Fertilization has negligible effects on nutrient export and stream biota in two North Florida forested watersheds
| Autor: | Erik B. Schilling, Robert T. Hensley, Paul H. Decker, Matthew J. Cohen, Camille A. Flinders, Daniel L. McLaughlin |
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| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
geography geography.geographical_feature_category Coastal plain fungi Forestry Biota Management Monitoring Policy and Law 010603 evolutionary biology 01 natural sciences Nutrient Agronomy Benthic zone Nutrient pollution Phytoplankton Environmental science Water quality Periphyton 010606 plant biology & botany Nature and Landscape Conservation |
| Zdroj: | Forest Ecology and Management. 465:118096 |
| ISSN: | 0378-1127 |
| DOI: | 10.1016/j.foreco.2020.118096 |
| Popis: | Managed pine forests cover nearly 130,000 km2 of the Southeastern U.S. and are important to the economic and ecological sustainability of the region. These stands are typically fertilized twice – at establishment and mid-rotation – to enhance timber production during a 25-year rotation. In Florida, Best Management Practices (BMPs) limit fertilizer application rates and require special management zones (SMZs) to reduce nutrient pollution. Recent adoption of numeric nutrient criteria (NNC) for streams and lakes in Florida has raised concerns that forest fertilization, even in compliance with BMPs, may result in excess nutrient loads and degrade stream ecological condition, particularly directly following fertilizer applications. We examined nutrient export dynamics and stream biota in two medium size watersheds (21 and 34 km2, respectively) dominated by loblolly pine (Pinus taeda) plantations in north Florida following fertilization. Over 54 months, we monitored stream discharge, nitrogen (TN, TKN, NO3-N, NH4-N), and phosphorus (TP, orthoP), as well as stream biota (benthic macroinvertebrates, phytoplankton chlorophyll a, periphyton and vascular plants) prior to and following watershed-scale fertilization. We condensed four years of scheduled fertilization into a single year, resulting in nutrient inputs substantially larger than typical. Because flow variation strongly controlled nutrient concentrations, we assessed pre- and post-fertilization concentration-discharge (C-Q) relationships, which remained unchanged. Annual mass export of N and P also remained unchanged, suggesting landscape retention of additional loads. Likewise, we observed no systematic change in biological indicators. These results suggest forest fertilization at BMP rates is unlikely to increase stream nutrient export, supporting the contention that fertilized pine forests in the southeastern coastal plain are protective of statewide goals for water quality and stream biotic integrity. |
| Databáze: | OpenAIRE |
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