Changes to Soil Properties in a Forested Wetland Following8 Years of Restoration

wetland;redoximorphic feature;soil morphology;Non-riverine wet hardwood forest

Baldwin, Alexander E ; Robert O. Evans, Committee Member,Michael J. Vepraskas, Committee Chair,Stephen W. Broome, Committee Member,Baldwin, Alexander E ; Robert O. Evans ; Committee Member ; Michael J. Vepraskas ; Committee Chair ; Stephen W. Broome ; Committee Member

University:North Carolina State University

关键词: wetland;    redoximorphic feature;    soil morphology;    Non-riverine wet hardwood forest;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/1193/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

Mitigation credits are awarded to land developers who successfully create or restore awetland to conditions found in a natural wetland. Because restored wetland vegetationadapts slowly to changes in hydrology, some restoration projects require a minimum of 15 to20 years before they can be judged as a success or failure based on vegetation. Wehypothesized that restoration success can be evaluated in shorter periods of time if soilproperties are used to gauge restoration success. The objectives of this study were to: 1)compare soil morphological, physical, and chemical properties in a restored wetland for twotime periods – before restoration and 8 years after restoration, and 2) to compare theseproperties between the restored site and a natural wetland. The study sites occurred in thelower Coastal Plain of North Carolina near Aurora. Soils in the restored site were describedin 1995, prior to restoration, and all classified as a Roanoke sandy loam (clayey, mixed,thermic Typic Endoaquults). The natural wetland was adjacent to the restoration site andwas classified as a non-riverine wet hardwood forest (NRWHF). In 2003, 30 soil pedonswere sampled, 26 in the restored site and four in the reference, to evaluate changes in soilproperties. All sampling occurred in the same sample plots sampled in 1995. It was foundthat redoximorphic (redox) concentrations increased significantly (p<0.05) in the upper 45cm after 8 years of restoration. The reference site had less redox concentrations than therestored site in the upper 45 cm. Plant available P, Ca, CEC, and BS% had decreasedsignificantly (p<0.05) in the restored site since 1995, but each of these properties was stillhigher than in the natural wetland. Total organic Carbon (TOC) had not increased in therestoration site and was approximately 20% of the amount of TOC found in the reference.Both sites met the hydric soil technical standard, which indicated that the soils in the restoredsite functioned as hydric soils. The mature trees in the NRWHF shaded the soil surface andcool the temperature enough to prevent TOC from oxidizing during the summer months.The water table in the reference site was 50 cm lower during the growing season than in therestored site. This caused redox concentrations to form 45 cm below the soil surface in thereference wetland, but they accumulated within 45 cm of the soil surface in the restored site.Evaluation of hydric soil restoration success could be done through use of the hydric soiltechnical standard, and possibly through changes in redoximorphic features. Most other soilphysical and chemical properties changed to slowly to be of value in evaluating restorationsuccess within an 8 year period.