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ISSN 1239-6095 (print) ISSN 1797-2469 (online) Helsinki 30 April 2009
Effects of air pollution from a nickel–copper industrial
complex on boreal forest vegetation in the joint Russian–
Norwegian–Finnish border area
Tor Myking
1)
*, Per A. Aarrestad
2)
, John Derome
3)
, Vegar Bakkestuen
4)5)
,
Jarle W. Bjerke
6)
, Michael Gytarsky
7)
, Ludmila Isaeva
8)
, Rodion Karaban
7)
,
Vladimir Korotkov
9)
, Martti Lindgren
10)
, Antti-Jussi Lindroos
10)
,
Ingvald Røsberg
11)
, Maija Salemaa
10)
, Hans Tømmervik
6)
and Natalia Vassilieva
7)
1)
Norwegian Forest and Landscape Institute, Fanaflaten 4, N-5244 Fana, Norway (*e-mail: tor.
myking@skogoglandskap.no)
2)
Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway
3)
Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi,
Finland
4)
Norwegian Institute for Nature Research, Gaustadalléen 21, N-0349 Oslo, Norway
5)
Department of Botany, Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, N-0318
Oslo, Norway
6)
Norwegian Institute for Nature Research, Polar Environmental Centre, N-9296 Tromsø, Norway
7)
Institute of Global Climate and Ecology, 107258, 20-B Glebovskaya Str., Moscow, Russia
8)
Kola Science Center, Russian Academy of Sciences, Institute of the Industrial Ecology of the North
(INEP), 184209, Fersmana st. 14a, Apatity, Murmansk region, Russia
9)
All-Russian Institute for Nature Protection, 113628, Moscow, Russia, M-628, Znamenskoe-Sadki,
Moscow, Russia
10)
Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland
11)
Norwegian Forest and Landscape Institute, P.O. Box 115, N-1431 Ås, Norway
Received 16 Aug. 2007, accepted 2 Jan. 2008 (Editor in charge of this article: Jaana Bäck)
Myking, T., Aarrestad, P. A., Derome, J., Bakkestuen, V., Bjerke, J. W., Gytarsky, M., Isaeva, L., Kara
-
ban, R., Korotkov, V., Lindgren, M., Lindroos, A J., Røsberg, I., Salemaa, M., Tømmervik, H. & Vassil-
ieva, N. 2009: Effects of air pollution from a nickel–copper industrial complex on boreal forest vegeta-
tion in the joint Russian–Norwegian–Finnish border area.
Boreal Env. Res. 14: 279–296.
The effect of air pollution from the Petchenganickel industrial complex, northwestern part
of the Kola Peninsula, on forest vegetation was studied by combining three dormant moni-
toring networks in Finland, Russia and Norway, comprising a total of 21 plots that were
revisited in 2004. Chemical composition of precipitation was monitored during 2004–
2005, and indicated continuing high deposition of heavy metals and SO
2
in the border area.
The cover of epiphytic lichens on the trunks of downy birch (Betula pubescens) and Scots
pine (Pinus sylvestris) was severely affected by pollution, and there was also a consist-
ent negative effect on the abundance and richness of lichens and bryophytes on the forest
were weak or absent. This study is an important reference for evaluating the effects of the
planned renovation of the smelter in Nikel.
280 Myking et al. • BOREAL ENV. RES. Vol. 14
Introduction
The border area between Russia, Norway and
Finland belongs to the north boreal and low-
alpine vegetation regions and is covered by
forest, alpine heathland, bogs and fens (Moen
1999). The area has been severely affected by
sulphur dioxide (SO
2
) and heavy metal emis-
sions since nickel and copper processing started
in Kolosjoki (later called Nikel) in 1942 (Jacob-
sen 2007). Emissions from the smelter in Nikel
and roasting factory in Zapolyarnyy, which
since 1946 has constituted the Petchenganickel
Mining & Metallurgical Combine (Jacobsen
2007), peaked at approximately 380 000 t SO
2
in
1979 (Henriksen et al. 1997), but have now been
reduced to about 120 000 t year
–1
(Milyaev and
Yasenskij 2004, cited after Kozlov and Zvereva
2007a). However, the SO
2
emissions from the
Nikel smelter alone are still 5–6 times higher
than the total Norwegian SO
2
emissions (Hagen
et al. 2006). The annual emissions of copper and
nickel during the period with the highest SO
2
emissions were about 500 and 300 t, respectively
(Aamlid 2002).
Air pollution has caused major environmen-
tal problems in the northwestern part of the Kola
Peninsula, and the vegetation has been changed
or destroyed. The cover of epiphytic lichens
around the smelters has been drastically reduced
(Aamlid et al. 2000, Aamlid and Skogheim 2001,
Bjerke et al. 2006), and the composition of the
ground vegetation has been severely affected.
In particular, the abundance of epigeic mosses
and lichens has been reduced (Tømmervik et al.
1998, 2003). In the years with extremely high
industrial emissions, visible injuries caused by
SO
2
were observed on many species includ-
ing Scots pine (Pinus sylvestris), downy birch
(Betula pubescens), dwarf birch (B. nana) and
bilberry (Vaccinium myrtillus) (Aamlid 1992).
Heavy metals have accumulated in the plant
tissues and soil, and there are clear signs of
decreased soil fertility and increased soil acid-
ity (Lukina and Nikonov 1997, Derome et al.
1998, Aamlid et al. 2000, Steinnes et al. 2000).
Thus, the condition of the terrestrial biota, as
well as of lakes and rivers (Traaen et al. 1991),
has been drastically affected. The Nordic Invest-
ment Bank and the Norwegian Government are
supporting the modernisation of the smelter in
Nikel. The goal is to reduce the emissions by
about 90%, thereby substantially decreasing the
pollution impact in the region by 2009 (Stebel et
al. 2007).
Over the years several projects have been
implemented for monitoring the condition of
terrestrial ecosystems in the border area (cf.
Tikkanen and Niemelä 1995, Aamlid et al. 2000,
Yoccoz et al. 2001). The Interreg IIIA Kolarc-
tic project “Development and implementation
of an environmental monitoring and assessment
program in the joint Finnish, Norwegian and
Russian border area” was carried out during
the period 2004–2006 (Stebel et al. 2007). This
project provided a new baseline by updating
long-term data series, as well as by integrating
and harmonising the approaches used in pre-
vious monitoring activities. By joining forces
trilaterally the effects of pollution could be stud-
ied over an exceptionally large area, ranging
from heavily polluted to almost unaffected areas,
which is crucial for drawing sound conclusions
about the effects of pollution on e.g. terrestrial
ecosystems. In this paper we address the hypoth-
esis that there is a differentiation in the impact
and geographical distribution of the effects of
pollutants on epiphytic lichens, ground vegeta-
tion and the growth and crown condition of
Scots pine due to the different sensitivity of these
plant groups to pollution. The results are used to
draw up recommendations for future monitoring
activities aimed at evaluating the effects of the
ongoing modernisation of the smelter in Nikel
on the vegetation in the region.
Material and methods
Study area and plot networks
The study area (69–70°N, 29–32°E) is located
close to the Arctic tree line in Scots pine and
birch forests, and encompasses the smelter in
Nikel, the roasting plant in Zapolyarnyy and the
surrounding affected area, as well as less affected
areas to the west and south (Fig. 1). The codes R,
N and F denote plots in Russia, Norway and
Finland, respectively, and the numbers denote
increasing distance from Nikel (Fig. 1 and Table
BOREAL ENV. RES. Vol. 14 • Vegetation and air pollutants from a nickel–copper industrial complex 281
450 m a.s.l. Precambrian bedrock partly covered
by coarse-textured podzolic till dominates the
area (Koptsik et al. 1999). Hard and infertile
gneissic and granitic bedrocks are dominant in
the south and north, whereas richer and more
easily weathered bedrocks cover large areas to
the southeast of Nikel, in the central part of the
area (Petsamo formation), and in the uppermost
part of the Pasvik Valley (Reimann et al. 1998).
The Barents Sea creates a climatic gradient with
a coastal climate in the north, and an increas-
ingly continental climate on moving towards the
south. The annual mean temperature close to the
the southern part of the Pasvik Valley, about 100
km from the coast. The annual normal precipita-
tion varies from 340–500 mm. The snow cover
is normally formed in mid December and lasts
to May (Aune 1993, Førland 1993). The prevail-
ing wind direction in the Nikel area is from the
south-southwest (Bekkestad et al. 1995, Hagen
et al. 2006). Reindeer grazing pressure in the
Norwegian and Finnish part of the study area is
Fig. 1. Location of the
monitoring plots.
282 Myking et al. • BOREAL ENV. RES. Vol. 14
Table 1. Plot codes, plot characteristics and monitored parameters. Sequence of plots is arranged in order of increasing distance from the Nikel smelter. The old plot
codes refer to the codes used in Aamlid et al. (2000), Yoccoz et al. (2001) and Stebel et al. (2007), and have been included to make the comparison easier. Determination
of the exact age of the stands on some of the Finnish plots was problematic because all of the stands were naturally regenerated and have never been managed since.
Plot characteristics Monitored parameters
Plot Old Distance Altitude Original Dominating Average Vegetation type Crown Stand Epiphytic Ground Deposition Humus
codes plot from Nikel (m a.s.l.) project
1
tree stand age (Påhlsson 1994) condition growth lichens vegetation chemistry
codes smelter in 2004
(km) (years)
R1 RUS2 5.1 26 1 Scots pine 52 Pinus–Vaccinium vitis-idaea X X Birch, X X
Scots pine
R2 RUS1 5.2 49 1 Scots pine 52
Pinus–Vaccinium vitis-idaea X X Birch, X X X
Scots pine
R3 S03 7.0 22 2 Birch
Betula–Empetrum–Cladonia Birch X X
N4 PC 8.1 70 1 Scots pine 60
Pinus–Vaccinium vitis-idaea X X X X X
N5 PD 11.9 50 1 Scots pine 45
Pinus–Cladonia X X X X
R6 N06 12.3 105 2 Birch
Betula–Vaccinium–Deschampsia Birch X X
R7 S05 14.1 131 2 Birch
Betula–Empetrum–Cladonia Birch X X
N8 PB 15.3 90 1 Scots pine 56
Pinus–Vaccinium vitis-idaea X X Birch X X
N9 PA 23.3 103 1 Scots pine 50
Pinus–Vaccinium vitis-idaea X X Birch X X
N10 N11 28.4 47 2 Birch
Betula–Vaccinium–Deschampsia Birch X X X
R11 S10 32.8 191 2 Birch
Betula–Empetrum–Cladonia Birch X X
R12 RUS0 42.2 193 1 Scots pine 67
Pinus–Vaccinium vitis-idaea X X Birch, X X X
Scots pine
F13 F4 42.3 177 3 Scots pine ~200
Pinus–Vaccinium vitis-idaea X Scots pine X X
F14 F1 42.7 100 3 Scots pine 200+
Pinus–Cladonia X Scots pine X X
F15 F2 49.4 120 3 Scots pine 200–300
Pinus–Vaccinium vitis-idaea X X X
F16 F7 53.7 173 3 Scots pine 235
Pinus–Vaccinium vitis-idaea X Scots pine X X
F17 F5 54.0 172 3 Scots pine 185
Pinus–Cladonia X Scots pine X X
F18 F3 55.8 100 3 Scots pine ~200
Pinus–Vaccinium vitis-idaea X Scots pine X X X
F19 F8 61.7 160 3 Scots pine 188
Pinus–Vaccinium vitis-idaea X Scots pine X X
F20 F6 64.7 140 3 Scots pine 192
Pinus–Vaccinium vitis-idaea X X X
F21 F9 79.3 120 3 Scots pine 191
Pinus–Vaccinium vitis-idaea X Scots pine X X
1
Skogforsk-NINA-VNIIPRIRODA-IGCE project (Aamlid
et al. 2000). 2: NINA-NGU-INEP-METLA monitoring network (Yoccoz et al. 2001). 3: Finnish Lapland Damage
Project (Tikkanen and Niemelä 1995).
BOREAL ENV. RES. Vol. 14 • Vegetation and air pollutants from a nickel–copper industrial complex 283
low, 1.1–1.3 reindeer km
–2
in Norway and about
1.6 reindeer km
–2
in Finland. For comparison, the
density of reindeer in West Finnmark, Norway,
is 9–10 reindeers km
–2
. There is no reindeer
husbandry practiced in the Russian part of the
border area (Nieminen 2004, The Directorate for
Reindeer Husbandry 2007).
Twenty one plots were selected from three
different monitoring projects with a different
monitoring design, covering a gradient from
heavily polluted areas to those with almost no
pollution impact. The eight Norwegian and Rus-
sian plots, established in boreal Scots pine forest
as a part of the Skogforsk-NINA-VNIIPRI-
RODA-IGCE project (Aamlid et al. 2000), are
distributed along an east–west transect (N9, N8,
N5, N4, R2, R1), with a remote plot to the south-
east (R12) that is the least affected by air pollu-
tion (Table 1 and Fig. 1). These plots consist of a
rectangular 25 m ¥ 40 m area for the assessment
of tree vitality, forest growth and ground vegeta-
tion. Analysis of epiphytic lichen vegetation on
birch and Scots pine stems was performed in the
buffer zone surrounding the plot. The ground
vegetation was analysed in 2004 on ten 1 m ¥
1 m quadrates within each of the Norwegian
plots, randomly selected from the original 20
established quadrates. All 20 quadrates were
used on the Russian plots.
INEP-METLA monitoring network (R3, R6,
R7, N10, R11) were established in birch forest,
and are distributed along a north–south transect
sub-plots arranged in a cross, with one central
and four adjacent subplots 10 m from the central
subplot (Yoccoz et al. 2001). Each subplot is
15 m ¥ 15 m and the distance from the centre
subplot to the adjacent subplots centres is 25 m.
Assessments of epiphytic lichen cover were
made within the subplots, and the ground vegeta-
tion was analysed within 1 m ¥ 1 m quadrates
quadrates per plot.
The nine plot clusters selected from the Finn-
ish Lapland Damage Project (F13, F14, F15, F16,
F17, F18, F19, F20, F21) were all established in
Scots pine forest (Tikkanen and Niemelä 1995)
(Table 1 and Fig. 1). Each cluster consists of 3–4
circular subplots. One subplot was selected as a
sample plot to represent the ground vegetation of
the whole cluster. The size of the subplot is 300
m
2
, with a radius of 9.8 m. A total of 7–12 quad-
rates of 1 m ¥ 1 m were systematically estab-
lished along two transects within the subplot for
the ground vegetation assessments.
Sampling and chemical analysis of
precipitation
Bulk deposition was monitored on plots in
Norway, Russia and Finland for a period of one
year (Table 2). The plots in Norway and Finland
were established at the beginning of June 2004.
For logistical reasons the plot in Russia was
established at the beginning of October 2004.
The equipment for collecting the rain and snow
samples was identical on all the plots, and was
based on the design used in Finland as a part of
the Forest Focus/ICP Forest deposition monitor-
ing programme (http://www.icp-forests.org/pdf/
Chapt6_compl2006.pdf). Bulk deposition was
monitored during the snowfree period using 5
rainfall collectors located in an open area (i.e.
no tree cover) close to the plots, and 3 snowfall
collectors located at the same points during the
winter. The collectors were emptied at 4-week
Table 2. Annual precipitation (mm), average pH and deposition of metals, sulphate, ammonium, nitrate and chlo-
ride (mg m
–2
year
–1
) in bulk deposition at plots in Russia, Norway and Finland in 2004–2005. Sequence of plots is
arranged in order of increasing distance from the Nikel smelter.
Plot Precip. pH Cu Ni SO
4
-S Zn Fe Al Na Cl Ca Mg K NO
3
-N NH
4
-N
R2 461 4.62 20.9 17.3 102 4.0 14.0 6.3 414 898 70.7 73.2 73.7 7.1 51.3
N4 722 4.94 24.4 27.3 355 8.6 16.5 9.8 517 1686 74.3 104 73.7 57.0 60.5
N10 678 4.91 10.0 7.8 331 5.8 5.6 10.5 763 2188 86.8 123 66.9 61.6 52.7
R12 423 4.51 1.5 0.9 53 4.8 3.7 5.7 130 316 24.7 19.6 22.2 8.6 54.4
F18 485 4.95 1.7 2.7 103 6.2 1.0 7.3 175 306 23.4 23.5 27.3 38.4 28.8
284 Myking et al. • BOREAL ENV. RES. Vol. 14
intervals. During the snowfree period all the
sample collectors were bulked on site to give one
composite sample for each plot. The total volume
of the bulked samples was recorded (determined
sent to the laboratory for analysis. During the
winter the samples in all the individual collec-
tors had to be transported to the laboratory for
thawing, weighing and bulking. Maintenance of
to the laboratory were carried out in accordance
the Forest Focus/ICP Forests deposition moni-
toring programme.
Because the sampling period was not exactly
one year, the results for annual deposition were
adjusted accordingly. pH was measured on the
-
ters, the Cu, Ni, Zn, Fe, Al, Na, Ca, Mg and K
concentrations were determined by inductively
coupled plasma atomic emission spectrometry
(ICP/AES), and the SO
4
-S, Cl, NO
3
-N and NH
4
-
N concentrations by ion chromatography.
Assessment of epiphytic lichens
Assessment of the epiphytic lichen cover was
carried out on plots with birch and Scots pine on
ten randomly chosen stems with a dbh > 5 cm
(dbh = diameter at breast height 1.3 m above
the ground) on each plot (Table 1). The lichen
cover was recorded at four heights on the stems:
135 cm, 150 cm, 165 cm and 180 cm above the
ground level by using a simple measuring tape
with a marker at each centimetre (Aamlid et al.
2000). Starting from north, the number of centi-
metre markers covering a single lichen species
was recorded for each height. Percentage lichen
cover on each plot was calculated by dividing
the total lichen cover on the circumference at
each height, and then calculating the average
for each stem and plot. Estimation of correla-
relationship between the lichen cover and the log
transformed distance from the pollution source.
The log transformed distance for Scots pine did
not follow normal distribution, and Spearman’s
this data set.
Ground vegetation assessments and
environmental variables
Two hundred and twelve quadrates distributed
on 21 plots were analysed to assess the diversity
and abundance of lichens, bryophytes and vas-
cular plants in 2004 (45 quadrates from Norway,
80 from Russia and 87 from Finland). In each
quadrate, the relative cover of each species was
estimated together with the cover of litter, stones,
bare ground and the height and the relative cover
of the shrub and tree layers above the quadrates.
Species covering less than 1% were given the
value of 1%. Taxonomic nomenclature follows
Lid and Lid (2005) for vascular plants, Frisvoll
et al. (1995) for bryophytes, and Santesson et al.
(2004) for lichens.
The average cover of stones, bare ground,
shrub and tree layers per plot were estimated as
an average of the assessments within the 1 m ¥
1 m quadrates and used as environmental vari-
ables to explain the variation in ground vegeta-
tion. Extrapolated climatic data from WorldClim
(Hijmans et al. 2005), with a spatial resolution
of one square kilometre, were used as climatic
explanatory variables, together with the log
transformed distance from the pollution source,
altitude of the plots and chemical data from the
organic soil layer. The concentration of Cu and
Ni in the humus layer was used as an indirect
pollution explanatory variable owing to the lack
of any direct measurements of the pollution
impact.
Statistical analysis of ground vegetation
and environmental variables
The variation in species composition in the total
dataset of 212 quadrates was analysed with indi-
rect gradient analysis (ordination) in terms of
detrended correspondence analysis DCA (Hill
1979, Hill and Gauch 1980). This method
describes major gradients using species abun-
dances irrespective of any environmental varia-
ble. Direct gradient analysis, in terms of canoni-
cal correspondence analysis (CCA) (ter Braak
1986, 1987), was used to explain the vegetation
gradients by measured environmental variables,
using average species abundance data per plot
BOREAL ENV. RES. Vol. 14 • Vegetation and air pollutants from a nickel–copper industrial complex 285
response models (DCA and CCA) were chosen
since the length of the vegetation gradient was
more than 2.0 standard deviation units, as rec-
ommended by ter Braak and Prentice (1998).
The gradient analyses were performed with
CANOCO 4.1 (ter Braak and Smilauer 2002).
Rare species were “downweighted” in the DCA
and the CCA analyses by the standard procedure
in the programme. The species data were log-
transformed in the DCA analysis due to a very
high range of abundance values (1%–100%).
Plot R6 was given the weight of 0.1 in the CCA
analysis due to its occurrence as an “outlier” in a
standard CCA. Only those variables which were
to the vegetation gradients in the unrestricted
Monte Carlo permutation tests with 499 random
Crown condition and stand growth
The tree measurements included assessment of
crown density, crown colour, and height and
diameter growth. All trees with a dbh > 5 cm
on each plot were included. Crown density was
assessed on Scots pine, with reference to a
normally dense crown for trees in the region
(Aamlid and Horntvedt 1997, Aamlid et al.
2000). The assessments were carried out by
trained observers using binoculars, and the trees
were inspected from different sides at a distance
of about one tree length. Only the upper two
thirds of the tree crown were assessed, and the
crown density was estimated in 1% classes.
Mechanical damage arising from snow break,
wiping etc was excluded. Crown colour was esti-
mated using the ICP Forest classes (http://www.
icp-forests.org/pdf/Chapt2_compl06.pdf); class
0 = normal green, class 1 = slight yellow, class
2 = moderate yellow, class 3 = strong yellow.
Only vigorous trees, non-suppressed by neigh-
bouring trees, were included in the calculations
of tree vitality. In Finland, Norway and Russia
28–41, 40–83 and 40–88 non-suppressed Scots
pine trees, respectively, were available for the
assessment of crown condition on each monitor-
ing plot. Simple linear regression was used to
estimate the relationship between crown density
and growth parameters in Scots pine at the indi-
vidual tree level.
Tree height was measured digitally (Vertex
III, Hagløf, Sweden AB), and stem circumfer-
ence was measured 1.3 m above ground level to
an accuracy of 1 mm. The position at the stem
was clearly marked to ensure repeated meas-
urements at the same place in the future. Tree
volume was calculated according to the volume
functions of Brantseg (1967). The increase in
tree height, stem circumference and tree volume
were calculated by dividing the data from 2004
by the 1998 data. Data from 1998 were not avail-
able from Finland, and growth was thus only
reported for the Norwegian and Russian Scots
pine plots.
Sampling and chemical analysis of the
humus layer
Twenty sub-samples of the organic layer (exclud-
ing the litter layer) were collected in a 3 m ¥ 4 m
grid on each plot, and then pooled. The sampling
took place close to the quadrates for the vegeta-
tion analysis. pH was measured in an aqueous
slurry, total carbon and nitrogen on a CHN ana-
lyser, and total phosphorous, copper and nickel
by ICP/AES following acid digestion in a micro-
wave oven.
vegetation assessments, crown condition and
stand growth, epiphytic lichens, and collection
two weeks of August 2004.
Results
Deposition
In 2004–2005, the annual precipitation on the
monitoring plots in Russia and Finland ranged
between 420–485 mm (Table 2). On the two plots
in Norway, which are the closest to the sea, the
annual precipitation was 678 and 722 mm. The
bulk deposition of sulphate was relatively high
on these plots (331 and 355 mg SO
4
-S m
–2
year
–1
)
(Table 2), while on all the other plots sulphate
deposition was low (53–103 mg SO
4
-S m
–2
year
–1
).
286 Myking et al. • BOREAL ENV. RES. Vol. 14
Similar deposition peaks also occurred for Na,
Cl and Mg at the Norwegian plots. The plots
received sulphate from two sources: the smelting
and roasting industry in Nikel and Zapolyarnyy,
respectively (gaseous SO
2
and SO
4
2–
), and sul-
phate in aerosols from the sea (e.g. as MgSO
4
).
The average deposition of Cu, Ni, and Fe was
substantially elevated on the plots north of Nikel
(Table 2 and Fig. 1). The temporal variation
in deposition around Nikel is characterised by
occasional peaks that vary in synchrony for the
main pollutants. At plot N4 the four-week aver-
ages for Cu, Ni and sulphate varied from about
zero to 0.144 mg l
–1
, 0.141 mg l
–1
and 1.25 mg l
–1
,
respectively.
Epiphytic lichens
The Finnish and Russian pine plots were all
species-poor. The dark pendant lichen Bryoria
fuscescens, possibly also including some thalli
of other Bryoria species, was by far the most
common lichen on the pine trees. On the Finnish
plots it was recorded four times as often as the
second most common lichen, the small-foliose
Imshaugia aleurites. The plots at a distance of
about 5 km from Nikel had the lowest lichen
abundance with less than 1% total cover, and the
cover was less than 10% at a distance of 42–43
km. The plots farther away from Nikel had up
to 23.4% total lichen cover. Thus, there was a
strong relationship between the distance to Nikel
and the lichen cover on the pine trees (r
2
= 0.86)
(Fig. 2).
The Russian and Norwegian plots with birch
were also species-poor, and Parmelia sulcata was
by far the most common species on birch with
about 60% of all records (Fig. 2). Lichens were
absent on four plots situated at distances between
5 and 14 km from Nikel. On the plot closest to
Nikel a few minute thalli were recorded, giving
an overall relative cover of 0.8%. The remain-
ing plots situated between 15 and 79 km from
Nikel had between 6% and 24% relative cover.
-
tion between the lichen cover and distance from
Nikel (r
2
= 0.52) (Fig. 2).
Vegetation types
All the Finnish plots, the Norwegian plots N4, N5,
N8 and N9 and the Russian plots R1, R2 and R12
are situated in northern boreal Scots pine forests
(Fig. 1 and Table 1). The ground vegetation of the
pine forest plots was generally rich in lichens with
species such as Cladonia arbuscula, C. crispata,
C. gracilis, C. sulphurina, C. rangiferina, C. stel-
laris, C. uncialis, C. coccifera, C. chlorophaea
and C. . The most common bryophytes
were oligotrophic mosses such as Dicranum
fuscescens, D. scoparium, Pleurozium schreberii
and Polytricum juniperinum. Liverworts, mainly
Barbilophozia spp. and Lophozia spp. were also
common. The most abundant dwarf shrubs were
Empetrum nigrum ssp. hermaproditum, Rhodo-
dendron tomentosum (syn. Ledum palustre), Vac-
cinium myrtillus and V. vitis-idaea. Herbs and
grasses had a sparse distribution, except Avenella
(syn. ), which
occurred on most of the plots.
Two of the Finnish plots (F14 and F17) and
the Norwegian plot N5 had a species composition
0
5
10
15
20
25
30
0 10 20 30 40 50
Distance from Nikel (km)
Lichen cover (%)
0
5
10
15
20
25
0 20 40 60 80
Distance from Nikel (km)
Lichen cover (%)
a b
Fig. 2. Total lichen cover
on (a) birch (Betula pubes-
cens) and (b) pine (Pinus
sylvestris) as a function of
distance from Nikel.
BOREAL ENV. RES. Vol. 14 • Vegetation and air pollutants from a nickel–copper industrial complex 287
similar to the dry, oligotrophic vegetation type of
“Pinus sylvestris–Cladonia spp. type” described
in Påhlsson (1994), which is comparable to the
“Cladonia woodland, Cladonia–Pinus sylvestris
subtype” in Fremstad (1997). The rest of the
Finnish plots, the Norwegian plots N4, N8 and
N9 and the Russian remote plot R12 were more
dominated by dwarf shrubs and thus resembled
the relatively dry “Pinus sylvestris–Vaccinium
vitis-idaea type” (Påhlsson 1994), comparable
to the “Vaccinium-vitis-idaea–Empetrum nigrum
coll. subtype of the Vaccinium woodland” (Frem-
stad 1997). The Russian plots R1 and R2 proba-
bly also belong to this vegetation type. However,
to determine their original vegetation type.
The Norwegian plot N10 and the Russian
plots R3, R6, R7 and R11 are situated in birch
forests. These plots were characterized by almost
the same species as the plots in the pine forests.
However, in general, the birch forest plots had
a lower cover of lichens, and additional species
such as Chamaepericlymenum suecicum (syn.
Cornus suecica), Orthilia secunda, Pedicula-
ris lapponica, and Trientalis europaea indicated
slightly more mesic vegetation.
Plot N10, rich in Vaccinium myrtillus, and
partly also R6, resembles the “Betula pubescens
ssp. czerepanovii–Vaccinium myrtillus–Des-
type” (Påhlsson 1994), com-
parable to the “Vaccinium myrtillus–Empetrum
nigrum coll. subtype of the bilberry woodland”
(Fremstad 1997) on slightly mesic and humid
soil. Plot R6 was also characterized by the low
fern Gymnocarpium dryopteris and Solidago vir-
gaurea. The Russian birch plots R3, R7 and
R11 probably belong to the somewhat dryer
“Betula pubsecens ssp. czerepanovii–Empetrum
hermaphroditum-Cladonia spp. type” (Påhls-
son 1994), comparable to the “Vaccinium-vitis-
idaea–Empetrum nigrum coll. subtype of the
Vaccinium woodland” (Fremstad 1997).
Gradients in species composition of the
ground vegetation
The DCA ordination of the total of 212 quad-
rates showed a gradient from dry, lichen-domi-
nated forests to medium dry, dwarf shrub domi-
described vegetation types (Fig. 3). However,
the species composition of the Russian plots in
were very different from the vegetation on the
–0.5 3.0
–0.5
2.0
Russian adjacent plots
Russian remote plots
Norwegian plots
Finnish plots
DCA axis 1
DCA axis 2
Pollution impact
Lichen dominated
dry forest
Dwarf shrub dominated
medium dry forest
Fig. 3. Detrended corre-
spondence analysis (DCA)
diagram of 212 quadrates,
axes 1 and 2, with inter-
preted environmental gra-
dients. “Russian remote
plots” refer to R11 and
R12. (From Stebel et al.
2007, adapted by the
authors of this paper).
288 Myking et al. • BOREAL ENV. RES. Vol. 14
other plots, as shown by their distinct separation
on the high DCA axis 2 scores. These differ-
ences were mainly related to the occurrence and
abundance of bryophytes and epigeic lichens in
the ground layer (Fig. 4). Mosses and liverworts
were almost absent on the Russian plots close
to the Nikel smelter. Some bryophyte species
(Dicranum spp., Hylocomium splendens, Pla-
giothecium laetum) were not found on these
plots at all. The Finnish plots had, in general, a
medium bryophyte cover, while the ground layer
on the Norwegian and the Russian plots farthest
away from Nikel were dominated by mosses and
partly by liverworts.
The lichen cover was very sparse on plots
close to the pollution source (Fig. 4), and mainly
comprised pioneer cup lichens (e.g. Cladonia
chlorophaea, C. botrytis, C. gracilis, C. -
data, C. sulphurina). The cover was even less
than indicated, because species covering less
than 1% were given the value of 1%. The Finn-
ish plots and the Norwegian plot N5 had the
highest abundance of epigeic lichens, with a
dominance of reindeer lichens (Cladonia arbus-
cula, C. mitis, C. rangiferina and C. stellaris) in
additions to species of Cetraria and Peltigera.
Lichens were also common on the most remote
Russian plots.
The average number of species per 1 m ¥
1 m quadrate was lowest on the plots close to the
Nikel smelter due to the relatively few species
of mosses and lichens (Fig. 5). The number of
dwarf shrubs (including all woody species below
50 cm, e.g. Empetrum nigrum ssp. hermaph-
roditum, Rhododendron tomentosum, Vaccinium
myrtillus, V. vitis-idaea) was relatively constant
on all the plots. In general, the number of herbs
and grasses was lowest on the Finnish plots,
which also had the highest number of lichen
species.
Relationships between species
composition and environmental
variables
The CCA showed that the most important vari-
ables explaining the variation in species compo-
sition of the ground vegetation were total phos-
phorous in the humus layer (P), humus pH, total
copper concentration in the humus (Cu), distance
from the pollution source (Distance), carbon/
nitrogen ratio of the humus (C/N), total nickel
concentration in the humus (Ni), mean annual
temperature (Mean year temp) and the litter
cover on the ground (Litter), in slightly decreas-
ing importance, as shown by the length of the
biplot arrows (Fig. 6). Precipitation, altitude, tree
and shrub cover and the cover of stone and bare
-
cant related to the species variation.
A partial constrained correspondence analy-
sis (Borcard et al. 1992) with the “pollution vari-
ables” Ni and Cu in the humus layer as the envi-
ronmental variables and pH, P, C/N, litter and
mean annual temperature as covariables showed
0
10
20
30
40
50
60
70
80
90
100
R1
R2
R3
N4
N5
R6
R7
N8
N9
N10
R11
R12
F13
F14
F15
F16
F17
F18
F19
F20
F21
Average cover (%)
Lichens
Liverworts Mosses
Fig. 4. Average percent-
age cover of bryophytes
and epigeic lichens on
the monitoring plots.
Sequence of plots (left to
right) arranged in order of
increasing distance from
the Nikel smelter.
BOREAL ENV. RES. Vol. 14 • Vegetation and air pollutants from a nickel–copper industrial complex 289
p = 0.04) to the
variation in species composition, when the vari-
ation explained by the other variables had been
taken into account.
The ground vegetation on the Russian plots
close to Nikel was positively correlated to plots
with medium to high total P concentrations, rela-
tively high pH, high total Cu and Ni concentra-
0
5
10
15
20
25
R1
R2
R3
N4
N5
R6
R7
N8
N9
N10
R11
R12
F13
F14
F15
F16
F17
F18
F19
F20
F21
Average species number
Lichens Liverworts Mosses Herbs, grasses Dwarf shrubs
–1.0 1.0
–1.0
1.0
Litter
Distance
Mean year temp
pH
C/N
P
Ni
Cu
F14
F15
F18
F13
F17
F20
F16
F19
F21
N9
N8
N4
N5
R12
R2
R1
N10
R6
R3
R7
R11
Env. variables
Samples:
Russian adjacent plots
Russian remote plots
Norwegian plots
Finnish plots
CCA axis 2
CCA axis 1
Fig. 5. Average number
of plant species per 1 m
2
in different plant groups
on the monitoring plots.
Sequence of plots (left to
right) arranged in order of
increasing distance from
the Nikel smelter.
Fig. 6. Canonical cor-
respondence analysis
(CCA) diagram of species
abundance data and envi-
ronmental variables from
21 plots, axis 1 and axis
2. Environmental varia-
bles represented by biplot
arrows. “Russian remote
plots” refer to R11 and
R12.
290 Myking et al. • BOREAL ENV. RES. Vol. 14
tions and low C/N values in the humus, shown
by the direction of the biplot arrows (Fig. 6). In
general, these plots had the highest litter cover
and they were all situated in areas with relatively
high mean annual temperatures. The plots which
were characterized by high lichen cover (Fig. 4)
had the highest C/N ratios, lowest pH and total
P, Cu and Ni concentrations in the humus layer.
Especially the Finnish plots showed a relation-
ship with low mean annual temperatures. Most
Norwegian plots were characterized by vegeta-
tion commonly found on sites with medium and
high humus P concentrations and medium values
of pH, C/N ratio and Ni.
Crown condition
Discoloration in Scots pine was not recorded in
the study area. The crown density was high and
stable across the two assessments on the mod-
erately polluted Norwegian plots as compared
to the heavily polluted plots in Russia, and the
remote plots at a distance of more than 42 km
from Nikel (Table 3). The average stand age on
the Finnish plots were, however, considerably
higher than those on the plots in Norway and
Russia (Table 1).
Stand growth of Scots pine was calculated as
percentage increase in the increment of height,
basal area and volume between 1998 and 2004
(Table 3). The highest increase in basal area was
associated with the plots close to the smelter in
Nikel, and the lowest with a remote plot (R12).
The difference between the Norwegian plots was
small and unrelated to distance from the smelter.
The height increment was relatively even along
the gradient, except for the comparably low
increments at two plots situated at each end of
the pollution gradient (R2, R12). As the volume
increment was calculated from the increment
in basal area and height, the highest volume
increment was found close to the smelter, and
the lowest on the remotest plot. The correlation
-
cant (p < 0.0001), but moderate (r
2
≤ 0.14).
Discussion
The results of this study show that industrial
pollution is still affecting the vegetation in the
border area. The most pronounced effects are
associated with epiphytic lichens, which are
known to be very sensitive to SO
2
emissions in
this area and elsewhere (Hawksworth and Rose
1976, Tarhanen et al. 2000). Plots in the vicin-
ity of Nikel had no or a very modest epiphytic
lichen cover, whereas there was an increase in
lichen cover with increasing distance from the
smelter on both pine and birch stems (Fig. 2).
The SO
2
concentration generally decreases
with increasing distance from the Nikel smelter,
with the highest concentrations in the southwest-
Table 3. Crown density and growth increase in Scots pine. The values for the Finnish plots are means of three
adjacent plots. Different single letters (growth increase) show significant differences between plots at
p < 0.05, two
letters (e.g. ab) implie no significant difference vs. values with the individual single letters (e.g. a and b). Sequence
of plots is arranged in order of increasing distance from the Nikel smelter.
Plot Crown density (%) Growth increase (%) 1998–2004
2004 2005 Basal area Tree height Volume
R1 82.1 34.4
b
15.9
a
49.1
b
R2 76.8 38.4
a
12.1
b
56.1
a
N4 94.3 93.6 23.6
cd
14.5
a
36.2
c
N5 93.9 93.0 21.7
d
14.7
a
34.5
c
N8 92.9 92.3 25.4
cd
14.0
ab
36.0
c
N9 93.4 93.8 27.3
c
15.7
a
39.9
c
R12 57.9 10.6
e
07.0
c
16.5
d
F14, 15, 18 74.5
F13, 17, 20 79.6
F16, 19, 21 85.3
BOREAL ENV. RES. Vol. 14 • Vegetation and air pollutants from a nickel–copper industrial complex 291
ern-northeastern sectors of the pollution source
(Bekkestad et al. 1995, Hagen et al. 2000, Stebel
et al. 2007). Although the SO
2
emissions from the
Petchenganickel combine have been reduced to
ca. one third over the last three decades, annual
emissions still amount to about 120 000 tonnes
(Henriksen et al. 1997, Milyaev and Yasenskij
2004). The deposition of Ni, Cu and Fe were
strongly elevated (Table 2). However, on some
of the plots (e.g. in Finland), the Cu and Ni
concentrations were extremely low, and in many
-
lytical equipment. As a result, there was a clear
spatial gradient in the deposition. The decline in
heavy metal concentrations with distance from
Nikel is more abrupt than the reduction of SO
2
concentrations, because the heavy metals are
present as particles in aerosols (Bekkestad et
al. 1995, Bjerke et al. 2006). Accordingly, the
harmful effect of SO
2
on epiphytic lichens may
occur at greater distances from Nikel than indi-
cated by the low heavy metal concentrations
in deposition in the periphery of the study area
(Table 2). Owing to the climatic heterogeneity,
which the cover of epiphytic lichens is reduced
by the emissions, beyond the epiphytic desert
zone. Two distant plots at 28 km and 42 km from
Nikel had a relatively low lichen cover; one was
at a relatively high altitude south of Nikel (R12),
and the other to the north, close to the Barents
Sea (N10). It is likely that the severe climate,
rather than air pollution, was the most important
factor limiting the epiphytic lichen vegetation
on these two plots. Similar conclusions concern-
ing the effect of climate on epiphytic lichens in
this region have also been drawn by Aamlid and
Skogheim (2001) and Bjerke et al. (2006). In our
study the environmental conditions are probably
more variable across the birch plots than pine
plots, since some of the birch plots are situated
further north towards the coast. For instance, the
high deposition of SO
4
, Na, Cl, and Mg on the
comparably high precipitation rates and the high
concentrations of these compounds in sea water
(Dring 1986). In addition, the temperatures at the
coast are higher during winter and lower during
summer than further inland (Aune 1993). All the
Norwegian plots are situated in an area which
was considered to be an epiphytic lichen desert
in 1982–1983 (Bruteig 1984). Comparison with
et al. 2000) shows that the lichen cover has
increased notably on birch on the least polluted
plots west of Nikel. This indicates that the reduc-
tion in the SO
2
lichen recolonisation. However, our data (Fig.
2) suggest that the impact area extends at least
20 km to the west of Nikel and probably even
further to the north because of the predomi-
nant wind directions from south-southwest (cf.
Aamlid and Skogheim 2001, Hagen et al. 2006).
Interestingly, this corresponds relatively well to
the area around Nikel delimited by the modelled
isoline for 10 µg m
–3
SO
2
(Bekkestad et al. 1995),
a pollution level regarded as a critical mean level
The main variation in the ground vegetation
within the monitoring network was related to dif-
ferences in natural environmental variables such
as climate and soil conditions. The relatively dry,
naturally acidic soils (low pH) with low nutrient
availability (high C/N ratio) and limited graz-
ing impact on the Finnish plots favour lichen-
dominated ground vegetation, while higher pH
values and a lower C/N ratio in the humus layer
of the Norwegian plots (except N5) may indi-
cate slightly more fertile soils favouring mosses,
herbs and grasses (Fig. 5). However, although
the density of semi-domestic reindeers is low
and at about the same level in the Norwegian
and Finnish part of the monitoring area (Niem-
inen 2004, The Directorate for Reindeer Hus-
bandry 2007), local differences in grazing pres-
sure might affect the species composition of the
ground vegetation. The vegetation on the Finnish
plots and the remote Russian plots might also be
generally lower annual mean temperatures and
lower winter temperatures (Hijmans et al. 2005),
which favour lichen-dominated ground vegeta-
tion (Haapasaari 1988).
On the Russian side of the border area,
however, there are no semi-domestic reindeer
(Jernsletten and Klokov 2002, Tømmervik et al.
2003). The plots close to Nikel should therefore
potentially have as high a lichen cover, if not
affected by air pollution, as the remote Russian
plots. However, the lichen cover close to Nikel
292 Myking et al. • BOREAL ENV. RES. Vol. 14
is generally lower than that on most of the other
monitoring plots (Fig. 4). Elevated levels of SO
2
and heavy metals are toxic to lichens and bryo-
phytes, especially bio-available Cu in mosses
(Shaw 1990, Salemaa et al. 2004), which may
contribute to their lower coverage and diversity
in the vicinity of the Nikel smelter (Figs. 4 and
5). Moreover, the total Ni and Cu concentrations
in the humus layer decreased with increasing dis-
tance from the pollution source (Fig. 6), and the
the change in species composition on moving
away from the smelter, even when the variation
related to natural environmental variables was
taken into account. This strongly suggests that
the emissions affect both the cover and richness
of epigeic lichens and bryophytes in the vicinity
of the Nikel smelter (Figs. 4 and 5). A reduction
in epigeic lichens and bryophytes has previously
been reported in the same area by Tømmervik et
al. (1998, 2003), Chernenkova and Kuperman
(1999), Aarrestad and Aamlid (1999) and Aamlid
et al. (2000) as an effect of air pollution from
Nikel and Zapolyarnyy.
The pollution gradients, however, were not
strictly related to the distance from the pollution
source. The reduced bryophyte and lichen cover
was clearly evident at the Russian plot R6 12.3
km to the north-east of the Nikel smelter, while
there was no indication of any pollution effect
on the Norwegian plot N5 11.9 km west of the
smelter (Fig. 6). This can be explained on the
basis of the above-mentioned pollution corridor
running mainly in a southwest-northeast direc-
tion from the smelter, which is probably related
to the prevailing wind directions in the area
(Bekkestad et al. 1995, Hagen et al. 2006, Stebel
et al. 2007).
One fact that possibly may have an impact
on the species composition of the ground vegeta-
tion on the Russian plots is the high frequency
Russian area (Knjazev and Nikonov 2003, Tøm-
mervik et al. 2003, Knjazev and Isaeva 2006,
Knjazev and Sukhareva 2007). Although the
-
Degradation of the ground vegetation leads
to increased litter accumulation, and the deposi-
tion of air pollutants may lower the mineraliza-
tion and decomposition rates of the litter due to
reduced microbiological activity (Fritze 1989).
The accumulation of litter will tend to sup-
press recolonization and plant growth due to the
unfavourable temperature and moisture condi-
tions (Salemaa et al. 2001, Kozlov and Zvereva
2007b). Soil pH might also be reduced through
the effects of sulphur deposition, as reported by
Lukina and Nikonov (1995) in the Nikel area,
and changes in soil acidity may subsequently
lead to changes in the species composition.
Thus, even though the main vegetation gra-
dients in the joint Finnish–Norwegian–Russian
monitoring network can be partly explained by
several natural factors (e.g. climate, humidity,
soil fertility) and human disturbance (e.g. rein-
the emissions of SO
2
and heavy metals from
the Nikel smelter have and are still affecting the
main effects are reduced species richness and
and increased litter accumulation on the forest
Empetrum nigrum ssp.
hermaphroditum and Vaccinium vitis-idaea seem
to be less sensitive to the pollution, as dem-
onstrated earlier (cf. Monni et al
et al. 2001, Zvereva and Kozlov 2004). These
effects are clearly visible at plots close to the
smelter in Nikel where many species of mosses,
liverworts and lichens have disappeared, while
those that have survived have low occurrence and
cover values. It is unclear whether pollution has
affected the ground vegetation at the Norwegian
and Finnish plots. Accordingly, the impact area
for ground vegetation appears to be smaller than
the area where epiphytic lichens are reduced
or absent. This is in agreement with the higher
critical annual mean SO
2
estimate for natural veg-
etation and forests in areas of low temperatures
(15 µg m
–3
SO
2
) than for epiphytic lichens (10
µg m
–3
SO
2
situated 135–180 cm above the ground surface
are not protected by snow during winter, and
could be exposed to air pollution throughout the
year. Thus, life history traits may partly explain
the higher sensitivity of epiphytic lichens to SO
2
.
Our data on crown condition and the growth
of pine do not provide conclusive evidence that
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