A Banded Vegetation Pattern in a High Arctic
Community on Axel Heiberg Island, Nunavut, Canada
Author: Liptzin, Daniel
Source: Arctic, Antarctic, and Alpine Research, 38(2) : 216-223
Published By: Institute of Arctic and Alpine Research (INSTAAR),
University of Colorado
URL: https://doi.org/10.1657/1523-
0430(2006)38[216:ABVPIA]2.0.CO;2
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles
in the biological, ecological, and environmental sciences published by nonprofit societies, associations,
museums, institutions, and presses.
Your use of this PDF, the BioOne Complete website, and all posted and associated content indicates your
acceptance of BioOne’s Terms of Use, available at www.bioone.org/terms-of-use.
Usage of BioOne Complete content is strictly limited to personal, educational, and non - commercial use.
Commercial inquiries or rights and permissions requests should be directed to the individual publisher as
copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit
publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to
critical research.
Downloaded From: https://bioone.org/journals/Arctic,-Antarctic,-and-Alpine-Research on 09 Aug 2022
Terms of Use: https://bioone.org/terms-of-use
Arctic, Antarctic, and Alpine Research, Vol. 38, No. 2, 2006, pp. 216–223
A Banded Vegetation Pattern in a High Arctic Community on
Axel Heiberg Island, Nunavut, Canada
Daniel Liptzin
Department of Earth and Environmental
Science, University of Pennsylvania, 254-B
Hayden Hall, 240 South 33rd Street,
Philadelphia, PA 19104-6316, U.S.A.
Current address: Institute of Arctic and
Alpine Research and Department of
Ecology and Evolutionary Biology,
University of Colorado, 1560 30th Street,
Boulder, CO 80309, U.S.A.
liptzin@colorado.edu
Abstract
On Axel Heiberg Island, Nunavut, Canada, a banded vegetation pattern occurred on
a hillside where patterned ground and unidirectional abiotic fluxes, such as downslope
water flow or wind, were not present. The parent material was the obvious source of the
plant pattern, as the soils occurred on five distinct types of alluvial deposits. To examine
the observed pattern, plants were inventoried and soils were sampled in July 1999. Twelve
vascular species of plants, but no non-vascular species, were present at the site. Neither
water, often thought to limit plant distribution in the High Arctic, nor any of the other
measured soil variables, predicted plant abundance. The best predictor of plant abundance,
based on regression tree analysis, was total soil nitrogen; however, higher plant density
was associated with lower nitrogen. The five soil types differed in plant density and soil
properties. Even though the sand soil always had soil nutrients equal to or lower than the
blocky clay soil, the sand and clay soils had the highest plant density and the blocky clay
soil the lowest. Although the vegetation pattern is obvious, the underlying mechanism
creating the pattern is not.
Introduction
The Queen Elizabeth Islands represent the northernmost land in
Canada. This group of High Arctic islands covers more than 400,000
km
2
, but only approximately 175 vascular plant species are found there
(Porsild and Cody, 1980). Although the geographic distribution of
these species has been documented, the ecological and physiological
tolerances controlling species distributions are less well understood.
Many factors combine to affect plant function at these latitudes: a short
growing season, cold air and soil temperatures, high wind speeds,
permafrost, soil churning, low sun angles, low precipitation, and low
nutrient concentrations (Savile, 1972). In fact, this entire region has
been described as a marginal environment for plant growth (Svoboda
and Henry, 1987). The poorly developed soils are typically little
modified by vegetation; thus, surficial geology plays a large role in
determining where plants in general and particular species can grow
(Edlund, 1994).
In the High Arctic the environmental variables controlling plant
distribution and abundance depend on scale. Regional-scale patterns
of plant diversity in the High Arctic are correlated with summer
temperature, while at the local scale, soil moisture seems to drive the
distribution of plants (Edlund and Alt, 1989; Batten and Svoboda,
1994). Soil moisture in the High Arctic is usually related to topo-
graphic position and microtopographic features, such as patterned
ground. Cryptogamic crust also tends to increase soil moisture. Be-
cause of the higher soil moisture, the protected sites for germination,
and a reduction in soil cryoturbation, greater cryptogamic cover tends
to increase vascular plant diversity and abundance (Anderson and
Bliss, 1998; Gold and Bliss, 1995; Bliss et al., 1994). Although water
seems to control much of the structure and function of High Arctic
plant communities, plants do not appear to be water stressed even in
the driest soils (Gold and Bliss, 1995).
Vegetation patterns at many spatial scales are often controlled by
a variety of differences in soil properties including parent material and
topography (Jenny, 1994). In the High Arctic, like most regions, certain
plant species tend to be grow on soils derived from calcareous bedrock
(Porsild and Cody, 1980). The chemical composition in layers of the
Mancos Shale in the western United States creates predictable
vegetation patterns (Potter et al., 1985). In arid regions, coarser textured
soils support higher plant densities because these soils actually provide
more water for plants (Noy-Meir, 1973). Different plant communities
and soils develop based on topographic position largely driven by
differences in soil moisture (Billings, 1973). Although many soil factors
affect plant distribution, in the High Arctic, most research has focused
on the effects of patterned ground (Anderson and Bliss, 1998).
One vegetation pattern, banded vegetation, is defined as
vegetation growing in a linear pattern, often with little plant cover
between bands. Three mechanisms have been elucidated to create this
pattern in different settings: a unidirectional flow of water downslope,
stress from a unidirectional wind, and linear microtopography resulting
from freeze-thaw cycles. Banded vegetation, or ‘‘tiger stripes,’’ typ-
ically occurs on shallow slopes in arid regions of North America,
Australia, and Africa and results from a positive feedback: established
plants intercept water and nutrients flowing down the shallow slopes
facilitating the establishment of additional plants across the slope
(White, 1971; Aguiar and Sala, 1999). In temperate regions the vege-
tation may develop a banded pattern when plants are killed by
exposure to unidirectional winds. Salt spray, in coastal regions, can kill
exposed trees and creates a wave-like regeneration pattern (Campbell,
1998). Similar wave patterns develop in forests in New England and
Argentina exposed to high winds from a consistent direction (Foster,
1988; Puigdefabregas et al., 1999). Patterned ground in cold regions
can form as stripes oriented down the slope creating non-random
vegetation patterns associated with the microtopographic variation
(Washburn, 1956; Anderson and Bliss, 1998). However, few banded
vegetation patterns have been described in herbaceous communities,
and banded vegetation patterns unrelated to patterned ground are
undescribed in the arctic literature.
This study documents the contour-parallel banded vegetation
pattern in a cold steppe plant community on Axel Heiberg Island in the
High Arctic and seeks to determine its potential causes. Microscale
vegetation patterns in high arctic plant communities are poorly
understood, and banded vegetation patterns unrelated to patterned
216 / ARCTIC,ANTARCTIC, AND ALPINE RESEARCH Ó 2006 Regents of the University of Colorado
1523-0430/06 $7.00
Downloaded From: https://bioone.org/journals/Arctic,-Antarctic,-and-Alpine-Research on 09 Aug 2022
Terms of Use: https://bioone.org/terms-of-use
ground are undescribed. Unlike banded vegetation pattern worldwide,
there was neither patterned ground present nor evidence of either
unidirectional transport of water or death of plants caused by wind. The
obvious origin of the vegetation pattern was the parent material
consisting of layered sedimentary deposits. More specifically, this
study was designed to answer the following questions:
(1) What is the microscale spatial distribution of plants?
(2) Is this vegetation pattern related to the spatial distribution of
soil type/sedimentary deposits? That is, is the plant distri-
bution correlated with soil moisture or other soil variables that
vary among the soil types?
Methods
STUDY AREA
This study was conducted at the fossil forest site east of the
Geodetic Hills on Axel Heiberg Island, Nunavut, Canada (798559N,
898029W). Described in detail by Christie and McMillen (1991), the
fossil forest site is a hill 1.3 km long and 0.5 km wide, with an
elevation of 200–300 m, and is composed of flat-lying, unconsolidated,
Eocene sediments with repeated beds of sand, silt, and lignite (Fig. 1).
Erosion by wind and mass wasting has been measured at 0.3 cm yr
1
in
flat areas and up to 11 cm yr
1
in steeper areas (Bigras et al., 1995).
Patterned ground was absent in the study area. Rills often develop on
the lower slopes, usually beginning in sand beds.
The climate is characterized by low temperatures and scant
precipitation. The mean annual temperature at Eureka, 60 km east, is
198C, and the July–August mean is 48C. The growing season lasts
from approximately 15 June to 25 August (Maxwell, 1981). Precipi-
tation averages 68 mm yr
1
, with 22 mm during the growing season,
and approximately one-third falling as rain. The weather during 1999,
when the data were collected, was particularly warm and dry with
a July/August mean temperature of 5.9 8C and only 5.8 mm of pre-
cipitation (Canadian National Climate Data and Information Archive;
http://www.climate.weatheroffice.ec.gc.ca).
VEGETATION AND SOIL SAMPLING
Plants and soils were sampled during the last week of July 1999.
Three transects were established down the southeast-facing slope of the
site perpendicular to the distinct vegetation bands running across the
slope. The transects were 55 m long, approximately 150 m apart, and
the slope angle averaged 158. All plants within one meter of each
transect were identified and counted, with each ramet of the clonal
species counted as an individual. Plants of non-clonal species were
classified as seedlings if neither flowers nor seeds were present or
remaining from previous years. Most of these seedlings were small, but
larger plants without reproductive structures and even the small plants
may in fact be quite old and not truly be seedlings. Each meter of
transect (representing an area 2 m
2
) will be referred to as a plot for
a total of 168 plots in the plant data set.
To determine the association between plant cover and soil char-
acteristics, five soil types were described based on the characteristics
of the Eocene deposits: blocky clay, clay, sand, white, and organic. The
soil types occurred several times along the transects but were not always
laterally continuous between transects. All soils were covered in 1–3 cm
of homogenous gravel-sized slopewash, transported downhill by con-
temporary mass-wasting processes. The five soil types were easily
distinguishable visually and were separated by abrupt boundaries. The
blocky clay soil was composed of large stable aggregates, while the clay
soil was sticky and lacked aggregates. Preliminary data indicated some
mineralogical differences between these two clay soils, but they both
were both gray with a silt loam to silty clay loam texture once the
aggregates of the blocky clay soil were crushed (D. Liptzin, unpublished
data). The sand soils had a sandy loam texture and occasionally contained
a band of lithified and oxidized sandstone. White soils, corresponding
to the white layers described by Tarnocai et al. (1991), were composed
of platy quartz of unknown origin. Organic soils corresponded to the
Eocene lignitic beds and contain only small amounts of mineral soil. All
soil types ranged in pH from 5 to 6, and were classified as Regosolic
Static Cryosols (Soil Classification Working Group, 1998).
A hillslope profile was created using slope angles and changes in
soil type (Fig. 2). Soils were sampled every 2 m along the transects
FIGURE 1. A view of the fossil
forest hill. The flat-lying sedi-
mentary deposits are clearly
visible, but the bands of plants
running parallel to these deposits
are more difficult to see because
of the low plant density. The
black box illustrates the orienta-
tion of the transects.
D. LIPTZIN / 217
Downloaded From: https://bioone.org/journals/Arctic,-Antarctic,-and-Alpine-Research on 09 Aug 2022
Terms of Use: https://bioone.org/terms-of-use
except in areas with many consecutive plots with blocky clay soils,
which were sampled approximately every 5 m. A soil pit was exca-
vated to 50 cm at each sampling location underneath the plant nearest
the transect. Pedogenic horizons were never visible, but changes in soil
type were noted. The depth of the deepest visible roots was measured.
Active layer depth within the soil pit was determined by the presence
of ice.
The soil data set was based on seven variables measured on soils
from a subset of the plots in the plant data set (n ¼ 49). The top 8 cm of
soil was sampled by forcing a 1700 cm
3
aluminum box into the soil.
Samples were kept in plastic bags until reaching the University of
Pennsylvania. The samples were air dried at room temperature to
a constant weight. Soils were sieved (2 mm), and the modern litter and
roots and Eocene organic matter remaining in the sieve were removed.
Organic matter was not removed from the organic soil samples because
they were considered organic soils. Gravimetric water content was
determined as (wet weight dry weight)/dry weight. Aggregates . 2
mm were weighed separately to calculate the percentage of the soil in
stable aggregates and then remixed with the dry, sieved soil. Organic
carbon and total nitrogen concentrations were measured on ground
samples using a Carlo Erba elemental analyzer (Fisons Instruments
NA1500, Dearborn, MI, U.S.A.) on samples ground in a ball mill.
Exchangeable K, Mg, and Ca were extracted from the soil with 1M
NH
4
Cl for 12 h and measured by Inductively Coupled Plasma Atomic
Emission Spectrometry (Perkin-Elmer Plasma 400, Shelton, CT,
U.S.A.).
DATA ANALYSES
The spatial distribution of the vegetation was described by
plotting plant density against distance along each transect. To test if the
plants were randomly distributed, the frequencies of plant density were
compared against a Poisson distribution. The expected and observed
values were combined into 10 bins with the stipulation that the
expected value was never less than five.
The plots in the plant data set were ordinated using plant density
for plant species with principal components analysis using PC-ORD
4.0. However, since PCA cannot handle plots with no species present,
only 129 of the 168 plots could be used in the analysis. In addition,
Draba and Melandrium were left out of the analysis since so few
individuals were present. A canonical correspondence analysis was
done in PC-ORD using the 43 plots in both the plant and the soil data
set with a plant density . 0. The rows and the columns were stan-
dardized by centering and normalizing for the ordination, and a Monte
Carlo test was performed to test for significance of the axes.
The plant and soil data sets were used to test for differences
among the five soil types. Differences among soil types based on the
variables measured in the soil data set (water, aggregates, total soil N
and C, and exchangeable Ca, Mg, and K) were tested with a MANOVA
followed by univariate ANOVA models on each of the soil variables
using SAS (release 8.02). Two of these variables, exchangeable K and
total N, were log transformed to improve normality. Means were
calculated for all five soil types, and a post hoc Tukey’s test was used
to assess differences only among the three common soil types (blocky
clay, clay, and sand). The plant data set was analyzed using ANOVA
models and post hoc Tukey’s comparisons to examine the main effect
of soil type on plant density and species density.
Regression models were used to analyze the relationship between
soil characteristics and plant density. All seven measured soil variables
were tested separately with simple regressions. A series of multiple
regression models were built based on the variables predicted to be
most important for High Arctic ecosystems. The models were built and
tested by adding, in order, water, nitrogen, aggregates, and then the
exchangeable cations.
The non-parametric technique, regression tree analysis, was em-
ployed to determine which of the soil properties best predicted the
plant density using S-Plus 2000 software. This technique partitions the
data set (soil data set, n ¼ 49) into two subsets based on the predictor
variable that minimizes the variance. A full tree was created with a
minimum of three plots in each terminal node. The full tree was pruned
to five branches as this was the point where the decrease in variance
per parameter added began to decline.
Results
VEGETATION DISTRIBUTION
The distribution of plants along the transects clearly shows the
banded pattern (Fig. 3). The mean plant density on all the plots was 28
plants m
2
, and a Chi-square test revealed that the plants were non-
randomly distributed (df ¼ 9, v
2
¼ 1496, P , 0.001). The vegetation
bands were largely a consequence of the high abundance of two clonal
species: Alopecurus alpinus and Stellaria crassipes . However, other
species also occurred in the bands, and these two species occurred
outside of the bands. The proportion of non-clonal plants classified as
seedlings was significantly higher outside of the bands (F
1,101
¼ 5.91,
P , 0.05). Every band, defined as plant density . 15 plants m
2
,
was associated, at least in part, with some soil type other than the
blocky clay soil (Fig. 3). Often there were no plants in the blocky clay
soil, for up to 8 consecutive meters along the transect. The sand soil
always had some plant cover.
FIGURE 2. Hillslope profile for
transect 1. The elevations of the
soil types other than blocky clay
are listed at right with sand soil at
227.4–228.8 m, clay soil at 231.8–
232.6 m, organic soil at 235.4–
235.9 m, white soil at 238.6–239.2
m, organic soil at 239.8–240.5 m,
and clay soil at 240.5–240.8 m.
Blocky clay soil occurs every-
where else and is depicted with
the hatched shading. The slope-
wash is shown with the dotted
shading; its depth is exaggerated
vertically approximately 30 times.
The vertical line demonstrates
how the depth to non-blocky clay
soils was calculated.
218 / ARCTIC,ANTARCTIC, AND ALPINE RESEARCH
Downloaded From: https://bioone.org/journals/Arctic,-Antarctic,-and-Alpine-Research on 09 Aug 2022
Terms of Use: https://bioone.org/terms-of-use
The vegetation bands corresponded to the sedimentary deposits,
with fewer plants occurring in the blocky clay soils. Even though the
blocky clay soils supported lower plant densities, they had similar or
higher concentrations of moisture and nutrients compared to the other
soils, suggesting a physical, not a chemical cause. There were some
instances where the blocky clay soil supported high densities of plants,
but there was almost always another soil type less than 0.5 m below the
soil surface (Fig. 4). Even though neither water nor nutrients were
higher in the blocky clay soil less than 0.5 m above non-blocky clay
soils, there were significantly more plants in these soils compared
to other blocky clay soils (F
1,25
¼ 17.90, P , 0.0005).
Twelve species of herbaceous perennial vascular plants occurred
in the study area (Table 1). Notably, non-vascular species were absent
from the transects. Some species were abundant and found on all soil
types (Alopecurus alpinus, Cerastium alpinum, Erysimum pallasii,
Papaver radicatum, Puccinellia angustata, and Stellaria crassipes). Of
these ubiquitous species only E. pallasii occurred more frequently on
a relative basis on blocky clay soil than on sand soil (Table 2). Others
were rare regardless of soil type (Draba sp., Luzula confusa, and
Melandrium sp.). Three species were limited almost exclusively to the
sand soil, but were often abundant there (Arnica alpina, Oxyria dignya,
and Taraxacum pumilum). The first PCA axis of the plant species
composition splits the sand soil, and the three species that grow only
there, from the other soil types and species (Fig. 5). The second PCA
axis separates the four other soil types. The Monte Carlo test indicated
that the axes of the CCA were not significant, and thus the results will
not be discussed.
EFFECTS OF SOIL TYPES
Neither soil moisture nor nitrogen, often thought to be limiting
to High Arctic plants, could predict plant density. Neither could any
other soil variable individually or any of the tested multiple regression
models. However, species density was negatively related to the per-
centage of aggregates (F
1,41
¼ 10.91, P , 0.005). The regression tree
analysis provided a way to determine which soil variable best explained
the difference in plant density. The pruned tree revealed that nitrogen
was best predictor such that plots with a total soil nitrogen less than
0.0985% tended to have more plants (Fig. 6). The low nitrogen node
was further subdivided such that the highest plant density occurred in
plots with fewer aggregates and higher calcium and the lowest plant
density occurred in plots with more aggregates and higher carbon.
The MANOVA analysis indicated significant differences among
the soil types (Pillai’s trace ¼ 1.71, df ¼ 28,164, F ¼ 4.39, P , 0.001).
The univariate ANOVA models revealed that the three common soil
types differed significantly in moisture, calcium, magnesium, nitrogen,
plant density, species density, and aggregates but not in potassium or
carbon. In general, organic soil had the highest values for soil nutrients,
sand soil and white soil had the lowest values, and clay soil and blocky
clay soil were intermediate (Table 3). Clay soil had significantly more
moisture than sand and blocky clay soils. Blocky clay soil had sig-
FIGURE 3. Plant density along the three transects. Zero is the
uphill end of the transect. Large open symbols represent the
four non-blocky clay soil types.
FIGURE 4. Relationship between plant density for all blocky
clay soils and the calculated depth to a non-blocky clay soil.
D. LIPTZIN / 219
Downloaded From: https://bioone.org/journals/Arctic,-Antarctic,-and-Alpine-Research on 09 Aug 2022
Terms of Use: https://bioone.org/terms-of-use