[COLLOQUE] GENTREE Final Conference 27-31 January 2020 séance 27

GENTREE Final Conference : François LEFÈVRE - INRAE Avignon · France

GENTREE Final Conference 'Genetics to the rescue - managing forests sustainably in a changing environment'

27-31 January 2020, Avignon, France

http://www.gentree-h2020.eu/

François LEFÈVRE - INRAE Avignon · France : How much genetic selection for growth can result from silviculture? A new demo-genetic simulation approach.

The genetic composition of forest stands dynamically evolves drivenby the combination of natural processes and management practices.

Evolution-oriented forest management consists in understanding andstewarding these combined processes to enhance short-term adaptationand productivity while maintaining long-term evolvability.

Silviculture is a sequence of practices, each having multiplepossible genetic impacts, depending one on the other. Moreover,silvicultural practices interact with demographic changes due toother natural causes like environment changes.

All these dependenciesand interactions make an analytical approach of the resultingevolutionary dynamics, based on quantitative genetics, very complex.

Here, we developed a demo-genetic simulation approach of this issue.Previous demo-genetic models in forest systems mainly focused on thepossible impacts of silviculture on the overall (neutral) genediversity.

Here we focus on the selection effects on growth.

Wecoupled a quantitative genetics model to a growth dynamics modelcalibrated for Cedrus atlantica, and simulated various scenarios ofsilviculture, using the CAPSIS simulation platform(http://capsis.cirad.fr/capsis/help_en/luberon2).

We compared theeffect of various management practices on (i) the growth, (ii) thegenetic quality and (iii) the evolutionary potential of the stand.

Weshow that different silviculture sequences may result in verydifferent levels of selection intensity for growth, which havedifferent impacts on the dynamics of genetic means and variances fromone generation of trees to the next.

We also show the importance ofall stages of interventions, including those in the juvenile stage,on the final genetic impacts.

Finally, we show that the effectivegenetic impacts of a given silviculture guideline are highlyinfluenced by pragmatic choices in the forest and by localdisturbance regimes.

This work should be considered as a “proof ofconcept” showing that demo-genetic models coupling forest dynamics,quantitative genetics, silviculture practices and naturaldisturbances are feasible.

Such models provide a powerful approach toinvestigate the potential genetic impacts of silviculture and guideevolution-oriented forest management.

We are currently extending thisapproach to other species and other contexts.