AN ABSTRACT OF THE THESIS OF J. Edward Dealy for the degree ofDoctor of Philosophy in Forest Management presented on ;14L-23; /2 Title: ECOLOGY OF CURLLEAF MOUNTAIN-MAHOGANY (CERCOCARPtJS LEDIFOLIUS NUTT.) IN EASTERN OREGON AND ADJAC-NT AREAJJ Abstract approved: signature redacted for privacy. Dr. Richard K. Hermann C ercocarpus ledifolius (curlleaf mountain- mahogany),a small, hardwood evergreen tree, was studied to provide informationon germination and initial seedling growth characteristics, and the species' relationship to its environment.and associated vegetation. Exceptional germination for this species resulted from botha wet cold treatment at 4°C for 170 days (88 percent), and a 15-minute soak in a 30 percent solution of H202 (64 percent).Total and partial embryo excision indicated two possible deterrents to germination: mechanical impedance by the seed coat or a gas diffusion block by the membrane surrounding the embryo.The latter was concluded to be the most likely deterrent. Planting techniques must provide for seed coat deterioration by fall seeding (which allows moist winter conditions to do this)or by a brief, strong chemical treatment before spring planting. A pronounced specialization was demonstrated for rapid root growth in relation to top growth of seedlings for at least 120 days following germination.Under optimum laboratory conditions, the six most vigorous seedlings extended roots an average 1. 13 m in 120 days, but developed only 4 cm2 of leaf area and 2. 35 cm of shoot height, indicating a high potential for re-establishment of natural stands after decimation by fire or logging, or in the face of grass and shrub competition.Seedling stem diameter immediately above the root crown was an indicator of root vigor.Seedlings with the largest diameter stems were deepest rooted. Relationships among Cercocarpus ledifolius ecosystemswere examined and 12 habitat types with their attendant plant associations, phases, and successional stages were delineated.Associations and their phases occurred due to topo.edaphic influences.No serious competition between C. ledifolius and other tree species existed in associations described. Where conifers occurred theywere uncom- mon and not expanding their territory.Graminoids were the most predominant understory group in all associations basedon dominance and constancy, with south slope associations generally having higher values than those on north slopes.Soil development was weak with no significant differences in solum development noted between exposures.However, percent surface stone on southerlyexposures was twice that on the northerly, and percent buried stone volume in the solum was almost one-thirdgreater on southerlyexposures. The survival of C. ledifoliusand the communities in which it was dominant were dependent on fireresistant rocky sites.Trees in these niches were largerand older than those on nearbynon rocky sites and providedan available seed source in case fire decimated adjacent stands. Ecology of Curlleaf Mountain-Mahogany (Cercocarpus ledifolius Nutt. ) in Eastern Oregon and Adjacent Areas by J, Edward Dealy A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy June 1975 APPR OVED: /)I Signature redactedfor privacy. r L,t - Professor of Forest Management In charge of major Signature redactedfor privacy. Hea17ofDepar'nentof Forest Management Dean of Graduate School Date thesis is presented Typed by Ilene Anderton forJ. Edward Dealt ACKNOW LEDGEMENTS This research was financed by the U. S. D. A. Forest Service through the Pacific Northwest Forest and Range Experiment Station. Appreciation is extended to Mr. Philip A. Briegleb and Dr. Robert E. Buckmann, Directors, and Mr. Robert Harris, Mr. Robert F. Tarrant, and Mr. Charles J. Petersen, Assistant Directors, Pacific Northwest Forest and Range Experiment Station for their support in this program. Special thanks are due to Mr. Justin C. Smith, former Project Leader, for his support and encouragement, and Dr. Jack Ward Thomas, Project Leader, for manuscript editing, and constant encouragement and support in the final phase of this program. I extend a personal thanks to Dr. Richard K. Hermann, com- mittee chairman, for his wisdom, advice and encouragement and for his review of the manuscript.Also thanks are due his committee members for manuscript review. I appreciate the help of Pamela S. Talley, field assistant, for collection of field data, data analysis, and preparation of figures and tables.Her tireless efforts have made the final phase of this program much easier. I thank the secretarial staff of the La Grande Wildlife Habitat and Range Research Laboratory for manuscript preparation, especially Mrs. Marion L. Halsey for her exceptionalsupervision and extended personal efforts. Tb my wife, June, I extendmy deep appreciation for her personal sacrifice, encouragement and patienceover an extended period of time, and for her constant willingnessto assist in manu- script preparation,Also, I thank my children, John, Joe, and Kim for their exceptional cooperation throughoutthis endeavor. TABLE OF CONTENTS Page INTRODUCTION 1 PAST WORK 5 Tree Description 5 Distribution 7 Anatomy 7 Germination and Initial Growth io Nutrition 17 Insect Occurrence 19 Ecosystem Relationships 23 Soil Relationships 25 ORIGIN AND HISTORICAL DISTRIBUTION 27 Phylum Origin 27 Madro-Tertiary Flora 28 Species Migration 31 Ecological Position 32 METHODS 34 Study Area 34 Blue Mountains 34 Basin and Range Province 36 Owyhee Uplands 36 Germination and Initial Growth 37 Ecosystem Sampling 39 GERMINATION AND INITIAL GROWTH 42 Seed Production 42 Seed and Seedling Predation 42 Viability and Seed Examination 44 Stratification and Germination 46 Root Growth 52 Discussion 57 RECENT HISTORY OF CERCOCARPUSLEDIFOLIU5 STANDS 64 Logging 64 Animal Use 65 Tree Age -Stem Diameter Relationships 66 Page Discus sion 67 ECOSYSTEM RELATIONSHIPS 69 Cercocarpus ledifolius/Artemisiatridentata/ Festuca idahoensis h. t, 74 Poa sandbergii SuccessionalStage 74 !c2aruS ledifolius /Artemis ia tridentata / Agropyron canirLum h. t. 77 Stipa lemmonii SuccessionalStage 80 C ercocar pus ledifolius /Artemisiatridentata/ Poaamplah.t. 81 Stipa lcmmonii SuccessionalStage 81 Cercocarpus ledifolius/Festucaidahoensis h. t. 85 Cercocarpus ledifolius/Festuca idahoensis- Agropyron spicatum h. t. 88 Cercocarpus ledifolius/Elymuscinereus h.t. 91 Cercocarpus ledifôlius/Symphoricarposalbus/ Festuca idahoensjs h. t. 94 Cercocarpus ledifolius/Symphoricarposoreophilus/ Poa ampla h. t. 99 Arnica cordjfolja Phase 103 Cercocarus ledifolius/Symphoricarposoreophilus h.t. 107 Balsamorhjza sagittata Phase, Poasandbergii Successional Stage 107 Cercocarpus ledifolius/Symphoricarposoreophilus/ Festuca idahoensis h.t. 111 Poa sandbergii SuccessionalStage iii Cercocarpus ledifolius/Calamagrostisrubescens h. t. 116 Stipa lemmonii SuccessionalStage 119 Cercocarpus ledifolius/Calamagrostisrubescens- Festuca idahoensjs h.t. 122 Stipa lemmonii. SuccessionalStage Ecosystems with Relic Trees 125 Uncorrelated Ecosystems 129 Habitat Type Correlation 130 SUMMARY AND CONCLUSIONS 139 BIBLIOGRAPHY 142 APPENDIX A 149 APPENDIX B 159 LIST OF FIGURES Figure Page Profile of the occurrence of Cercocarpus ledifolius in the conifer zone.Gross elevation, exposure, soil depth, and interspecies relationshipsare illustrated.Slanted shading below the horizon line indicates a general (and exaggerated) soil depth relationship. 2 Profile of the occurrence of Cercocarpus ledifolius in the high desert steppe.Gross elevation, exposure, soil depth, and interspecies relationship are illustrated.Slanted shading below the horizon line indicates a general (and exaggerated) soil depth relationship. 4 Photograph of the largest known Cercocarpus ledifoliuslocated on the Humbolt National Forest, Nevada, 6 Distribution of the genus Cercocarpus (all shading) and the species C. ledifolius (crosshatching). 8 Physiographic divisions of the study area.After Dicken (1955). 35 Distribution of Cercocarpus ledifolius (dashes) and descriptive study plots (dots)in the study area. 40 Comparison of Cercocarpus ledifolius seedling height to root extension in a growth chamber environment. 55 Comparison of Cercocarpus ledifolius seedling stem diameter to root length in a growth chamber environment. 56 Figure Page Regression curves showing Cercocar ledifolius tree diameters in relation to age for stands in the Whitehorse Mountains (stand A) and the Trout Creek Mountains (stand B). 68 Young Cercocarpus plants browsed heavily by deer and elk. 72 Illustration of a relic stand of Cercocarpus ledifolius showing the largest diameter tree (64 cm) yet discovered in the study area.Note smaller trees in the background on less rocky soil. 98 Mean dominance and constancy values of shrubs (S), graminoids (G), and forbs (F) comparedamong groups of similar plant associations. 136 Mean dominance and constancy values of shrubs (S), graminoids (G)9 and forbs (F) for all plant associations combined (solid line), associationson south slopes (dashed line)9 and associationson north slopes (dotted line). 137 LIST OF TABLES Table Page Treatment effects on germination of Cercocarpus ledifolius seed (Woolfolk, 1959). 12 Analyses of Cercocarpus ledifolius (Hickman, 1966). Data is in percent except for the Ca:P ratio. 18 A tabulation of insects found on Cercocarpus ledifolius including order, family, genus, species, and their relationships to the plant. 20 Results of X-ray examination and viability tests of broken