Fire Effects on Nitrogen Cycling in Native and Restored Calcareous Wetlands

[摘要] Fire is an important natural process and management tool in the Florida Everglades, but few studies have examined its effects on nutrients; nitrogen (N) in particular has received little attention across the whole Everglades system. In this study, we investigated fire effects on the N cycle in both a high-phosphorus (P) restored wetland and a low-P reference calcareous wetland (marl prairie) in the Hole-in-the-Donut region of the southern Everglades. Potential N mineralization, denitrification, extracellular enzyme activities, and periphyton N2 fixation rates were measured immediately (two days), one month, and one year after a prescribed burn. Results showed differing responses of N cycle processes between the two sites: N availability increased immediately after the fire at the low-P reference site, but did not increase immediately at the high-P restored site. We also saw a greater increase in denitrification immediately after the fire in the reference site (118% increase) compared to only 20% increase in the restored site. Periphyton N2 fixation in the restored site tended to be stimulated, but was inhibited in the reference site after the fire. The underlying mechanisms for these changes are not clear, but fire residues (ash and char) may directly and indirectly affect the N cycle. These findings have implications for management of fire intensity in natural and P-impacted sites.

[学科分类] 生态、进化、行为和系统

[关键词] aminopeptidase;denitrification;marl;nitrogen fixation;periphyton;restoration