Floristic Quality Assessment and Monitoring of Brown Bridge Quiet Area Wetlands
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Floristic Quality Assessment and Monitoring of Brown Bridge Quiet Area Wetlands Prepared by: Phyllis J. Higman Michigan Natural Features Inventory P.O. Box 13036 Lansing, MI 48901-3036 For: Grand Traverse Conservation District 1450 Cass Road, Traverse City, Michigan, 49685 October 30, 2013 Report Number 2013-17 Acknowledgements This work was made possible by a Great Hyde assisted with early surveys and delivery of Lake Restoration Initiative grant through the a workshop for local stewards. Brian Klatt and Environmental Protection Agency, awarded to Glenn Palmgren provided valuable guidance on the Grand Traverse Conservation District in sampling strategies and Reb Ratliff provided Traverse City, Michigan. Many thanks to Robin enthusiastic energy to kick off the field sampling Christensen for writing the grant and for inviting and assemble necessary field gear. Thanks to us to do this work. Suzan Campbell and Daria you all. Cover photos by Phyllis J. Higman, 2012- 2013. Clockwise from left to right: Brown Bridge Pond, Brown Bridge Dam, The Boardman River Coursing through the Brown Bridge Quiet Area after Dam Removal, and Newly Exposed Bottomlands at Brown Bridge Quiet Area after Dam Removal. Copyright 2013 Michigan State University Board of Trustees. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, marital status, or family status. Table of Contents Table of Contents ..................................................................................................................................... i Introduction ............................................................................................................................................. 1 Methods .................................................................................................................................................. 3 Floristic Assessment.......................................................................................................................... 3 Point-line Intercept Sampling ............................................................................................................ 3 Results ................................................................................................................................................... 4 Floristic Quality Assessment ............................................................................................................. 4 Point-line Intercept Sampling ............................................................................................................ 5 Discussion ............................................................................................................................................... 6 Floristic Quality Assessment ............................................................................................................. 6 Forested Wetlands....................................................................................................................... 6 Open Wetlands ........................................................................................................................... 7 Combined Wetlands .................................................................................................................... 8 Point-line Intercept Sampling ............................................................................................................ 8 References............................................................................................................................................... 9 Appendix A. Grand Traverse Invasive Species Network Top Twenty.................................................. A-1 Appendix B. Recent Taxonomic Changes ........................................................................................... B-1 Genera in Michigan Flora whose family assignments here changed ............................................... B-3 New Species added to the website March 2013 .............................................................................. B-4 Additions and Name Changes to Michigan Flora, Volumes 1-3 ..................................................... B-5 Appendix C. Point Intercept Transect Photos ...................................................................................... C-1 Appendix D. FQA Data ...................................................................................................................... D-1 Forested Wetlands ......................................................................................................................... D-3 Open Wetlands .............................................................................................................................. D-9 Forested and Open Wetlands ....................................................................................................... D-15 Appendix E. Point-Line Intercept Sampling Data .................................................................................E-1 Figures Figure 1. Brown Bridge Dam. ................................................................................................................. 1 Figure 2. Brown Bridge Pond ................................................................................................................ .1 Figure 3. Brown Bridge Wetlands ........................................................................................................... 1 Figure 4. Location of transects. ............................................................................................................... 3 Brown Bridge Quiet Area FQA and Monitoring, 2013, Page i Tables Table 1. Invasive plant documented at Brown Bridge by GTCD prior to dam removal ........................... .2 Table 2. Comparison of Floristic Quality Data from 1992 to 2013........................................................... 4 Table 3. All non-native species documented in the Brown Bridge Wetlands during 2012-2013 .............. .5 Table 4. Relative cover of species with 1% or higher cover in any sample area. ...................................... 6 Table 5. Non-native species documented in 1992 .................................................................................... 7 Brown Bridge Quiet Area FQA and Monitoring, 2013, Page ii Introduction The Brown Bridge dam was constructed on the immediate vicinity of the dam and reservoir the Boardman River in 1921 for producing (A-D, Figure 3), and the likelihood of the spread hydropower, creating the 191 acre Brown Bridge of invasive plants. These studies concluded that pond, approximately 12 miles southeast of wetlands A and B would be largely sustained by Traverse City (Figures 1 and 2). In 2004, it was groundwater discharge, while 60% of wetland C determined that it was no longer economically all of wetland D would be converted to non- feasible to use the dam for hydropower, and it wetland (USFWS 2011). This would result in was decommissioned in 2006. Subsequently, an anticipated loss of 61.1 acres of wetland to be the aging structure became a safety hazard, offset by the expected development of 74 acres requiring several water drawdowns and spurring of wetland on newly exposed bottomlands after consideration of alternatives for the dam, the drawdown of the reservoir. These newly including removal and restoration of the original exposed soils, however, would be extremely cold water river. vulnerable to invasion by non-native plants, Environmental studies were undertaken to including at least 12 highly invasive species that assess potential impacts from dam removal, pose a significant threat to the restoration including consequences for existing wetlands in (USFWS 2011, Christensen and Beachy 2012). Figure 1. Brown Bridge Dam. Figure 2. Brown Bridge Pond. Figure 3. Brown Bridge wetlands documented in the draft Environmental Impact Statement (USFWS 2011). Brown Bridge Quiet Area FQA and Monitoring, 2013, Page 1 The bottomlands have been a hotspot for Network (ISN), led by the Grand Traverse invasive species establishment during the Conservation District, resulted in comprehensive previous partial drawdowns. Twenty-six species invasive plant surveys of the Brown Bridge were documented in Brown Bridge Quiet Area Quiet Area. Infestations of all detected species prior to dam removal (Table 1). Twelve of these were mapped and an invasive species are among the top twenty invasive plants for the management plan was developed (Christensen region—those that land managers believe pose and Beachy 2012). Implementation of the plan the biggest threat to high quality natural areas was initiated prior to dam removal, including (Appendix A). Of highest concern were the treatments for bull thistle, Canada thistle, reed sizeable infestations of reed canary grass, non- canary grass and non-native phragmites. native phragmites, narrow-leaved cat-tail and Follow-up treatments for these and several other Canada thistle found in the immediate vicinity of species were implemented immediately after the reservoir. All four of these are particularly dam removal, according to a carefully planned aggressive colonizers. schedule, and using best known treatment The commitment to minimize the spread of techniques for each targeted species. existing infestations and prevent new species The conservation community is poised to from establishing in the restoration is strong. continue to detect