Survival of species in fragmented forest landscapes

1. Survival of species in fragmented forest landscapes Ilkka Hanski Metapopulation Research Group

2. 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

3. fragmentation threatens biodiversity

4. 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

5. 1945 Metapopulation Research Group

6. 1955 Metapopulation Research Group

7. 1965 Metapopulation Research Group

8. 1975 Metapopulation Research Group

9. 1985 Metapopulation Research Group

10. 1995 Metapopulation Research Group

11. 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

12. Explaining the occurrence of four species of old-growth bracket fungi in spruce forest fragments Logistic regression model Isolation history Decaying wood p p Amylocystis lapponica <0.001 <0.001 Fomitopsis rosea <0.001 Phlebia centrifuga 0.056 <0.001 Cystostereum murraii 0.037 Note! Current isolation nor time since isolation did not explain the occurrence of the species when analysed separately Metapopulation Research Group

13. 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

14. 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

15. Metapopulation Research Group

16. Decline in the amount of habitat Metapopulation response: thick line = equilibrium thin lines = predicted changes Metapopulation Research Group

17. Metapopulation Research Group

18. common species species doomed to extinction

19. Transient time depends on three factors 1. Strength of the perturbation Short transient time Long transient time Metapopulation Research Group

20. Transient time depends on three factors 2. Species and landscape specific turnover rate Long transient time Short transient time Metapopulation Research Group

21. Transient time depends on three factors 3. Distance to the extinction threshold Long transient time Short transient time Short transient time Metapopulation Research Group

22. 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

23. 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

24. Area of old-growth forest in Finland S Finland 0.6% N Finland 10.4% Entire Finland 5.5% Metapopulation Research Group

25. Threatened beetles in boreal forests (based on data and analysis by Pertti Rassi) Metapopulation Research Group

26. message # 3Extinction 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

27. The response of species to a change in habitat/landscape quality Metapopulation Research Group

28. Punttila, Siitonen & Lindström, julkaisematon Metapopulation Research Group

29. Punttila, Siitonen & Lindström, julkaisematon Metapopulation Research Group

30. The three-toed woodpecker - an example of the treshold condition at the regional scale Metapopulation Research Group

31. message # 4 The response of species to a change in habitat quality is typically non-linear and involves a threshold Metapopulation Research Group

32. 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

33. The slow process of disappearence of endangered species in the current forest landscape Metapopulation Research Group

34. The outcome of comprehensive implementation of the new forestry practice

35. Let us focus the same conservation effort within 10% of forested land

36. Conservation measures within 10% of forested land but now located next to the currently most valuable forest stands

37. 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