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Establishment of native plants on disturbed sites in arctic Alaska Item Type Thesis Authors Cargill, Susan Marjorie Download date 30/09/2021 11:19:16 Link to Item http://hdl.handle.net/11122/9318 INFORMATION TO USERS The most advanced technology has been used to photo graph and reproduce this manuscript from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. 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University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 313/761-4700 800/521-0600 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Order Number 8918587 Establishment of native plants on disturbed sites in arctic Alaska Cargill, Susan Marjorie, Ph.D. University of Alaska Fairbanks, 1988 UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ESTABLISHMENT OF NATIVE PLANTS ON DISTURBED SITES IN ARCTIC ALASKA A THESIS Presented to the Faculty of the University of Alaska in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy By Susan Marjorie Cargill, B.Sc., M.Sc. Fairbanks, Alaska September 1988 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ESTABLISHMENT OF NATIVE PLANTS ON DISTURBED SITES IN ARCTIC ALASKA Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Roads, camps and other structures associated with the Trans-Alaska Pipeline were placed on gravel pads to protect underlying permafrost. Gravel was mined from floodplains, resulting in loss of riparian wildlife habitat. Revegetation of abandoned pads using non-native grasses has been unsuccessful. Native plants might be more persistent and contribute to replacing lost habitat. The naturally-occurring pioneer community on gravel pads consists mainly of willows Salix alaxensis and !3. glauca, fireweed Epilobium latifolium, horsetails Equisetum arvense and legumes in the genera Astragalus, Oxytropis and Hedysarum, all species of riparian gravel bars. Ten years after abandonment mean total cover of native species on 16 gravel pads was only 2.7% and mean number of species per site was 4.4. Distance from riparian seed sources explained 25% and 40% of variation in cover and diversity respectively. Legumes were more restricted to sites near the river than were fireweed and willows. In the laboratory, no germination of S. alaxensis occurred at water potentials < -0.2 MPa, which probably 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 occur often on gravel pads. In the field, germination was increased by watering or by a rough surface which provided moister microsites. Growth of seedlings was limited by the supply of mineral nutrients. Survival was high and not limited by availability of water or nutrients. In the laboratory, few legume seeds germinated at water potentials < -0.5 MPa. In the field, germination was higher on a rough surface which provided moister microsites. Greenhouse experiments indicated that symbiotically-fixed nitrogen contributed significantly to the growth of legume seedlings, especially when availability of mineral N was low. Rhizobia-free legume seedlings transplanted to a gravel pad developed nodules whether or not they were inoculated with rhizobia, but total weight and nodule weight tended to be higher in inoculated seedlings. Some native plants, primarily riparian species, are capable of establishing and growing on abandoned gravel pads. The low cover and diversity of naturally-colonized sites are attributed to 1) limited dispersal from riparian seed sources, 2) lack of water for germination and 3) lack of nutrients to support growth. Both willows and legumes have promise for use in restoration. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS Abstract.................................................... 1 List of Figures............................................ 6 List of Tables............................................. 8 Acknowledgments........................................... 10 Introduction.............................................. 11 Chapter 1 - Application of successional theory to tundra restoration: a review................... 15 Abstract............................................. 15 Introduction......................................... 16 Mechanisms of succession........................... 17 Floodplain succession in interior Alaska......... 20 Natural succession in the Arctic.............. ....22 Restoration of mesic disturbed sites.............. 23 Recovery of vehicle tracks in tundra.............. 27 Restoration of xeric disturbed sites.............. 30 Conclusions.......................................... 32 Acknowledgments..................................... 33 Chapter 2 - Patterns of natural revegetation on abandoned gravel pads in arctic Alaska............34 Summary.............................................. 34 Introduction......................................... 35 Methods and Materials...............................37 Study area..................................... 37 Soil characteristics.......................... 39 Transects.......................................40 Dispersal of willow seeds.....................42 Statistical analysis.......................... 42 3 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 Chapter 2, cont. Results.............................................. 44 Soil characteristics.......................... 44 Species composition........................... 44 Cover of native species and sown grass....... 46 DECORANA ordination........................... 49 Dispersal of willow seeds.................... 52 Discussion........................................... 55 Acknowledgments..................................... 60 Chapter 3 - Establishment of Salix alaxensis on abandoned gravel pads in arctic Alaska........... 61 Summary.............................................. 61 Introduction.........................................62 Methods and Materials...............................64 Study area..................................... 6 4 Germination.................................... 65 Seedling transplants.......................... 69 Soil analysis.................................. 72 Results.............................................. 73 Germination.................................... 73 Survival....................................... 78 Seedling growth at Toolik.....................80 Seedling growth at remote sites.............. 85 Discussion........................................... 87 Acknowledgments..................................... 92 Chapter 4 - Establishment of native legumes on abandoned gravel pads in arctic Alaska............93 Summary.............................................. 93 Introduction.........................................94 Methods and Materials...............................97 Study area..................................... 97 Stratification and scarification.............98 Effect of water potential on germination.... 99 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5 Chapter 4, cont. Effect of "safe sites" on germination......100 Effect of N availability on nodulation.... 101 Nodulation of tranplanted seedlings........ 103 Results.......... 104 Stratification and scarification............104 Effects of water potential on germination..104 Effect of "safe sites" on germination...... 107 Effect of N availability on nodulation.... 110 Nodulation of transplanted seedlings....... Ill Discussion..........................................114 Acknowledgments.................................... 118 Conclusions.............................................. 119 Appendix