TECHNICAL REPORTS 1812 Postfire nutrient release into ecosystem via plant ash is critical to the understanding of fire impacts on the environment. Factors determining a postfire nutrient budget are prefire nutrient content in the combustible biomass, burn temperature, and the amount of combustible biomass. Our objective was to quantitatively describe the relationships between nutrient losses (or concentrations in ash) and burning temperature in laboratory controlled combustion and to further predict nutrient losses in field fire by applying predictive models established based on laboratory data. Te percentage losses of total nitrogen (TN), total carbon (TC), and material mass showed a significant linear correlation with a slope close to 1, indicating that TN or TC loss occurred predominantly through volatilization during combustion. Data obtained in laboratory experiments suggest that the losses of TN, TC, as well as the ratio of ash total phosphorus (TP) concentration to leaf TP concentration have strong relationships with burning temperature and these relationships can be quantitatively described by nonlinear equations. Te potential use of these nonlinear models relating nutrient loss (or concentration) to temperature in predicting nutrient concentrations in field ash appear to be promising. During a prescribed fire in the northern Everglades, 73.1% of TP was estimated to be retained in ash while 26.9% was lost to the atmosphere, agreeing well with the distribution of TP during previously reported wild fires. Te use of predictive models would greatly reduce the cost associated with measuring field ash nutrient concentrations. Estimation of Postfre Nutrient Loss in the Florida Everglades Y. Qian University of Florida S. L. Miao and B. Gu South Florida Water Management District Y. C. Li* University of Florida T he Florida Everglades, which occupies an area of approximately 6200 km 2 , is one of the largest and most unique wetlands in the world. Although this highly P limited freshwater wetland was historically sawgrass [Cladium mariscus (L.) ssp. jamaicense (Crantz) Kük] dominant, thousands of hectares have been replaced by cattail (Typha domingensis Pers.) which is characteristic of P-enriched habitats (Miao and Sklar, 1998; Richardson et al., 1999), due to anthropogenic activities. Tese activities are leading to significant ecosystem changes in geographic extent, environmentally driven factors (e.g., hydrology and fire), biotic diversity, and nutrient biogeochemical cycling (Noe et al., 2001; Noe and Childers, 2007). To accelerate the ecosystem recovery process, active management of the existing cattail marsh, including prescribed fires, is considered a potential tool for Everglades restoration (Miao and Carstenn, 2006; Qian et al., 2009). A large-scale and long-term ecosystem study (the Fire Project) is currently conducted in Water Conservation Area 2A (WCA 2A) to assess whether repeated fire can be an effective management tool to accelerate recovery in highly nutrient enriched area (Miao and Carstenn, 2006). On the other hand, anthropogenic activities (e.g., changes in land use and climate) can increase the risk of a wildfire, which is an essential process in South Florida to regulate the structure and function of ecosystems (Wade et al., 1980). Terefore, it is essential to evaluate nutrient composition of plant ash and redistribution from plant ash into the sediment-water system, for assessing fire effects on nutrient availability in the Everglades. Nutrient transport during and postfire have been studied previ- ously. Te pathways through which nutrients contained in vegetation or surface soil are redistributed by a fire are via nonparticulate (vola- tilization) and/or particulate (ash) pathways (Raison et al., 1985). Nutrients (e.g., C, N, and S) with relatively low volatilization tem- perature are most likely removed from the burned site through vola- tilization and result in atmospheric pollution (Cachier et al., 1995; McNaughton et al., 1998; Liu et al., 2000; Wan et al., 2001). Other- wise, nutrients remaining in ash can be redistributed to adjacent areas via wind, rainfall, erosion, runoff, and leaching, or be deposited on- site and thus may have a significant impact on the soil nutrient status Abbreviations: DA, discriminant analysis; DDI water, double deionized water; H zone, highly-impacted zone; MLR, multiple linear regression; M zone, moderately-impacted zone; R zone, reference zone; WCA 2A, Water Conservation Area 2A. Y. Qian and Y.C. Li, Tropical Research & Education Center, Soil and Water Science Dep., IFAS, Univ. of Florida, 18905 SW 280th St., Homestead, FL 33031; S.L. Miao and B. Gu, South Florida Water Management District, 3301 Gun Club Rd., West Palm Beach, FL 33406. Copyright © 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including pho- tocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Published in J. Environ. Qual. 38:1812–1820 (2009). doi:10.2134/jeq2008.0391 Received 28 Aug. 2008. *Corresponding author (yunli@uf.edu). © ASA, CSSA, SSSA 677 S. Segoe Rd., Madison, WI 53711 USA TECHNICAL REPORTS: ECOSYSTEM RESTORATION