Graduation Year

2001

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Department

Biology

Degree Granting Department

Biology

Major Professor

Bruce C. Cowell, Ph.D.

Committee Member

Ingrid Bartsch, Ph.D.

Committee Member

Peter Stiling, Ph.D.

Abstract

Wetland mulching is the transfer of soil (often from a wetland area which is going to filled or otherwise impacted) on to the surface of a wetland creation area. The primary intent of mulching is to transfer wetland vegetation in the form of seeds and propagules, from the natural wetland to the creation area. This technique also is used to transfer organic matter and microbial fauna existing in the soil to the creation area. My study examines the effects that wetland mulching has on: 1) percent organic matter in the soil, 2) the wetland affinity of plant communities present, 3) species richness, 4) vegetative cover, 5) vegetative biomass production, 6) soil pH and 7) nutrient content. I examined a total of 33 herbaceous wetland creation areas (17 mulched and 16 non-mulched) in the immediate Hillsborough County, Florida area that were constructed between 5 and 11 years ago. A soil organic matter analysis was conducted in September 1999. Two vegetative analyses were conducted in November 1999 (at the end ofthe wet season) and in June 2000 (at the end ofthe dry season) using three 1-square meter quadrats per wetland. Soil nutrient and plant biomass analyses were conducted in August 2000 on a subsample of the wetland areas.

Mulched wetland areas had a significantly higher (p<0.001) mean percent soil organic matter in the soil than non-mulched wetlands (5.92% ± 0.48% v. 2.61% ± 0.33%, respectively). The wetland affinity weighted average (WA) of plant communities was significantly lower in the mulched than the non-mulched wetlands for both the November 1999 (1.45 ± 0.05 v. 1.82 ± 0.07) and June 2000 (1.79 ± 0.06 v. 2.04 ± 0.09) vegetative analysis events (p<0.001 and p=0.05, respectively). During the November 1999 event, the non-mulched wetlands had a greater mean species richness per quadrat (9.20 ±0.46 v. 10.56 ±0.52, p<0.05) and lower Total Percent Cover (TPC) per quadrat (82.49 ±2.30 v. 76.21 ± 2.31,p=0.04) than mulched wetlands. Fewer differences in the vegetative parameters were found between the mulched and non-mulched wetlands in June 2000, however these results were affected by drought conditions in the months leading up to the sampling.

In the subsample of wetland sites examined during the soil nutrient and biomass analysis (August 2000), the concentration of available secondary macronutrients: Mg, Ca and K was greater in the mulched than non-mulched wetlands. Differences were detected in Mg (60.28 ± 6.83 kg/ha and 29.54 ± 3.88 kg/ha, p<0.001), Ca (1181.68 ± 231.20 kg/ha and 195.34 ± 52.65 kg/ha, p<0.001) and K (66.01 ± 8.14 kg/ha and 33.12 ±2.89 kg/ha, p<0.001). No significant differences were detected for primary nutrients, soil pH or above ground plant biomass. Based on this study and others conducted, wetland mulching seems to be most influential on vegetative parameters during the first few years of existence, however after five to ten years, the differences are still apparent but less substantial.

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