Interactions Between Hydrology and Antecedent Land Use on Carbon Quantity, Quality and Metabolism in Restored Wetlands
Abstract
Wetlands are valuable ecosystems that provide ecosystem services such as nutrient cycling, and carbon sequestration. Each of these ecosystem services are influenced by the quality and quantity of dissolved organic matter (DOM), which is in turn shaped by wetland characteristics, such as hydrology, and past land use. Because of the ecological value of wetlands, the Clean Water Act mandates that new wetlands must be created to mitigate the destruction of natural wetlands. However, there are questions about how wetland creation approaches and outcomes influence ecosystem function and carbon metabolism. This project examined DOM composition and carbon metabolism in three created wetlands that differed substantially in hydrology, and past land use, with the goal of identifying key characteristics that drive DOM chemistry and carbon cycling in these systems. The wetlands, located in the High Acres Nature Area in Fairport New York, have distinct hydrology, ranging from permanent standing water to seasonal flooding. Antecedent land-use history also differs between the sites and includes a gravel mine repository, agricultural field, and cow pasture. Porewater and soil was collected at a depth of 10cm from each of the created wetlands. The DOM in the pore water was analyzed using NMR, fluorescence spectroscopy, and a TC/TN analyzer and CO2 and CH4 production rates were measured in anaerobic soil incubations. Differences in DOM quantity and composition were observed between the three sites, the proportion of carbohydrates were lower in the permanently flooded site than the seasonally flooded site, while the alkyl constituency was higher in the permanently flooded site. The fluorescence index of each wetland indicated that the DOM in each wetland is microbially derived, the freshness index indicated that the wetland with permanent standing water had the least degraded DOM. Average CO2 to CH4 production ratios in each wetland ranged from 5.02 to 6.2, with no significant differences observed between the three wetlands. These results suggest that DOM characteristics in restored wetlands can vary considerably in response to site characteristics, but that these differences have less impact on production of carbon gases, with all sites in this wetland complex producing substantially more CO2 than CH4 under anaerobic conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B41E2762H
- Keywords:
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- 0404 Anoxic and hypoxic environments;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0481 Restoration;
- BIOGEOSCIENCESDE: 0497 Wetlands;
- BIOGEOSCIENCES