Charis Anaïs Kanellos thesis defense

Event details :

Thesis Title: Forest futures: How land use, environmental policy and climate risk shape forest dynamics

Thesis supervised by Sylvain Caurla and co-supervised by Miguel Rivière, Thierry Brunelle & Antonello Lobianco

The jury is composed of:

• Mr Luc Doyen, Research Director, CNRS Montpellier – Rapporteur
• Ms Fanny Henriet, Research Director, CNRS Paris – Rapporteure
• Mr Julien Wolfersberger, Senior Lecture, AgroParisTech – Examiner
• Ms Marielle Brunette, Research Director, INRAE- Examiner

Abstract:Forests play a fundamental role for both ecosystems and human society, providing a wide range of ecosystem services including the production of timber and non-timber resources, carbon storage and sequestration, flood protection and erosion prevention, soil formation and air purification, as well as cultural benefits such as recreation. Forest management and land use change directly influence the provision of these services. Within a given forest stand, forest management at the “intensive margin”, such as changes in rotation periods, species diversification within stands, or the use of clear-cutting, can significantly alter forest structure. At the landscape level, land use changes at the “extensive margin” affects ecosystem services through land conversions as afforestation and deforestation. In the scientific
literature, changes at the “intensive” and “extensive” margins are often studied separately. The objective of this thesis is precisely to fill this gap and investigate trade-offs and synergies between harvesting within existing forests — at the “intensive margin” — and modifying forest area through land-use change — at the “extensive margin”. To do that, this work considers interactions between demand for wood, ecosystem services provisioning, and climate change with a special attention given to incentives to carbon storage and risk of forest wildfires.

This topic is addressed through three articles. The first article reviews the current state of literature on how land-use change and forest management are accounted for in environmental assessments of wood products. We found that, while land-use changes are increasingly taken into account in the forestry literature, they remain a relatively minor aspect in Environmental impact assessments of wood products due to methodological and conceptual limitations.

The second article develops a theoretical model to analyze the relationships between land use allocation and harvest intensity under various economic and ecological scenarios. How managers choose to allocate their land between primary and secondary forest and agriculture depends on the interplay between the costs and benefits of each land use and the harvest intensity of secondary forests. We showed that when there are few constraints on either resource, both intensified harvesting and deforestation occur simultaneously. These changes can contribute to a decline in forest resources and the potential associated ecosystem services and carbon sinks. In contrast, in a highly constrained context, for example by conservation policies or ecological shocks such as tree mortality, primary and secondary forests act as
substitutes, and trade-offs arise between harvest intensification and forest expansion.

The third article builds on this framework, incorporating risks of forest fire disturbances, to assess how forest fire anticipation and foresight influence these results. When forest fire is fully anticipated, increased harvesting during the damage lowers carbon storage compared to the baseline, but improves economic welfare compared to ex post adaptation scenario. The welfare costs of imperfect anticipation are sensitive to the timing of the fire and to its intensity. When the forest fire occurs early on at high damage rates, it reduces resources availability and forest manager’s capacity to adapt. Conversely, when the forest fire occurs later, managers have more time to adjust their management strategies and minimize the loss due to damage. Overall, our findings underscore the importance of integrating climate risk into forest management planning to minimize potential impacts.