Factors influencing epiphytic lichen communities in aspen

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Factors influencing epiphytic lichen communities in aspen

Transcript Of Factors influencing epiphytic lichen communities in aspen

FACTORS INFLUENCING EPIPHYTIC LICHEN COMMUNITIES IN ASPEN-ASSOCIATED FORESTS OF THE BEAR RIVER RANGE, IDAHO AND UTAH by Paul C. Rogers A dissertation submitted in partial fulfillment of the requirement for the degree of DOCTOR OF PHILOSOPHY in Ecology

Approved:

_________________________ Dr. Ronald J. Ryel Major Professor

_________________________ Dr. Dale L. Bartos Committee Member

_________________________ Dr. Terry L. Sharik Committee Member

_________________________ Dr. Leila M. Shultz Committee Member

_________________________ Dr. Roger Rosentreter Committee Member

_________________________ Byron R. Burnham Dean of Graduate Studies

UTAH STATE UNIVERSITY Logan, Utah
2007

ii
Copyright © Paul C. Rogers 2007 All Rights Reserved

iii ABSTRACT
Factors Influencing Epiphytic Lichen Communities in Aspen Forests of the Bear River Range, Idaho and Utah
by
Paul C. Rogers, Doctor of Philosophy Utah State University, 2007
Major Professor: Dr. Ronald J. Ryel Department: Wildland Resources
In western North America, quaking aspen (Populus tremuloides Michx.) is the most common hardwood in montane landscapes. Fire suppression, grazing, wildlife management practices, and climate patterns of the past century are some of the threats to aspen coverage in this region. Researchers are concerned that aspen-dependent species may be losing habitat, thereby threatening their long-term local and regional viability. Though lichens have a rich history as air pollution indicators, I believe that they may also be useful as a metric of community diversity associated with habitat change. To date, few studies have specifically examined the status of aspen’s epiphytic lichen community in the Rocky Mountains. A preliminary study was conducted using 10 transect-based plots to assess lichen species substrate preferences between aspen and various conifer species and to gain basic knowledge of species diversity. Following this work, I established 47 plots in the Bear River Range of northern Utah and southern Idaho to evaluate the effects of forest succession on epiphytic macrolichen communities. Plots

iv were located in a narrow elevational belt (2,134-2,438 m) to minimize the known covariant effects of elevation and moisture on lichen communities. Results show increasing lichen diversity and a decrease in aspen-dependent species as aspen forests succeed to conifer cover types. The interactive roles of stand aspect, basal area and cover of dominant trees, stand age, aspen bark scars, and recent tree damage were examined in relation to these trends. An aspen index score was developed based on lichens showing an affinity for aspen habitat. I present a landscape-level multivariate analysis of shortand long-term factors influencing epiphytic lichen communities in aspen forests. Nonmetric multidimensional scaling (NMS) ordination stressed the importance of succession and local air pollution sources in shaping lichen communities. I also investigated the role of historic human intrusions and climate on aspen forests and aspendependent epiphytic lichens at the landscape-level. Implications of this work include 1) realization of nitrogen impacts on ecosystems, 2) the potential for using lichens as bioindicators for monitoring aspen stand health, and 3) suggestions for working with natural disturbance regimes to minimize human impacts on aspen and associated species.
(177 pages)

v ACKNOWLEDGMENTS
This work was funded by grants from USDA Forest Service – Rocky Mountain Research Station, USDA Natural Resources Conservation Service, and Utah Agricultural Experiment Station. I am thankful for reviews of each draft by Dr. Leila Shultz, Dr. Terry Sharik, Dr. Dale Bartos, and Dr. Roger Rosentreter, which greatly improved the quality and clarity of the paper. My major professor, Dr. Ronald Ryel, was instrumental in seeing this project through to its final form. His tireless efforts on my behalf will be appreciated for years to come.
The U.S.D.A. Forest Service, Rocky Mountain Research Station, provided numerous resources which made the research possible. Utah State University facilitated storage and cataloguing of lichen voucher samples. John Lowry, Utah State University GIS/Remote Sensing Lab, was very helpful with geographic data acquisition and numerous technical pointers in using GIS software. The staff at Utah State University library, Special Collections, and Scott Bushman, USDA Forest Service, Logan Range District, provided invaluable service related to locating pertinent historical documents. Dr. Henrik Hedenås, of Umeå University (Sweden), Department of Ecology and Environmental Sciences, was an important tutor regarding lichen and European aspen interactions. Dr. Bruce McCune, Oregon State University, introduced me to lichen ecology and provided helpful direction in setting up the preliminary study design.
My friends and colleagues in the Logan area provided moral support throughout this process. I had the unflagging support of many family members of Rogers, Hedrich, and related clans. My greatest teachers are those nearest at hand; my family – Emmon

vi Hedrich Rogers, Leidy Hedrich Rogers, and Anne Elizabeth Hedrich – gave freely of their wisdom, compassion, and love that, in sum, comprise my motivation and my raison d’être.
Paul C. Rogers

vii CONTENTS
Page
ABSTRACT....................................................................................................................... iii
ACKNOWLEDGMENTS ...................................................................................................v
LIST OF TABLES............................................................................................................. ix
LIST OF FIGURES .............................................................................................................x
CHAPTER
1. INTRODUCTION .............................................................................................1
Study background ...................................................................................2 Chapter previews.....................................................................................6 References .............................................................................................12
2. ASPEN INDICATOR SPECIES IN LICHEN COMMUNITIES IN THE BEAR RIVER RANGE OF UTAH AND IDAHO .........................................17
Introduction ...........................................................................................17 Study site...............................................................................................19 Methods.................................................................................................19 Results ...................................................................................................21 Discussion .............................................................................................23 References .............................................................................................27
3. LICHEN COMMUNITY CHANGE IN RESPONSE TO SUCCESSION IN ASPEN FORESTS OF THE SOUTHERN ROCKY MOUNTAINS USA.....34
Introduction ...........................................................................................34 Study area..............................................................................................37 Methods.................................................................................................38 Results ...................................................................................................43 Discussion .............................................................................................48 Conclusion ............................................................................................58 References .............................................................................................59
4. ASPEN SUCCESSION AND NITROGEN LOADING: A CASE FOR EPIPHYTIC LICHENS AS BIOINDICATORS IN CHANGING FORESTS ........................................................................................................74

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Introduction ...........................................................................................74 Methods.................................................................................................76 Results ...................................................................................................82 Discussion .............................................................................................86 References .............................................................................................95
5. HISTORICAL PATTERNS INFLUENCING LICHEN COMMUNITIES AND ASPEN FORESTS OF THE SOUTHERN ROCKY MOUNTAINS..108
Introduction .........................................................................................108 Methods...............................................................................................110 Results .................................................................................................116 Discussion ...........................................................................................122 Conclusions .........................................................................................130 References ...........................................................................................131
6. SUMMARY AND FUTURE RESEARCH...................................................148
Future research ....................................................................................152 References ...........................................................................................156
APPENDIX ....... .............................................................................................................158
CURRICULUM VITAE..................................................................................................161

ix LIST OF TABLES

Table

Page

2.1 Lichen species tallied by aspen and conifer substrates....................................31

2.2 Indicator Species Analysis by substrate type...................................................32

3.1 Plot stratification by aspen stand types............................................................64

3.2 Lichen species frequencies by primary tree substrate groups..........................64

3.3 Pearson correlation coefficients (r) by cover groups and response variables..65

3.4 Indicator Species Analysis by aspen stand type group ....................................65

4.1 Study site stratification by succession groups and cover requirements.........101

4.2 Summation of lichen species tallied by frequency, percent frequency, and pollution sensitivity group in the Bear River Range......................................101

4.3 Comparison of ANOVA and ANCOVA results using the co-variate Distance to Urban Center...............................................................................102

4.4 Coefficients of determination for correlations between environmental variables and ordination axes.........................................................................103

5.1 Stratification of field plots by aspen stand types ...........................................138

5.2 Frequency and percent frequency of lichen tally for study area....................138

5.3 Indicator Species Analysis results for lichens species by stand types ...........139

5.4 Coefficients of determination (r-values) for correlations between environmental variables, lichen species, and primary ordination axes..........140

x LIST OF FIGURES

Figure

Page

2.1 Aspen-conifer plot locations………………………………………………….33

3.1 Study area with plot locations stratified by aspen stand type groups ..............67

3.2 Box plots depicting ANOVA results by stand type for aspen cover, conifer cover, aspen basal area, and total basal area........................................69

3.3 Box plots depicting ANOVA results by stand type for response variables.....70

3.4 Lichen species abundance trends with changes in aspen stand type ...............72

3.5 Conceptual model of aspen succession to conifer in relation to aspendependent lichen species and prominent biotic disturbance factors ................73

4.1 Map of study area showing geographic relationship of plots by aspen stand type to ammonia monitoring network ..................................................104

4.2 Scree plot graphing stress versus dimensionality from nonmetric multidimensional scaling (NMS) results .......................................................105

4.3 Ordination joint plot from nonmetric multidimensional scaling (NMS) with environmental variables plotted as vectors…………………………….106

4.4 Ordination joint plot from nonmetric multidimensional scaling (NMS) with lichen species plotted as vectors ............................................................107

5.1 Study area that mapping location of 47 lichen sampling plots, their stand type designations, and ammonia (NH3) monitoring stations .........................141

5.2 Stand structure trends using ANOVA for four aspen stand types……… …142

5.3 Aspen stand ages (year of establishment) for study plots, corresponding climate reconstructions and long-term (1000-year) climate reconstructions for northern Utah and southern Idaho............................................................144

5.4 Line graphs of lichen abundance by aspen stand type group.........................145

5.5 NMS joint plot with significant lichen species plotted as vectors and all species shown within ordination “species space”..........................................146
AspenAspen ForestsUtahLichen SpeciesNonmetric