Macro- and microecological succession in wetlands following major disturbance

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2007-06

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The Ohio State University

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Abstract

Destruction of wetlands continues at an alarming rate, with loss of almost half of the wetlands in the continental United States. The severity and persistence of environmental effects due to wetland destruction are largely unknown. This research project was designed to examine the influence of wetland disturbance on three of its major features: vegetation, soil chemistry, and soil microbial diversity. Three wetland sites were selected: i) an area of a wetland that has been disturbed by the construction of an underground oil pipeline (referred to as Disturbed); ii) the other half of the same wetland, which has not been directly disturbed (Undisturbed); and iii) a wetland in close proximity to act as a positive control (Larue). Vegetation and soil sampling was executed in three seasons (spring, summer, and fall) over a period of three years (2004-2006). The majority of new species acquired in the Disturbed wetland were non-native and/or invasive and noxious. Significant differences in soil chemistry of the Disturbed wetland were clearly evident: soil pH significantly increased (P < 0.0001) while levels of P, B, Zn, Fe (lbs/acre), NH4-N (ppm), % organic matter, % moisture, and cation exchange capacity were all significantly decreased (P < 0.0001). The Disturbed wetland also had lower water permeability. Soil microbial diversity was examined by using a combination of Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis (PCR-DGGE). All three sites showed variations in DGGE profile with respect to season and year, however, the results clearly indicated that the soil of the Disturbed wetland had lower diversity compared to the other two sites; and these differences were maintained throughout the 3-year sampling period. Collectively, these findings show that the disturbance of the wetland, and the ensuing soil treatments (fertilizer and sowing) altered wetland chemistry, vegetation and microbial diversity. Furthermore, these practices were not effective in returning the wetland to its previous “undisturbed” state, at least within the three years after the disturbance. Other strategies need to be considered if we are to lessen the medium- to long-term impacts of wetland disturbance and destruction, and to create more effective wetland restoration strategies.

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Denman Undergraduate Research Forum poster presentation, fourth place

Keywords

Denaturing Gradient Gel Electrophoresis, microbial diversity, Polymerase Chain Reaction, soil chemistry, succession, vegetation, wetland

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