University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 8-1981 An Examination of the Seed Rain and Seed Bank and Evidence of Seed Exchange Between a Beech Gap and a Spruce Forest in the Great Smoky Mountains Noel Bruce Pavlovic University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Part of the Life Sciences Commons Recommended Citation Pavlovic, Noel Bruce, "An Examination of the Seed Rain and Seed Bank and Evidence of Seed Exchange Between a Beech Gap and a Spruce Forest in the Great Smoky Mountains. " Master's Thesis, University of Tennessee, 1981. https://trace.tennessee.edu/utk_gradthes/1433 This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a thesis written by Noel Bruce Pavlovic entitled "An Examination of the Seed Rain and Seed Bank and Evidence of Seed Exchange Between a Beech Gap and a Spruce Forest in the Great Smoky Mountains." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Master of Science, with a major in Ecology and Evolutionary Biology. E. E. C. Clebsch, Major Professor We have read this thesis and recommend its acceptance: H. R. DeSelm, Edward Buckner Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a thesis written by Noel Bruce Pavlovic entitled 11An Examination of the Seed Rain and Seed Bank and Evidence of Seed Exchange Between a Beech Gap and a Spruce Forest in the Great Smoky Mountains_.' I have examined the final copy of this thesis for form and content and recommend that it be accepted in partial fulfill­ ment of the requirements for the degree of Master of Sc ience, with a major in Ecology. " '1 � r /'I I � j- /. ·, . {_ LL,{, c E.l�t\ E. C. Clebsch, Major Professor We have read this thesis and recommend its acceptance: Z>� � H:./2. £J£v�u-�.IA�/ ;_]c.DcL/.- Accepted for the Council: Vice Chancellor Graduate Studies and Research AN EXAMINATION OF THE SEED RA IN AND SEED BANK FOR EVIDENCE OF SEED EXCHANGE BETWEEN A BEECH GAP AND A SPRUCE FOREST IN THE GREAT SMOKY MOUNTAINS A Thesis Presented for the Master of Sci ence Degree The University of Tennessee , Knoxville Noel Bruce Pavlovic August 1981 ACKNOWLEDGMENTS I would like to express my sincerest appreciation for the support and encouragement of my major professor , Dr. E. E. C. Clebsch throughout this study . The guidance and assistance of Dr. Robert Farmer, Dr. Edward Buckner, and Dr. Hal DeSelm are greatly appreciated . Dr. P. Delcourt was hel pful in conifer seed identification. Thanks are in order for the Graduate Program in Ecology that provided transportation vehicles and funds , computer funds, a graduate teaching assistantship, and growth chambers during this project. The permi ssion from Dr. Farmer to use the Tennessee Val ley Authority greenhouse at Norris, TN was vital in being able to complete this study. A Millard Markle Award for Field Biology from Earl ham College, Richmond, IN contributed to the purchase of the majority of equipment used in this study . This work would not have been possible wi thout the permission and assistance of Don Defoe and the National Park Service to conduct field work in the Great Smoky Mountains National Park. En lightening discussions with Paul Schmalzer, Anne Stocum, and Steve Seagle were inval uable in developing some of the ideas within this manuscript and in the data analysis. Paul and Anne al so helped in the field work. Jorge Ganem was kind enough to provide transporta­ tion to the study site for several weeks during the summer of 1979. Thomas Patrick was a big help in identifying the sedges and rushes . Maureen Cunningham was kind enough to provide frequent transportation i i iii to Norris, TN and to water the seed bank flats in the green­ house. Mrs . Marilyn Caponetti was most helpful in providing advice on manuscript preparation and in typing the manuscript as wel l. I wou ld like to express my sincerest appreciation to my parents, Arthur and Barbara Pavlovic, for their encouraging me to follow my own interests and to Charl ie and Virginia Baer for teaching me an appreciation for the natural world. My deepest appreciation extends to my wife, Sarah, who put up with the high elevation Smoky•s weather during her free time, numerous attacks by bird tanglefoot during the field work, and with my long hours of study and writi ng. ABSTRACT The vegetation, seed rain, and seed banks were examined in a beech gap and a spruce stand in the high elevation Smoky Mountains to quantify the seed exchanges between these two plant communities . This information is of interest because these beech gaps are believed to be slowly invaded by Picea rubens along the abrupt boundary between the stands. Five transects of seed traps were set up perpendicular to the boundary, extend ing into each community. Sticky and gravity traps were placed at preset intervals along the transects to collect seed rain for one year. At each seed ra in sample site a soil core was collected to examine viabl e seeds and vegetative propagules in the soil. The vegetation analys is showed quantitative differences rather than compositional differences between the tree canopies of the beech gap and spruce stand . The beech gap was dominated by Fagus grandi­ fol ia, whereas the spruce stand was dominated by Picea rubens and Betula lutea. The shrub layer and herbaceous vegetation differed greatly between these two plant communities. Canopy transects across the boundary demonstrated a narrow ecotonal zone rather than a disti nct boundary between the communities although from a distance the boundary appeared sharp . The seed rain data showed substantial seed dispersal of Betula lutea and Picea rubens and minimal dispersal of Cacal ia rugel ia into iv v the beech gap from the spruce stand . Some seeds of Poa alsodes were able to disperse into the spruce stand from the beech gap. Evidence is presented showing that Eupatorium rugosum wa s dispersed from the Cli ngman 's Dome Road into the beech gap and possibly into the spruce stand as well. The seed bank data confirmed the exchange of seeds of these species except for Cacalia rugel ia. The seed bank results agreed with other seed bank studies, in the absence of seeds of late successional woody species such as Fagus grandifol ia and Picea rubens. In contrast with most seed bank studies , the seed banks in these communities had a high similarity with the overlying vegetation. Multi variate analytical techniques showed significant differences in the seed banks between these adjacent plant communities. Reciprocal averaging showed a beech gap seed bank species gradient which is highly correlated with sample core slope position. This seed bank gradient is probably in response to a moisture topo­ graphic gradient affecting the overlyi ng herbaceous species populations. The implications of the limited seed exchanges between these communities are discussed in terms of the possible invasion of the spruce stand vegetation into the beech gap. The potential role of seeds stored in the soil in succession and vegetation dynamics is discussed . TABLE OF CONTENTS CHAPTER PAGE INTRODUCTION 1 I. LITERATURE REV IEW . 5 II. THE STUDY AREA. 19 Geology .. 19 Soi ls . 22 Cl imate . 23 Vegetation. 26 III. METHODS . 33 Vegetation Data 33 Seed Rain . 34 Seed Bank . 37 Environmental Variables . 39 IV. ANALYTICAL METHODS ... 40 Ordination ....... 41 Cluster Analys is ............ • . • 44 Discriminant Function Analys is .. 46 Diversity ........... 49 Germination Value ....... 50 Jaccard 's Coefficient of Simi larity . 51 Descriptive Statistics. 52 V. THE VEGETATION. 53 VI. THE SEED RA IN .. 64 VII. THE SEED BANK . 78 Reciprocal Averaging ............ 83 Cluster Analysis and Discriminant Analysis.. 89 Reciprocal Averaging Revisited . 91 Seed Bank Depth Distribution . ... 95 Pheno 1 ogy of Emergence. 99 Vegetative Reproduction ................ 102 VIII. THE VEGETATION , SEED RAIN AND SEED BANKS . 105 IX. DISCUSSION ......• .... 117 Dispersal Across Boundaries • . 117 vi vii CHAPTER PAGE Succession and Regeneration ..... 122 Origin and Maintenance of Beech Gaps. 126 X. CONCLUS ION. 132 LITERATURE CITED . 135 APPENDICES . 149 APPENDIX A . 150 APPENDIX B . 151 VITA • • • . 155 LIST OF TABLES TABLE PAGE 1. Summary of Forest Seed Bank Literature ..... 11 2. Beech Gap and Spruce Stand Overstory Vegetation 54 3. Beech Gap and Spruce Stand Shrub Vegetation . 58 4. Beech Gap Herbaceous Vegetation .. 60 5. Spruce Stand Herbaceous Vegetation. 62 6. Summary of the Beech Gap and the Spruce Stand Seed Ra in by Seed Trap Type. 68 7. Summary of Betula lutea Germination and Viability Tests 72 8. Summary of the Beech Gap and Spruce Stand Seed Banks. 80 9. Seed Densities per m2 by Depth in the Beech Gap Seed Bank . 96 10. Summary of Phenology of Emergence . 100 11. Vegetative and Sexual Reproduction .. .•10 3 12. Summary of Woody Vegetation, Seed Rain, and Seed Bank by Densities in Each Community . 106 13. Summary of the Plant or Seed Density in the Beech Gap and Spruce Stand Vegetation, Seed Rain and Seed Bank. 110 14. Similarity Between the Vegetati on, Seed Rain, and Seed Banks Within and Between the Communities.