Lakeshore Vegetation of Sky Lakes Wilderness Study Area, Oregon

LAKESHORE VEGETATION OF SKY LAKES WILDERNESS STUDY AREA, OREGON by Constance Rutherford A Thesis Presented to The Faculty of Humboldt State University In Partial Fulfillment of the Requirements for the Degree Master of Arts June, 1984 LAKESHORE VEGETATION OF SKY LAKES WILDERNESS STUDY AREA, OREGON by Constance Rutherford We certify that we have read this study and that it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a thesis for the degree of Master of Arts. Major Professor Approved by the Graduate Dean ABSTRACT Eleven vegetation types occurring within two communities have been described for the lakeshore habitat of the Sky Lakes area. The shrub-dominated community has two closely related heath shrub types. The herb-dominated community comprises a diversity of types ranging from monotypic stands of sedge growing in standing water to more mesic meadows supporting sedge, grass, and herb mixtures. It is proposed that eleven vegetation types can be arrayed along a soil moisture gradient. Microtopographical influences, elevation, and succession interact with the soil moisture gradient to produce a diversity of lakesites, each of which displays a unique subset of the potential lakeshore vegetation types. iii ACKNOWLEDGEMENTS I would like to give my heartfelt thanks to the following people who have been a part of this project: Dr. Andrew Moldenke, formerly of U.C. Santa Cruz, for piquing my interest in plant ecology. The USDA Forest Service, Rogue River National Forest, Butte Falls Ranger District, for allowing me to carry out this study while serving as a backcountry ranger in Sky Lakes Wilderness Study Area. Kurt Werner, for assisting me with the fieldwork. Pamela King, for assisting in the identification of bryophytes, and Teresa Prendusi, for assisting in the identification of Gramineae. Dr. Daniel Norris, for making a trip to Blue Canyon Basin in my behalf, for assisting in the identification of bryophytes and Carices, and for review of the manuscript. Dr. John Sawyer, my major professor, for exploring Seven Lakes Basin with me, for the time spent discussing and reviewing the manuscript, and particularly for being good-natured about my closet conga playing. Drs. Michael Mesler and Kenneth Lang, the rest of my committee, for review of the manuscript. Tom Atzet, plant ecologist for USDA, Forest Service, Siskiyou and Rogue River National Forests, for review of the manuscript. Dr. Terry Roelofs, for his encouragement and friendship. Bruce Bingham, for unravelling the secrets of how to use the Word 11 processor. Debbie McCreary, for her friendship as well as her typing expertise. Mignonne Bivin, for her artistic rendering of the lakeshore vegetation. My family, and my friends Traver Downes, Nancy McCleister, Mark Leibowitz, John Richards, and Gary Greenberg for their support of my diverse lifestyle. iv TABLE OF CONTENTS ABSTRACT iii ACKNOWLEDGEMENTS iv LIST OF FIGURES viii LIST OF TABLES ix I INTRODUCTION Statement of problem 1 History of use 2 II. SKY LAKES AS A STUDY AREA Location 4 Geology and soils 8 Climate 10 Forest vegetation 11 III. METHODS Field procedures 12 Data analysis 14 IV. RESULTS Shrub-dominated community 17 Phyllodoca empetriformis - Vaccinium scoparium type 17 v Vaccinium occidentale - vaccinium scoparium type 18 Herb-dominated community 19 Calamagrostis canadensis type 19 Mixed Sedge type 20 Mixed Herb type 21 Carex scopulorum type 22 Deschampsia caespitosa type 22 Carex kelloggii type 23 Carex aquatilis type 24 Carex aquatilis - moss type 25 Carex rostrata type 25 Key to communities and types 31 V. DISCUSSION Differences between forest and lakeshore habitats 33 Factors contributing to uniqueness of lakesites 33 Soil moisture gradient 36 Microtopographical influences 38 Elevation 41 Succession 42 Geographical distribution of vegetation types by lake basin 45 Summary 48 Comparison to other studies 49 vi Impact 51 REFERENCES CITED 53 APPENDICES A. List of vascular taxa found in the area . .57 B. List of bryophyte taxa found in the area. .62 C. Site factor mean and modal values 63 D. Elevation and acreage of lakes studied. 64 vii LIST OF FIGURES Figure 1. Map showing location of Sky Lakes Wilderness Study Area in relation to the southern Cascade region 5 2. Topographic map of Seven Lakes Basin 6 3. Topographic map of Blue Canyon Basin 7 4. Dendrogram of vegetation types 16 5. Distribution of lakeshore vegetation types against soil moisture gradient 37 6. Variations in shoreline profile due to microtopography 39 7. Distribution of lakeshore vegetation types against elevation gradient 44 viii LIST OF TABLES Table 1. Association table for vascular taxa 27 2. Association table for bryophyte taxa 30 3. Distribution of vegetation types among lakes 35 4. Relative frequency of occurrence of eight selected shrubs in two shrub types. 43 ix INTRODUCTION Statement of problem In the Pacific Northwest, numerous studies have reported on the forest-meadow mosaic that occurs extensively in the subalpine zone. This mosaic has also been noted further south in the Klamath Mountains and in the Sierra Nevada. To date, little attention has been given to the vegetation of the southern Cascades. As the southern Cascades fall predominantly within the montane zone and lower range of the subalpine zone, the forest-meadow mosaic is not as extensive as it is further north. More typically, meadow vegetation is associated with lake systems. Meadow vegetation is variable and includes shrub as well as herb communities. Sky Lakes Wilderness Study Area is a region of the high Cascades directly south of Crater Lake National Park, Oregon. While much of the area is forested, a number of small lakes and associated lakeshore vegetation exhibit a dramatic contrast. Franklin (1978) states that present baseline data collection in wilderness areas is "woefully inadequate", and that "meadows, margins of lakes and ponds, and 2 timberline forests are examples of fragile ecosystems particularly likely to be heavily impacted by visitors" and "should receive special attention in inventory". The purpose of this study is to describe the vegetation within the lakeshore habitat of Sky Lakes area, to suggest environmental factors that contribute to the variability in lakesites, and to discuss how these factors interact to produce a series of lakes with rather individual expressions of a potential lakeshore vegetation. History of use Local ranchers and hunters have been frequenting the Sky Lakes area since the Medford and Klamath Falls areas were settled in the mid 1800's. While the number of visitors has steadily increased, current horse use has dropped to about 10% of the total use. As in the past, most use is by local residents. Ninety percent are visitors from within a 150 mile radius of Sky Lakes. The area was designated as Sky Lakes Recreation Unit in 1935. At that time it is estimated that 750 visitors per year used the area. The management direction at that time encouraged the erection of shelters, campgrounds, and fireplaces. Over the next 40 years, the area was reclassified four times while maintaining some concept 3 of limited use. Finally in 1977, the area was designated as Sky Lakes Wilderness Study Area as part of the federal wilderness classification efforts of the time. To date, wilderness status is not resolved. By the early seventies, a need to adjust management policies was recognized. During the previous decade, access had improved, and with increased backpacking, visitor use in 1975 reached 5,000 visitors per year. Most of the improvements erected in the 30's were removed by 1973. Two years later, the Sky Lakes Management Plan added a regulation prohibiting camping within 100 feet of any lake. However, several areas had already received heavy use. In 1977, three lakeshore areas were cordoned off completely and revegetation efforts begun. THE STUDY AREA Location Sky Lakes Wilderness Study Area is part of two National Forests, the Winema National Forest and the Rogue River National Forest. It extends along the crest of the southern Cascades between Crater Lake and Highway 140. It is an area about six miles wide and 27 miles long, and totaling 72,000 acres. It is dotted with more than 200 bodies of water, most of which are concentrated in three lake basins: Seven Lakes Basin, Blue Canyon Basin, and Sky Lakes Basin. The first two are on the west side of the crest, and are the object of this study. Seven Lakes Basin constitutes the headwaters of the Middle Fork of the Rogue River [T34, R5E], while Blue Canyon Basin constitutes the headwaters of the South Fork of the Rogue River [T35, R5E] (Figures 1, 2, and 3). These two basins were chosen for study as the geologic history and climatic conditions are similar, thus minimizing differences in vegetation due to these factors. While sharing these similarities, there is a latitudinal spread of 15 miles between the two lake basins as well as a slight difference in range of lake 5 Figure 1. Map showing location of Sky Lakes Wilderness Study Area (shaded) in relation to the southern Cascade region. 6 Figure 2. Topographic map of Seven Lakes Basin. 7 Figure 3. Topographic map of Blue Canyon Basin. 8 elevations, allowing for a comparison of the two lake basins based on local variation. Geology and Soils The Cascade Range is comprised of two physiographic provinces, the Western Cascades and the High Cascades (Badura and Jahn, 1977). The Western Cascades province includes the west slope of the Cascade Range, and is the result of volcanic activity during the Oligocene and Miocene. The High Cascades province includes the crest of the Cascades and the eastern slopes. The High Cascades province is geologically younger as it is composed of andesitic and basaltic depositions of late Pliocene and Pleistocene age. The two most prominent volcanos in the area are Mt.

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