Recent Changes in Soil Total Phosphorus in the Everglades: Water Conservation Area 3

Abstract

We assessed recent changes in the distribution of soil total phosphorus (TP) in Water Conservation Area 3 (WCA-3) of the Everglades. Soil cores were collected in 1992 and 2003 at 176 sites. To reflect hydrologic boundaries within the system, WCA-3 was divided into three zones (3AN, 3AS, and 3B). Total P was mapped on both a mass (TPm) and a volumetric basis (TPv) to determine if spatial distributions varied depending on the choice of units.Interpolated maps for both years showed that the highest levels of TPm were located in 3AN and in boundary areas of all zones that received surface water inputs of P from canals. Increases in TPm were greatest in central 3AN in an area adjacent to the Miami Canal that received inputs from a water control structure. Interpolated maps for TPv illustrated that a hotspot present in 1992 had disappeared by 2003. The highest levels of TPv in 2003 were located in northwestern 3AN, a region of WCA-3 that has been chronically overdrained and burned in 1999. From 1992 to 2003, increases in TPm were observed for 53% of the area of WCA-3, while only 16% of WCA-3 exhibited increases in TPv. In 1992, approximately 21% of WCA-3 had TPm concentrations in the 0-10 cm layer > 500 mg kg −1 , indicating P enrichment beyond historic levels. Eleven years later, 30% of the area of WCA-3 had TPm > 500 mg kg −1 . This indicated that during this period, the area of WCA-3 with enriched TPm concentrations increased about one % year −1 .

Spatial distributions and eco-partitioning of soil biogeochemical properties in the Everglades National Park

“…Historically, much work has been done to spatially document soil properties in the northern marshes of the Everglades, namely the Water Conservation Areas (WCAs) Reddy et al 1994;Newman et al 1997). These previous studies have enabled recent comparisons and assessments of restoration efforts (Bruland et al 2007;Marchant et al 2009). …”

Impacts of fire and phosphorus on sawgrass and cattails in an altered landscape of the Florida Everglades

“…Wu et al (1997) and Smith and Kadlec (1985) also showed that the effects of fire and TP on cattail expansion can be predicted. Behind both changes in cattail expansion (Rutchey et al 2005) and increases in soil TP (Bruland et al 2007), fire might be another force altering the Everglades.…”

“…Although these quantities of ha are for a different impoundment (WCA-2A) of the Everglades, they show that the April, 1999 fire in the northern WCA-3A impoundment was an unusually large fire that consumed much more of the landscape. This large fire itself may have been the result of the altered hydrological regime and spatial mosaic of vegetation, topography and landscape patterns, which therefore changed the fire patterns and consequently the landscape patterns (Young et al 2011, Bruland et al 2007, Scheidt and Kalla 2007, Wu et al 2002, Arabas 2000.…”

“…These phosphorus loadings have over time resulted in elevated soil P concentrations, which are considered a primary factor accelerating cattail growth over sawgrass and influencing cattail invasion and distribution in the Everglades , Miao and Debusk 1999, Rutchey and Vilchek 1999, Doren et al 1997, Newman et al 1996, Davis 1991. The issue regarding how fire and water depth interact and affect nutrient release and, in particular, how this then stimulates sawgrass re-growth and cattail expansion within nutrient impacted areas has become an important restoration consideration for ecologists and land managers (Hagerthey et al 2008, Scheidt and Kalla 2007, Bruland et al 2007, Ross et al 2006, Lockwood et al 2003, Arabas 2000, Herndon et al 1991.…”

Reply to comment by Julian on “Spatial and temporal phosphorus distribution changes in a large wetland ecosystem”

“…Data with flags and outliers outside three standard deviations were excluded from the analysis. In addition, in order to compare sampling events from different years and sources and to minimize bias due to different sampling densities and geospatial designs, we constrained the number of samples to only include sites located close to each other, following geostatistical procedures used in similar studies [Bruland et al, 2007;Grunwald et al, 2008].…”