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Nutrient and Hydrology Effects on Soil Respiration in a Northern Everglades Marsh
Author(s) -
DeBusk W. F.,
Reddy K. R.
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.7020
Subject(s) - microcosm , environmental science , peat , water column , nutrient , plant litter , marsh , water table , hydrology (agriculture) , soil respiration , soil water , environmental chemistry , wetland , chemistry , ecology , groundwater , soil science , geology , biology , geotechnical engineering
Microbial respiration in peat and overlying plant litter, as influenced by water level and phosphorus enrichment, was evaluated for an Everglades (Florida, USA) marsh ecosystem by measuring CO 2 and CH 4 release from soil–water microcosms. Intact cores of peat, overlying plant litter, and surface water were collected at seven locations in cattail ( Typha domingensis Pers.) and sawgrass ( Cladium jamaicense Crantz) stands along a phosphorus (P) enrichment gradient in Water Conservation Area 2A (WCA‐2A). Each soil–water microcosm was outfitted with a controlled air circulation system whereby outflow gas from the headspace could be analyzed for CO 2 and CH 4 to determine flux of C from the soil–water column to the atmosphere. Gaseous C flux was determined for flooded conditions (10‐cm water depth) and for water levels of 0, 5, 10, and 15 cm below the peat surface. Overall, decreasing water level resulted in significantly increased C flux, although rates were significantly higher under flooded conditions than under nonflooded, saturated‐soil conditions, presumably due to O 2 availability associated with algal photosynthesis within the litter layer in the water column. Carbon flux decreased significantly for sites increasingly distant from the primary hydrologic and nutrient inflows to WCA‐2A. The microcosm study demonstrated that the C turnover rate was significantly increased by accelerated nutrient loading to the marsh, and was further enhanced by decreasing water level under drained conditions. Our results also demonstrated that photosynthesis within the water column is a potentially important regulator of C mineralization rate in the litter layer of the marsh system.