LICHENS IN THE INLAND RAINFOREST: CLIMATE BIOMONITORING AND POPULATION STRUCTURE OF LOBARIA PULMONARIA (L.) HOFFM.

by

Asha Marie MacDonald

B.Sc. (Honours), Dalhousie University, 2010

THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE IN

NATURAL RESOURCE AND ENVIRONMENTAL STUDIES (BIOLOGY)

UNIVERSITY OF NORTHERN BRITISH COLUMBIA

January 2013

© Asha Marie MacDonald, 2013

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Abstract

Rapid climate change is predicted for British Columbia’s Inland Temperate

Rainforest (ITR). This research proposes that ITR lichens may be sensitive indicatorsof

these changes and describes a climate biomonitoring protocol using arboreal lichen

communities. Initial findings of 39macrolichen taxa are reported, including a number of

rare species, such as Nephroma occultum Wetmore, N. isidiosum (Nyl.) Gyelnik, and

Sticta oroborealis Goward & Tonsberg. Previous research suggests that the tripartite

cyanolichen Lobariapulmonaria (L.) Hoffm.is an important indicator species, however,

little is known of its population dynamics in the ITR. In a retrospective study using dated

branch segments, the size class distribution and reproductive status of L.

pw/monan'apopulations was measured on subalpine fir (Abies lasiocarpa Nutt.) and

mountain alder (Alnus incana ssp. tenuifolia (Nutt.) Breitung)within ITR riparian

zones.L. pulmonaria communities on fir and alder differed in many respects, especially in

their total biomass, however, the number of thalli did not differ significantly between

species along dated branch segments. Branch diameter was a significant predictor for the

presence of reproductive thalli on subalpine fir, with branch age being a better predictor

on mountain alder. Minimum generation times and maximum growth rates for L.

pulmonaria in the ITR may be much faster than previously estimated elsewhere.

Table of Contents

Abstract ii

Table of Contents iii

List of Tables iv

List o f Figures v

Glossary vi

Acknowledgement vii

Dedication viii

Introduction 1

Chapter 1 Climate Biomonitoring in the Inland Temperate RainforestIntroduction 7Methods 12Results 16Discussion 19

Chapter 2 Population Structure of Lobaria pulmonaria in the Inland TemperateRainforestIntroduction 23Methods 27Results 35Discussion 48

Conclusion 56

References 60

Appendix 1: Average abundance ratings for all field sites 69

Appendix 2: AIC comparisons for candidate logistic regression models 71

List of Tables

Table 1:

Table 2:

Table 3:

Table 4:

Abundance classes for macrolichens sampled on the trunks o f A. incana ssp. tenuifolia at 1.5 — 3 m from the ground.

Average abundance ratings for the lichen taxa observed at all 20 field sites.

Mixed-effects logistic regression model parameters for branch segment data from subalpine fir and mountain alder.

Mixed-effects logistic regression model parameters for predictingthe presence of reproductive structures with specific thallus mass.

List o f Figures

Figure 1:

Figure 2:

Figure 3:

Figure 4:

Figure 5:

Figure 6:

Figure 7:

Figure 8:

Figure 9:

Figure 10:

Location of climate change lichen biomonitoring stands within protected areas. 13

Branch sampled in lab, and cut into segments prior to analysis o f segment ages. 29

Example of scanned image from which area measurements of individual thalli were made. 31

Regression of thallus weights and areas for thalli < 10 mg 32

L. pulmonaria thallus area and weight comparisons for a) subalpine fir, and b) mountain alder. 36

Mean number o f individual thalli with increasing branch segment age class. 38

L. pulmonaria changes in size class distribution with increasing branch segment age. 42

Mean L. pulmonaria thallus sizes for different reproductive classes for both phorophyte species. 44

Mean specific thallus mass o f L. pulmonaria thalli with increasing reproductive effort. 45

Differences in reproductive capacity for branch segments o f differing age classes on a) subalpine fir, and b) mountain alder. 46

v

Glossary: (definitions largely follow Brodo et al. 2001)

Apothecia: a disc or cup-shaped ascoma (fungal reproductive structure)

Cyanolichema lichen with cyanobacteria as a photobiont.

Isidia: a minute thalline outgrowth that is corticate and contains photobiont cells. Isidia

are easily detached from the thallus and serve as vegetative reproductive units.

Lichenometry: a method of dating surfaces using lichen growth rate and size. The size

of the oldest lichen on a particular surface allows estimates on how long that surface has

been available for colonization.

Mycobiont: the fungal component (symbiont) in a lichen thallus.

Phorophyte: the individual tree on which a lichen grows. So-called to avoid the term

“host tree”, which implies parasitism.

Photobiont: the photosynthetic component (symbiont) in a lichen thallus, either algae or

cyanobacteria.

Soralia: an area of the thallus in which the cortex has broken down or cracked and where

soredia are produced.

Soredia: vegetative propagules of a lichen consisting o f a few algal cells entwined and

surrounded by fungal filaments, and without a cortex.

Thallus: in lichens, the vegetative body consisting of both algal and fungal components.

Tripartite: referring to lichens, such as L. pulmonaria, that consist of a mycobiont, a

cyanobacterial photobiont, and an algal photobiont.

Acknowledgement

I wish to thank my supervisor, Darwyn Coxson, for providing much-needed

guidance and advice throughout this thesis, and for being the best supervisor ever. Thank

you also to my wonderful committee members Curtis Bjork and Chris Johnson, whose

contributions to my understanding were a great help. Thanks also to Trevor Goward

(Enlichened Consulting) and Kaela Perry (UNBC) for help with this project. Funding for

this research has been provided by the Future Forest Ecosystems Scientific Council of

British Columbia, the National Science and Engineering Council o f Canada, the

University of Northern British Columbia, and B.C. Ministry o f the Environment (Parks

100).Project mapping was provided by Shane Doddridge and Scott Emmons (UNBC GIS

Laboratory).

Dedication

This thesis is dedicated to Alex Brandt, for his love, support, and never-ending

patience over the past years, to my family, for encouraging me to succeed, and of course

to Bonnie and Ms. Muffin, whose unconditional love and friendship continue to be much

appreciated.

Introduction

Lichens as Bioindicators

Lichens are composed of two or more different species living together to form the

thallus, or lichen body. The lichen thallus generally includes one fungal partner (the

mycobiont) and one or more algal and/or cyanobacterial partners (the photobionts). In

addition to their biodiversity value, lichens contribute to temperate forests by providing

essential habitat and nutritional requirements for a variety o f wildlife (Shamoff and

Rosentreter, 1998) and invertebrates (Shamoff, 1998). Cyanolichens, lichens that have a

cyanobacterial photobiont, are also important in fixing nitrogen for plant use in temperate

forests, where nitrogen is often limiting (Campbell and Fredeen, 2004).

Lichens have often been used as bioindicators o f environmental conditions, both

through analysis of shifts in species composition of lichen communities, with some species

being more tolerant of pollution exposure than others, and as passive traps for

environmental contaminants, many of which preferentially accumulate in lichen

tissue.Indicatorssuch as theseare important to scientists and land managers as they will

show measurable changes in abundance and health in response to shifting environmental

variables. The advantage o f using appropriately chosen indicator species to assess the state

of an ecosystem is that living organisms effectively integrate the influence o f both past

and present day events, while sampling is relatively cost-effective as empirical

environmental measurements are minimized.Although limitations exist with the use of

indicator species (e.g. Ferretti and Erhardt, 2002; Will-Wolf et al. 2002), this technique for

1

understanding ecosystems is widely employed globally in many diverse environments.

Indicators may be used for measuring a variety of ecosystem characteristics, including

species richness (e.g. Campbell and Fredeen, 2004), environmental continuity (e.g. Selva,

1994), pollution or eutrophication levels (Nimis et al. 2002), and climate variables (e.g.

van Herk et al. 2002). Successive measurements o f indicator species constitute biological

monitoring, or biomonitoring, a widespread and useful technique for examining

environmental changes over time.

The sensitivity of lichens to atmospheric conditions,due to the complexity and

instability of the symbiotic relationship between lichen partners, makes these organisms

particularly effective biomonitoring tools. Lichens lack the root system of higher plants,

and have therefore adapted to absorb nutrients directly from the atmosphere. This results

in an accumulation of a variety of pollutants in their thalli, making them effective

indicators of pollution as they generally show sensitivity to these compounds. Lichens

have been popular atmospheric pollution biomonitoring tools for decades, for compounds

including sulphur dioxide, nitrogen compounds, radioactive fallout, and a variety o f heavy

metals (see Nimis et al. 2002 for review).More recently, the sensitivity of a variety of

lichen species to climate variables has prompted their use as indicators for climate change

in many regions around the world (e.g. Insarov and Schroeter, 2002; Sancho et al. 2007).

For example, evidence that lichen communities are responding to climate change has been

documented through long-term monitoring o f lichen populations in the Netherlands, where

changes in species composition are likely due to increasing temperature (van Herk et al.

2002).

2

The Inland Temperate Rainforest - A Unique Ecosystem

Old-growth coniferous stands in the ITR support exceptionally rich epiphytic

lichen communities, especially cyanolichens (Campbell and Fredeen, 2004; Radies and

Coxson, 2004; Goward and Spribille, 2005; Radies et al. 2009; Spribille et al. 2009). This

richness is thought to derive from a combination of factors, including a unique

combination of maritime and continental climate, long site continuity, diverse epiphytic

substrates, and a landscape-level diversity imposed by mountain topography (Goward and

Spribille, 2005). The ITR is predominantly located in British Columbia between the

latitudes 50 and 54°N (Goward and Spribille, 2005), and has been defined by Stevenson et

al. (2011) to include the wet and very wet subzones of the Interior Cedar-Hemlock (ICH)

biogeoclimatic zone (Meidinger and Pojar, 1991).

The ITR shares many characteristics with its coastal counterparts, including large

diameter western redcedar (Thuja plicata Donn ex D. Don) trees,some speculated to be

over 1000 years old (Radies et al. 2009), and a dense understory o f devil’s club

(Oplopanax horridus Miq). The ITR is, however, a globally unique temperate rainforest,

in that it is separated from wet coastal areas by a region of dry climate, and has an

unusually (for temperate rainforests) continental winter climate. Although limited in

geographical extent,the ITR provides important habitat for many species, including the

threatened mountain caribou ecotype (Rangifer tarandus caribou) (Stevenson et al. 2001),

and many disjunct populations of characteristically coastal species (Goward and Spribille,

2005).

3

Understanding Climate Change Impacts in the ITR

Given the uniqueness o f the ITR, understanding the response of this ecosystem to

climate changes will be critical in making future management decisions. Climate change

models can go some ways towards addressing this challenge, however, the scarcity of

climate stations in the ITR and the limited period of recordfor many sites imposes

significant limits on the application of modeling approaches (Dery, 2012). Current climate

modeling haspredicted that the ITR will shift towards drier climates in the next century,

and the range for western redcedar in central British Columbia is likely to contract

(Stevenson et al. 2011). Hamann and Wang (2006) have predicted through modeling that

the ICH zone climatic envelope is likely to move upslope, meaning that ITR stand climate

conditions will shift to areas with less soil moisture available from snowmelt runoff. It has

been predicted that a larger overall area of British Columbia will transition to ICH climate

conditions (Wang et al. 2012).

Climate change in the ITR will have a number o f effects on species interactions.

For example, higher temperatures may lead to a greater number o f pest outbreaks, causing

potential mortality or damage to a number of tree species (Stevenson et al. 2011).

Although mature individuals o f long-lived tree species may persist in an unfavourable

climate, they will likely become more vulnerable to pests and disease, and recruitment and

growth levels may decrease (Hamann and Wang, 2006). Individual species will react to

climate change depending on their specific climatic and ecological requirements; thus, the

shifting o f forest vegetation caused by future climate change is likely to be complex

(Hamann and Wang, 2006). The use of lichens as bioindicators for changing climate

4

variables provides an additional means o f supplementing formal modeling approaches,

allowing us to extend our knowledge of tangible climate change impacts to areas where

we would otherwise have limited information.In the first chapter o f this thesis, a climate

biomonitoring protocol is proposed that uses lichens to assess climate change impacts in

the ITR.

Lobaria pulmonaria in the ITR

One of the primary foliose lichen species that has previously been used as a

bioindicator in wet coniferous forests worldwide is the tripartite lichen Lobaria

pulmonaria (L.) Hoffm. (e.g. Nilsson et al. 1995). This species has been described as a

tripartite lichen due to the three bionts contained within eachthallus: a fungal biont that

provides the substantive structure of the lichen thallus, a green-algal biont that provides a

carbon source for the other bionts, and a cyanobacterial biont (also called blue-green

algae), which is confined to specialized structures called cephalodia, but can fix

atmospheric nitrogen and thereby enrich the other two bionts. Wet ITR forests contain

abundant populations ofLobariapulmonaria (Radies and Coxson, 2004), in fact, the

abundance of L. pulmonaria has been proposed as a bioindicator for lichen species

diversity in the ITR (Campbell and Fredeen, 2004).

Much of the research on L. pulmonariaestablishment, growth, and fecundity has

occurred in Europe, where the abundance and geographical range o f this species is largely

reduced due to anthropogenic influences. However, we have little counterpart information

for L. pulmonaria populations in western North America. To address this knowledge gap,a

5

detailed study of Lobaria pulmonariapop\x\aX\on dynamics in old-growth forest habitats of

the ITR is provided in Chapter 2. This study will be especially significant, as the L.

pulmonaria populations in old-growth wet ITR forest stands represent one o f the few areas

in the world where L. pulmonaria has not previously been exposed toregional air pollution

impacts or confined to refugia from past forest clearing.

The present study of L. pulmonaria population dynamics uses statistical models to

relate the area, weight, and reproductive capacity o f individual thalli to the age, diameter,

and distance from trunk of the branch segment that they are growing on. A major study

component compares sympatric populations growing on deciduous and coniferous tree

species. This research will contribute to our understanding of L. pulmonaria population

dynamics, and will provide a reference point for how this lichen exists in an optimal

habitat. This information is critical for comparisons with less optimal conditions where the

regeneration of L. pulmonaria is a concern, both outside of the ITR region at present, and

in areas of the ITR where future habitat degradation may occur from climate change and

forest harvesting.

6

Chapter 1: Climate Biomonitoring in the Inland Temperate Rainforest

Introduction

Given the limited geographical extent o f the ITR, it is critical that management

strategies ensure that stands with high biodiversity values are represented within protected

areas and that appropriate buffer zones are designated around these cores (Stevenson et al.

2011). Unfortunately, in much of the ITR, land management practices have had the

opposite effect, where stands with high biodiversity values, such as old forests in wet toe-

slope positions, have been disproportionately targeted for logging (Radies et al. 2009). In

the Slim Very Wet Cool Variant of the Interior Cedar-Hemlock Zone(Delong, 2003) of the

upper Fraser River watershed, for instance, old cedar stands now represent less than 7% of

the landscape (Radies et al. 2009).Less than 1.5% of the landscape in the ICHvk2 has fully

protected area status, raising serious conservation concerns.

In addition to habitat loss and fragmentation, climate change is threatening old

forest-dependent taxa in the ITR. Small, irregularly shaped old forest remnants will be

particularly vulnerable to stochastic climate events, due to edge effects and changes in

local microclimate (Stevenson et al. 2011). Understanding how the ITR responds to

climate change is an urgent priority for land managers. Climate change predictions for the

ITR show expected increases in mean annual temperature of 2.8 to 4.0°C in the Very Wet

Cool Interior Cedar-Hemlock (ICHvk) subzone (Meidinger and Pojar, 1991), and 1.9 to

4.1°C in the Wet Cool Interior Cedar-Hemlock (ICHwk) subzone (Meidinger and Pojar,

1991) by the end of the century (Stevenson et al. 2011). Climate models also predict that

7

the increases in temperature in the ITR will be more pronounced during the winter months,

leading to less precipitation falling as snow (Stevenson et al. 2011). This may have major

consequences for the ecology o f ITR forest stands, as wet soils in the valley bottoms and

toe-slope positions have historically been maintained by the ground seepagefrom

theannual melt of upslope winter snowpack. These wet soils have resulted in significantly

long fire-retum intervals in the ITR of between 800 and 1200 years (Sanborn et al. 2006);

an increase in fire occurrence will change the composition and dynamics o f these forests.

Climate variables are one o f the major factors determining lichen distributions

(Ellis and Coppins, 2010). A climatic balance of humidity, temperature, and light

availability is critical for maintaining the carbon balance in lichens, where photosynthetic

carbon assimilation must be sufficient to allow for thallus maintenance and growth

(Palmqvist et al. 2008). The lack of a root system in lichens means that they must rely

solely on atmospheric humidity. Cyanolichens, in particular, require greater hydration than

chlorolichens to be photosynthetically active (Lange et al. 1986), making them especially

sensitive to moisture gradients (e.g. Ellis et al. 2009). Lichens may also be vulnerable to

temperature fluctuations, particularly at mild sub-zero temperatures (Bjerke, 2011), as

cellular damage may occur in partially hydrated thalli (Bjerke, 2009). If light levels are too

low for photosynthesis but hydration is available, lichens will respire (Green et al. 2008),

resultingin negative impacts on thallus maintenance and growth. Conversely, excess UV

radiation reduces net photosynthesis and growth (Gauslaa et al. 2006). Sensitivity to the

interaction of these climatic variables causes many lichens to display a high level of

habitat specificity, making them useful as climate change biomonitors.

8

Current climate biomonitoring protocols using lichens are based on modeling

inputs from large data sets in regions where the lichen flora and their distributions are very

well known (Ellis et al. 2007; Giordani and Incerti, 2007; Ellis and Coppins, 2010).

Distributional data on lichens is often compared with major climatic variables such as

rainfall and temperature in order to group lichens by climatic requirements (Will-Wolf et

al. 2002; Giordani and Incerti 2007). These guilds may then be used to monitor climatic

variables in long-term monitoring efforts (Gombert et al. 2005). However, care must be

taken when grouping species by ‘climatic requirements’, as the climate responses are often

more complex than assumed (Ellis and Coppins, 2010). Species with similar climatic

requirements may, for example, have different responses to climate change (Ellis et al.

2009). The use of biomonitoring protocols that employ the entire lichen community, as

opposed to one or a few species, may therefore provide a better picture of climate change

response in a given ecosystem. The monitoring of entire lichen communities over time has

been used extensively in Europe (e.g. Asta et al. 2002; van Herk et al. 2002) and elsewhere

in North America (McCune, 2000).

The ecology and geographical distributions of lichen species in British Columbia

remain imperfectly known, as indicated by an abundance of new species descriptions from

the province in recent years (Tonsberg and Goward, 2001; Spribille etal. 2009), with

many more soon to be described (Trevor Goward, personal communication). The

comparison of lichen distribution maps with macroclimatic gradients is therefore not a

feasible method for understanding the climate responses o f lichens in British Columbia, as

species distributions are uncertain. In Europe, where lichenology has a much longer

history, more detailed distributional data for many species is available (e.g. van Herk et al.

9

2002; Ellis and Coppins, 2007). Considerable research has been conducted on the large-

scale impacts of climate on Lobaria pulmonaria and other Lobaria species in Europe

(Ellis and Coppins, 2007; Ellis et al. 2009).

In the ITR, cyanolichens are exceptionally abundant and diverse in areas where

humidity levels are high (Goward and Arsenault, 2000b; Radies et al. 2009). Riparian

zones are examples o f humid habitats that serve as important lichen biodiversity hotspots

and corridors in western North America, particularly for cyanolichens (McCune et al. 2002;

Peterson and McCune, 2003; Doering and Coxson, 2010), supporting species that are rare

or absent from the surrounding upland (non-riparian) forest. Doering and Coxson (2010)

found riparian corridors near British Columbia’s wet ITR forests to be refugia for old

growth associated macrolichens, including many rare cyanolichens. Peterson and McCune

(2003) similarly studied lichen hotspots in riparian zones in Oregon, and found higher

lichen diversity in riparian zones. Riparian zones in the ITR are also nutrient-receiving

sites (Stevenson et al. 2011), and this may further augment the diversity o f epiphytic

cyanolichens (Doering and Coxson, 2010), which are more abundant where soil nutrient

levels are high (Goward and Arsenault, 2000b).

Epiphytic cyanolichen diversity is also known to increase with the abundance of

hardwood phorophytes in North America (Goward and Arsenault, 2000a; Peterson and

McCune, 2003), likely facilitated by pHenrichment as in Europe(Gilbert, 1986).Hardwood

trees are recognized as important for maintaining lichen biodiversity in temperate forests

around the world (Neitlich and McCune, 1997; Dettki and Esseen, 1998; Gu et al. 2001;

Snail et al. 2005b).The present research has focused on riparian populations o f Alnus

incana ssp. tenuifolia(Nutt.) Breitung (mountain alder) (Stevenson et al. 2011), a genus

10

that is recognized widely for its role in supporting high cyanolichen diversity (Goward and

Arsenault, 2000c).

The potential of riparian zones for maintaining stand-level biodiversity gives them

special conservation importance in forest management, warranting further research on

these ecosystems. This, combined with the species richness o f riparian lichen

communities, has prompted the selection ofriparian alder stands in the ITR for long-term

biomonitoring plots using epiphytic macrolichens. It is expected that these rich lichen

communities will show measurable changes over time as climate shifts in this ecosystem.

Changes in the lichen species composition will likely be observable before shifts in the

dominant forest vegetation occur, giving advance warning to forest managers on which

areas should be targeted for conservation, and aiding in the mitigation of climate change in

the ITR.

The objective of my study is to serve as a baseline reference for future research on

the effects of climate change in the ITR. This baseline will provide comparative

information as future climate changes cause shifts in the distribution and abundance of

climate-sensitive ITR macrolichen species. Furthermore, the response of individual

species may be able to provide insight into which aspects of climate change are having the

greatest impact through analysis of the ecological restrictions o f individual species. For

example, if declines are observed in species known to be sensitive to increasing

temperatures, managers may be able to target cold-air drainages for conservation priority.

Similarly, if species requiring abundant moisture are declining, humid habitats can be

prioritized for conservation.

11

Methods

Field sites were selected within protected areas on the south side o f the upper

Fraser River watershed (locally known as the Robson Valley), between Sugarbowl-Grizzly

Den and Slim Creek Provincial Parks, approximately 110km east o f Prince George, British

Columbia, Canada (614458-619128 E, 5963162-5958677 N). Valley bottom forests in

this region fall within the Very Wet Sub-Boreal Spruce (SBSvk) biogeoclimatic subzone

of Meidinger and Pojar (1991), showing a transition at mid-elevation to the Wet Cool

Interior Cedar-Hemlock (ICHvk2) biogeoclimatic subzone.Field sites were located in the

ICHvk2 subzone. SBSvk forests are dominated by hybrid white spruce (Picea engelmanni

x glauca) and subalpine fir (Abies lasiocarpa). ICHvk2 forests are dominated by western

redcedar (Thuja plicata) and western hemlock (Tsuga heterophylla), with some Douglas

fir {Pseudotsuga menziesii), subalpine fir, and hybrid white spruce, depending on site

conditions.

Four drainages within the ITR were sampled (Figure 1). Drainages were separated

by areas of upland forest, and were all at approximately the same elevation (685 - 785 m),

aspect (south-facing), and mesoslope position (toe-slopes). Five sites were purposefully

selected from each of the four drainages, for a total of 20 field sites. These sites consisted

of stands of Alnus wcawtf clustered in the gullies of the drainages. Stands were distinct

within each drainage, separatedfrom neighboring alder stands by conifer stands o f no less

than 5 m width. The average stand width (based on 3 measurements) and number of

individual alders were documented for each site.

12

Lichen B iom onito rlng P lo ts , , ,........ i 1“ U jfiB C W IAS

Figure 1. Location of climate change lichen biomonitoring stands within protected areas of east-central British Columbia, Canada. These plots fall within provincial parks (Slim Creek Provincial Park, cross-hatch), legally established Old Growth Management Areas (dark grey), and non-legal (guidance) Old Growth Management areas (medium grey).

Three individual trees were selected at each field site (total = 60 trees sampled),

based on those with the most abundant cyanolichens, in particularLobaria pulmonaria. L.

pulmonariaabundance has previously been found to be an indicator of macrolichen

diversity in the ITR (Campbell and Fredeen, 2004), including many bipartite cyanolichens

(lichens with no green algal biont, only a cyanobacterial biont), which are likely to be

more sensitive to climate variables than chlorolichens (e.g. Ellis et al. 2009). The

geographic coordinates were recorded for all sampled trees and each tree was marked with

a plastic tag for future reference. Photos o f each stem sampled have been archived at the

University of Northern British Columbia (c/o Darwyn Coxson).

13

The following variables were measured for each alder tree: tree height, diameter at

breast height (DBH), and distance from the creek. Lichen communities on alder stems

were sampled at heights from 1.5 - 3 m above ground, which is above the average late

winter snowpack. Sites were established in late winter 2011, a year of record high

snowpack, so future snowpack burial o f measured stem segments is not anticipated.

The main live trunk of each tree was sampled, as were secondary live trunks with a

DBH of more than 15 cm. All macrolichen species present within the sample region on

these trunks were recorded and their abundance rated (Table 1). An adapted version of the

Braun-Blanquet method was used, after McCune et al. (2000), to measure lichen

abundance with an added level of definition after > 10 thalli. Lichen sample specimens

were collected for archival at the Beatty Biodiversity Museum Herbarium (UBC) in

Vancouver, British Columbia.

Table l.Abundance classes for macrolichens sampled on the trunks of Alnus incana at 1.5 - 3 m above ground level.

Abundance class Definition

0 No individuals o f this species present

1 1 - 2 individual thalli of this species present

2 3 - 1 0 individual thalli o f this species present

3 > 10 thalli, but covering < 50% of trunk area sampled

4 Covering > 50% o f sampled trunk area

Linear regression was used to examine the relationships between macrolichen

species richnessand stand width, plot elevation, and stand size (number o f alders). Linear

14

regression was also used to assess the influence on species richness of stem distance from

the nearest stream edge, diameter at breast height, and stem height. Data were transformed

where necessary to meet assumptions o f normality o f distribution. Analyses were carried

out using STATA statistical software (V12.1; StataCorp, 2011). Unless otherwise noted, all

reported mean values are accompanied by their standard deviation.

15

Results

A total of 39 different macrolichen taxa were found on the alder trunks on the

sample trees (Table 2). Alectoria sarmentosa (Ach.) Ach.andLobariapulmonaria were the

only species to reach an abundance class o f 4 on a single phorophyte (data not shown). L.

pulmonaria was the most abundant species (Table 2, Appendix 1). The least abundant

species were Physcia alnophila (Vainio) Loht., Moberg, Myllys & Tehler and Ramalina

pollinaria^SMQstx.) Ach. (Table 2, Appendix 1).

16

Table 2.Summary o f species abundance ratings on alder trunks across all 20 field sites in riparian zones of the inland temperate rainforest. Values were calculated using abundance rating (Table 1) averages obtained from all three sample trees at each site. Site-specific values are given in Appendix 1.

Species Mean SD Max. Min.Alectoria sarmentosa (Ach.) Ach 0.90 1.05 3.67 0.00Bryoria fuscescens (Gyeln.) Brodo & D. Hawksw. 1.58 0.51 2.33 0.67Cladonia spp. P. Browne 0.50 0.47 1.67 0.00Dendriscocaulon spp. Nyl. 1.42 0.54 2.33 0.33Hypogymnia entermorpha (Ach.) Nyl. 0.38 0.42 1.33 0.00H ypogym niaphysodes (L.) Nyl. 1.08 0.68 2.67 0.00Hypogymnia tubulosa (Schaerer) Hav. 0.63 0.48 1.67 0.00Hypogymnia vittata (Ach.) Parrique, 2.53 0.50 3.00 1.33Leptogium burnetiae C. W. Dodge 0.13 0.29 1.00 0.00Lobariapulm onaria (L.) Hofftn. 3.23 0.46 4.00 2.00Lobaria retigera (Bory) Trevisan 0.23 0.33 1.00 0.00Lobaria scrobiculata (Scop.) DC. 0.85 0.58 1.67 0.00Melanelixia subaurifera (Nyl.) 0 . Blanco et al. 0.18 0.38 1.33 0.00Nephroma bellum (Sprengel) Tuck. 0.15 0.37 1.33 0.00Nephroma helveticum Ach. 0.57 0.53 1.67 0.00Nephroma isidiosum (Nyl.) Gyelnik 1.15 0.62 2.00 0.00Nephroma occultum Wetmore 0.15 0.23 0.67 0.00N ephrom aparile (Ach.) Ach. 2.78 0.29 3.00 2.00Nephroma resupinatum (L.) Ach. 0.10 0.24 0.67 0.00Parmelia hygrophila Goward and Ahti 1.62 0.80 3.00 0.00Parmelia sulcata Taylor 3.07 0.17 3.67 3.00Parmeliopsis ambigua (Wulfen) Nyl. 0.05 0.12 0.33 0.00Parmeliopsis hyperopta (Ach.) Arnold 0.03 0.10 0.33 0.00Peltigera collina (Ach.) Schrader 0.60 0.60 2.00 0.00Physcia alnophila (Vainio) Loht., Moberg, M yllys 0.02 0.07 0.33 0.00& Tehler (Lohtander et al. 2009)Platismatia glauca (L.) W. L. Culb..& C. F. Culb. 1.55 0.90 3.00 0.00Polychidium spp. (Ach.) Gray 0.19 0.32 1.00 0.00Pseudocyphellaria anomala Brodo & Ahti 0.42 0.63 2.33 0.00Ramalina dilacerata (Hoffm.) Hoffm. 0.03 0.15 0.67 0.00Ramalina pollinaria (Westr.) Ach. 0.02 0.07 0.33 0.00Ramalina thrausta (Ach.) Nyl. 2.93 0.17 3.00 2.33Sticta sp. (chlorolichen) 0.25 0.36 1.00 0.00Sticta fuliginosa (Hoffm.) Ach. 0.55 0.44 1.33 0.00Sticta limbata (Sm.) Ach. 0.05 0.16 0.67 0.00Sticta sylvatica (Hudson) Ach. 0.67 0.66 2.00 0.00Tuckermannopsis chlorophylla (Willd.) Hale 0.83 0.57 2.00 0.00Usnea chaetophora Stirton (Halonen et al. 1998) 0.45 0.53 1.67 0.00Usnea glabrata (Ach.) Vainio 0.10 0.27 1.00 0.00Usnea sp. (fdipendula Stirton or scabrata Nyl.) 1.45 0.51 2.33 0.67

17

Tree heights ranged from 3.6 to 13.4 m, with an average o f 9.5 ± 2.3m, measured

in vertical distance from ground level (i.e., not considering the increased actual height of

leaning trees). Diameter at breast height ranged from 7.0 to 26.1 cm, with an average of

18.8 ± 3 .9 cm. The distance of each tree from the creek ranged from 0 to 32 m, with an

average of 7.7 ± 6.6 m.

The total counts of individual macrolichen species on the sampled alder

trunkswere 34, 29, 36, and 32 species for drainages 1 - 4 , respectively. Species richness

at each site ranged from 18 to 29 species, with an average of 23.2 ± 3.0 species per site.

The number o f macrolichen species on individual alder trunks ranged from 9 to 24

species, with an average of 16.2 ± 3.5.

Elevation did not influence site species richness (p = 0.41, F = 0.71, 19 df), and

neither did the width of the stand being surveyed (p = 0.38, F = 0.79,19 df). Stand size

(number of trees per stand) also did not have an effect on site level macrolichen species

richness (p = 0.08, F = 3.38, 19 df; data transformed with an inverse square root

function).

At the level of individual trees, tree height had no significant effect on species

richness (p = 0.369, F = 0.82, 59 df), and neither did the distance from the sample tree to

the stream (p = 0.399, F = 0.76, 59 df; data transformed using the square root function).• j

Diameter at breast height had a significant negative effect on species richness (R = -

0.305, p = 0.007, F = 7.97, 57 df).

18

Discussion

The number of locally and globally rare species found in this study highlights the

importance of ITR riparian zones in maintaining regional biodiversity. Nephroma

occu/twm (known in some Canadian conservation literature as cryptic paw), a species of

special concern (COSEWIC, 2006), was found on 13% of the studied trees. The British

Columbia Conservation Data Centre (BC Ministry of Environment, 2012) ranks this

species, as well as Nephroma isidiosum, Lobaria retigera{Bory) Trevisan, Sticta

oroborealis, and Sticta wrightHTuck. as rare and of conservation priority in the province.

A number of the species found along the creek drainages may also be considered

oldgrowth indicators in the ICH (Goward and Arsenault, 2000b;Campbell and Fredeen,

2004). The finding of numerous provincially rare and uncommon species in this study is

consistent with recent research suggesting an exceptionally rich lichen flora in the ITR

(Spribille et al. 2009).

The observed negative influence o f diameter at breast height on macrolichen

species richness was, at first, puzzling. This may have occurred due to competitive

exclusion of lichen taxa on the larger sampled trees, especially competition from the

often dominant Lobariapulmonaria. Based on field observations, alder stems smaller

than the ones included in our study also hosted less lichenspecies richness. Doering and

Coxson (2010),studying similar riparian alder ecosystems in the adjacent SBS zone, also

found stems below 10 cm DBH to have much lower lichen species richness. It is

therefore likely that the medium diameter trunks (i.e., the smaller trunks that were

sampled) represent the peak lichen floras for these alders. It is thus suggested that future

19

monitoring measurements include some additional sample trees, representing medium-

diameter trunks with peak lichen floras. Doering and Coxson (2010) noted that the

number of alder stems > 10 cm DBH influenced canopy lichen species richness. In the

present research however, no influence of the absolute number o f trees per stand

occurred. The variables of elevation, stand width, tree height, and distance from the

sample tree to the stream also failed to correlate to species richness. These results

support the similarity of sample units in this study, indicating that none o f these variables

are currently exerting a heavy influence on the lichen communities within the sampled

area.

Future effects of climate change on the lichen communities documented in this

study will be complex. Climate and other variables must be suitable for all symbionts

and for their mutual interactions before establishment can occur (Goward, 2011).

Although establishment may be limited by climate, thalli may also persist where climate

becomes unsuitable for further establishment (Ellis and Coppins, 2007). This can be

misleading for climate monitoring, as established thalli may influence estimates on the

climatic requirements of indicator species (Ellis and Coppins, 2007). This research has

attempted to account for this by recording the abundance class o f each species, which

will change more rapidly over time than will absolute presence/absence data.

Winter climate warming, as is predicted for the ITR (Stevenson et al. 2011), has

the potential to seriously harm lichen communities (Bjerke, 2011). In mild subfreezing

temperatures, which are warm enough for hydration, physiologically active lichens will

respire and use up valuable carbon reserves during the low light o f the winter months

(Schroeter and Scheidegger, 1995; Bjerke, 2011). The formation of ice crystals is also a

2 0

concern as temperatures fluctuate, especially when thalli are partially hydrated.Partial

hydration prevents the full activation o f extracellular ice nucleation activity in lichens,

leading to cellular damage from intracellular ice crystals (Bjerke, 2009). The responseof

lichens to climate change is thus dependent on a number of climatic variables such as

light availability, humidity, and temperature. Therich assemblage of lichen species

documented in our biomonitoring plots will likely show an array of responses to climate

change in the ITR. It is hoped that this diversity of response will shed light not only on

how climate change is impacting the ITR, but also on how the individual species are

likely to respond to climate change in general.

There are many issues to address when designing a long-term biomonitoring

protocol (Ferretti and Erhardt, 2002; Insarov and Schroeter, 2002; Will-Wolf et al.

2002). One important issue for epiphytic lichens is substrate longevity. In the ITR,

branches o f A. incana are frequently bent or broken off in years o f heavy snow pack. The

present study was therefore restricted to alder trunks, which last longer than individual

branches.

We have also tried to ensure that field sampling methods will be repeatable,

although future sampling will require trained lichenologists, as this study has used a rich

lichen community for biomonitoring. This decision may have increased potential

measurement error when compared to using a single indicator species, however, the

community sampled will provide a greater probability of differential response by various

community members, and is therefore preferable to biomonitoring with a single indicator.

Ideally, long-term biomonitoring plots should be situated in protected areas,

where plots will not be disturbed by other human-caused activities (Insarov and

21

Schroeter, 2002). Our plots all fall within varying degrees of protection, from the high

level of protection provided by provincial parks (Slim Creek Provincial Park) to the

lesser protection provided by Old Growth Management Areas (OGMAs), which prevent

logging but not other resource extraction or road access development (see Geo BC (2012)

for a description of legal OGMAs, and Post (2008) for a discussion of the limitations of

“guidance” or non-legal OGMAs). The information gathered from our biomonitoring

plots has the potential to bothassist management o f these protected areas, by allowing for

greater conservation priority o f refuge habitats as climate change impacts the ITR, as

well as provide a benchmark against which changes in surrounding forests in the timber

harvesting landbase can be assessed.

22

Chapter 2: Population Structure of Lobaria pulmonaria in the Inland TemperateRainforest

Introduction

A rich cyanolichen community inhabits the ITR (Goward and Spribille, 2005).

Within this ecosystem, Lobaria pulmonaria (L.) Hoffm.populations reach exceptional

levels of abundance in undisturbed old-growth stands (Campbell and Fredeen, 2004). L.

pulmonaria is a tripartite cyanolichen whose abundance is strongly associated with older

forest stands in British Columbia (e.g. Campbell and Fredeen, 2004) and in other regions

of the world (Gu et al. 2001;Ockinger and Nilsson, 2010). The abundance o f L.

pulmonaria in old-growth stands of the ICH biogeoclimatic zone has been noted in

previous studies (Campbell and Fredeen, 2004; Radies and Coxson, 2004;Radies et al.

2009). Campbell and Fredeen (2004), for example, estimated that old-growth ITR forests

support an average of 100 kg/ha dry mass o f L. pulmonaria, while Benson and Coxson

(2002),using detailed branch-level sampling,estimated cyanolichen abundance (primarily

L. pulmonaria)at 350 kg/ha.For comparison, populations of this species in undisturbed

old-growth forests of Finland have shown occupancy at only 39 trees per hectare (Gu et

al. 2001). The nearly unparalleled success o f theZ. pulmonaria populations in wet ITR

forests suggests that this ecosystem provides highly suitable growing conditions, from

factors such as climate, to propagule and photobiont source populations, substrate

availability, and atmospheric conditions.

The conservation of lichens is dependent on an understanding of the factors that

influence their distribution and abundance, including dispersal, establishment,

23

growth,and fecundity (Scheidegger and Werth, 2009). In general, very little is known

about these factors for the majority of lichens. Dispersal dynamics in Lobaria

pulmonariahave been examined by several authors(Sillett et al. 2000; Dettki et al. 2000;

Walser, 2004;Werth et al. 2006, 2007; Hilmo et al. 2009;), although many questions

remain outstanding (Scheidegger and Werth, 2009). Establishment and juvenile

development are also critical life history stages, the success of which are determined by a

number of factors (Dettki et al. 2000; Scheidegger and Werth, 2009; Hilmo et al. 2009).

The growth o f juvenile and mature L. pulmonariathalli may be measured in area gain

and/or weight gain. Both methods for determining thallus growth have been described

for European populations of this species (Gauslaa et al. 2006; Gauslaa et al. 2009).

Growth estimates for L. pulmonariam the ITR using measurements of weight gainare

described by Coxson and Stevenson (2007a, 2007b).

In metapopulation theory, extinction risk decreases with the increasing size,

connectivity, and quality of habitat patches (Smith and Smith, 2006). For epiphytic

species, individual trees may be considered habitat patches, surrounded by an unsuitable

matrix (Lobel et al. 2006; Ockinger and Nilsson, 2010). Mature trees in ITR riparian

zones are important refugia for cyanolichens (Doering and Coxson, 2010). This may

reflect both optimal conditions for growth and establishment on these trees as well as

past stochastic events relating to stand history and stand dynamics. Trees with high

lichen loading may play an important role as propagule source populations within the

larger region. Proximity to propagule sources (i.e., the connectivity of habitat patches)

has repeatedly been demonstrated as an important factor determining epiphyte

establishment (Dettki et al. 2000; Snail, 2003; Sn&ll et al. 2003).SiIlett et al. (2000) and

24

Hilmo et al. (2011) both found Lobaria pulmonaria (among other species) were equally

successful in establishing in young forests as in old-growth, suggesting dispersal is a

major restriction on lichen establishment in many older forests. Similarly, Snail et al.

(2005b)foundpatch connectivity was an important predictor o f L. pulmonariapresence.

Lobaria pulmonaria inhabits predominantly hardwood phorophytes in Europe

(e.g. Gu et al. 2001; Ockinger and Nilsson, 2010), however, abundant L.

pulmonariapop\x\aX\ons can be found on both deciduous and coniferous trees in British

Columbia’s ITR (Goward and Aresenault, 2000c). Although growing conditions for

lichen communities differ considerably between conifers and deciduous trees, due to

differences in factors such as light availability (Coxson and Stevenson, 2007b), water

availability (Gauslaa et al. 2009), and bark pH (Goward and Arsenault, 2000a; Gauslaa

and Goward, 2012), both can develop high cyanolichen loading within ITR stands.

In this chapter, the development of Lobaria pulmonariapopufotions has been

examined within riparian corridors in ITR forests, by analyzing the number of

individuals, thallus sizes, and reproductive capabilities along dated branch segments.

Sympatric populations of L. pulmonariaon two phorophyte species have been compared,

one coniferous (subalpine fir), and the other deciduous (mountain alder), using a

retrospective study approach based on the use o f dated branch segments .Measurements

were taken o f the areas, weights, and reproductive classes o f L. pulmonaria thalli

alongdated live branch segments. These measurementswere subsequently used to

estimate changes in specific thallus mass (after Gauslaa et al. 2012) on branches o f

different age and phorophyte species, as well as for thalli of different sizes and

reproductive classes.Among questions that have been examined in this research are: How

25

does the size class distribution and number o f individual thalli o f L. pulmonaria change

as substrate ages? How do the reproductive capabilities of a population change as it

ages? How do the areas and weights o f individual thalli compare? And what, if any,

differences occur betweenL pulmonaria population numbers, thallus sizes, and

reproductive capacities on the best example of a deciduous species and a coniferous

species of phorophyte in the ecosystem of interest?

26

Methods

Sample trees were located in the same drainages described in Chapter 1, east of

Prince George in the upper Fraser watershed (Fig 2.). Branches from two phorophyte

species were sampled, subalpine fir {Abies lasiocarpa Nutt.) and mountain alder (Alnus

incana) from within these drainages, with a target of 40-50 trees o f each species

distributed among all four drainages. Similar protocols were followed in selecting

sample branches from both species: sample trees were identified at a distance by their

abundance of cyanolichens, primarily Lobaria pulmonaria. Trees with abundant

cyanolichens were not selected if they were found within the drip-zone of a western

redcedar {Thuja plicata) or a cottonwood {Populus balsamifera) tree, where additional

influences of throughflow leachate may influence lichen growth (Goward and Arsenault,

2000a; Gauslaa and Goward, 2012). Trees were all selected within topographically

similar primary and secondary creek drainages, with similar elevation, aspect, and levels

of light exposure.

The diameter at breast height (DBH) and tree height was measured for each

sample tree. One branch was selected from the south-facing side o f each sample tree at

between 3 and 5 m above the depth of the winter snowpack (2m), but below the point at

which canopy communities become dominated by Alectoriod lichens (Benson and

Coxson, 2002). The height above ground on the trunk where each branch was attached

was recorded. Branches were then removed and brought back to the lab, where they were

cut into 30-cm segments along the main axis of the branch (Figure 2). Where two axes

were plausible as the main axis, the one with a greater abundance of cyanolichens was

27

chosen for sampling. All Lobaria pulmonaria thalli > 0.5 cm in diameter were then

removed from the remainder of each branch to obtain total estimates of biomass per

branch. From the main axis, all L. pulmonaria specimens were moistened and carefully

removed,then flattened in paper and air-dried. Great care was taken to separate individual

thalli from one another; all lobes that could be distinguished as belonging to the same

individual were counted as one thallus. A subset of thalli was further oven-dried at 65 °

C for 24 hours and then re-weighed to determine a correction factor for the weight

measurements ofthalli that were air-dried.

The age of each30-cm branch segment was determined by counting tree rings at

each end under a dissecting microscope, after exposed surfaces were sanded with 400-

grit sandpaper. The average of the two ages from each end of the branch segment was

used as our estimate of branch segment age.Branch diameter was measured to the nearest

millimeter, and the average diameter o f both ends was used in segment analysis.

28

Figure 2.Example of an Alnus incana branch typical o f those sampled. Main axis has been selected and cut into 30-cm segments for analysis of branch age and diameter. Lobaria pulmonaria thalli were subsequently removed and thallus areas, weights, and reproductive capacities analyzed.

29

Air-dried flattened thalli from the main axiswere scanned using an Epson 1640

Scanner (model G650C)with the WinFOLIA 2003d software program (Regent

Instruments Inc.) to determine the area of each thallus to the nearest 0.01 cm (Figure 3).

Each thallus was weighed to the nearest milligram using a Sartorius top-loading balance

(model BA 310P). A subset of approximately 100 Lobaria pulmonaria thalli weighing

less than 10 mg from each tree species were re-weighed with a Sartorius analytical

balance (model CPA2245) to the nearest 0.1 mg. Linear regression between square-root

transformed thallus areas and weights in this subset of L. pulmonaria thalli showed a

highly significant relationship (R2 = 0.9763, n = 111, F= 4409, p < 0.001 for subalpine

fir, R2 = 0.974, n = 110, F = 3701, p < 0.001 for mountain alder). Thefinal mass of thalli

weighing less than 10 mg was subsequently estimated from the regression with thallus

area (Figure 4) (weight = -0.0081 + 0.1052*area for subalpine fir, -0.0049 + 0.1022*area

for mountain alder).

30

Figure 3. Example of a scanned image used to calculate the area of Lobaria pulmonaria thalli using WINFOLIA software.

31

a) 0.12

0.10 -

0.08 -

•§> 0.06 -‘3£

0.04 -

0.02 -

0.000.0 0.2 0.4 0.6 0.8 1.0 1.2

b) 0 .12 -|------------------------------------------------------------------------------------------

0.10 -

0.08 -

• f 0.06 - £

0.04 -

0.02 -

0 . 0 0 -i-------------------------1-------------------------1-------------------------1-------------------------1-------------------------1-------------------------

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Area

Figure 4. Regression plots of Lobaria pulmonaria thallus weights vs. areas for thalli< 10 mg on a) subalpine fir (n = 111), and b) mountain alder (n = 110) as measured on an analytical balance. This regression analysis was subsequently used to estimate thallus weights for all L. pulmonaria thalli < 10 mg.

32

The reproductive status of thalli was determined through the visual identification

(lOx magnification lens) of soredia/isidia or apothecia. Reproductive status was divided

into four categories: non-reproductive, marginal soredia only, both marginal and laminal

soredia, and sorediate with apothecia. Less than 0.1 % of thalli sampled showed

soredia/isidia covering more than 50 % of the thallus and so this reproductive class (as

described by Gauslaa, 2006) was omitted. The distribution of the reproductive status of

thalli was then compared for each age class between tree species.Sampled trees and

branches were characterized using the mean and standard deviationof tree height and

DBH, branch height, branch diameter at base, branch length, and the total Lobaria

pulmonaria dry weight on each branch. Data on individual thalli were combined within

each segment for the analysis of how L. pulmonaria populationswere influenced by

branch segment.

Transformed data were highly skewed, thus,mixed-effects logistic regression

(Gilles et al. 2006) was used to model the statistical relationships between lichen

abundance and reproductive status and branch segment age, diameter, and distance from

trunk.For these models, individual tree served as a random effect and independent

variables as fixed effects. The dependent variables analyzed for each segment included

the number of individual thalli, total segment Lobaria pulmonaria area, total segment L.

pulmonaria weight, maximum L. pulmonaria thallus size per segment, and reproductive

capacity of each segment. To create a binary variable, thesedata were divided at the

median value for each tree species, with the exception of segment reproductive capacity,

which was divided into “reproductive” and “non-reproductive” categories based on the

presence/absence o f at least one fertile thallus. Independent variables included average

33

segment age, average segment diameter, and average distance from the trunk. Each

independent variable was also represented as a nonlinear quadratic function. From this

full set o f variables, modified Akaike’s Information Criterion (AICc) was used to select

the most parsimonious model (Anderson et al. 2000).The influence of thallus area and

Specific Thallus Mass (STM) on the dependent variable of reproductive capacity

(presence/absence of soredia/isidia/apothecia) was further examined at the level of

individual thalli,using separate logistic regression models. The relationship between

thallus area and STM was also tested using a Spearman’s rank correlation.

The fit o f the most parsimonious models were assessed using the receiver

operating characteristic (ROC) fit to 20 % of the data that were withheld during model

fitting (Fielding and Bell, 1997). The ROC is an accepted unbiased method o f assessing

the predictive accuracy of logistic regression models (Fielding and Bell, 1997). Models

with ROC scores of 0.5-0.7 are considered to have poor model fit, 0.7-0.9 are good, and

>0.9 are highly accurate (Manel et al. 2001). Comparisons testing for differences in

continuous dependent variables between tree species were made using the Wilcoxon-

Mann-Whitney test.Statistical analyses were conducted using STATA v. 12.1 (Statacorp,

2011) and SigmaPlot v. 12 (Systat Software Inc., 2012).Unless otherwise noted, mean

values were reported with their standard error.

34

Results

A total of 49 subalpine fir and 41 mountain alder trees were sampled. The mean

height of subalpine fir was 12.36 ± 0.50 m, and theirmean DBHwas 22.01 ± 0.90 cm.

The mean height of mountain alder was 9.70 ± 0.36 m, with a mean DBH o f 16.81 ±

0.65 cm. Subalpine fir branches had an average length of 2.33 ± 0.07 mwith a mean basal

diameter of 22.99 ± 0.83 mm.The mean length of mountain alder branches was2.35 ±

0.10m,and their mean basal diameter was 24.36 ± 0.80 mm. Cutting branches into 30-cm

segments along their main axis resulted in 393 segments for subalpine fir, and 338

segments for mountain alder .Mean branch height was 3.70 ± 0.12m on subalpine fir and

3.30 ± 0.12 on mountain alder.

The mean weight o f total Lobaria pulmonariablomass per branch was 71.03 ±

3.57 g on subalpine fir and 12.31 ± 0.57 g on mountain alder. The maximum number of

L. pulmonaria thalli found along the main axis of a single branch was 149, on mountain

alder. The maximum number of thalli found along the main axis o f a subalpine fir branch

was 122. Ambient moisture accounted for 5.00 ± 0.05 % of thallus weights (n = 25). The

mean number of thalli along the main axis o f sampled branches was 50.12 ± 3.53 for

subalpine fir and 54.56 ± 5.64 for mountain alder. A significant positive correlation was

found betweenthallus weight and area on both tree species (rs=0.998, n = 2455, p<0.001

for subalpine fir, rs = 0.998, n=2455, p<0.001 for mountain alder) (Figure 5).

35

a) 16

b)

14 -

a■EH

400 600 8002000

Thallus area (cm2)

Figure 5.Relationship between Lobaria pulmonaria thallus area and thallus weight in a) subalpine fir (n = 2456), and b) mountain alder (n = 2257).

36

The most parsimonious logistic regression models varied according to tree

species and dependent variable (Table 3). The quadratic function of segment distance

from trunk had a relatively uniform influence in all models, with other parameters

showing more variation (Table 3).

Number o f thalli per branch segment

Subalpine fir and mountain alder showed a similar relationship between the

number o f L. pulmonaria thalliper branch segment and increasing age (Figure 6). The

number o f thalli per branch segment did not differ significantly between the tree species

for branch segments of all ages (z = 0.325, p = 0.745). Branch segment age and distance

from trunk successfully predicted the presence of more than the median number o f L.

pulmonaria thalli forboth subalpine fir (ROC 0.770 ±0.054) and mountain alder (ROC

0.813 ±0.053), although distance from trunk was non-significant for mountain alder

(Table 3). Branch segment age had a significantly higher positive coefficient for

predicting the number of thalli on alder when compared to fir (Table 3).

37

14

eQ00oo .

owOJOS3C

Tree species

FirAlder

2 3

Branch segment age class

Figure 6. Mean number of individual Lobaria pulmonaria thalli with increasing branch segment age classes.Error bars represent ± 1 SE.The number o f thalli in increasing segment age classes was 639, 563,487, and 767 for subalpine fir and 461, 784, 576, and 436 for mountain alder. Age classes are defined in Figure 7.

38

Table 3. Parameters from the most parsimonious mixed-effects logistic regression models for branch segment data from subalpine fir (n = 311) and mountain alder (n = 266)(Appendix 2). Binary dependent variables were generated using the median value of the corresponding data, with the exception of reproductive capacity, which was categorized as either “reproductive” or “non-reproductive” for each branch segment. ROC scores were calculated based on 20% of segment data withheld (nfjr= 81; naider= 65). Coefficients highlighted in bold were non-significant (p > 0.005).

Dependent variables

Number o f thalli per segment

Segment L. pulmonaria area (cm2)

Segment L. pulmonaria weight (g)

Large thallus presenceSegment reproductive capacity

Model parameters Fir Alder Fir Alder Fir Alder Fir Alder Fir Alder

Constant-4.625 ± -11.411 ± -5.968 ± -6.678 ± -5.306 ± -6.951 ± -7.091 ± -6.482 ± -6.603 ± -5.910 ±1.177 2.676 1.244 1.940 1.196 2.215 1.354 1.943 1.361 2.206

Average segment age0.436 ± 0.074

1.177 ± 0.240

-0.692 ± 0.172

0.071 ± 0.128

0.897 ± 0.248

-0.669 ± 0.174

-0.606 ± 0.190

Average segment -0.010 ± -0.028 ± -0.014 ± -0.002 ± -0.018 ± -0.013 ± -0.012 ±age2 0.002 0.006 0.004 0.002 0.006 0.004 0.004Average distance 0.020 ± 0.021 ± 0.024 ± 0.014 ± 0.022 ± 0.024 ± 0.032 ± 0.014 ± 0.026 ± 0.009 ±from trunk 0.008 0.012 0.003 0.013 0.009 0.015 0.010 0.013 0.010 0.014Average distance 0.000 ± 0.000 ± 0.000 ± 0.000 ± 0.000 ± 0.000 ± 0.000 ± 0.000 ± 0.000 ± 0.000 ±from trunk2 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000Average segment 0.649 ± 0.480 ± -0.346 ± 0.698 ± 0.719 ±diameter 0.118 0.195 0.228 0.128 0.124Average segment 0.000 ± -0.009 ± 0.011 ± -0.016 ± -0.016 ±diameter2 0.000 0.005 0.006 0.003 0.003AICc 339.015 229.694 296.402 217.170 299.494 215.003 279.665 217.704 259.392 229.147

ROC0.769 ± 0.813 ± 0.850 ± 0.823 ± 0.839 ± 0.822 ± 0.861 ± 0.800 ± 0.866 ± 0.823 ±0.054 0.053 0.045 0.053 0.045 0.053 0.043 0.057 0.041 0.052

Dependent variable median value

4 4 30.905 9.640 0.375 0.137 14.815 3.850 - -

39

Total L. pulmonaria area and weight per branch segment

Totalarea o f Lobaria pulmonaria per branch segment differed significantly

between tree species (z=4.361, p<0.001, nfir= 392 and naider = 331).Branch segment

diameter and distance from trunk parameters predicted the total area of L. pulmonaria on

subalpine fir branches (ROC 0.850 ± 0.045; Table 3). Total area o f L. pulmonaria was

best predicted on mountain alder using parameters o f branch segment age and distance

from trunk (ROC 0.823 ± 0.053), although distance from trunk was non-significant

(Table 3).Total Lobaria pulmonaria weight on both fir and alder branches was best

predicted using all parameters of branch segment age, diameter, and distance from trunk

(ROC 0.839 ± 0.045 and 0.822 ± 0.053, respectively; Table 3).Branch segment age

wasnon-significant for subalpine fir, while distance from trunk was non-significant on

mountain alder (Table 3).

Presence/absence o f large thalli

Segment diameter and distance from trunk successfully predicted the presence of

at least one thallus above the median size o f 14.815 cm2on subalpine fir (ROC = 0.861

±0.043; Table 3). Distance from trunk had the largest coefficient in this model when

compared to all other models (Table 3). Coefficients for parameters of segment diameter

also had relatively large absolute values (Table 3). The presence o f thalli above the

median size o f 3.85 cm2on mountain alder was best predicted with parameters o f branch

segment age and distance from trunk (ROC = 0.800 ± 0.057; Table 3).Size classes of

40

Lobaria pulmonaria on branch segments o f increasing age class showed differing

patterns between tree species (Figure 7). Specific thallus mass was strongly correlated

with thallus size for both subalpine fir and mountain alder (rs = 0.8991, n = 2455,

p<0.001 and rs = 0.9387, n = 2257, p<0.001, respectively). Significant differences were

found for L. pulmonaria STM between tree species (z=-6.019, p<0.001, n=2455 and

2257, respectively).

41

Subalpine Fir Mountain Alder

l l■ ■« 40

I» 30

LMi

§ 20

L. pulmonaria thallus size class

Figure l.Lobariapulmonaria changes in size class distribution with increasing branch segment age for subalpine fir and mountain alder. Branch segment age classes were defined as 1: (0 - 15) years (nnr = 132, naider = 137), 2: [15 - 20) years (nfir = 52, naider = 79), 3: [20- 24) years (nfir = 46, n^der = 50), and 4: > 24 years (nfir = 162, n^der = 65) old. Thallus size classes were defined as (0 — 0.25) (nfir = 477, naider= 533), [0.25 - 0.75) (nfir = 407, n alder = 532), [0.75 - 2) (n fir = 449, nalder = 485), [2 - 8) (n fir = 487, n alder = 396), and > 8 (nfjr = 636, naider = 311) cm2.

42

Reproductive capacity

Branch segment diameter and distance from trunk were successful at predicting

the presence of reproductive structures on the branches o f subalpine fir andmountain

alder (ROC 0.866 ± 0.041 and ROC 0.823 ± 0.052; Table 3). With the exception o f

segment distance from trunk for the mountain alder model, all coefficients were

significant (Table 3). Logistic regression modelsrelating reproductive structures to thallus

sizewere inconclusive, as modelshad complete separation. Thalli above the median size

for both species predicted the presence of reproductive structures.This relationship

isknown from previous studies (e.g. Hilmo et al. 2011), and is depicted in Figure 8.

Specific thallus mass was highly successful at predicting whether thalli were reproductive

on both subalpine fir (ROC 0.899 ± 0.014) and mountain alder (ROC 0.883 ± 0.018),

with higher mg/cm2 thalli more likely to be reproductive (Table 4, Figure 9).

43

250

g 200

- S

4*<3O|s.as j<o

150 -

100 -

50

Tree species

fiaiaiii] FirAlder

1 2 3 4

L. pulmonaria reproductive class

Figure 8. Mean Lobariapulmonaria thallus sizes for different reproductive classes for both phorophyte species. Error bars represent ± 1 SE. The number of individuals for each reproductive class were 1667, 534, 196, and 58 for subalpine fir and 1864, 262, 125, and 6 for mountain alder for classes 1, 2, 3 and four, respectively.

Table 4. Mixed-effects logistic regression model parameters for predicting the presence of reproductive structures with specific thallus mass, ± standard error (nfjr = 1972and nalder =1816). ROC scores were calculated with 20% of withheld data (nfir = 484 and n aider = 441). Model parameters and ROC scores are reported with corresponding standard errors.

F ir AlderParam eter Value SE Value SE

Constant -10.192 0.495 -9.882 0.573Specific thallus mass 0.869 0.042 0.618 0.037ROC score 0.899 0.014 0.883 0.018AICc 1433.757 943.690

44

Tree species

BBBB Fir■ ■ Alder

I 2 3

L. pulmonaria reproductive class

Figure 9. Mean specific thallus mass of Lobaria pulmonaria thalli with increasing reproductive effort.Error bars represent ± 1 SE. The number o f thalli in each reproductive class for both tree species is given in Figure 8.

Reproductiveeffort (from non-reproductive, to marginal and eventually lamina]

soredia/isidia, to apotheciate thalli) increased with branch segment age (Figure 10). This

pattern was more clearly observed on subalpine fir than mountain alder, as there were

fewer reproductive thalli on the latter.

45

a) 100

Reproductive class o f L.

pulm onaria thalli

1 2 3 4

Branch segment age class

Figure 10. Differences in reproductive capacity iorLobaria pulmonaria on branch segments of differing age classes on a) subalpine fir and b) mountain alder. Branch segment age classes are described in Figure 7; for definitions of reproductive class, see Methods.

46

To further understand generation times, the production o f soredia/isidia on both

phorophyte species was compared to minimum branch segment age.Eight sorediate

Lobaria pulmonaria thalli were found on branch segments having an average age o f < 10

years on subalpine fir (3.3 % of thalli on segments < 10 years old), and ten on mountain

alder (11.4 % of thalli on segments < 10 years old), suggesting that the minimum

generation time for these populations o f L. pulmonaria is less than 10 years.Eleven thalli

on subalpine fir under the size of 1 cm2and 22 on mountain alder had marginal apothecia.

The largest thallus found within the smallest branch segment age class (average age <15

years) was 147.33 cm2.

47

Discussion

Lobaria pulmonaria populations from the two phorophyte species were strikingly

different, with significantly higher biomass and thallus sizes observed on fir. Distance

from trunk was a significant parameter for subalpine fir, but not in any o f the models for

mountain alder. Presumablythis is because mountain alder branches represent a relatively

uniform habitat, with branch segments having a relatively even light exposure and

precipitation interception along their length.Conifer branches, conversely, have very

different lichen growing environments along their length (Goward, 1998; Hilmo, 1998),

as well as a vertical gradient (Goward, 2003). Differing microclimates along branches

cause changes in lichen community structure at increasing distances from the trunk

(Hilmo, 1998; Lyons et al. 2000). Shelter from dense and permanent needles on higher

branches of subalpine fir cause a gradient in lower branch environments, from very dry

with relatively low light exposure near the trunk, to the outer foliar zone with high light

and precipitation exposure (Goward, 1998), where needles and Nephroma spp. are

prevalent, and L. pulmonariathaW'i are absent or very small.Differences in canopy

exposure along subalpine fir branches may explain why logistic models using the

absolute measurements of branch segment age were unsuccessful or insignificant at

predicting total segment L. pulmonaria area, weight, reproductive capacity, or the

presence of large thalli along subalpine fir branches, whilemodels using branch segment

age parameters were successful for mountain alder. The large variance in canopy closure

along subalpine fir branches means that L. pulmonaria success was likely not only

dependent on absolutebranch segment age, but also on overall tree morphology, distance

48

from trunk, and distance from adjacent branches. Shelter from nearby branches above and

below the sample branch could potentially have had a strong impact on L. pulmonaria

populations on subalpine fir while causing no observed change in mountain alder.

Dendrochronology of live branchsegments was used to estimate the maximum age

of Lobaria pulmonaria thalli. Although the use o f dated substrates is common in

lichenometric research (e.g. Loso and Doak, 2006), few studies have employed

dendrochronology to describe population structure of epiphytic lichens, and none of these

with L. pulmonaria. Notable research includes the use o f branch age and diameter for

understanding chlorolichen biomass accumulation (Esseen et al. 1996), establishment

rates (Hilmo et al. 2005), and growth rates (Arseneau et al. 1998). Stone and McCune

(1990) also used dendrochronology to determine the age of individual Evernia prunastri

(L.) Ach. thalli. Rhoades (1983) examined Lobaria oregana(Tuck.) Mull. Arg. population

dynamics in Douglas-fir forests o f the Pacific Northwest, using equation models to

estimate annual thallus growth. He found higher reproductive capacity in larger thalli, as

well as similar size-class distribution trends to those described herein for L.

pulmonariaon subalpine fir. Previous research on the growth rate o f individual L.

pulmonaria thalli has largely relied on the marking of the sample trees, and sampling at

intervals without destructively impacting thalli (e.g. Gauslaa, 2006). This method is

limiting in that long-term analyses are challenging.The removal o f entire branches for

more detailed analysis of dendrochronology, as in the present research, allows for the

descriptions o f community development within a short-term study period, as well as

providing insight into growth and establishment rates. This technique does, however,

necessitate the averaging of branch segment ages, and therefore does not determine exact

49

annual estimates of growth parameters. In addition, the precise establishment date of

thalli cannot be determined, only their maximum possible age. Despite these limitations,

it is a useful sampling technique for understanding the recent development o f epiphytic

lichen communities and growth parameters of individual thalli.

Lobaria pulmonaria abundance was much higher on subalpine fir than mountain

alder. In field observations, thalli on mountain alder had a much darker pigmentation than

those on subalpine fir. In addition, mountain alder thalli had significantly higher specific

thallus masses than subalpine fir; both of these factors suggest high levels o f UV

radiation for L. pulmonaria inhabiting alder phorophytes (Gauslaa et al. 2009). Although

light availability has the potential to increase the growth of L. pulmonaria in the ITR

(Coxson and Stevenson, 2007a), this effect can easily be negated by desiccation and UV

damage risks with too much exposure. Light exposure causes an increase in fungal

melanin levels, in order to protect photobionts from UV radiation. This leads to darker

pigmentation that may in turn attract more heat and cause further stress to thalli (Gauslaa

and Solhaug, 2001). It has also been shown that simultaneous drying and high light

exposure, as would occur during the winter months on exposed mountain alder branches,

is damaging to L. pulmonaria thalli (Gauslaa et al. 2012). Photoinhibition and thallus

damage have been demonstrated repeatedly for L. pulmonaria in exposed environments

(e.g. Gauslaa et al. 2001; Gauslaa et al. 2006). In addition to the negative impacts o f UV

radiation, there are potential issues o f shading by deciduous foliage in the summer

months, when growth in L. pulmonaria is at its greatest (Larsson and Gauslaa, 2011;

Larsson et al. 2012).Many of these factors are possible explanations for the differences in

50

abundance observed between sympatric subalpine fir and mountain alder L.

pulmonariapopulaiions.

The maximum observed thallus size was 147.33 cm2for branch segments from

subalpine fir that were an average o f less than 15 years old. Larsson and Gauslaa (2011)

used the measured growth rates of juvenile thalli to model how large European Lobaria

pulmonaria thalli would be after a given number of years. Fifteen year old thalli were

only expected to reach approximately 5 cm2 in size (Larsson and Gauslaa, 2011). The

present research therefore suggests significantly faster growth rates than previously

estimated forZ. pulmonaria, with an average maximum growth rate as fast as 9 cm2

year'1 in the first 15 years of growth.

Specific thallus mass (STM) is a measure of lobe thickness in weight per unit area

which varies greatly among Lobaria pulmonaria thalli by season, age, and in different

light and humidity environments (Larsson and Gauslaa, 2011; Gauslaa and Goward,

2012; Larsson et al. 2012). Active photosynthesis causes STM to increase through the

CO2 assimilation by photobionts (Larsson and Gauslaa, 201 l).Decreased turgor pressure

for fungal hyphae occurring under 60 % humidity can also cause increases in STM by

impeding fungal expansion (Larsson and Gauslaa, 2011). Increasing lobe age and

transplantation to higher light environments have also been shown to increase STM in L.

pulmonaria^Gauslaa, 2006). Larsson et al. (2012) note that studies on lichen populations

of both weight and area are scarce, although these two types o f growth are not always

correlated and are in fact controlled by a number of different internal and external factors

(Gauslaa et al. 2009).

51

In accordance with previous research, STM showed a strong positive correlation

with thallus size and presumably thallus age on both tree species (Larsson and Gauslaa,

2011). Specific thallus masses were significantly different between phorophytes, with

thalli on alder branches having thicker lobes. Thalli with higher STM will have slower

area growth rates (Gauslaa et al. 2006), which in turn supports the finding o f lower total

Lobaria pulmonaria area on mountain alder compared to subalpine fir. The results o f this

study also confirm that higher STM is strongly correlated with increased reproductive

effort. This trend occurred on both tree species, however, more reproductive thalli overall

were found on subalpine fir than on mountain alder. This is possibly because thalli on

subalpine fir were simply larger and therefore more likely to be reproductive, and also

possibly because the reproductive structures themselves contributed somewhat to the

STM of a given thallus.

The presence of sorediate/isidiate individuals on branch segments < 1 0 years old

on both phorophyte species suggests that generation times for Lobaria pulmonaria in the

ITR may be much shorter than those previously estimated in Europe, at >17 years

(Larsson and Gauslaa, 2011), or 22 - 25 years (Scheidegger et al. 1997). Because o f the

ideal environment in the ITR, where very little air pollution occurs, and frequent

humidity during the summer months is common, my findings may provide evidence for

the reproductive potential of this species under optimal conditions. A number o f thalli < 1

cm2 were found with soredia present. The smallest thallus with an apothecium was 1.35

cm2, suggesting that if a size threshold for reproduction does exist for L. pulmonaria, as

has been shown for other lichen species (Ramstad and Hestmark, 2001), the minimum

area required is small.

52

The almost complete absence of Lobaria pulmonaria thalli with soredia covering

more than 50% of their surface area in our study contrasts with European research, as

does the lower percentage of apotheciate thalli (1.4% vs. 3%) (Gauslaa, 2006).The lower

percentage of apotheciate thalli and profusely isidiate/sorediate thalli found in my study

when compared to European research (Gauslaa, 2006) indicates that ITRX.

pulmonariawcre not as prolific in their reproductive strategies. In accordance with

Gauslaa (2006), however, laminal soredia did not occur in the present study until

marginal soredia were common. In lichens, it is generally acknowledged that the small,

sexual ascospores are more effective at long distance dispersal, while asexual

reproductive structures that contain both symbionts are more effective at local dispersal -

where that genotype combination has been particularly successful (Scheidegger and

Werth, 2009). Larger asexual spores have more resources available during establishment,

allowing for higher establishment success (Lobel et al. 2006). Walser (2004) used genetic

techniques that indicated that asexual propagules of L. pulmonaria were not effectively

dispersed over large ranges. Hilmo et al. (2011) found that the larger isidioid soredia o f L.

pulmonaria had greater establishment success than the smaller L. scrobiculata soredia.

Few thalli with apotheciawere noted in this research,suggesting that L. pulmonaria in the

ITR may be limited to short-distance dispersal.

Surprisingly, although overall Lobaria pulmonaria abundance was much higher

on subalpine fir than on mountain alder, the number o f individuals per branch segment

did not differ significantly between tree species. This is interesting because previous

research has indicated that the establishment success o f L. pulmonaria declines with

increasing branch exposure (Hilmo et al. 2009), and alder branches were more exposed

53

than fir branches. The number of individual thalli was highest on branch segments of

intermediate ages on both tree species, suggesting that these environments offer the

conditions most conducive to thallus establishment. Size class distributions on branch

segments of different age classes, however, contrasted strongly between fir and alder.

Recruitment rates on older sections o f fir branches were lower than on mountain alder,

perhaps because the optimal growing conditions occurring on fir trees, which support

high L. pulmonaria biomass and promote large thalli, are causing the exclusion of smaller

thalli and thus inhibiting establishment.

The Lobaria pulmonar/'ubiomass measurements found on subalpine fir branches

support previous findings that this species reaches exceptional abundance in the ITR

(Campbell and Fredeen, 2004, Radies and Coxson, 2004), as well as achieving rapid

growth rates (Coxson and Stevenson, 2007a) and large numbers o f individual thalli

(Campbell and Fredeen, 2004). These abundance levels highlight the uniqueness o f the

ITR and support the need for its conservation (Radies et al. 2009), especially as L.

pulmonaria abundance is an effective indicator for the high cyanolichen species richness

in this ecosystem (Campbell and Fredeen, 2004).

In contrast to many regions in Europe, the ITR represents habitat for Lobaria

pulmonaria that is virtually free from urban and industrial air pollution effects such as

nitrogen compounds and sulphur dioxide. Given alsothe longevity of the forests

examined in this research, it is likely that conditions for these populations o f L.

pulmonaria have remained constant (up to 50 years for mountain alder, and 54 years for

subalpine fir).This population differs frompopulations in Europe, where lichens are

increasing towards historicaldistributionfollowing decreasing air pollution (Ockinger and

54

Nilsson, 2010). Although this lichen is not currently at risk in the ITR, in Europe it is

endangered and faces extirpation in many regions. Whilethis research has described

population parameters in an environment very different from European forests, these

results forX. pulmonariaundov ideal conditions are highly applicable as a standard for

understanding optimal establishment, generation time, and growth rates for this important

species.

55

Conclusion

Arboreal macrolichens are important contributors to terrestrial ecosystems. As

indicators of ecosystem health, they are also useful tools for understanding environmental

change and informing management decisions in forested landscapes. The ITR o f British

Columbia represents a unique habitat that is ecologically important for a number o f

species (Stevenson et al. 2011), including a rich cyanolichen assemblage (Campbell and

Fredeen, 2004; Goward and Spribille, 2005; Spribille et al. 2009) that is yet to be

completely described.The high growth rates and low generation times for L. pulmonaria

presented in this research, along with the rich lichen communities documented on

mountain alder trunks, speak to the global uniqueness of the ITR as an ecosystem.

Management challenges in the ITR arise from maintaining economic stability in

the region through forest harvesting, while allowing for biodiversity conservation

measures such as protected areas. Detailed knowledge o f how climate change is

impacting the ITR may benefit managers in that areas with a greater climate buffering

capacity may be targeted for conservation.The lichen biomonitoring protocol presented in

Chapter 1 of this thesis may improve knowledge of future climate change impacts in the

ITR. This research provides a baseline for future reference that may help to identify areas

of maximum climate buffering capacity, that is, where the lichen communities remain the

most stable as climate shifts. Conservation may then be prioritized for the sites with

minimum changes in these epiphytic lichen communities, protecting refugia of

biodiversity. These refugiamay also increase the colonization potential o f the surrounding

ecosystem as species begin to disappear from neighbouring areas, although this will

56

depend on the dispersal mechanisms of individual species. The relatively low percentage

of apotheciate Lobaria pulmonaria thalli found in the present research suggests that long-

range dispersal may be a concern for this species if suitable habitat becomes fragmented,

either through continued forest harvesting, or through a decline in suitable habitats due to

climate change.Thus, the number and proximity of refugia, aspotential propagule sources

for surrounding areas,may be an important factor in maintaining the populations o f L.

pulmonaria currently found in the ITR.

The conservation o f the lichens themselves is a concern as climate shifts, but they

will also act as indicators of how climate change is affecting the ITR more generally. The

39 lichen taxa I have documented will likely show differential responses to climate

change depending on their ecological restrictions. This may give a detailed indication of

changing environmental conditions in advance o f more apparent impacts. If there were a

decrease in precipitation and snow melt, for example, we would expect to see declines in

the distribution of cyanolichens, which are dependent on high humidity. I f declining

cyanolichen populations are observed, future managers may be able to mitigate the

effects this has on other organisms by protecting as many humid habitats as possible. The

advance warning provided through lichen biomonitoring may give managers an

advantage in selecting optimal sites for conservation before these stands are harvested.

Protection of these sites will help to protectmanyspecies from climate change impacts,

such as the vegetation and wildlife that depend on these disappearing environmental

conditions. An understanding o f epiphytic lichen responses to climate change may

therefore assist managers in understanding climate change responsesfor the ITR

ecosystem as a whole.

57

Lobaria pulmonaria populations in the ITR are exceptionally successful under

current conditions. The second chapter of this thesis has focused on L. pulmonaria as this

species is one of the best-studied lichens globally,facilitating comparisons o f the present

ideal growing conditions in the ITR to previous research in other ecosystems. The present

research has shown that growth rates may be faster, and generation times shorter, for this

species than have been previously estimated elsewhere. The results of the present

research on L. pulmonaria establishment, growth, and reproductive parameters are useful

in expanding our understanding of the population dynamics o f this globally important

species. Additionally, this research has shown significant differences in how this species

adapts to growing on coniferous versus deciduous phorophytes, namely that although

establishment does not appear to differ between the two tree types, the reproductive effort

and growth rates o f L. pulmonaria are higher on conifers in riparian zones o f the ITR,

likely due at least partially to UV damage to thalli growing on alder.

In order to survive in the landscape, epiphytic lichens must maintain gene flow

between suitable forest patches, and ideally, colonize regenerating areas (Snail, 2003).

Habitat fragmentation is an additional risk facing lichen communities in the ITR.

Fragmented old-growth forest patches, which are being generated through harvesting,

may lead to declines in Lobaria pulmonaria populations at a regional scale (Gu et al.

2001; Ockinger and Nilsson, 2010). Proximity to propagule sources (i.e., the connectivity

o f habitat patches) has been repeatedly demonstrated to be an important factor

determining epiphyte establishment (Dettki et al. 2000; Snail, 2003; Snail et al. 2003;

Snail et al. 2005a). Despite current L. pulmonaria abundance levels, the destruction of

old-growth habitat in the ITR is therefore a concern. This ecosystem is currently under

58

intensive harvesting pressure and undisturbed, high-biodiversity stands are at risk. The

description of the current population structure o f L. pulmonaria in the ITR that has been

presented in Chapter 2 has provided insight into future population regeneration

capabilities of this lichen following forest fragmentation both in British Columbia and

beyond. It is important to understand these optimal growing conditions so that future

regeneration rates can be put into context.The baseline information documented in this

research will be helpful in future analyses as this ecosystem adapts to climate change.

59

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Appendix 1. Average abundance ratings for the lichen taxa observed on mountain alder trunks at 20 field sites in the ITR. Species names follow Esslinger (2010). The definitions of abundance ratings are given in Table 1.

Average abundance rating for each of 20 sites Avg.

Species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20across all sites

Alectoria sarmentosa 0.7 0.0 0.0 1.3 0.7 3.0 2.3 1.0 1.7 2.0 0.7 0.7 0.0 0.0 0.3 0.7 0.0 1.7 0.0 0.0 0.83Bryoria fuscescens 1.0 2.0 1.7 1.7 2.0 0.7 1.7 1.7 2.0 2.0 2.3 2.0 0.7 1.7 1.7 1.7 2.0 1.7 0.7 1.0 1.58Cladonia spp. Dendriscocaulon

0.7 1.0 0.3 0.3 1.0 0.7 1.3 0.3 1.7 0.0 0.0 0.0 0.3 0.3 0.3 0.7 0.0 0.0 0.3 0.7 0.50

spp.1.3 1.3 1.7 2.0 1.3 1.0 0.3 0.7 1.7 1.0 1.7 1.7 1.0 2.3 1.3 1.3 0.7 1.7 2.3 2.0 1.42

HypogymniaenteromorphaHypogymniaphysodesHypogymniatubulosa

0.7 1.0 0.3 0.3 1.0 0.3 0.0 0.3 1.0 1.3 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.3 0.38

0.7 0.3 1.3 1.7 1.0 1.3 0.7 0.3 2.3 1.0 0.3 1.7 1.0 1.7 2.7 0.7 1.3 1.0 0.7 0.0 1.08

0.7 1.7 1.0 0.3 0.7 0.0 0.7 0.7 0.3 0.3 0.0 1.7 0.0 0.7 1.3 0.7 0.3 0.3 0.7 0.7 0.63

Hypogymnia vittata 3.0 2.7 2.7 2.7 2.7 2.7 3.0 2.7 3.0 3.0 2.7 2.7 2.0 2.7 3.0 2.0 2.3 2.7 1.3 1.3 2.53Leptogium burnetiae 0.0 0.0 0.0 0.7 0.3 0.0 0.0 1.0 0.0 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.13Lobaria pulmonaria 4.0 3.0 3.7 3.0 3.0 3.7 3.7 3.0 3.3 3.0 3.3 3.7 3.7 3.0 2.7 3.3 3.7 2.0 3.0 3.0 3.23Lobaria retigera 1.0 0.3 0.0 0.0 0.0 0.7 0.7 0.3 0.0 0.0 0.0 0.3 0.0 0.0 0.7 0.0 0.0 0.0 0.0 0.7 0.23Lobaria scrobiculata Melanelixia

0.3 1.3 1.0 0.0 1.3 0.7 0.0 1.0 1.3 0.0 1.3 1.7 0.0 1.3 1.3 1.7 1.0 0.3 0.7 0.7 0.85

subaurifera Nephroma bellum Nephroma

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 1.0 0.0 0.0 1.3 0.0 0.0 0.0 0.0 0.0 0.7 0.3 0.0 0.18

1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 1.3 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.15

helveticum ssp. sipeanum

0.0 0.7 0.3 0.3 1.0 0.7 0.0 0.7 0.3 0.0 0.3 1.7 0.7 1.7 1.0 0.0 1.3 0.0 0.3 0.3 0.57

Nephroma isidiosum 1.7 1.3 1.7 1.0 1.0 1.0 1.0 1.7 1.3 0.0 1.7 1.7 1.3 2.0 2.0 0.3 1.3 0.3 0.7 0.0 1.15Nephroma occultum 0.3 0.3 0.0 0.7 0.0 0.7 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.3 0.3 0.0 0.0 0.0 0.0 0.15Nephroma parile 2.7 3.0 2.7 3.0 2.0 3.0 2.7 3.0 2.7 2.3 3.0 3.0 2.7 3.0 3.0 3.0 2.3 3.0 3.0 2.7 2.78Nephromaresupinatum

0.0 0.0 0.0 0.7 0.7 0.0 0.0 0.0 0.0 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.10

Parmelia hygrophila 0.0 0.0 1.3 0.7 1.3 1.7 2.0 2.0 3.0 2.7 1.3 2.7 1.7 1.3 1.0 1.7 2.0 2.3 2.0 1.7 1.62

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Average abundance rating for each o f 20 sitesAvg.

Species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 across all sites

Parmelia sulcata 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.7 3.0 3.0 3.0 3.0 3.0 3.3 3.0 3.3 3.0 3.0 3.0 3.0 3.07Parmeliopsis ambigua Parmeliopsis hyperopia Peltigera collina

0.0 0.3 0.3 0.0 0.3 0.0 0.0 0.0 ).0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.05

0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.03

1.0 0.7 0.0 0.7 0.7 0.0 1.7 0.7 1.3 0.3 0.0 0.3 1.3 0.7 0.0 0.3 0.0 0.0 2.0 0.3 0.60Physcia alnophila 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.02Platismatia glauca 0.3 1.0 2.0 2.7 1.7 2.0 2.7 1.0 3.0 3.0 0.7 2.0 0.3 1.0 2.3 0.0 1.3 1.7 1.0 1.3 1.55Polychidium spp. 0.0 0.0 0.3 0.0 0.0 0.7 0.0 0.0 0.3 0.0 1.0 0.7 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.19Pseudocyphellariaanomala

0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 1.0 2.3 0.0 0.3 1.7 0.7 0.7 0.0 0.3 0.7 0.42

Ramalina dilacerata 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.03Ramalina pollinaria 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.02Ramalina thrausta 2.3 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 2.7 3.0 3.0 3.0 3.0 3.0 3.0 3.0 2.7 2.93Stictaoroborealis &S. wrightiiSticta juliginosa

0.0 0.0 0.0 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.3 0.7 1.0 0.0 0.0 0.0 1.0 0.3 0.7 0.25

0.7 0.7 0.7 1.0 0.0 0.0 0.0 0.0 0.0 0.3 0.3 0.7 0.3 1.3 1.0 1.0 0.7 0.3 1.3 0.7 0.55Sticta limbata 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.7 0.0 0.05Sticta sylvatica 0.0 0.3 0.0 0.0 1.3 1.0 0.7 2.0 2.0 0.3 0.7 1.7 0.0 0.0 0.3 0.7 1.0 0.0 0.7 0.7 0.67Tuckermannopsis chiorophylla Usnea chaetophora

0.0 1.3 0.0 1.0 0.7 1.0 1.7 0.7 1.0 2.0 0.7 1.3 0.3 0.7 1.7 0.3 0.0 0.7 1.0 0.7 0.83

0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.3 0.3 1.0 0.3 1.0 0.3 1.0 0.7 1.7 1.0 0.45Usnea glabrata 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.3 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.10Usneafilipendula& U. scabrata 2.0 1.7 0.7 1.3 1.3 1.3 1.3 1.3 1.7 1.7 1.3 1.7 1.7 2.0 2.3 1.3 2.3 0.7 0.7 0.7 1.45

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Appendix 2. AIC comparisons for candidate logistic regression models used to explain variation in the number of L. pulmonaria thalli per segment, the total area and weight of L. pulmonaria per segment, the presence/absence of at least one reproductive thallus per segment, and the presence/absence of large thalli.

Model Parameters

Dependentvariable

Treespecies

AICcomparisons Age Diameter Distance Age +

DiameterAge + Distance

Distance + Diameter

Age + Distance + Diameter

Number of thalli per segment

Fir AICc 341.826 357.532 398.265 343.988 339.015 350.679 341.858A AIC 2.812 18.518 59.251 4.973 0.000 11.664 2.844

Alder AICc 230.087 285.494 284.566 233.023 229.694 270.974 232.208A AIC 0.393 55.800 54.872 3.329 0.000 41.280 2.514

Total Fir AICc 305.677 305.974 346.949 303.615 300.458 296.402 296.929segment L. A AIC 9.275 9.572 50.547 7.213 4.056 0.000 0.527pulmonaria

Alder AICc 222.430 246.323 243.200 224.387 217.170 232.789 219.568area A AIC 5.260 29.153 26.031 7.217 0.000 15.620 2.398Total Fir AICc 309.642 310.497 344.628 307.490 303.302 299.851 299.494segment L. A AIC 10.148 11.002 45.134 7.996 3.807 0.356 0.000pulmonaria

Alder AICc 220.890 244.600 237.959 221.000 215.040 229.624 215.003weight A AIC 5.887 29.597 22.957 5.997 0.038 14.622 0.000

Segmentreproductivecapacity

Fir AICc 266.589 267.152 329.337 265.021 263.619 259.392 260.905A AIC 7.196 7.760 69.944 5.629 4.227 0.000 1.512

Alder AICc 235.248 257.709 242.142 238.083 229.147 241.742 231.102A AIC 6.101 28.562 12.994 8.936 0.000 12.595 1.955

Maximum thallus size per segment

Fir AICc 290.278 293.564 339.727 289.424 282.094 279.665 280.190A AIC 10.613 13.899 60.062 9.759 2.429 0.000 0.525

Alder AICc A AIC

224.0076.302

250.29932.595

242.63124.927

225.6717.967

217.7040.000

234.73617.032

219.6231.918

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