Transcript Suomen uhanalaisten lajien ensisijaiset uhkatekijät (Rassi et al. 2000)

Survival of species in fragmented
forest landscapes
Ilkka Hanski
Metapopulation Research Group
Contents
• How to assess the consequences of
fragmentation in dynamic landscapes?
• Time delay in metapopulation response to
changing environment
• Extinction thresholds and implications for
biodiversity conservation
• Conclusion: What is needed to protect
biodiversity in our boreal forests?
Metapopulation Research Group
fragmentation threatens
biodiversity
How to estimate isolation and hence
the effect of fragmentation?
• Isolation has a temporal as well as a spatial
component --- current isolation versus how did
that isolation evolve
• Solution: construct a model with which the
occurrence of focal species in all parts of the
landscape is predicted, including the focal
fragments
• Simulate the occurrence of the species assuming
the observed history of fragmentation
Metapopulation Research Group
1945
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1955
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1965
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1975
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1985
Metapopulation Research Group
1995
Metapopulation Research Group
Probability for a particular forest fragment to
be occupied
1.0
Fragment 2
0.8
0.6
Fragment 9
0.4
Fragment 5
Fragment 1
0.2
0.0
1940
1950
1960
1970
1980
1990
2000
2010
year
Metapopulation Research Group
Explaining the occurrence of four species of oldgrowth bracket fungi in spruce forest fragments
Logistic regression model
Isolation history
Decaying wood
p
p
Amylocystis lapponica
Fomitopsis rosea
Phlebia centrifuga
Cystostereum murraii
Note!
<0.001
0.056
0.037
<0.001
<0.001
<0.001
Current isolation nor time since isolation did not explain
the occurrence of the species when analysed separately
Metapopulation Research Group
message # 1
To understand a dynamic process, such as the
effect of habitat fragmentation on
biodiversity, it is helpful to employ a
dynamic model
Metapopulation Research Group
Metapopulation dynamics in
dynamic landscapes
• How long is the delay in metapopulation
response to change in landscape structure?
• Which factors influence the length of the
time delay?
Metapopulation Research Group
Metapopulation Research Group
Decline in the amount
of habitat
Metapopulation response:
thick line = equilibrium
thin lines = predicted changes
Metapopulation Research Group
Metapopulation Research Group
Metapopulation response to habitat loss
Deterministic result
Time delay
17.5
Average and 90% confidence
intervals of 200 simulations
15
12.5
10
7.5
5
2.5
0.5
common
species
1
1.5
2
2.5
3
species doomed
to extinction
Transient time depends on three factors
1. Strength of the perturbation
3
3
2. 5
2. 5
2
2
1. 5
1. 5
1
1
0. 5
0. 5
0
0
0
0. 5
1
1. 5
2
2. 5
3
Short transient time
0
0. 5
1
1. 5
2
2. 5
3
Long transient time
Metapopulation Research Group
Transient time depends on three factors
2. Species and landscape specific
turnover rate
3
3
2. 5
2. 5
2
2
1. 5
1. 5
1
1
0. 5
0. 5
0. 5
1
1. 5
2
2. 5
3
Short transient time
0. 5
1
1. 5
2
2. 5
3
Long transient time
Metapopulation Research Group
Transient time depends on three factors
3. Distance to the extinction threshold
Long transient time
Short transient time
M  
Short transient time
M  
M  
Metapopulation Research Group
message # 2
Time delay in metapopulation response to
habitat loss and fragmentation is especially
long in the case of the threatened species
Metapopulation Research Group
Predicted change in the shape of the ‘commonness’
distribution following environmental change
Extinction debt =
Number of species
that will go extinct
Number of species
that have gone extinct
Metapopulation Research Group
Area of old-growth
forest in Finland
S Finland
N Finland
0.6%
10.4%
Entire Finland
5.5%
Metapopulation Research Group
Threatened beetles in boreal forests
(based on data and analysis by Pertti Rassi)
Percentage of regionally
extinct species
90
8
80
58
70
8
60
19
85
50
2
45
24
40
57
34
30
68
20
33
48
10
12
0
1
2
3
4
SW coastal Finland
5
6
7
8
NE inland Finland
Percentage of natural-like
forest remaining
18
16
14
12
10
8
6
4
2
0
1
2
3
4
SW coastal Finland
5
6
7
8
NE inland Finland
Metapopulation Research Group
message # 3
Extinction debt in Finnish forests
• Based on the recent red data book, we may
estimate that there are nearly 2,000 extinct
or threatened species in Finnish forests
• In addition, there is a large and rapidly
increasing number of regionally extinct or
threatened species in southern Finland
Metapopulation Research Group
Lajiston vaste
The response of species to a change
in habitat/landscape quality
Ympäristön muutos
Ympäristön muutos
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Punttila, Siitonen & Lindström, julkaisematon
Leptusa pulchella, asuttujen puiden osuus sopivista puista
(yksi piste = asuttujenpuiden osuus yhdessä metsikössä)
Asuttujen puiden osuus, %
1
0.8
0.6
0.4
28 metsikköä
0.2
124 puuta
7 metsikköä
9 metsikköä
58 puuta
91 puuta
0
1
10
50
50
100
Lahopuun tilavuus,
m3/ha Research Group
Metapopulation
1000
Punttila, Siitonen & Lindström, julkaisematon
Olisthaerus substriatus, asuttujen puiden osuus sopivista puista
(yksi piste = asuttujen puiden osuus yhdessä metsikössä)
Asuttujen puiden osuus, %
1
0.8
28 metsikköä
7 metsikköä
124 puuta
58 puuta
9 metsikköä
91 puuta
0.6
0.4
0.2
0
1
10
50
50
100
Lahopuun
tilavuus, m3/ha
Metapopulation
Research Group
1000
The three-toed woodpecker - an example of the treshold
condition at the regional scale
1A
0.20
1B
2B

0.15
p
*
0.10
3D
2A
3B
0.05
3C
3A
0.00
0
50
100
150
200
250
300
M
Metapopulation Research Group
350
400
message # 4
The response of species to a change in habitat
quality is typically non-linear and involves
a threshold
Metapopulation Research Group
The new forestry guidelines is this the solution?
If commercial forestry will occupy all the
non-protected forest land, and if all this
forested land will be managed according to
the guidelines, the new guidelines may
represent a change to the worse
Metapopulation Research Group
300
70
250
60
50
200
Frequency
Number of sites occupied
The slow process of disappearence of endangered
species in the current forest landscape
150
100
40
30
20
50
10
0
0
-20
0
20
Years
40
60
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
Metapopulation Research Group
Number of sites occupied
The outcome of comprehensive
implementation of the new forestry practice
300
300
250
250
200
200
150
150
100
100
50
50
0
0
-20
0
20
40
60
-20
Years
0
20
40
60
Years
60
60
50
Frequency
50
40
40
30
30
20
20
10
10
0
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
Number of sites occupied
Let us focus the same conservation effort
within 10% of forested land
300
300
250
250
200
200
150
150
100
100
50
50
0
0
-20
0
20
40
60
-20
Years
Frequency
20
40
60
Years
70
30
60
25
50
0
20
40
15
30
10
20
5
10
0
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
Number of sites occupied
Conservation measures within 10% of forested land but now
located next to the currently most valuable forest stands
300
300
250
250
200
200
150
150
100
100
50
50
0
0
-20
0
20
40
60
-20
Frequency
Years
20
40
60
Years
60
30
50
25
40
20
30
15
20
10
10
5
0
0
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Forest site quality
Concluding messages
• Our forests have a large extinction debt
• It is cost-effective to act now
• The new measures introduced in Finland
(retention trees, protection of small patches of key
habitats, etc.) may make the situation worse if all
the forested land will be treated similarly
• It would pay to concentrate the conservation
efforts… basically, we need more area out of
commercial forestry
Metapopulation Research Group