, Paleaquults, EndoaquodsHyde, Murville, Pantego, PortsmouthPoorly DrainedMineral Soils-on flood plains12 to 16Fluvaquents, EndoaqueptsBibb, ChastainMineral Soils-on flats10 to 12Endoaqualfs, Alaquods, Paleaquults,EndoaquultsRains, Roanoke, Tomotley, LeafSomewhat Poorly DrainedMineral Soils7 to 9Endoaquults, Paleaquults, AlaquodsAugusta, Lenoir, LeonModerately Well DrainedMineral Soils6 to 7Hapludults, QuartzipsammentsAltavista, Craven, Pactolus