Fire is a critical driver of phosphorus (P) cycling and ecosystem development, especially in seasonally inundated, intermittent wetlands. Intermittent wetlands with longer hydroperiods generally have higher plant and soil organic carbon (C) than those with shorter hydroperiods. However, it is uncertain how fire affects C and P cycling among intermittent wetlands with different hydroperiods. We tested the interactive effects of fire and hydroperiod on soil and plant C and P cycling in intermittent wetlands at Archbold Biological Station, located in the southcentral Florida scrub, an area with detailed prescribed fire history and active fire management. We used historic information relating fire history, hydroperiod, and soil C and P to predict how wetlands with different hydroperiods differentially use and allocate fire-released P above- and below-ground. To test this, we collected data on plant species composition and % cover, as well as plant and soil C and P concentrations from shorter- (n = 6) and longer-hydroperiod wetlands (n = 6). We then burned both shorter- (n = 4) and longer-hydroperiod wetlands (n = 4), maintaining replicates of both as no-burn controls (n = 4). We measured changes in water, soil, and plant C and P concentrations following fire.
Results/Conclusions
Historic measurements found higher soil C and P concentrations in longer-hydroperiod wetlands that had been recently burned (< 2 years) compared to unburned and burned wetlands with shorter-hydroperiods (P < 0.05). Before our experimental burn treatment, we detected higher soil C concentrations in longer- than shorter-hydroperiod wetlands, and soil P was similar among wetlands despite differences in soil C concentrations. Plant C was an order of magnitude higher than soil C, and plant P was nearly 2x greater than soil P, but both plant C and P were similar among all wetlands. Post burning, we predict Understanding how variation in hydroperiod and fire frequency affect ecosystem biogeochemistry and how wetland plants and soils differentially utilize available P can improve conservation of intermittent wetlands.