Enhancing and speeding up natural evolutionary processes through management: assisted migration; the role of breeding

Transcription

1 Enhancing and speeding up natural evolutionary processes through management: assisted migration; the role of breeding François LEFEVRE INRA, Avignon (France) URFM, Ecology of the Mediterranean Forests

2 Plan 1) CC challenges: velocity / intensity / time scale 2) Genetic diversity & dynamic processes, the role of breeding 3) Management options & questions

3 1) CC challenges: velocity 14 biomes scenario A1B Loarie et al, 2009 velocity (kms.year-1) residence time (years) ( C/mm).year-1 ( C/mm).km-1 unfragmented area velocity range 14 biomes Mediterranean forest rank (1=best) / /14

4 1) CC challenges: intensity H. Davi spruce & fir in South East France, 2007

5 1) CC challenges: intensity A. Bentouati Cedrus forest of Belezma, Algérie, 2007

6 1) CC challenges: time scale Time scale for climate change ~ generation time for trees migration adaptation plasticity Generation 0 Generation 1 Generation 2 environmental change time scale

7 1) CC challenges: conclusions Velocity and intensity of CC are challenging At global scale, the main threats for Mediterranean forest is fragmentation Adaptive measures are needed with no delay We have to cope with multiple uncertainty and uncomplete knowledge

8 Plan 1) CC challenges: velocity / intensity / time scale 2) Genetic diversity & dynamic processes, the role of breeding 3) Management options & questions

9 2) Genetic diversity survival 100% 80% Different responses to climate in different provenances of mediterranean pines (1 site of test): 60% 40% 20% 0% variation among species variation within species P. halepensis P. brutia frost Pichot, in prep. drought

10 2) Genetic diversity Pinus contorta: 142 provenances, 60 sites variation of plasticity plasticity Rehfeldt et al, 2001

11 2) Dynamic processes survival Cedrus sp.: 40 provenances, 3 sites example of early selection Years Bariteau & Vauthier, 2007

12 2) Dynamic processes The history of Cedrus in France Regeneration 2004 Algeria 1863 France G0 transfer - mixture - drift - selection 1939 G0+G G0+G1+G2 1993

13 2) Dynamic processes 260 hauteur à 13 ans 240 Performance of Cedrus provenances in France: introduced material sometimes become well adapted to the local conditions France 220 Algérie Maroc C. libani diamètre à 25 ans

14 2) Dynamic processes Cedrus introduced in France: adaptive evolution across 3 generations within a forest Fallour-Rubio et al, 2009

15 2) The role of breeding The longest breeding experience : recurrent selection of maize (Illinois, USA) evolvability and response to selection Moose et al, 2004

16 2) The role of breeding Response to selection Long-term vs. short-term breeding strategies: genetic diversity is the fuel for future evolution Generations of selection

17 2) Genetic diversity: conclusions Huge genetic diversity of trees may provide solutions Think in terms of dynamic properties: plasticity, adaptability rather than adaptedness, migration capacity Monitor these dynamic properties in order to cope with uncertain future Limits to adaptation may be internal (genetic diversity, genetic parameters) or external (velocity or intensity of changes)

18 Plan 1) CC challenges: velocity / intensity / time scale 2) Genetic diversity & dynamic processes, the role of breeding 3) Management options & questions

19 3) Management options & questions Changing the paradigm in the context of CC: Conservation of genetic resources => Monitoring evolutionary changes

20 3) Management options & questions Two fundamental principles, in local and global perspectives: maintain the genetic diversity over the long term by using appropriate forestry practice foster evolutionary processes to keep stands adapted to their changing environment as closely as possible

21 3) Management options & questions Main drivers of evolutionary changes at local scale: Biological drivers - genetic content - dispersal -... Demographic drivers - reproductive population size - mating system & variance in mating success - generation overlap - stand density & competition -... Biotic and abiotic environment - selection intensity - positive and negative biotic interactions -... human impact

22 3) Management options & questions Assisted migration: a classical concept in conservation biology re-considered, from demographic rescue, to genetic enrichment in the CC context demographic rescue increase diversity reduce inbreeding Positive impact demographic swamping migration load (maladaptation) reduce Ne Negative impact

23 3) Management options & questions growth production Introduction of selected material: which material? environment today

24 3) Management options & questions growth production Can we predict the future environment? What risk can we accept today to anticipate for tomorrow? environment tomorrow? tomorrow? tomorrow? today tomorrow?

25 3) Management options & questions growth production Can we predict the future environment? What risk can we accept today to anticipate for tomorrow? How much material introduce? What protocol? environment tomorrow? tomorrow? tomorrow? today tomorrow?

26 3) Management options & questions Nat regeneration Plantation local Plantation non-local + local adaptation best local sampling natural selection locally integrated local adaptation selected material fairly integrated enhances diversity new adaptation - risk small pop size risk few seedlings risk little diversity risk poor sampling little nat. selection risk unsuff. diversity risk maladaptation demogr. swamping risk disturb. ecosystem => max nb reprod trees suff seedling density mix stands/region neighbour regions higher init density broad genetic base keep track of the genetic origin

27 3) Management options & questions Nat regeneration Plantation local Plantation non-local + local adaptation best local sampling natural selection locally integrated local adaptation selected material fairly integrated enhances diversity new adaptation - risk small pop size risk few seedlings risk little diversity risk poor sampling little nat. selection risk unsuff. diversity risk maladaptation demogr. swamping risk disturb. ecosystem => max nb reprod trees suff seedling density mix stands/region neighbour regions higher init density broad genetic base keep track of the genetic origin Integrating multiple aspects: eg the question of density

28 3) Management options & questions Assisted migration, a general term with several options including silviculture, ecological engineering and landscape planning: 1) global perspective: increase migration capacity through fecundity and dispersal ability increase migration capacity by improving recruitment conditions increase migration capacity through landscape optimisation... 2) local and global perspective: increase migration capacity through fecundity and dispersal ability increase migration capacity by improving recruitment conditions genetic rescue with selected material species substitution...

29 3) Management options: conclusions Two fundamental objectives: maintain the diversity and foster evolutionary processes Do not put all your eggs in the same basket, keep the capacity for further adjustment of the strategy Use gradual adaptive response, caution with the miracle solution Keep track of all movement of forestry material and keep on observing climatic impacts Integrate multiple processes of the response to CC

30 General conclusion Need for observatories ~ a posteriori experiment Need for multi-disciplinary expertise integrate existing knowledge Need for further research: dynamic and process-based models of forest dynamics and function integrate response to CC trend & variation Need for combined research - action