Mediterranean forests under climate change

Transcription

1 Mediterranean forests under climate change François LEFEVRE EFIMED Young Leadership Programme on Forest-based Bioeconomy November 2018, Barcelona

2 INRA URFM

3 Mont Ventoux (France)

4 INRA URFM

5 ONF

6 INRA URFM Resilience and adaptation of forest social-ecological systems in the context of global change

7 CTFC

8 Google 8

9 INRA URFM

10 Climate change Not just a change of state but a state of change multiple uncertainties : global scenarios & local impacts extreme events complexe interactions impact of adaptive measures IPCC 2013 short term vs long term forestry horizon.010

11 Climate change Forests are part of the solution IPCC

12 The resilience approach of dynamic systems Adaptive cycle and panarchy Holling 1986, Gunderson & Holling

13 The resilience approach of dynamic systems Adaptive cycle and panarchy Holling 1986, Gunderson & Holling

14 The resilience approach of dynamic systems Adaptive cycle and panarchy Gunderson & Holling

15 The resilience approach of dynamic systems Adaptive cycle and panarchy Gunderson & Holling

16 The resilience approach of dynamic systems Mediterranean forest dynamics driven by management x disturbance interactions Blondel

17 The resilience approach of dynamic systems Resilience vs stability Resilience sensu stricto originally defined by Holling (1973) as the persistence of unstable systems. Based on this interpretation, resilience has three properties: the amount of change the system can undergo without changing structure and function; the capacity of self-organization; the capacity to learn and adapt. Carpenter et al

18 The resilience approach of dynamic systems Resilience thinking The resilience and stability viewpoints of the behavior of ecological systems can yield very different approaches to the management of resources. The stability view emphasizes the equilibrium, the maintenance of a predictable world, and the harvesting of nature's excess production with as little fluctuation as possible. ( ) A management approach based on resilience, on the other hand, would emphasize the need to keep options open, the need to view events in a regional rather than a local context, and the need to emphasize heterogeneity. Flowing from this would be not the presumption of sufficient knowledge, but the recognition of our ignorance; not the assumption that future events are expected, but that they will be unexpected. The resilience framework can accommodate this shift of perspective, for it does not require a precise capacity to predict the future, but only a qualitative capacity to devise systems that can absorb and accommodate future events in whatever unexpected form they may take. Holling (1973) Resilience and Stability of Ecological Systems. Annual Review of Ecology, Evolution and Systematics 4:

19 What about the adaptive capacity of trees? Genetic diversity across biomes and species Resistance to cavitation : variation across biomes and between species Maherali et al

20 What about the adaptive capacity of trees? Genetic diversity among provenances within-species Pinus sylvestris Pinus pinaster Future scenarios : the genetic diversity matters Benito-Garzón et al

21 What about the adaptive capacity of trees? Genetic diversity among individuals within each forest Pinus pinaster progenies tested in drought and control conditions Fuel for future adaptation France Spain (wet) Spain (dry) Morocco Aranda et al 2010 TGG.021

22 What about the adaptive capacity of trees? but species' niches still have limits and there are empty niches there are also constraints that limit adaptation : 1. genetic constraints 2. developmental constraints 3. lack of genetic diversity 4. demographic stochasticity 5. random genetic drift 6. low mortality 7. asymetric gene flow Futuyma 2010; Kuparinen et al

23 What about the velocity of adaptation in trees? High genetic diversity in trees confers a great evolvability Pinus radiata : extended climatic use range after breeding and selection Native range Mean annual Tmean Tmean & use range precipitation coldest month hottest month California (5 pops) N-Z (Southland) N-Z (Kaingaroa) Chile (Valdivia) South Afr. (Cap) Aust. (Bathurst) Aust. (Tumut) China (Aba,Sichuan) Yan et al

24 % budset What about the velocity of adaptation in trees? High genetic diversity in trees confers a great evolvability Date Skrøppa et al

25 Towards evolution-oriented forestry Pathways of the impacts of human actions on the evolutionary drivers Lefèvre et al

26 Towards evolution-oriented forestry Benefits & risks analysis for the short and long-term One example: introduction of new genetic material better adapted to future climate genetic benefits genetic risks Short-term - maladaptation today Long-term - future adaptation - wrong prediction of - genetic enrichment future needs - gene swamping if narrow genetic diversity => introduced material must be selected not only for future adaptation but also limited vulnerability => introduced material must always have a large genetic base (resilience) => risk to loose very specific local adaptation must be considered.026

27 Better knowledge does not reduce complexity Uncertainty also relies in the knowledge Pinus sylvestris Fagus sylvatica Cheaib et al

28 Resilience : combine multi-actors expertise Example of interactions between scientists and forest managers Forest managers RD academic research Clarify questions for management Characterize silviculture practice Propose innovative pratice Identify pathways pratice impacts Define indicators of impacts Identify scientific questions Develop simulation tools.028

29 Take home messages Forests under climate change: what do we face? forest systems are particularly at risk due to climate change because they are perennial, but they are also part of the solution; forests are dynamic systems that continuously evolve forest is an actor of the SES; in most parts of the world, forests are social-ecological systems and their dynamics is driven by the interplay of natural processes and human actions; forestry decisions and actions have short term and long term impacts on forest dynamics over decades; in the context of change, there are multiple uncertainties regarding the response of the forests to disturbance and management;.029

30 Take home messages Forests under climate change: what to do? adopt a new paradigm: resilience thinking, which favours adaptive management strategies to cope with uncertainty and keep options open, as opposed to stability thinking which fixes a target objective and assumes minimum uncertainty ; use diverse forest management practices, and enable forest governance that encourage diversity rather than one solution fitting all are critical allow experimentation to face uncertain future ; think in terms of dynamics (impact on the processes of adaptation and adaptive capacity), manage trade-offs between short-term and long-term impacts; develop multi-actors dialogue (incl. forest as an actor) and combine complementary expertise: empowerment is fundamental..030

31 Take home messages Mediterranean forests under climate change: vulnerable and valuable Mediterranean forests are dynamic systems particularly exposed to climate change, which increases vulnerability but also, below certain limits (tipping points), contributes to resilience Mediterranean forests are a reservoir of biological resources and know how for adaptation to climate change in peripheral areas Mediterranean forests are model situations to investigate the processes of adaptation and resilience.031