Transcript KOLIseminarPENSA

The effect of planted tree species on the
diversity of herbaceous vegetation in a
reclaimed oil-shale opencast in Estonia
Margus Pensa, Helen Karu, Aarne Luud, Elga Rull,
and Riina Vaht
Adapting Forest Management to
Maintain the Environmental Services
Koli 21.-24.9.2009
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Estonian power industry
• 90% of Estonian electricity comes from
burning of oil shale
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Estonian power industry
• Because of that, per capita CO2 emissions
are very high
14 t CO2 yr-1
© Postimees
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Since 1918, the mining for oil shale has changed the landscape in an
area of 430 km2
Study sites were located in Narva opencast mine
(59° 18’N, 27° 45’E) that occupies ca 70 km2
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Natural ecosystems of Narva opencast...
Have been degraded to barren spoil...
Which have been afforested by planting
Scots pine (mainly)
Reclamation started in 1960 and has
been successful – forest productivity is
higher than before mining.
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However, forest is not only a wood-producing
factory but also a source of biodiversity
Photo: Jaak Põder
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Examples of protected animal species
found in Estonian oil-shale mining area
Ursus arctos – Brown bear
Canis lupus – Gray wolf
Lynx lynx -- Lynx
Pteromys volans – Flying squirrel
Pandion haliaetus -- Osprey
Aquila chrysaetos – Golden eagle
Haliaeëtus albicilla – White-tailed eagle
Ciconia nigra – Black stork
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Questions related to the reclamation of
Narva opencast:
• Do planted tree species act as ecosystem
engineers in reclaimed opencasts and create
different habitats, so that herbaceous
vegetation diverges at the later stages of
succession according to the dominant tree
species? (Pensa et al. 2004; 2008)
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Study sites in Narva opencast:
• Pioneer stage of vegetation on recently
(about five years ago) leveled mine spoil
• the Scots pine (Pinus sylvestris)
chronosequence (10, 20, and 30 years old
stands)
• 30-year-old planted stands dominated by
larch (Larix sibirica and L. decidua)
• by silver birch (Betula pendula)
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Study sites:
• by alder (Alnus glutinosa and Alnus incana)
• Spontaneously developed stands in an area
where the mine spoil had been left
unplanted (natural stands)
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Study sites
Narva opencast
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Initial nutirent status of barren spoil in
two oil-shale opencast in Estonia
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(Pensa et al. 2004. Rest Ecol)
The increase in tree biomass with time
is...
Basal area of tree layer, m 2 100 m-2
Broadleaved species
0.7
Alder
Birch
Larch
Natural
Pine10
Pine20
Pine30
Pioneer
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
5
10
15
20
Time, yr
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25
30
35
40
...negatively related to light conditions at
ground level in Narva opencasts
1.2
Direct solar factor
1.0
0.8
0.6
Alder
Birch
Larch
Natural
Pine10
Pine20
Pine30
Pioneer
0.4
0.2
0.0
0
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5
10
15
20
25
Time, yr
30
35
40
Differntiation in soil conditions with time
Braodleaved species
8.5
Alder
Birch
Larch
Natural
Pine10
Pine20
Pine30
Pioneer
20
15
10
8.0
Soil pH
Forest floor thickness, mm
25
7.5
Alder
Birch
Larch
Natural
Pine10
Pine20
Pine30
Pioneer
7.0
5
6.5
0
6.0
0
5
10
15
20
25
Time, yr
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30
35
40
0
5
10
15
20
25
Time, yr
30
35
40
Differntiation in soil conditions with time
Alder
140
Alder
Birch
Larch
Natural
Pine10
Pine20
Pine30
Pioneer
0.8
0.6
0.4
Alder
Birch
Larch
Natural
Pine10
Pine20
Pine30
Pioneer
120
Soil phosphorus, mg kg-1
Soil nitrogen concentration, %
1.0
0.2
0.0
100
80
60
40
20
0
0
5
10
15
20
25
Time, yr
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30
35
40
0
5
10
15
20
25
Time, yr
30
35
40
Richness of plant species – α, β, and γdiversities in different forest stands in Narva
opencast
Stand type
Herb layer
Shrub layer
Tree layer
α
β
γ
α
β
γ
α
β
γ
Pioneer
7,6
3,1
31
-
-
-
-
-
-
Pine10
7,0
3,3
28
2,6
2,7
7
2,1
1,4
3
Pine20
7,2
2,5
25
2,0
3,0
6
2,1
2,4
5
Pine30
7,5
2,7
28
3,1
3,2
10
2,2
2,7
6
Birch
7,0
2,9
27
4,0
3,0
12
2,4
2,1
5
Alder
10,6
2,4
36
2,4
3,3
8
2,0
3,7
5
Larch
7,2
3,6
33
2,8
3,6
10
1,9
2,5
7
Natural
9,9
4.0
50
3,5
3,7
13
2,9
2,4
7
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NMS ordination of herb species according to
stand type
Stand age
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Developmental patterns of herb layer in Narva
opencast
stress-tolerant species
Pine10
Natural
Pioneer
Pine20
Orthilia secunda
Pine30
Larch
Calamagrostis arundinacea
Birch
Calamagrostis epigeios
Tussilago farfara
Urtica dioica
Festuca gigantea
Alder
competitive species
Stand age
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Conclusions
• Tree species have created recruitment
limitations on the development of herb layer
• Broadleaved trees enhance the growth of
herbs, while conifers supress it
• As different herb species are favoured by
different tree species, the planting with
various tree species ensures higher regional
species richness
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Thank
you!
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[email protected]