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GEOGRAPHY 477
Exploring the transitional forest gap dynamics of small‐scale disturbances resulting in regeneration and increased species richness in Balu Pass, Glacier
National Park
Carley Coccola, Kim House, Kira Hoffman, and Annie Markvoort
December 15, 2011
Large and small scale natural disturbances shape and define characteristics of forest stands. This research examines the response of a western hemlock transitioning stand following small-scale gap producing events in Glacier National Park. A megaplot with three individual quadrats was selected for the study and dendrochronological, tree mensuration, vegetation and soil profile data was collected and analyzed. Results confirmed that three distinct age classes (new gap, intermediate gap, mature forest) were present in the megaplot, and that growth releases in dominant and sub-dominant trees corresponded with probable gap formation events. Productivity was found to increase in new gaps and stand dynamics were found to be significantly different in new and intermediate aged gaps. The dominant regeneration of western hemlock species on coarse woody debris supported the hypothesis that a transitional forest was present in this region of the Park.
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Table of Contents
List of Figures ..................................................................................................................... ii
1.0 Introduction ................................................................................................................... 1
2.0 Study Area .................................................................................................................... 3
3.0 Methods......................................................................................................................... 5
3.1 Plot Selection - Methods and Analysis ..................................................................... 5
3.2 Vegetation Survey - Methods and Analysis .............................................................. 6
3.3 Dendrochronology and Tree Mensuration - Methods and Analysis ......................... 7
3.4 Soil Samples - Methods and Analysis ...................................................................... 8
4.0 Results ......................................................................................................................... 9
4.1 Vegetation and Coarse Woody Debris Results ......................................................... 9
4.2 Dendrochronology and Tree Mensuration Results ................................................. 12
4.3 Soil Results ............................................................................................................. 18
5.0 Discussion ................................................................................................................... 19
6.0 Conclusion .................................................................................................................. 24
6.1 Limitations .............................................................................................................. 24
7.0 Acknowledgments ....................................................................................................... 25
References ......................................................................................................................... 26
Appendix A: Plant species observed in megaplot by Quadrat .......................................... 31
Appendix B: Estimated Percent Cover of Species in Structural Vegetation Layers by
Quadrat .............................................................................................................................. 32
Appendix C: Decay Classes for Course Woody Debris (BEC Field Manual) ................. 33
Appendix D: Age and health observations of 21 largest trees in megaplot ...................... 34
Appendix E: Tree Ring Growth Results ........................................................................... 35
Appendix F: Soil Properties and Results from pits in each Quadrat ................................ 43
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List of Figures
Figure 1: Location of Balu Pass, Glacier National Park, B.C. 3
Figure 2: Location and distribution of Interior-Cedar Hemlock zone in British Columbia 4
Figure 3: Schematic of the three quadrats within the megaplot. 6
Figure 4: Percent cover in each vegetation layer in the three surveyed quadrats. 10
Figure 5: Percent canopy closure of dominant and sub-dominant trees in the three
surveyed quadrats. 10
Figure 6: Species richness of ground cover, herbaceous and shrub layer is the three
surveyed quadrats. 11
Figure 7: Coarse woody debris transect. 12
Figure 8: DBH of mensurated trees in megaplot as a function of tree age. 13
Figure 9: Height of mensurated trees in megaplot as a function of tree age. 13
Figure 10: Average representative age of western hemlock trees per quadrat. 14
Figure 11: Age distribution of regenerating hemlock seedlings in quadrat one. 16
Figure 12: Height as a function of DBH for western and mountain hemlock species in
quadrat three. 17
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1.0 Introduction
An ecological disturbance is characterized by a temporary shift in equilibrium, resulting
in a pronounced change in an ecological system (Krebs, 1999). The forests of Glacier National
Park (GNP) experience several types of natural and anthropogenic disturbances that differ in
scale, intensity, and frequency. Large-scale natural disturbances within GNP occur as a result of
weather, insects, and disease (Parks Canada, 2009). Weather events, such as lightning and heavy
snowfalls cause avalanches and forest fires, which regularly damage entire forest stands
(Johnson et al., 1990). Forest pathology research has shown that western hemlock looper and
western balsam bark beetle cause significant damage and inhibit growth within Interior Cedar-
Hemlock (ICH) forests (McCloskey et al., 2009; Parks Canada, 2009; MacLauchlan et al.,
2003).
Humans have also had an effect on disturbances within the park. First Nations, including
the Secwepemc, Okanagan, and Ktunaxa people traditionally used the land within the park for
seasonal hunting and foraging (McCleave, 2008). Since the arrival of western settlers, significant
anthropogenic alterations of the landscape have occurred, such as the construction of the
Canadian Pacific Railway through Rogers Pass and the ongoing avalanche control along the
highway corridor (Downs, 1980). Regardless of the cause of disturbance, regeneration is often
inhibited in tree stands by intense snow pack and brush dominated species like alder (Alnus) or
thimbleberry (Rubus parviflorus) (Parks Canada, 2009).
Although large-scale disturbances have dramatic effects on a forest, small-scale
disturbances such as those producing gaps in the forest canopy can have greater overall effects in
a forest (Spies et al., 1990). Small canopy gaps, or forest gaps, are an important factor in
disturbance regimes and vegetation growth (Scharenbroch and Bockheim, 2007; Duncan et al.,
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1998). Forest gaps characterize a disturbance where a singular dominant tree dies or loses a
branch, creating a small opening in the forest canopy (McCarthy, 2001). Dominant trees are
often the tallest and oldest trees in a stand. These trees are often partially decayed and the first to
be affected by severe weather events (Coates, 2000).
Gaps naturally occur in old growth and mature forests and are an indicator of overall
forest health (Yamamoto, 2000). Researchers use gap dynamics to study the rate of regeneration
in a site and the pioneer species associated with single-tree disturbances (Runkle, 1992). The
theory of gap dynamics proposes that canopy gaps provide increased solar radiation, higher soil
temperatures, and soil moisture (Scharenbroch and Bockheim, 2007; Gray and Spies, 1997).
These conditions create microclimates that favour shade-intolerant species (Yamamoto, 2000).
The balance between increased sunlight and shade from stumps and coarse woody debris (CWD)
enhances seedling survival (Gray and Spies, 1997). CWD allows for recruitment of western
hemlock seedlings, which out-compete other species because of their ability to germinate in a
litter void of mosses (Peterson et al., 1997). These optimal growing conditions increase species
richness; defined as the number of different species within a given area (Peterson et al., 1997;
Siitonen et al., 2000). Gaps in the canopy cover affect species composition, succession, nutrient
cycles, and habitat structure (Spies et al., 1990). Forest gaps dynamics have been predominantly
studied in tropical and temperate hardwood forests and to a lesser extent in western Canadian
coniferous forests (Spies et al., 1990; Bartemucci et al., 2002).
This research examines whether new forest gaps support increased species richness and
productivity in ICH forests of GNP. The objectives of this research are twofold: (1) Describe
small-scale disturbances using dendrochronological and ecological survey techniques supported
3
by soil profile analysis to examine species replacement patterns. (2) Discuss whether
productivity and species richness increase or decrease as a gap matures.
2.0 Study Area
The study was conducted in Balu Pass, GNP in the Columbia Mountains of southeast British
Columbia, Canada (Figure 1). A megaplot was selected in the study area and located at
N51o18’01”, W117o31’26” at 1386 m above sea level. The megaplot has an east-facing aspect
with slope gradients ranging from 24% to 61%. According to British Columbia’s ecosystem
classification system, the megaplot is situated within the ICH biogeoclimatic zone with the sub-
classification mk1 (Figure 2), just below the elevation of Engelmann Spruce Sub-Alpine Fir
(ESSF) zone (Ketcheson et al., 1991).
Figure 1: Location of Balu Pass, Glacier National Park, B.C.
.
The climate in GNP is classified as interior continental, with cool, wet winters and warm, dry
summers influenced by easterly flowing air masses (Johnson et al., 1990). These rising air
masses cause expansion and cooling which result in high precipitation throughout the park. Mean
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annual precipitation is 1278 mm (Parks Canada, 2011) and average monthly temperatures range
from -9 to +20 degrees Celsius (Parks Canada, 2009b). Within the megaplot, soils ranged from
brunisolic to podzolic development, with an overall soil podzolic classification due to elevation
and precipitation (Coates, 2002).
Figure 2: Location and distribution of Interior-Cedar Hemlock zone in British Columbia (Ministry of Forests, 2011).
The ICH in GNP is an example of a productive forest with abundant tree species including:
western hemlock (Tsuga heteophylla), mountain hemlock (Tsuga mertensiana), sitka spruce
(Picea sitchensis), western red cedar (Thuja plicata), and sub-alpine fir (Abies lasiocarpa).
Characteristic vegetation of the area includes devil’s club (Oplopanax horridus), lady fern
(Athyrium filix-femina), oak fern (Gymnocarpium dryopteris), rosy twistedstalk (Streptopus
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roseus), spiny wood fern (Dryopteris expansa) oval-leaved blueberry (Vaccinium ovalifolium),
and black huckleberry (Vaccinium membranaceum) (Ketcheson et al., 1991; Pojar et al., 2008;
MOF, n.d).
3.0 Methods
3.1 Plot Selection ‐ Methods and Analysis
A large plot was chosen to obtain information on a wide range of species growing in
seemingly similar forest conditions (Clark and Clark, 1992). A rectangular plot measuring 40 m
x 15 m was established by determining a perimeter with a compass, measuring tape, and a hand-
held Garmin GPS receiver. Elevations and locations (latitude/longitude) were recorded at each
corner of the megaplot and slope was measured at five locations across the megaplot. Tree
density was estimated to ensure the megaplot contained a minimum of 20 trees. Plot size and
location were determined by the hypothesized existence of a single forest type with three distinct
age classes. These age classes were delineated to create three distinct quadrats: quadrat one was
classified as open canopy, quadrat two as closed canopy, and quadrat three as intermediate
forest. A sketched map was created to log the plot perimeter, age class perimeters, and locations
of significant CWD, soil pits, tree cores, and tree samples. Upon returning to the lab, a finalized
map with all of the relevant information was produced (Figure 3).
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Figure 3: Schematic of the three quadrats within the megaplot. .
3.2 Vegetation Survey ‐ Methods and Analysis A complete species list of mosses, herbaceous plants, and shrubby plants was assembled
within each of the three quadrats (Appendix A) (Pojar et al., 2008; Parish et al., 1996). For each
quadrat, the percent cover by layer of mosses, herbs, and shrubs was recorded and percent
canopy closure was estimated visually (Roush, 2007; BEC Field Manual, 1998). Within each of
these layers, the percent cover of each individual species was estimated visually to the nearest
1%, after averaging estimations made throughout the quadrat (Appendix B). The vegetation data
collected was used to demonstrate the qualitative differences between the three time series gaps.
Visual representations of species richness (ground cover, herbaceous, shrub) among the three
quadrats as well as percent cover by layer were created.
7
A survey of CWD, defined as fallen trees or branches, uprooted trees no longer living,
and other wooden debris that are not self-supporting, was taken via a transect, which crossed
through the three quadrats at the centre of the megaplot (BC MOE and MOF, 1998). Diameter
and decay class were recorded for every piece of CWD encountered along the transect with a
diameter greater than 7.5 cm (BEC Field Manual, 1998). CWD decay classes were recorded on a
scale of 1-5, with “6” added as an additional class for CWD that had undergone significant decay
(Appendix C). To reduce the chance of bias in the results, two individuals estimated and
compared classifications for each piece of CWD.
3.3 Dendrochronology and Tree Mensuration ‐ Methods and Analysis
Living tree cores and tree measurements were collected from the largest twenty-one trees
in the megaplot (Appendix D). Six mature hybrid sitka spruce trees were cored outside the plot
to assess the general age class of the stand and to evaluate whether the forest was transitioning to
a new dominant species. The trees in the plot and the hybrid trees were sampled using the
following standards. Trees were sampled radially at breast height using a 5.2 mm increment
borer. One core was taken per tree, but in the instances of rot, two cores were taken to provide a
longer chronology. Cores were stored in plastic straws for transport to the University of Victoria
Tree Ring Lab, where analysis was conducted. Circumferences of trees were measured on the
upper slope using a measuring tape at breast height (~1.3 m). Circumference measurements were
adjusted to diameter at breast height (DBH). This height was chosen because it is the standard
measurement to avoid swelling of the basal tree butt and other growth distortions (Roush,
2007).
8
Tree heights were acquired in metres using a Nikon range finder and these measurements
assisted with the on-site classification of dominant and co-dominant canopy trees. Species type,
overall tree health, and crown dimension were recorded to assess potential disturbances, such as
fire scars and insect outbreaks (Roush, 2007). Seed trees < 5 cm DBH and approximately 1 m in
height were cut with a handsaw. Cross-sectional cookies were taken for measurement. Individual
seedlings (<1 cm DBH and <1 m) were tallied and their age determined on site by counting
individual whorls.
To prepare for quantitative dendrochronological analysis, tree cores were air dried and
then glued on to slotted mounting boards (Hart el al., 2010). Cross-sections of cookies and
mounted cores were sanded with progressively finer sandpaper to a 600 grit-polish (Stokes and
Smiley, 1964). The exact age of each sample was determined using a Velmex stage and Wild
M3B microscope with 0.01 mm focusing power, coupled with a CCD video display. Exact-age
dating was applied where possible to provide a complete picture of the establishment and
mortality of trees in the plot (Gutsell and Johnson, 2002). Correlation analysis was conducted in
SPSS to verify if there was a relationship between the dependent variables (DBH and height) and
the independent variable (age), and to allow for the production of a simple model to predict age.
Analyses were also conducted to describe variations between quadrats.
3.4 Soil Samples ‐ Methods and Analysis
Three soil pits were dug to approximately 60 cm in the center of each of the three
quadrats and their locations were recorded with a hand-held Garmin GPS receiver. Soil horizon
depths as well as fabric and litter layers were measured with a measuring tape to millimeter
accuracy. The biotic composition of the litter layer was recorded to determine the presence of
9
organics, mycelium abundance, and detrital activity. The percent composition of fine fragments
(sand, clay, and silt) was estimated in each pit to determine the overall soil type. These were
estimated using a soil texture triangle, which included a taste test, moist cast test, and graininess
test (BEC Field Manual, 1998). The size and shape of the soil particles were classified and the
resulting drainage properties of the soil were estimated. The deposition of the area was noted
based on the surrounding local geomorphology. Soil samples containing gravels <7 cm from
each pit were collected in petri dishes for examination. Samples were taken from each horizon,
dried, and then classified using a Munsell color chart (BEC Field Manual, 1998).
4.0 Results
4.1 Vegetation and Coarse Woody Debris Results
The percent cover within each of the three structural vegetation layers (ground cover,
herbaceous, shrub) was highest in quadrat one (Figure 4). Quadrat two had lower percent cover
in each layer, and quadrat three had the lowest overall percent cover. These results were
consistent with the percent canopy closure of dominant and sub-dominant trees within each
quadrat (Figure 5). Quadrat one, the youngest hypothesized gap, had only two dominant trees
leading to 10% canopy closure. This contributed to the high percent cover of understory species
observed (Figure 4). Quadrat two, hypothesized to be relatively even-aged mature living forest,
had 85% canopy closure with low understory species biomass. Quadrat three, the hypothesized
intermediate gap, had a very dense sub-dominant tree layer, which coincided with the lowest
percent cover of understory biomass. Here, the distribution of western hemlock and mountain
hemlock resulted in a canopy closure of 95%.
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Figure 4: Percent cover in each vegetation layer in the three surveyed quadrats.
Figure 5: Percent canopy closure of dominant and sub-dominant trees in the three surveyed quadrats.
Species richness varied among the three quadrats (Figure 6). Quadrats one and two had
the same overall species richness although a higher number of mosses were growing in quadrat
one. It should be noted that although species richness was similar between these two areas,
richness reflects absolute counts of species and not percent cover. Percent cover was still
0 10 20 30 40 50 60 70 80 90 100
1 2 3
Total Percent Cover (%
)
Quadrat
% ground cover
% herbaceous
% shrub
0 10 20 30 40 50 60 70 80 90 100
1 2 3
Percent Canopy Closure (%
)
Quadrat
% Mountain Hemlock
% Western Hemlock
11
significantly higher in quadrat one (Figure 4). In quadrat three, species richness was substantially
lower in all sub-canopy layers. This coincided with the high canopy closure of sub-dominant and
dominant trees.
Figure 6: Species richness of ground cover, herbaceous and shrub layer is the three surveyed quadrats.
The volume, size, and decay of CWD varied significantly along the transect (Figure 7).
The first 15 metres of the transect were within quadrat one, where a high volume of CWD
existed. From 15 to 27 metres, the transect passed through quadrat two where several large,
standing hemlock trees resulted in very little CWD. From 27 to 40 metres, the transect passed
through quadrat three where a dense stand of small hemlock trees was growing. Here, the
volume of CWD increased again; however, this increase was noted in decay classes five and six.
Some of the CWD in this quadrat was severely decayed and could not be recorded in the CWD
transect results.
0
5
10
15
20
25
1 2 3
Species Richness (count)
Quadrat
Shrub/tree
Herb
Ground Cover
12
Figure 7: Coarse woody debris transect.
4.2 Dendrochronology and Tree Mensuration Results
The final chronology of the plot extended 270 years with the sample age uniformly
distributed. Pith was achieved for most of the trees in the survey area, but exact ages remained
unknown where rot was encountered. Based on statistical analysis, Pearson’s correlation (R)
was 0.948 between DBH and age and 0.932 between height and age. Due to this strong
relationship, DBH and height were plotted against age and a least squares regression was applied
(Figure 8 and 9 respectively) to determine whether age explained either of the dependent
variables. The coefficient of determination (R2) for height as a function of age was 0.8686,
whereas the R2 value for DBH as a function of age was 0.898.
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Figure 8: DBH of mensurated trees in megaplot as a function of tree age.
Figure 9: Height of mensurated trees in megaplot as a function of tree age.
y = 0.0025x ‐ 0.0045 R² = 0.898
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0 50 100 150 200 250 300
Diameter at Breast Height (m)
Ages (years)
y = 0.1084x + 2.2641 R² = 0.86861
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
0 50 100 150 200 250 300
Height (m)
Tree age (years)
14
As a result, age was concluded to have a stronger relative strength index with DBH than
with height (McGrew and Monrow, 2000). Therefore, the model produced for the linear
relationship of tree age and DBH was used to extrapolate estimated ages for trees where pith was
not achieved. The known and estimated ages were then plotted per quadrat to give an average
representation of western hemlock species within the survey area (Figure 10). The six hybrid
sitka spruce trees sampled outside of the megaplot were found to be complacent and
approximately 200 years old.
Figure 10: Average representative age of western hemlock trees per quadrat.
Each individual core was visually cross dated to assess and compare growth release rings
surrounding potential gap formations. Dendrochronological analysis resulted in an average age
class per quadrat, allowing for the examination of relationships within gaps and between
trees. A period of good growth throughout the megaplot was observed between approximately
1950 and 1960 AD. This growth did not correspond with any known gap formations and was
likely the result of favorable climatic conditions in the region. However, consistent growth
0
50
100
150
200
250
300
350
0 1 2 3
Age (years)
Quadrat
15
releases in trees surrounding gaps are suspected to be the result of the mortality of a dominant
tree (Speers, 2010). These growth results are specified below with respect to each quadrat
(Appendix E).
Quadrat One
Only two large trees were found within quadrat one as the rest of the quadrat consisted of
an open forest gap comprised of ground cover species, herbaceous plants, shrubs, and hemlock
seedlings. The average age throughout the open gap area was 11.9 years with a standard
deviation of 10.5 years. Good growth conditions were observed in the dominant trees in the gap
from approximately 1980-1985 AD, corresponding to the probable time of seedling germination
in the centre of the gap. Within the time periods 1940-1945 AD and 1920-1925 AD, trees
surrounding the gap demonstrated distinct growth releases, likely coinciding with the time of the
disturbance which formed the gap.
The age of the oldest sapling in quadrat one was 43 years and is likely one of the first
individuals to have re-colonized the gap following the disturbance. The three larger saplings in
the gap were identified as western hemlock and found on the perimeter of the open area. The age
of saplings and seedlings ranged considerably within the quadrat, and overall western hemlock
productivity was high. For example, on a single nursing log, 209 live one-year old hemlock
seedlings were counted. The age distribution of regenerating hemlock seedlings was plotted to
show the variability in the population (Figure 11).
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Figure 11: Age distribution of regenerating hemlock seedlings in quadrat one.
Quadrat Two
The trees in quadrat two were the oldest in the megaplot based on their average age of
216 years (Figure 10). Based on the dendrochronological results no overarching growth
correlations were observed among the total population of quadrat two. However, growth release
patterns in several trees of quadrat two corresponded with the estimated age of the gaps in
quadrats one and three.
Quadrat Three
The trees in quadrat three were an evenly aged distribution of western hemlock and
mountain hemlock species, with only 67.3% living trees (33) and 32.7% (16) dead trees. The
height of all the living trees plotted against DBH had a linear correlation with a Pearson’s R
value of 0.787 (Figure 12).
0 5 10 15 20 25 30 35 40 45 50
Age (years)
17
Figure 12: Height as a function of DBH for western and mountain hemlock species in quadrat three.
Our results point at two disturbances that affected growth in quadrat three over
approximately 120 years, as was evident in the older trees (approximately 200 years)
surrounding the gap in quadrat three. These trees demonstrated growth releases between 1930-
1940 AD. The average age of living, juvenile trees populating this intermediate gap is 68 years,
with a standard deviation of 11 years. The average age of the living trees corresponds with the
growth release of the larger trees surrounding the quadrat. The 200-year-old trees also
demonstrated a growth release approximately 1890-1900 AD, which might have also resulted
from a small-scale disturbance event. The gap in quadrat three is distinctive from the gap found
in quadrat one due to the older average stand age, higher density of trees, and higher rate of
mortality.
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4.3 Soil Results
Soils in quadrat one were classified as a silty loam and soils in quadrats two and three
were classified as fine sandy loams. These classifications were derived from the percent of fine
fragments. Although overall soil types in each quadrat were similar, substantial differences in the
litter and fabric layers as well as the A horizons existed between pits (Appendix F). Fine
fragments were classified as sands, silts or clays. Course fragments (>2 mm) were classified as
sub-angular in each pit and were relatively uniform in abundance. Sites were classified with a
colluvium deposition based on the slope and geomorphology of the area.
Soil pit one had no litter layer but a fabric layer of 2.3 cm depth. The colour of the humus
layer indicated there was a high level of organic material present. The A horizon was strongly
leached into the lower horizons creating a distinctly white appearance. This soil pit was
classified as a well-drained podzolic silty loam based on the presence of fine fragments, biotic
component, color, and underlying geomorphology.
Soil pit two also had no distinguishable litter layer and had the smallest observed fabric
layer of 1.9 cm depth. There was a trace of an organic layer present directly above the A layer
and below the humus layer. There were two A horizons identified in the pit, both of which were
less leached than pit one resulting in a more pinkish appearance. This soil pit was classified as a
well-drained podzolic fine sandy loam based on the greater percent of fine fragments, biotic
component, lighter color, and underlying geomorphology.
Soil pit three was the only pit that had a distinct litter layer. This litter layer was
significant and measured to 5.0 cm in depth. Pit three also contained the largest fabric layer at
3.0 cm, with significant amounts of consolidated matted mycelium matter. Beneath the trace
humus layer, two leached A horizons were present. Leaching was not as obvious as in pit one,
19
leaving the soil with a pinkish grey appearance. This soil pit was classified as a well-drained
podzolic fine sandy loam based on the greater percent of fine fragments, biotic component,
lighter color, and underlying geomorphology.
5.0 Discussion
Dendrochronological and forest mensuration results from the three quadrats within the
megaplot describe four potential single disturbance events over a period of approximately 120-
130 years. These four separate disturbances are most likely the result of dominant tree mortality
events, which was evident due to the abundance and decomposition of course woody debris in
the gap areas of quadrats one and three. Our results are consistent with mensuration studies
completed in the ICH of the Columbia Mountains by Wright el al., (1998) and those done by
Coates (2000, 2002) in northern British Columbia examining frequency of canopy gap
formations due to small-scale disturbances in mature, species-diverse forests. Small-scale
disturbances give rise to canopy openings, which support greater species richness as well as
greater species percent cover in all sub-canopy layers. Disturbances therefore play a key role in
determining the distribution and abundance of species in a forest (Pickett and White, 1985).
Our study site presented an opportunity to examine three distinct and diverse age classes
as well as their representative microclimates occurring within a very condensed setting. Our
results were consistent with our hypothesis that three distinct age classes existed, but also
furthered a subsequent hypothesis that small-scale disturbances regulate species replacement
patterns and can create transitional forests. This subsequent hypothesis was supported by the
presence of mature sitka spruce hybrids found in the area surrounding our study site. Although
subsequent analysis of the hybrid sitka spruce outliers revealed that they were in the same age
20
class as quadrat two (approximately 200 years old), it was important to note their complacent
rings, dominance in the forest canopy, and lack of seedlings present in the understory. The
reasons for this may be that the sitka spruce hybrids are being out-competed by western hemlock,
or that they simply prefer more heterogeneous stands and have specific microsite requirements.
Although these are hybrid species and it is difficult to determine their growth requirements, sitka
spruce are often found intermixed with other species, increasing the overall resilience of a stand
(Peterson et al., 1997).
Increased canopy heterogeneity suggests that the forest is transitioning from a mature to
an old growth stage. This hypothesis is further supported by the presence of several large
veteran trees, snags, CWD, and various stages of successional regrowth (BEC manual, 1998). In
areas like GNP, which have a high frequency of large-scale disturbances, small-scale
disturbances like those in this study may provide a niche for the future species composition of
the forest (Sherman et al., 2000).
The three quadrats in the megaplot are examples of an ICHmk1 in three distinct age
classes. Quadrat one in the megaplot represents the youngest age class in the study. Formed
likely by a single disturbance event, it had all the characteristics of a traditional forest gap
(Peterson et al., 1997). Here, a significant amount of partially decomposed CWD provided the
basis for new generations of western hemlock trees. In this quadrat, a single remaining veteran in
the southwest corner of the quadrat, which offered only 10% canopy closure, provided the shade
required to support primary succession in the gap. The average age of juvenile trees in the
quadrat was approximately 11 years. This, along with the presence of more than 200 new
seedlings supported quadrat one as the youngest age class in the megaplot.
21
As an intermediate age class, quadrat three demonstrated a more progressed stage of
hemlock gap colonization. The deep litter and fabric layers, coupled with stage six
decomposition of CWD confirmed that quadrat three is a gap, which likely formed following the
fall of a veteran tree. The amount and density of trees within this small quadrat (more than 30)
with a relatively even age of about 70 years, suggest that this quadrat was a mature gap with an
intermediate age class. Seedlings likely germinated following the formation of a gap and
subsequently out-competed each other for light and nutrients.
Quadrat two, in the centre of the megaplot, was the oldest age class in the study area,
with several evenly-spaced large hemlock trees spanning the quadrat. Although many of the trees
experienced some form of damage, there was no evidence of constant stress as evident in tight
ring widths among the stand. The limited amount of CWD indicated an absence of small-scale
disturbance events. A very thin fabric and litter layer in conjunction with an 85% closed canopy
substantially reduced the percent cover of species in the understory. The trees in quadrat two are
an example of a successional stand that is too large to be formed by a small, single disturbance
event. The consistent age stand (with all samples approximately 200 years or older) was likely
established following a larger scale disturbance.
Although it was hypothesized that species richness would increase with the formation
of a new gap, our results show that the overall species richness in our young gap did not differ
from species richness in a stable stand (quadrat two). These findings indicate that either there is
no increase in species richness with the formation of a gap, or that the spatial autocorrelation
between quadrat one and quadrat two caused species richness to be constant. However, in
comparing the two gaps, it was found that species richness in the young gap (quadrat one) was
significantly higher than richness in the intermediate gap (quadrat three). Despite the species
22
richness findings, significant differences in productivity between the three quadrats were
observed.
The plant community found in quadrat one represented species that are “gap requiring,”
made evident by the fact that they were present in high percentages in the gap (Appendix B)
(Avecedo, 1995). Microclimatic elements such as sunlight availability, increased precipitation,
soil temperature, substrate, organic matter, and edge effects (drip line) also influenced the type
and abundance of plants in the early successional gap community (Appendices A, B). Soil pits
were initially introduced in the study to compare potential differences between “gap requiring”
species and shade tolerant species, as well as their respective underlying substrates (Wright et
al., 1998). Although the organic component was higher in quadrat one, increased leaching of the
A horizon pointed to the potential lack of retention and absorption by dominant trees, which may
lead to less moisture availability due to the nature of a well drained soil (Appendix F). This lack
of moisture availability may influence the overall structure of the plant community.
The occurrence of small-scale disturbances, which increase the volume of CWD in a
forest, offers considerable regeneration potential for species such as western hemlock (Lertzman,
1992; Lorimer, 1984). This was apparent in our megaplot, where high amounts of fallen,
decomposing trees and CWD had a direct relationship with the growth of western hemlock
seedlings. As suggested in other studies, germination of western hemlock is dominant in
comparison with other tree species (mountain hemlock, subalpine fir, sitka spruce, western red
cedar) on fallen logs and tip-up mounds found in gaps created from a single tree-fall event
(Peterson et al., 1997; Lorimer, 1984;). Quadrat one provided a clear example of this where we
observed the growth of at least 209 seedlings on a single fallen veteran. More than 40 other
western hemlock trees between the ages of 3 and 43 were counted in the same quadrat. In
23
addition to the presence of CWD, the availability of abundant sunlight and water likely
supported early stages of germination.
Time varies based on microsite conditions, but in pristine conditions, germination occurs
approximately 2-3 years after a disturbance. The delayed germination within the megaplot could
be attributed to the elevation and reduced growing season of the site. Western hemlock trees
were dominant in the megaplot canopy and in the surrounding stand. Their dominance in the
understory as well suggests that western hemlock species are particularly good at regenerating in
areas with CWD. Although western hemlock demonstrates high seedling germination rates,
significant consequences of elevated gap productivity were also observed in quadrat three.
Quadrat three presented a situation where gap formation led to an increased rate of
regeneration that resulted in the subsequent mortality of juvenile western hemlock. It is
hypothesized that this was due to increased competition for limiting growth factors, such as
sunlight and nutrients. Likely the gap in quadrat three was highly productivity in the early stages
of its formation when sunlight was abundant and CWD nursing logs were moderately
decomposed. This is evident by the dense network of similarly aged western hemlock in the
stand growing on decaying remnants of CWD. High volumes of CWD lead to greater
concentrations of nutrients in the soil and higher moisture retention. These conditions are ideal
for species recruitment (Siitonen et al., 2000).
This supports our theory that most trees germinated during favorable conditions
following a small-scale disturbance. This response is typical in gap formations of the ICH,
known for its dense forest canopy and shade tolerant plant communities (Wright et al., 1998).
Also evident in quadrat three is the transition away from a gap phase as the stand matures, out-
competed species die, and dominant and sub-dominant trees take hold. This quadrat exemplifies
24
successional gap dynamics and the transition that occurs when light and nutrients are limiting
factors in a stand.
6.0 Conclusion
This study confirms our hypothesis that new forest gaps support increased species
richness and productivity in ICH forests of GNP. Our study demonstrated that young gaps with
large openings had higher species percent cover and richness in all vegetation layers in
comparison to intermediate gaps that have dramatically reduced percent cover and richness as
they progress into an intermediate age class. Good growth conditions resulting from small-scale
disturbances increase productivity, which can lead to increased density of the stand and higher
inter-intra species competition resulting in mortality. In all quadrats, western hemlock was the
dominant regenerating species, which suggests the megaplot was in a transitioning forest on the
edge of the ICH and ESSF biogeoclimatic zones. Germination of western hemlock trees was
most successful when CWD was present in decay class three or greater. Gaps increase
understory heterogeneity, which increases overall forest health and represents a key component
of old growth forest dynamics.
6.1 Limitations
Statistical differences between the quadrats could not be computed due to the lack of
repeated variables (McGrew and Monrow, 2000). Time constraints at the study site also limited
our ability to conduct and collect data in numerous megaplots for direct comparison.
25
7.0 Acknowledgments
We would like to thank Dan Smith and Jim Gardner for an amazing educational
experience in such a beautiful area. We would also like to thank our teaching assistant Kara
Pitman for all her assistance out in the field and back in the lab. Thanks to Jodi Axelson for her
ecological expertise and for helping us with our study goals and data collection, and thanks to
Bethany for all her positive energy. We had so much fun!
26
References
Bartemucci, P., Coates, K. D., Harper, K. A. and Wright, E. F. 2002. Gap disturbances
in northern old growth forests of British Columbia, Canada. Journal of Vegetation
Science, 13(5): 685-696. doi:10.1111/j.1654-1103.2002.tb02096.x
BC Ministry of Forests (MoF). n.d. The ecology of the Interior-Cedar Hemlock zone:1-6.
Retrieved from: http://www.for.gov.bc.ca/hfd/pubs/docs/Bro/bro48.pdf
Clark, D. and Clark, D. 1992. Life-history diversity of canopy and emergent trees in
neo-tropical rain-forest. Ecological Monographs, 62(3): 315-244.
Coates, D.K. 2000. Conifer seedling response to northern temperate forest gaps. Forest
Ecology and Management. 127: 249-269.
Coates. D.K. 2002. Tree recruitment in gaps of various size, clearcuts and undisturbed
mixed forest of interior British Columbia, Canada. Forest Ecology and Management.
155: 387-398.
Coupe, R., Stewart, A. C. and Wikeem, B. M. 1991. Chapter 15: Engelmann spruce
subalpine fir zone. In D. Meidinger and J. Pojar (Eds.), Ministry of Forests, Ecosystems
of British Columbia, 223-236. Victoria, Canada: Research Branch. Retrieved
http://www.for.gov.bc.ca/hfd/pubs/docs/srs/Srs06/chap15.pdf
Downs, A. (Ed). 1980. Incredible Rogers Pass. Frontier Books: Surrey, British
Columbia. Frontier Books: Surrey, British Columbia, 14, 34.
Duncan, R., Buckley, H., Urlich, S., Stewart, G., and Geritzlehner, J. 1998. Small-scale
species richness in forest canopy gaps: The role of niche limitation versus the size
of the species pool. Journal of Vegetation Science, 9(3): 455-460
doi:10.2307/3237109
27
Gray, A. N. and Spies, T. A. 1997. Microsite controls on tree seedling establishment in
conifer forest canopy gaps. Ecology, 78(8): 2458-2473. doi:10.1890/0012-9658
Gutsell, S.L. and Johnson, E.A. 2002. Accurately aging trees and examining their
height-growth rates: implications for examining forest dynamics. Journal of Ecology.
90:153-166.
Hart, S.J., Clague, J.J. and Smith, D.J. 2010. Dendrogeomorphic reconstruction of
Little Ice Age paraglacial activity in the vicinity of the Homathko Icefield,
British Columbia Coast Mountains, Canada. Geomorphology. 121: 197-205.
Johnson, E., Fryer, G., and Heathcott, M. 1990. The influence of man and climate on
frequency of fire in the Interior wets belt forest, British Columbia. Journal of Ecology,
78(2): 403-412.
Ketcheson, M. V., Braumandl, T. F., Meidinger, D., Utzig, G., Demarchi, D. A. and
Wikeem, B. 1991. Chapter 11: Interior Cedar-Hemlock zone. In D. Meidinger and J.
Pojar (Eds.), BC Ministry of Forests, Ecosystems of British Columbia, 167-181. Victoria,
Canada: Research Branch. Retrieved from
http://www.for.gov.bc.ca/hfd/pubs/docs/srs/srs06/chap11.pdf
Krebs, C. J. 1999. Ecological methodology. Menlo Park, California: Benjamin/Cummings. 39-40
Lertzman, K.P. 1992. Patterns of gap-phase replacement in a subalpine, old-growth
forest. Ecology, 73(2): 657-669.
Lorimer, C. 1984. Methodological considerations in the analysis of forest disturbance
history. Can. J. For. Res. 15: 200-213.
28
Maclauchlan, L.E, Bleiker, K.P, and Lindgren, B.S. 2003. Characteristics of subalpine fir
susceptible to attack by western balsam bark beetle (coleoptera: Scolytidae). Canadian
Journal of Forest Research, 33(8): 1538-1538. doi:10.1139/x03-071
McCarthy, J. 2001. Gap dynamics of forest trees: A review with particular attention to
boreal forests. Environmental Reviews, 9(1): 1-1. doi:10.1139/er-9-1-1
McCleave, J.M. 2008. Chapter 7: Mount Revelstoke and Glacier National Parks. The
regional integration of protected areas: a study of Canada's national parks. Unpublished
PhD dissertation. University of Waterloo, Waterloo, Ontario, 198-229.
McCloskey, S., Daniels, L. and McLean, J. 2009. Potential impacts of climate change on
western hemlock looper outbreaks. Northwest Science, 83(3): 225-238.
McGrew, J.C., and Monroe, C.B. 2000. An introduction to statistical problem solving in
Geography. United States of America: The McGraw-Hill Companies, Inc.
Parish, R., Lloyd, D., Coupé, R., and Antos, J. 1996. Plants of southern interior British
Columbia. Vancouver: Lone Pine Pub.
Parks Canada. 2009. Glacier National Park of Canada: Old growth inland forest.
Retrieved from: http://www.pc.gc.ca/pn-np/bc/glacier/natcul/natcul1/c.aspx
Parks Canada. 2009b. Teacher Resource Centre: Glacier National Park of Canada.
Retrieved from: http://www.pc.gc.ca/apprendre-learn/prof/itm2-crp-
trc/htm/fglacier_e.asp
Parks Canada. 2011. Glacier National Park of Canada - Weather and Climate. Retrieved
from: http://www.pc.gc.ca/pn-np/bc/glacier/visit/visit4.aspx
29
Peterson, E.B., Peterson, N.M, Weetman, G.F, and P.J. Martin. 1997. Ecology and
management of sitka spruce: emphasizing its natural range in British Columbia.
UBC Press: Vancouver, 80-81.
Pickett, S.T.A. and White, P.S. 1985. The Ecology of Natural Disturbance and Patch
Dynamics. Academic Press Inc., New York, NY.
Pojar, J., MacKinnon, A. and Coupe, P. B. 2008. Plants of Coastal British Columbia,
including Washington, Oregon & Alaska. Edmonton: Lone Pine Pub.
Roush, W. 2007. A substantial upward shift of the alpine treeline ecotone
in the southern Canadian Rocky Mountains. MSc Thesis: University of Victoria, 1-
175.
Runkle, J. R., 1951, and The Pacific Northwest Research Station (Portland, Or.). 1992.
Guidelines and sample protocol for sampling forest gaps. No. 283. Portland, Or:
U.S.D.A. Forest Service, Pacific Northwest Research Station.
Selkirk College. n.d. What is the biogeoclimatic ecosystem classification? Retrieved from
http://selkirk.ca/discover/bec/zones/whatis.html
Scharenbroch, B. C. and Bockheim, J. G. 2007. Impacts of forest gaps on soil
properties and processes in old growth northern hardwood-hemlock forests. Plant
and Soil, 294(1): 219-233. doi:10.1007/s11104-007-9248-y
Sherman, R.E., Fahey, T.J, and Battles, J. J. 2000. Small scale disturbance and
regeneration dynamics in a neotropical mangrove forest. Journal of Ecology.
88(1): 165-168.
30
Siitonen, J., Martikainen, P., Punttila, P. and Rauh, J. 2000. Coarse woody debris and
stand characteristics in mature managed and old-growth boreal mesic forests in
southern Finland. Forest ecology and management. 128: 211-225.
Spies, T., Franklin, J. and Klopsch, M. 1990. Canopy gaps in douglas-fir forests of the
Cascade Mountains. Canadian Journal of Forest Research. 20(5): 649-658.
doi: 10.1139/x90-087
Speers, J.H. 2010. Fundamentals of tree ring research. The University of Arizona Press.
Tucson, USA, 192-194.
Stokes, M.A. and Smiley, T.L. 1964. An Introduction to Tree-Ring Dating. Chicago:
University of Chicago Press, 69-73.
Wright, E.F., Canham, C.D. and Coates, K.D 2000. Effects of suppression and
release on sapling growth for 11 tree species of northern, interior British
Columbia. Canadian Journal of Research 5(1): 197-202.
Yamamoto, S. 2000. Forest gap dynamics and tree regeneration. Journal of Forest
Research, 5(4): 223-229. doi:10.1007/BF02767114
31
Appendix A: Plant species observed in megaplot by Quadrat
Quadrat 1 Quadrat 2 Quadrat 3 common name latin common name latin common name latin
Western hemlock tsuga heterophylla Western hemlock tsuga heterophylla
Western hemlock tsuga heterophylla
Mountain hemlock Tsuga mertensiana Mountain
hemlock Tsuga mertensiana Mountain hemlock Tsuga mertensiana
Indian hellebore Veratrum viride Sub‐alpine fir Abies lasiocarpa Queen's cup Clintonia uniflora
Queen's cup Clintonia uniflora One‐leaved foam flower Tiarella unifoliata Rosy twisted
stock Stretopus roseus
Oak fern Gymnocarpium dryopteris Bunch berry Cornus canadensis Oak fern Gymnocarpium
dryopteris
Spiny wood fern Dryopteris expansa Indian Hellebore Veratrum viride Spiny wood fern Dryopteris expansa
Creeping raspberry Rubus pedatus Queen's cup Clintonia uniflora Common
horsetail Equisetum arvense
Rosy twisted stock Stretopus roseus Oak fern Gymnocarpium dryopteris
Black huckleberry
Vaccinium membranaceum
Lady fern Athrium filix‐femina Spiny wood fern Dryopteris expansa
Oval‐leaved blueberry
Vaccinium ovalifolium
Pink wintergreen Pyrola asarifolia Creeping raspberry Rubus pedatus Hanging basket
moss Rhytidiadelphus loreus
Black huckleberry Vaccinium membranaceum
Oval‐leaved blueberry
Vaccinium ovalifolium Lady fern moss Thuidium
recognitum Oval‐leaved blueberry
Vaccinium ovalifolium
Rosy twisted stock Stretopus roseus Pipecleaner
moss Rhytidiopsis robusta
Devil's club Oplopanax horridus False azalea Nenziesia ferruginea
Hanging basket moss
Rhytidiadelphus loreus Spangle top Scolochloa
festucacea
Lady fern moss Thuidium recognitum
Black huckleberry
Vaccinium membranaceum
Schreber's red stem moss
Pleurozium schreberi
Western mountain ash Sorbus scopulina
Pipecleaner moss Rhytidiopsis robusta
Golden curls moss
Homalothecium aeneum
Common lawn moss
Brachythecium albicans Glow moss Aulaconnium
palustre
Golden curls moss Homalothecium aeneum
Clasping twisted stalk
Streptopus amplexifolius
Green tongue wort
Marchantia polymorpha
Pipecleaner moss
Rhytidiopsis robusta
32
Appendix B: Estimated Percent Cover of Species in Structural Vegetation Layers by Quadrat
Quadrat #1 % Ground Cover % Herbaceous Cover % Shrub Layer Hanging basket moss 5 Indian Hellebore 1 Devil's club 5 Lady fern moss 10 Queen's cup 10 Black huckleberry 40 Schreber's red stem moss 5 Oak fern 25 Oval‐leaved blueberry 30 Pipecleaner moss 60 Spiny wood fern 20 Western hemlock 15 Common lawn moss 10 Creeping raspberry 5 Mountain hemlock 10 Golden curls moss 5 Rosy twisted stock 4
Green tongue wort 1 Lady fern 30 Organic material 4 Pink wintergreen 5 Total % Cover by Layer: 95
20
75
Quadrat #2 % Ground Cover % Herbaceous Cover % Shrub Layer Golden curls moss 10 One‐leaved foam flower 3 Black huckleberry 13 Glow moss 10 Bunch berry 1 Western mountain ash 1 Pipecleaner moss 20 Indian Hellebore 1 False azalea 1 Organic material 60 Queen's cup 23 Oval‐leaved blueberry 10
Oak fern 45 Western hemlock 50
Spiny wood fern 7 Mountain hemlock 25
Creeping raspberry 7
Rosy twisted stock 10
Clasping twisted stalk 10
Spangle top 3 Total % Cover by Layer: 40
5
10
Quadrat #3 % Ground Cover % Herbaceous Cover % Shrub Layer Hanging basket moss 2 Queen's cup 10 Oval‐leaved blueberry 5 Lady fern moss 3 Rosy twisted stock 4 Western hemlock 70 Pipecleaner moss 5 Oak fern 5 Mountain hemlock 25 Organic material 90 Spiny wood fern 80
Common horsetail 1
Total % Cover by Layer: 10
2
5
33
Appendix C: Decay Classes for Course Woody Debris (BEC Field Manual)
34
Appendix D: Age and health observations of 21 largest trees in megaplot
Quadrat Spp Age DBH (m)
Height (m)
Canopy Class Damage Comments
1 Hw (210) 542 1.35 36.5 dominant 12.5m break and
regrowth 3 prong top. Very old. Rot inside
1 Hw 81 0.182 12 suppressed some near top appears healthy
2 Hw 223 0.376 18 intermediate top kill and regrowth at 4.5 m and 15.7m
no rot
2 Hw 200 0.583 27.8 co-dominant none apparent healthy
2 Hw (218) 249 0.618 29.1 co-dominant none apparent tree appears healthy. Centre rot,
core not finished
2 Hw 264 0.611 29.1 co-dominant none apparent tree appears healthy. Centre not reached, subtle rot.
2 Hw 273 0.748 29.4 co-dominant none apparent healthy, no rot. Core in two pieces
2 Hw (251) 228 0.567 24.2 co-dominant broken top height measured to broken top.
Wet and rot in centre
2 Hw (136) 325 0.809 31.6 co-dominant none apparent rot centre and woodpecker holes
2 Hw 266 0.529 25.7 co-dominant Split tree. split in small tree at 13.0m. 3rd stem dead
Split starts at 0.68m, tree stems separate at 3m. Second stem 17.7m high. Variable growth in core.
2 Hw 267 0.682 33.7 co-dominant none apparent edge of plot - gap. Rot at centre, pith reached.
2 Hw 72 0.111 2.7 suppressed none apparent top is growing crooked, could be attempting new crown
2 Bl 123 0.169 9 suppressed none apparent only subalpine fir in plot 3 Hw 260 0.557 31 co-dominant none apparent pith reached, some rot at centre 3 Hw 260 0.65 32.1 co-dominant none apparent no rot
3 Hw 255 0.701 34.1 dominant none apparent took first core - rot, discarded. Second core good. Near corner 3
3 Hw (147) 134 0.331 17 co-dominant broken top, scar at
base extensive rot
3 Hw 72 0.146 9 suppressed lower 3 metres branches dead, no foliage
Reached rot quickly in core
3 Hm 79 0.169 10 suppressed lower 3 metres branches dead, no foliage
major pistol butt, good core.
3 Hm 53 0.162 11 suppressed Unhealthy. lower 3 metres branches dead, no foliage
Young but healthy core appearance. Shadowed by upslope
3 Hw 68 0.182 13 suppressed lower 3 metres branches dead, no foliage
healthy, no damage. 1 piece core
*Western Hemlock = Hw; Mountain Hemlock = Hm; Subalpine fir =Bl. **For trees where pith was not reached, counted age is recorded in brackets, with extrapolated age based on Fig 8 in bold.
35
Appendix E: Tree Ring Growth Results
TREE DATA
Year Ring 1 2 3 4 5 6 7 8 9 10 11
12 13 14 15 16 17
18 19 20 21
2011 1 2+ 2+ 1 2+ 2+
1+
2010 2 2+ 2+ 1 2+ 2+ 1+
2009 3 2+ 2+ 1 2+ 2+
1+
2008 4 2+ 2+ 1 2+ 2+ 1+
2007 5 2+ 2+ 1 2+ 2+ 1+
2006 6 2+ 2+ 1 2+ 2+ 1+
2005 7 2+ 2+ 1 2+ 2+ 1+
2004 8 2+ 2+ 1 2+ 2+ 1+
2003 9 2+ 2+ 1 2+ 2+ 1+
2002 10 2+ 1 2+ 1+ 1+ 2+ 1 1 1+
2001 11 2+ 2+ 1+ 2+ 1 1
2000 12 2+ 2+ 1 1+ 2+ 1
1999 13 1 2+ 1 2+ 1 1+ 2+ 1
1998 14 1 2+ 2+ 1 1 2+ 1
1997 15 1 2+ 2+ 1 2+ 1 1
1996 16 2+ 2+ 1 2 1
1995 17 2+ 2+ 1 2 1
1994 18 2+ 2+ 1 2 2 1
1993 19 2+ 2+ 1 1 1+ 2 2 1
1992 20 2+ 2+ 1 2 2 1
1991 21 1 2+ 2+ 1+ 1 2 2 1
1990 22 2+ 2+ 1 2 2 1
1989 23 2+ 2+ 1 2 1
1988 24 2+ 2+ 2 1 2 2 1
1987 25 2+ 2+ 2+ 2 1 1
1986 26 2+ 2+ 2+ 2 1 1
1985 27 2+ 2+ 1 1
1984 28 2+ 2+ 1+ 1 1 1
1983 29 1+ 2+ 1 2+ 1 1 1 1 1
1982 30 2+ 2+ 1 2 1 1
1981 31 2+ 2+ 1+ 2 1 1
1980 32 1 2+ 2+ 1 1 1 2+
1979 33 2+ 2+ 1 1 1 2+ 2+
1978 34 2+ 2+ 1 1 1 1 2+
2+
36
1977 35 2+ 2+ 1 1 1 2+
1976 36 2+ 2+ 1 1 1 2 2+
1975 37 2+ 2+ 2 1 2 2
1974 38 2+ 2+ 1 2 1 2 2 2
1973 39 2 2+ 2+ 1 2 1 2 2
1972 40 1 2 1 2+ 1 2 1 1 2
1971 41 1 2 2+ 2 1 2 2+ 2
1970 42 1 2 1 2+ 2 2 2 2
1969 43 1 1 2+ 2 2 2 1 2
1968 44 1 1 2+ 2 2 2 2
1967 45 1 1 2+ 2 2 1
1966 46 1 1 2+ 2 2 2 1
1965 47 1 1 2+ 2 2 2 1
1964 48 1 2+ 2 2 2 1
1963 49 1 2+ 2 2 2 1
1962 50 1 2+ 2 1 2 1
1961 51 2+ 2+ 2 2 1 2 1
1960 52 2+ 2 2 1 2 1
1959 53 1 1 2+ 2 2 2 End year 1
1958 54 1 1 2+ 2 2 1+
1
1957 55 1 1+ 2+ 1 2 1
1956 56 2+ 2 1 2 1
1955 57 2+ 2 2 1
1954 58 2+ 2 2 1
1953 59 2+ 2 2 4 1
1952 60 2+ 2 4 1
1951 61 2+ 2 1 1 1+ 4 1
1950 62 2+ 2 1 1+ 4 1
1949 63 2+ 2 2 4 1
1948 64 2+ 2 2 4 1
1947 65 1 2+ 2 2 4 1 1
1946 66 1 1 1 1 2+ 2 2 4 1 1
1945 67 1 1 1 1 1 2+ 2 4 1 1
1944 68 1 1 1+ 2+ 2 1 4 4 End year
1
1943 69 1 1 1 1+ 2+ 2 4 1
1942 70 1 1 1+ 2 2 4 1
1941 71 1 2 2+ 2 4 1
1940 72 1 2++ 2 End year
4 End year 1
1939 73 1+ 1 2+ 2 4 1
1938 74 1 1 2+ 2 4 1
1937 75 1 2+ 2 4 1
37
1936 76 1 2+ 2 4 1
1935 77 2+ 2 1
1934 78 2+ 2 1+
1933 79 2+ 2 End year
1+
1932 80 1 2+ 2 1+
1931 81 1 2+ 2 End year
1+
1930 82 1 2+ 2 1+
1929 83 1 2+ 2 1+
1928 84 2+ 1 1 1+
1927 85 2+ 2 1+
1926 86 2+ 2
1925 87 1 1 2+ 2
1924 88 1 1 1 2+ 2 2 1+
1923 89 1 1 2+ 2 2 1
1922 90 1 1 1 2+ 2 2 1
1921 91 1 1 1+ 2+ 2 2 1
1920 92 1 1 1+ 1 2+ 2 2 1
1919 93 1 1 1 2+ 2 2
1918 94 1 1 1+ 2+ 1 2 2
1917 95 1 1 2+ 1 2 2
1916 96 2 2 2+ 2 2
1915 97 2 2 2+ 1 2+ 2
1914 98 2 2+ 1 2+ 2 1
1913 99 1 2 2+ 1 2+ 2
1912 100 2 1 2+ 2
1911 101 2 1 2+ 2
1910 102 2 1 2+ 2
1909 103 2 1 2+ 2
1908 104 2 1 2+ 2
1907 105 2 1 2+ 2
1906 106 2 2+ 2
1905 107 2 2 2+ 2
1904 108 2 2 2+ 2
1903 109 2 2 1 2+ 2
1902 110 2 2 1 2+ 2
1901 111 2+
2 1 2+
1900 112 2+ 2 1 2+
1899 113 2+
2 1 2+
1898 114 2+ 2 1 2+
1897 115 2+
2+ 2 1 2+
1896 116 2+ 2+ 2 1 2+
38
1895 117 2 2+ 2 1 2+
1894 118 2 2+ 2 2 1 2+ 1
1893 119 2 2+ 2 2 1 2+ 1
1892 120 2 2+ 2 1 2+ 1
1891 121 2 2+ 1 2+
1890 122 1 2+ 1 2+
1889 123 1 2+ 1 2+ End year
1888 124 1 2+ 1 2+
1887 125 2 2 1 2+
1886 126 2 1 2 1 2+
1885 127 2 1 1 2 1 2+
1884 128 2 1 2 1 2+ 1
1883 129 2 2 1 2+ 1
1882 130 2 2 1 2+ 1
1881 131 2 2 1 2+
1880 132 2 2 2+
1879 133 2 2 2+
1878 134 2 2 2+
1877 135 2 2 2+
1876 136 2 2
End
2+
1875 137 2+ 2+
rot 2+
1874 138 2+ 1 2+ 2+
1873 139 2+
1 2+ 2+ 1 1
1872 140 2+ 1 2+ 2+ 1 1
1871 141 2+
2+ 2+ 1
1870 142 2+ 2+ 2+ 1 1+
1869 143 2+
2+ 2+ 1
1868 144 2+ 2+ 2+
1867 145 2+
2+ 2+
1866 146 2+ 2+ 2+
1865 147 2+
2+ 2+ End rot
1864 148 2+ 2 2+
1863 149 2 1+ 2 2+
1862 150 2 2 2+ 1+
1861 151 2 2 2+ 1+
1860 152 2 2 2+ 1+
1859 153 2 2 2+ 1+
39
1858 154 2 2 2+ 1
1857 155 2 2 2+ 1
1856 156 2 2 2+ 1
1855 157 2 1 2 2+ 1
1854 158 2 1 2 1 1
1853 159 2 1 2 2+ 1
1852 160 2 2+ 1
1851 161 2 2+ 1 1+
1850 162 2 2+ 1 1+
1849 163 2 2+ 1 1+
1848 164 1 2 2+ 1 1+
1847 165 1 2 2+ 1 2
1846 166 1 1 1 2 2+ 1 1+
1845 167 1+ 1 1 2 2+ 1 1+
1844 168 1+
1 1 2+ 1 1+
1843 169 1+ 1 1 1 2+ 1 1+
1842 170 1+
1 1 2+ 1 1+
1841 171 1 1 2+ 1 1+
1840 172 2 1 2+ 1 1+
1839 173 2 1 2+ 1
1838 174 2 1 2+ 1
1837 175 2 2+ 1
1836 176 1 2 1 2+ 1
1835 177 1 2 2 2+ 1
1834 178 1 2 2+ 1
1833 179 1 2 2+ 1
1832 180 1 4 2 2+ 1
1831 181 1 4 2 2+ 1
1830 182 1 4 2 2+ 1
1829 183 1 4 2 2+ 1
1828 184 1 2 4 2 2+ 1
1827 185 1 2 4 2 2+ 1
1826 186 1 2 4 2 2+ 1 1
1825 187 1 4 1 2 2+ 1 1
1824 188 1 4 2 2+ 1 1
1823 189 1 4 rot 1 2 2+ 1
1822 190 1 4 2 2+ 1
1821 191 1 4 2 2+ 1
1820 192 1+ 4 2 2+ 1
1819 193 1+ 4 2 2+ 1
1818 194 1+ 4 2 2+ 1
40
1817 195 1+
4 2 2+ 1
1816 196 1+ 4 2 2+ 1
1815 197 1 4 2 2+ 1
1814 198 1 4 2 2+ 1
1813 199 1 4 2+ 1
1812 200 1 End year 2+ 1
1811 201 1 2+ 1
1810 202 1 rot 2+ 2 1
1809 203 1 1 2+ 2 1
1808 204 1 2+ 1
1807 205 1+ 2+ 1
1806 206 1+
2+ 1
1805 207 1 2+ 1
1804 208 1 2+ 1
1803 209 1 2 2+ 1
1802 210 End ‐ rot 2+ 2
1+
1801 211 2+ 1+
1800 212 2+ 1+
1799 213 2+ 1+
1798 214 2+ 1+
1797 215 2+ 1+
1796 216 2+ 1
1795 217 2 2+ Rot 1
1794 218 2 End‐ rot 2+ 1
1793 219 2 2+ 1
1792 220 2 2+ 1
1791 221 2 2 2+ 1
1790 222 2 2 2+ 1
1789 223 End year
2 2+ 1
1788 224 2 2+ 1 2
1787 225 2 2+ 1 2
1786 226 2 2+ 1 1
1785 227 2 2+ 1 1
1784 228 2 2+ 1 1
1783 229 2 2+ 1 1
1782 230 4 2 2 1 1
1781 231 4 2 2 1 1
1780 232 4 2 2 1 2
1779 233 4 2 2 1
41
1778 234 4 2 2 1
1777 235 4 2 2 1
1776 236 4 2 2 1
1775 237 4 2 2 1
1774 238 4 2 2 1
1773 239 4 2 2 1
1772 240 4 2 2 1
1771 241 4 2 2 1
1770 242 4 2 2 1
1769 243 4 2 2 1
1768 244 4 2 2 1
1767 245 4 2 2 rot? 1
1766 246 2 2 1
1765 247 2 2 1
1764 248 2 2 1
1763 249 2 2 1
1762 250 2 2 4 1+
1761 251 End‐rot
4 1+
1760 252 4 1+
1759 253 4 1+
1758 254 4 1+
1757 255 4 4 1+ End
year
1756 256 4 4 1
1755 257 4 4 1
1754 258 4 4 1
1753 259 4 4 1
1752 260 4 4 1 End year
1751 261 4 4 End year
1750 262 4 4
1749 263 4 4
1748 264 End year 4
1747 265 4
1746 266 End year 4
1745 267 End year
1744 268
1743 269
1742 270
1741 271
1740 272
1739 273 End year
42
*1 complacent rings *1+ very complacent rings *2 narrow rings *2+ very narrow rings *4 complacent rings in first years of growth
43
Appendix F: Soil Properties and Results from pits in each Quadrat
Pit Horizons
Depth
Biotic Compositi
on
Colour % Fine Fragments Sorting Shape
Soil Porocit
y Draina
ge Soil Type
Deposition code colour Sand Clay Silt
1
F 2.3 yes1 -- -- n/a n/a n/a
gravels, pebbles,
some cobbles
Sub-rounded or sub-angular
Mod. Porous
well drained
silty loam colluvial
H(O) trace yes -- -- n/a n/a n/a
A(E) 12 n/a 7.5yr 6/1 grey 55% 5% 40%
B1 20 n/a 7.5yr 3/4
dark brown 70% 0% 30%
B2 11 n/a 7.5yr 4/6
strong brown 90% 0% 10%
2
F 1.9 yes2 -- -- n/a n/a n/a
fine sand, large rocks,
cobbles, gravels, pebbles
Sub-rounded or sub-angular
Highly Porous
well drained
fine sandy loam
colluvial
H(O) trace yes -- -- n/a n/a n/a
A(E) 1 7 n/a 7.5yr 6/2
pinkish grey 65% <5% 30%
A(E) 2 7 n/a 7.5yr 5/2 brown 65% 5% 30%
B1 16 n/a 7.5yr 4/4 brown 70% <5% 25%
B2 15 n/a 7.5yr 4/6
strong brown 55% 5% 40%
3
Litter 5 n/a -- -- n/a n/a n/a
gravels, pebbles, cobbles
large rocks
Sub-rounded or sub-angular
Highly Porous
well drained
fine sandy loam
colluvial
F 3 yes3 -- -- n/a n/a n/a
H trace yes -- -- n/a n/a n/a
A(E) 1 14 n/a 7.5yr 6/2
pinkish-grey 80f% <5% 15%
A(E) 2 5 n/a 7.5yr 5/2 brown 65f% 5% 30%
B1 4 n/a 7.5yr 3/3
dark brown 65% 5% 30%
B2 20 n/a 7.5yr 4/4 brown 65% 5% 30%
1. moderate consolidated mat 2. consolidated mat - moderate 3. highly matted decomposing debris
