Effects and Effectiveness of USDA Wetland Conservation Practices in the Mid-Atlantic Region: A Report on the Conservation Effects Assessment Project Mid-Atlantic Regional Wetland Assessment 2008 - 2015 December 23rd, 2015 Investigators: University of Maryland Department of Geographical Sciences Megan Lang U.S. Department of Agriculture, Agricultural Research Service Hydrology and Remote Sensing Laboratory Greg McCarty U.S. Department of Agriculture, Agricultural Research Service Coastal Plains Soil, Water, and Plant Research Center Thomas Ducey, Patrick Hunt, and Jarrod Miller University of Maryland, Department of Environmental Science and Technology Martin Rabenhorst, Andrew Baldwin, Daniel Fenstermacher, Metthea Yepsen, Eliza McFarland, and Amir Sharifi U.S. Department of Agriculture, Agricultural Research Service Pasture Systems and Watershed Management Research Unit Clinton Church U.S. Geological Survey Judy Denver and Scott Ator Mitchell Ecological Research Service Joseph Mitchell Smithsonian Environmental Research Center Dennis Whigham U.S. Department of Agriculture, Agricultural Research Service Office of National Programs Mark Walbridge Cover Photo: Photo taken by Metthea Yepsen at a MIAR CEAP-Wetland study site. 2 Table of Contents Executive Summary ................................................................................................................................................ 6 A. Introduction ........................................................................................................................................................ 9 1. The Mid-Atlantic Region: Gulf Atlantic Coastal Flats ................................................................................... 9 2. Wetland Restoration ...................................................................................................................................... 11 3. The Mid-Atlantic Regional CEAP-Wetland Study ....................................................................................... 12 4. Report Format ............................................................................................................................................... 14 B. MIAR CEAP-Wetland Study Components ...................................................................................................... 16 1. Above-Ground Plant Biomass and Nutrient Content.................................................................................... 16 Introduction ................................................................................................................................................... 17 Methods......................................................................................................................................................... 17 Results ........................................................................................................................................................... 18 Discussion ..................................................................................................................................................... 19 Conclusions ................................................................................................................................................... 20 References ..................................................................................................................................................... 21 Tables ............................................................................................................................................................ 23 Figures........................................................................................................................................................... 25 2. Soil Organic Carbon Storage ........................................................................................................................ 30 Introduction ................................................................................................................................................... 31 Methods......................................................................................................................................................... 31 Results and Discussion ................................................................................................................................. 32 Conclusions and Implications ....................................................................................................................... 34 References ..................................................................................................................................................... 35 Figures........................................................................................................................................................... 37 3. Soil Physicochemical Parameters, Potential Denitrification, and Abundance of Denitrifiers ...................... 40 Introduction ................................................................................................................................................... 42 Methods......................................................................................................................................................... 42 Results and Discussion ................................................................................................................................. 44 Conclusions ................................................................................................................................................... 48 References ..................................................................................................................................................... 49 Tables ............................................................................................................................................................ 52 Figures........................................................................................................................................................... 60 4. Phosphorus Levels and Mobility .................................................................................................................. 63 Introduction ................................................................................................................................................... 64 Methods......................................................................................................................................................... 64 Results and Discussion ................................................................................................................................. 65 Conclusions ................................................................................................................................................... 67 3 References ..................................................................................................................................................... 68 Tables ............................................................................................................................................................ 71 Figures........................................................................................................................................................... 73 5. Change in Depressional Wetland Water Volume Storage on the Delmarva Peninsula: Opportunities for Improved Storm Flow Mitigation ..................................................................................................................... 77 Introduction ................................................................................................................................................... 78 Methods......................................................................................................................................................... 78 Results and Discussion ................................................................................................................................. 81 Summary and Conclusions ........................................................................................................................... 84 References ..................................................................................................................................................... 85 Tables ............................................................................................................................................................ 87 Figures........................................................................................................................................................... 88 6. Plant Community Biodiversity and Quality .................................................................................................. 95 Introduction ................................................................................................................................................... 96 Methods......................................................................................................................................................... 96 Results ........................................................................................................................................................... 97 Discussion ....................................................................................................................................................