Climate Change Vulnerability Assessment for Poor Fen in Wisconsin

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1 Climate Change Vulnerability Assessment for Poor Fen in Wisconsin In 2014, the Wisconsin DNR s Natural Heritage Conservation program conducted ten vulnerability assessment workshops across Wisconsin to evaluate the potential impacts of climate change on over 50 natural communities. At one workshop, a team of conservation professionals utilized experience and published literature to assess the vulnerability of Poor Fen based on the potential impact and adaptive capacity of the ecological processes, dominant and important plant species, and stressors to the community. a Ryan O'Connor, WDNR Distribution of Poor Fen in Wisconsin based on NHI data Executive Summary Increasing temperatures may lead to more water loss through evaporation, altering delicate hydrologic balances. However, with similar to slightly increased precipitation and higher groundwater recharge projected, hydrologic changes may be minimal. If water levels do rise or drop over time, sites with floating "bog" mats may be able to fluctuate naturally. Nutrient enrichment through changing landuse and groundwater pollution may be one of the greatest threats, and could increase non-native invasive species. However, several factors may reduce vulnerability. Low topographic position and connections to cold groundwater may reduce the impact of modest increases in temperature. Many dominant species appear to tolerate or even benefit from moderate increases in temperature and relatively high species diversity may reduce the impact of individual species losses. Moderately acidic soils also provide a buffer against invasive species. Potential Impacts: Moderately negative to negative + Adaptive Capacity: Moderate to moderately low Overall Estimated Vulnerability: Moderate to high a For information on how this assessment was conducted, please see the CCVA Vulnerability Determination Process on the WICCI Plants and Natural Communities working group website.

2 Greatest Potential Impacts: Potential changes to water budgets may have a gradual but pronounced effect on Poor Fen, with increasing temperatures leading to higher evapotranspiration and evaporation. If this exceeds changes in precipitation and groundwater supply, a gradual lowering of the water table could occur. 1, 2 However, overall precipitation is projected to remain steady or increase slightly, 3 and groundwater recharge is expected to increase due to higher precipitation in the non-growing season, 4 potentially reducing the impact of potential water loses. Consistent with this idea, groundwaterfed fens in Austria were determined to be the least vulnerable of all peatlands to climate change, though communities also dependent on precipitation were somewhat more vulnerable. 5 Nutrient enrichment may be one of the greatest short-term threats, and could occur through changing landuse and groundwater pollution. 4 Nutrient loading could increase non-native invasive species such as non-native cat-tail, Phragmites, and glossy buckthorn. Invasives also benefit 4, 6-8 from longer growing seasons and generally have broad environmental tolerances and adapt well to rapid change. Risk of wildfires is likely to increase, 9, 10 but if they are of low to moderate severity, they could benefit Poor Fen, as many of the dominant species resprout readily after fire. However, catastrophic fire that consumes subsurface layers of peat during drought could severely alter sites, although the risk of widespread catastrophic wildfire is likely low. Factors that most influence Adaptive Capacity: Poor Fen is supported at least partially by cold groundwater and sites are typically located in low-laying basins that serve as frost pockets, somewhat reducing exposure to warmer temperatures. Poor Fens also have a built-in buffer against extreme events and more variable precipitation, as sponge-like Sphagnum moss holds water, slowly releasing it during periods of low precipitation, and increasing growth during periods of high water. 11, 12 In addition, sites with a floating mat may be able to fluctuate with modestly higher or lower water levels if changes do occur. While some species like bog laurel appear to be sensitive to warmer temperatures, the majority of species tolerate or even thrive under warmer conditions, 13 or are found much further south, 14 implying they may be limited by appropriate geology and hydrology rather than temperature. While invasive species are a major concern, moderately acidic, low nutrient soils often help the community resist invasions. Although Poor Fen is restricted by specific geologic and hydrologic requirements, the community has relatively high species diversity. While the community is somewhat uncommon and sites are often isolated from another, they often occur within large peatland complexes and species may be able to shift within sites in response to changing local conditions. These large peatlands are also often situated high in the watershed, surrounded by large forested landscapes and may be buffered from stressors such as increased runoff and sedimentation from extreme storms. Key uncertainties: Much of the research on impacts of climate change on peatlands was conducted in Canada or northern Minnesotaare findings from these studies equally applicable in Wisconsin, where northern peatlands are at southern edge of their range? Although many Poor Fens have traits that help them resist change and/or adapt to changing water levels, are there thresholds that once crossed (water budget changes, nutrient inputs) would be a tipping point? Peatland water budgets are complex; more modeling and monitoring is needed in different types of wetlands to assess how changes in water budgets will affect peatland communities differently. In initial vulnerability assessment ratings, several non-forested peatland communities were considered as a single group, with a single rating given of potential impacts, adaptive capacity, and overall vulnerability for Open Bog, Poor Fen, Muskeg, and Patterned Peatland. While differences between peatland communities were considered in this written assessment, vulnerability assessment ratings should be reevaluated for individual peatland communities.

3 Climate Change Vulnerability Determination for Poor Fen in Wisconsin Low Change Scenario (PCM B1) High Change Scenario (GFDL A1FI) Potential Impacts: Moderately negative Negative Adaptive Capacity: Moderate Moderately low Overall Estimated Vulnerability: Moderate High Confidence: Medium evidence, medium-high agreement Participants at the northern non-forested wetland workshop

4 Poor Fen Key Factors and Processes Occurs within large peatland basins in northern Wisconsin as well as small lake basins, nearly always high in the watershed. Sometimes occurs as a floating "bog" mat. Usually weakly minerotrophic. Water table at surface with constantly saturated organic soils, with anaerobic conditions limiting decomposition. Water budget driven by groundwater, but influenced by precipitation and evapotranspiration. Sphagnum plays a key role in maintaining acidity, forming localized mounds, and absorbing or releasing excess water. Fire helps maintain open conditions, though severe fire that consumes subsurface peat could set back succession. Often occurs in peatland complexes with Northern Sedge Meadow, Open Bog, Muskeg, Black Spruce Swamp, and Northern Tamarack Swamp. Potential Impacts under Climate Change Sites with a floating mat could potentially adjust to changing water levels. Extreme storms are likely to increase, but wetlands high in the watershed may be impacted less from the secondary impacts of large precipitation events (e.g., downstream sedimentation, spread of invasive species propagules by floodwaters, etc.). 15 Anaerobic conditions are likely to be maintained unless regional water levels experience a severe long-term drop. While possible, most scenarios project similar to somewhat wetter annual precipitation. 3 Peatlands can also theoretically selfbuffer by rising and falling with water tables: at low water, peat decomposes to the level of the water table, and at higher water, peat re-accumulates. 12 Groundwater recharge is expected to increase due to higher precipitation in the non-growing season. 3, 4 However, higher temperatures will also increase evapotranspiration and evaporation. If this exceeds changes in water supply (e.g, precipitation and groundwater availability), water budgets could reverse, leading to a gradual lowering of the water table. 1, 2 However, recent modeling determined that groundwater-fed fens were the least vulnerable of all peatlands to climate change in Austria, though communities also dependent on precipitation were found to be moderately vulnerable. 5 More frequent extreme rain events could especially impact precipitation-driven wetlands, although Sphagnum provides a buffer to the potential impact of increasingly variable precipitation. Hummock-forming Sphagnum mosses resist decomposition, potentially reducing potential for peat and hummock loss during short-term drought. 16 Conditions that are suitable for wildfire will likely increase, 9 10 though low to moderate intensity fire may benefit Poor Fen. Severe fires that consume subsurface peat in times of drought would be highly detrimental, 10 although the risk of widespread catastrophic wildfire is likely low. Communities may shift slightly within sites in response to changes in water budgets and fire, with drier conditions likely favoring the expansion of trees and shrubs expanding Muskeg and Black Spruce or Tamarack Swamp, and wetter conditions favoring Poor Fen, which is typically has water tables closer to the surface and has higher dominance of graminoids than other peatland systems.

5 In the absence of species-specific climate impact models, geographic range and edaphic requirements can be used as a surrogate to estimate the potential impacts of climate change on the following important species. Species with a wide geographic range and broad tolerance of edaphic conditions are generally anticipated to be less vulnerable to changing environmental conditions. 17 Important Shrubs, Herbs, & Mosses Current Range 14 and Potential Impacts under Climate Change Leatherleaf (Chamaedaphne calyculata) Ranges south to northeast IL; disjunct populations in NC & SC. Cover increased modestly under both warmer and drier conditions in an experimental setting. 13 Bog rosemary (Andromeda polifolia) Ranges south to northern IL, IN. Rare in OH, PA. Cover increased under both warmer and drier conditions in an experimental setting. 13 Bog laurel (Kalmia polifolia) Ranges south to central WI and southeast MI. Cover decreased under warmer conditions in an experimental setting. 13 Narrow-leaved woolly sedge (Carex lasiocarpa) Yellow lake sedge (C. utriculata) Tussock cotton-grass (Eriophorum virginicum) Small cranberry (Vaccinium oxycoccos) Pitcher-plant (Sarracenia purpurea) White beak-rush (Rhynchospora alba) Pod-grass (Scheuchzeria palustris) Ranges south to north-central IL and IA. Increased under wetter and warmer 11, 13 conditions in an experimental setting. Ranges south to northern IL, IN, and central OH. Disjunct west to CO, OK, NM, etc. Ranges south to central IN, OH, scattered to piedmont in NC, SC. Ranges south to southern WI, rare in northern IL and IN. Ranked as highly vulnerable to climate change in Pennsylvania using NatureServe CCVI. 18 Unaffected by warming in an experimental setting. 13 Responds well to low to moderate intensity fire, but is killed by severe fire that consumes underlying peat. 19 Ranges south to northern IL and IN, disjunct to Atlantic coastal plain (NC, SC). Ranges south to northern IL and IN, disjunct to Atlantic coastal plain (NC, SC, GA). Cover increased under wetter conditions but decreased under warmer conditions in an experimental setting. 13 Ranked as moderately vulnerable to climate change in Pennsylvania using NatureServe CCVI. 18 Ranges south to northern IL, IN, central OH. Cover increased under wetter conditions and warmer conditions in an experimental setting. 13 Bryophytes (mainly Sphagnum) Distribution varies; Sphagnum productivity increased under wetter conditions 11 but cover decreased slightly with warmer conditions 13 in an experimental setting. Many bryophytes are highly sensitive to drying and decline if water tables drop. 20 Stressors/Threats Non-native invasive cat-tail (Typha angustifolia, T. X glauca), Phragmites Invasive shrubs (glossy buckthorn) Nutrient enrichment of groundwater Overuse of groundwater resources Hydrologic disruption (roads, etc.) Conversion of peatlands to cranberry farms. Potential Changes to Stressors/Threats under Climate Change Acidic peatlands generally resist many invasive species, however if nutrient enrichment occurs, non-native cat-tail is favored, especially if water tables rise long-term Increased use of road salt favors Phragmites. Some invasives may have increased productivity with increasing CO 2 and reduced snowpack. 7 New invasives are likely to arrive. If water tables drop, shrubs generally increase. 13 Abundant seed production and dispersal combined with broad environmental tolerances allow invasive shrubs to take advantage of altered hydrology and tolerate rapid changes. 8 Nutrient enrichment is likely to increase in agricultural areas, 4 which may expand northward. If groundwater withdrawals increase due to increasing demand, water tables could be lowered, but impacts likely will be basin-specific 24 and may vary from year to year with regional precipitation trends. Shrubs generally increased in cover under drier conditions in experimental peatland mesocosms. 13 Sites with impounded water may convert to emergent marsh.

6 References 1 Moore, M.V., M.L. Pace, J.R. Mather, P.S. Murdoch, R.W. Howarth, C.L. Folt, C.Y. Chen, H.F. Hemond, P.A. Flebbe, and C.T. Driscoll Potential effects of climate change on freshwater ecosystems of the New England/Mid-Atlantic region. Hydrological Processes 11 (8): Watras, C.J., J.S. Read, K.D. Holman, Z. Liu, Y.Y. Song, A.J. Watras, S. Morgan, and E.H. Stanley Decadal oscillation of lakes and aquifers in the upper Great Lakes region of North America: Hydroclimatic implications. Geophysical Research Letters 41 (2): Kucharik, C., D.J. Vimont, K. Holman, E. Hopkins, D. Lorenz, M. Notaro, S. Vavrus, and J. Young Wisconsin Initiative on Climate Change Impacts Climate Working Group Report: Climate Change in Wisconsin. University of Wisconsin-Madison. Madison, WI. 4 Wisconsin Initiative on Climate Change Impacts [WICCI] Water Resources Working Group Report. Nelson Institute for Environmental Studies, Universty of Wisconsin-Madison and the Wisconsin Department of Natural Resources. Madison, WI. 5 Essl, F., S. Dullinger, D. Moser, W. Rabitsch, and I. Kleinbauer Vulnerability of mires under climate change: implications for nature conservation and climate change adaptation. Biodiversity and Conservation 21 (3): Kercher, S.M., and J.B. Zedler Flood tolerance in wetland angiosperms: a comparison of invasive and noninvasive species. Aquatic Botany 80: Ryan, M.G., and J.M. Vose Effects of climatic variability and change in J.M. Vose, D.L. Peterson and T. Patel- Weynand (Eds.), Effects of climatic variability and change on forest ecosystems: a comprehensive science synthesis for the U.S. Forest sector. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. Portland, OR. 8 Dukes, J.S., J. Pontius, D. Orwig, J.R. Garnas, V.L. Rodgers, N. Brazee, B. Cooke, K.A. Theoharides, E.E. Stange, and R. Harrington Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can we predict? Canadian Journal of Forest Research 39 (2): Dale, V.H., L.A. Joyce, S. McNulty, R.P. Neilson, M.P. Ayres, M.D. Flannigan, P.J. Hanson, L.C. Irland, A.E. Lugo, C.J. Peterson, D. Simberloff, F.J. Swanson, B.J. Stocks, and B.M. Wotton Climate Change and Forest Disturbances. BioScience 51 (9): Burkett, V., and J. Kusler Climate Change: Potential Impacts and Interactions in Wetlands of the United States. Journal of the American Water Resources Association 36 (2): Weltzin, J.F., J. Pastor, C. Harth, S.D. Bridgham, K. Updegraff, and C.T. Chapin Response of Bog and Fen Plant Communities to Warming and Water-level Manipulations. Ecology 81 (12): Dise, N.B Peatland response to global change. Science 326 (5954): Weltzin, J.F., S.D. Bridgham, J. Pastor, J. Chen, and C. Harth Potential effects of warming and drying on peatland plant community composition. Global Change Biology 9 (2): Kartesz, J.T. The Biota of North America Program (BONAP) North American Plant Atlas. Accessed Juen 20, Zedler, J.B How frequent storms affect wetland vegetation: a preview of climate-change impacts. Frontiers in Ecology and the Environment 8 (10): Turetsky, M.R., S.E. Crow, R.J. Evans, D.H. Vitt, and R.K. Wieder Trade-offs in resource allocation among moss species control decomposition in boreal peatlands. Journal of Ecology 96 (6): Thuiller, W., S. Lavorel, and M.B. Araújo Niche properties and geographical extent as predictors of species sensitivity to climate change. Global Ecology and Biogeography 14 (4): Furedi, M., B. Leppo, M. Kowalski, T. Davis, and B. Eichelberger Identifying species in Pennsylvania potentially vulnerable to climate change. Pennsylvania Natural Heritage Program, Western Pennsylvania Conservancy. Pittsburg, PA. 19 Matthews, R.F Vaccinium oxycoccos. In: Fire Effects Information System [Online]. U.S. Department of Agriculture, Forest Service Rocky Mountain Research Station, Fire Sciences Laboratory 20 Vile, M.A., K.D. Scott, E. Brault, R.K. Wieder, and D.H. Vitt Living on the edge: The effects of drought on Canada's western boreal peatlands in Z Tuba, N Slack and L. R Stark (Eds.), Bryophyte ecology and climate change.. Cambridge University Press. Cambridge UK. 21 Woo, I., and J. Zedler Can nutrients alone shift a sedge meadow towards dominance by the invasive Typha glauca. Wetlands 22 (3): Zedler, J.B Climate Change and Arboretum Wetlands. edited by University of Wisconsin Arboretum. Madison, WI. 23 Boers, A.M., and J.B. Zedler Stabilized Water Levels and Typha Invasiveness. Wetlands 28 (3): Eheart, J.W., and D.W. Tornil Low flow frequency exacerbation by irrigation withdrawals in the agricultural midwest under various climate change scenarios. Water Resources Research 35 (7):

7 Northern Non-forested Wetlands Workshop Participants Workshop Date: October 6, 2014 Location: Ashland, Wisconsin Peggy Burkman Mike Gardner Paul Hlina Sarah Johnson Carly Lapin Amanda Little Tracey Ledder Colleen Matula Linda Parker Michele Wheeler National Park Service, Apostle Islands National Lakeshore Northflow, LLC University of Wisconsin-Superior Lake Superior Research Institute Northland College WDNR-Natural Heritage Conservation University of Wisconsin-Stout Lake Superior National Estuarine Research Reserve WDNR-Forest Sciences USDA Forest Service, Chequamegon-Nicolet National Forest WDNR-Water Resources Facilitators: Ryan O Connor Amy Staffen WDNR-Natural Heritage Conservation WDNR-Natural Heritage Conservation dnr.wi.gov WICCI.WISC.EDU Suggested Citation: Wisconsin Initiative on Change Impacts [WICCI] Climate Vulnerability Assessments for Plant Communities of Wisconsin. Wisconsin Initiative on Climate Change Impacts, Madison, WI.