Connecticut’s Freshwater Wetlands
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The spatial and temporal transport and transformation of chemicals, including phosphorus, nitrogen, sulfur, carbon, and metallic ions (calcium, magnesium, potassium, sodium), in a wetland and their chemical pathways through the biotic and abiotic components of the wetland are referred to as wetland biogeochemistry. Cycling may occur within a wetland or between wetland and surrounding upland. The wetland soil is a principal conduit for these chemical pathways. Wetland soils are defined as those soils which are sufficiently saturated or flooded during the growing season that they develop anaerobic conditions and will support only hydrophytic vegetation. Wetland soils are mineral soils (consisting of less than 20-35% dry organic matter) or organic soils (where organic matter exceeds these percentages). Mineral soils develop a distinct profile (soil horizons) due to alternating wet and dry periods and aerobic and anaerobic soil conditions (causing the oxidation or reduction of soil metallic ions). Organic soils (called peat soils and made up of large and small fibrous matter) are less dense and have far greater water holding capacity. The peat forms from dead leaves, woody plant parts, herbaceous plants and mosses such as
. Oxidized soils are brown to red in color. Reduced soils are blue-gray to black in color. Nitrogen is a key element in wetland and upland soils, and microorganisms play an important role in the retention or loss of nitrogen in the soil. Bedrock geology of a wetland site may have much to do with the types of organisms living in that wetland. Climate is equally important to a site’s biota (Broker 1994). Wetlands produce, store or transform chemicals. Many wetlands show a seasonal pattern of nutrient uptake and release. Wetland net primary productivity through photosynthesis may be high or low. Human impacts on wetland biogeochemistry, (tree removal, stream channelization, delivery of waste water or agricultural runoff to a wetland, can be considerable.