Climate change and plant-herbivore interactions in boreal and arctic ecosystems. Pekka Niemelä University of Turku

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1 Climate change and plant-herbivore interactions in boreal and arctic ecosystems Pekka Niemelä University of Turku

2 BACCI - report

3 Changes in snow cover

4 Kellomäki et al.

5 Effect of climatic change on growth of Scots pine (Kellomäki et al.)

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7 Deciduous trees benefit climatic change Cental European climate?

8 Climate change can affect plant-herbivore interaction by several mechanisms: Quality of host plants changes Growth and life cycle of herbivores changes Habitat conditions (abiotic) changes Trophic interactions changes Predators, parasites, pathogens, etc

9 Mekrijärvi chamber experiment 16 chambers: -Elevated CO2 -Elevated Temperature -Elevated CO2 and Temp. -Control Test plants: -Pine -Birch -Willows

10 The effect of climatic change on resistance of birch Kuokkanen et al. Fertilization decreses the level of defence CO 2 + T decreases the defence level Interaction between soil and climate!

11 Carbon/nutrient-balance The balance beween nutrients and carbon regulates the level of defence against herbivores

12 Compensatory growth in relation to climatic change Birches grown in: 1. elevated CO 2 and 2. temperature under 3. optimal N fertilisation, 4. defoliation levels from 25-75% of leaf biomass Cont, 25, 50, 75% defoliation

13 Forest defoliations in North-West Russia L Number of outbreaks has increased Intensity of defoliation has increased Kozlov & Shelikovkin, unpub.

14 The effect of winter temperatures Low winter temperatures may kill the overwintering eggs Pine sawfly (Neodiprion sertifer) outbreaks in pine forests Autumnal moth (Epirrita autumnata) Huge outbreaks in mountain birch forests

15 Pines defoliated by pine sawfly (Neodiprion sertifer)

16 Life cycle of N. sertifer: overwinters as an egg

17 Distribution of Neodpirion sertifer Distribution in central and southern Finland

18 Areal distribution of outbreaks of N. sertifer

19 Cold hardiness of the eggs of N. sertifer Veteli et al. 2005

20 Effect of climate change on winter temperatures

21 The effect of climate change on the frequency of outbreaks

22 Egg parazitism and coldhardiness of eggs Veteli et al. Temperature window to escape parazatism

23 Mountain birch forest killed by Epirrita autumnata Some birches have survived

24 Larva of E. autumnata Eggs are owervintering on twigs

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26 Tenow 1972

27 Outbreaks of Autumnal moth

28 Topographical distribution of damages Norway, Tana, 2003; Lauri Kapari

29 Neuvonen and Virtanen 1998

30 Tenow 1972

31 Lake of cold air Lake of cold air in rivervalleys High egg mortality in rivervalleys

32 Neuvonen and Virtanen 1998

33 Neuvonen and Virtanen 1998 Climatic change and outbreaks in river valleys

34 Conclusion During mild winters outbreaks increase also in rivervalleys Climate change will increase the outbreak frequencies of Autumnal moth

35 Topography of outbreaks Why dwarf birches have been defoliated? Norway, Tana, 2003; Lauri Kapari

36 Winter moth (Operopthera brumata)

37 Tenow 1972

38 Defoliation history (Jepsen et al. 2009) Epirrita Operophtera Operophtera Vegetation map: Johansen (2009) Defoliation map: Jepsen et al. (2009)

39 New geometrid moth entering into mountain birch forests

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41 Growth of reindeer population in Finland

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44 Effect of reindeer grazing on vegetation Den Herder et al, 2000

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48 Moth-reindeer-birch interactions Climate change has increased geometrid moth outbreaks How recovery of mountain birch forests is affected by reindeer grazing?

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50 WP 4: Moth-Reindeer-Birch Dynamics in Northernmost Fennoscandia Leader: Pekka Niemelä (Turku, Finland) Co-leader: Rolf Anker Ims (Tromsö, Norway) Researchers and collaborators: Jane Jepsen (Tromsö, Norway) Otso Suominen (Kevo, Finland) Tero Klemola (Turku, Finland) Piippa Wäli (University of Oulu, Finland) Annu Ruotsalainen (University of Oulu, Finland) Anna-Maija Markkola (University of Oulu, Finland) + doctoral students, postdocs

51 Reindeer density contrast Poor Low density Rich Low density Poor High density Pulmankijärvi/Polmak lake Vegetation map: Johansen (2009)

52 Distribution of defoliation in the area Vegetation map: Johansen (2009) Defoliation map: Jepsen et al. (2009)

53 How to study moth-reindeer birch interaction?

54 Paired exclosure plots with different accessibility to herbivores 30 m? no S no S+L 2 m no 30 m? no S S S+L S+L S no S+L S S+L Large herbivore exclosure Small + large herbivore exclosure (with mesh roof) Study plot without exclosure