Ecological Drivers of Plant Community Composition in a Patterned Fen at Seney National Wildlife Refuge, Michigan Alex Graeff [email protected]
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Northern Michigan University NMU Commons All NMU Master's Theses Student Works 8-2018 Ecological Drivers of Plant Community Composition in a Patterned Fen at Seney National Wildlife Refuge, Michigan Alex Graeff [email protected] Follow this and additional works at: https://commons.nmu.edu/theses Part of the Botany Commons, and the Plant Biology Commons Recommended Citation Graeff, Alex, "Ecological Drivers of Plant Community Composition in a Patterned Fen at Seney National Wildlife Refuge, Michigan" (2018). All NMU Master's Theses. 549. https://commons.nmu.edu/theses/549 This Open Access is brought to you for free and open access by the Student Works at NMU Commons. It has been accepted for inclusion in All NMU Master's Theses by an authorized administrator of NMU Commons. For more information, please contact [email protected],[email protected]. ECOLOGICAL DRIVERS OF PLANT COMMUNITY COMPOSITION IN A PATTERNED FEN AT SENEY NATIONAL WILDLIFE REFUGE, MICHIGAN By Alexander J. Graeff THESIS Submitted to Northern Michigan University In partial fulfillment of the requirements For the degree of MASTER OF SCIENCE Office of Graduate Education and Research April 2018 ABSTRACT ECOLOGICAL DRIVERS OF PLANT COMMUNITY COMPOSITION IN A PATTERNED FEN AT SENEY NATIONAL WILDLIFE REFUGE, MICHIGAN By Alexander J. Graeff Regional variation in geomorphology, vegetation, fen landforms, and water chemistry create a variety of unique peatlands across the Northern Hemisphere. In the Great Lakes region, patterned fens have been extensively studied in northern Minnesota, but largely ignored in Michigan. The purpose of this study was to describe vegetation, landforms, and water chemistry in a patterned fen at Seney National Wildlife Refuge. Percent cover of plant species and environmental variables were measured at 298 relevé style plots across 6 landform types: triangular swamp forests, featureless water tracks, peripheral water tracks, strings, flarks, and ponded sedge lawns. Additionally, several morphometric parameters were calculated using GIS and communities were analyzed using multivariate techniques. Ordinations reveal variation within and between landform types related to moisture and chemical gradients. Dune islands contribute to the unique nature of Seney’s hydrology and are directly associated with (1) ponded sedge lawns, (2) patterned water tracks, and (3) triangular swamp forests. Many features at the Seney fen resemble those described in Minnesota’s patterned peatlands, yet there are considerable differences in vegetation and landform development. Key words: patterned peatland, fen, vegetation, water chemistry i Copyright by Alexander J. Graeff May 2018 ii ACKNOWLEDGEMENTS First, I need to thank my thesis advisor, Dr. Alan Rebertus, for not only his guidance in thesis work but for his passion in ecology. Through his breadth of knowledge of the natural world, my appreciation for all things ecological developed into a (presumably) lifelong passion. I thank Dr. Matthew Van Grinsven for helping with the logistics of water sampling, as well as data analysis. My field assistants, Nick Zoller, Anna Slowik, and Gannon McCormick were critical for data collection and their presence in the wilderness only added to the greatness of it all. Greg Corace and Seney National Wildlife Refuge made this study possible through the permission to study in the wilderness area, methodology design, input on thesis drafts, and funding for field technicians. I also thank Robert Regis for his continual input and guidance in remote sensing applications for use in this project. This thesis is written in the format for submission to the Canadian Journal of Botany (http://www.nrcresearchpress.com/doi/pdf/10.1139/cjb_instruct01_e). iii TABLE OF CONTENTS List of Tables……………………………………………………………………………..vi List of Figures……………………………………………………………………………vii Introduction…………………………………………………………………….………….1 Methods……………………………………………………………………………………5 Study site…………………………………………………………………………..5 Sampling design……………………………………………………..…………….7 Environmental data…………………………………………..……………………7 Vegetation sampling………………………………………………………………8 Data analysis…………………………………………..…………………………..9 Geographic Information System…………………………………………………10 Results………………………………………………………………………………..…..13 Landscape characteristics………………………………………………………...13 Peat and water chemistry………………………………………………………...15 Vegetation and environmental drivers…………………………………………...16 Peripheral water tracks…………………………………………………...17 Strings and featureless water tracks……………………………………...18 Triangular swamp forests……………………………………………..….19 Ponded sedge lawns and flarks…………………………………………..19 Discussion……………………………………………………………………………..…21 Overview and regional context of the Seney fen……………………………..….21 Seney Patterned Peatlands: Variation within and between landforms…………...22 iv Peripheral water tracks (PERI)…………………………………………..22 Triangular swamp forests (TSF)…………………………………………23 Patterned water tracks……………………………………………………24 Strings……………………………………………………………………25 Flarks and their relationship to ponded sedge lawns…………………….26 Featureless water tracks and their relationship to strings……………..…26 Possible impacts of ditching in the Seney fen…………………………………...27 Water chemistry and vegetation patterns in space and time……………………..28 Conclusions……………………………………………………………...……….30 Summary…………………………………………………………………………………32 References…………………………………………………………………………..……51 v LIST OF TABLES Table 1. Study design details for each landform type........................................................35 Table 2. Descriptions of variables included in canonical correspondence analysis..........36 Table 3. Summary of cover types in the core study area at Seney National Wildlife Refuge................................................................................................................................37 Table 4. Significance values for linear mixed-effects models...........................................38 Table 5. Environmental averages by landform type..........................................................39 Table 6. Environmental correlations in canonical correspondence analyses.....................40 Table 7. Dominant species by landform type....................................................................41 Table 1A. Plant species, codes, and associated landforms................................................62 Table 2A. Water track widths grouped by pattern intensity..............................................68 Table 3A. String and flark morphometry averaged by transect and by observed patterning intensity..............................................................................................................................69 Table 4A. Environmental averages by transect.................................................................70 vi LIST OF FIGURES Figure 1. The study area and digitized (core) study area in relation to Seney National Wildlife Refuge and Strangmoor Bog National Natural Landmark..................................42 Figure 2. Aerial photos of several patterned fen features..................................................43 Figure 3. Weighted histogram of patterned water track vectors........................................44 Figure 4. Boxplots for each environmental variable grouped by landform type for each season.................................................................................................................................45 Figure 5. Non-metric multidimensional scaling plot.........................................................46 Figure 6. Canonical correspondence analysis with all plots and environmental variables.............................................................................................................................47 Figure 7. Canonical correspondence analysis with plots grouped by transect..................49 Figure 8. Canonical correspondence analysis subsets with (1) strings, and (2) flarks and ponded sedge lawns...........................................................................................................50 Figure 1A. Aerial photos showing fen landforms in three different regions of the study area.....................................................................................................................................73 Figure 2A. Aerial photo of Walsh Ditch and The Spreads................................................75 Figure 3A. Aerial photo of the study area with numbered transects.................................76 Figure 4A. A digitized map of the Seney fen showing areas of patterning and buffered islands................................................................................................................................77 Figure 5A. Canonical correspondence analysis with the easternmost plots in each landform coded separately.................................................................................................78 vii INTRODUCTION Patterned fens are peatlands found throughout boreal regions of North America and Eurasia, and also sparingly in the southern hemisphere. They are characterized by alternating “strings” and “flarks” which form striking, patterned landscapes. Strings (from German Stränge) are low shrubby ridges dominated by sphagnum moss or hummock forming sedges, and flarks (from Swedish flarke) are linear hollows dominated by hydrophytic species (Heinselman 1965, Glaser 1992a, Rietkerk et al. 2004, Laitinen et al. 2005, Rydin et al. 2013). Patterned fens are of global and local conservation concern for a variety of reasons. Patterned fens