Simulating tree growth response to climate change in structurally-complex oak and beech stands across Europe

In Europe, forests cover approximatively 35% of land area and offer a vast amount of goods and services: wood and non-wood production, biodiversity conservation, soil and water protection, carbon storage, recreation. For the last decades, the release of CO2 in the atmosphere and the lengthening of the vegetation period due to warmer conditions generally have had a positive impact on the forest productivity but, in the same time, the dryer conditions have also locally led to productivity decline and mortality events. Given the future climate projections, it is likely that these trends will accelerate in the future and have an impact on European forest state but local site conditions could modulate this impact. A promising approach to increase the forest resilience to future conditions is to favour uneven-aged structure and species mixture. Models able to simulate the response of structurally-complex stands to climate change are therefore crucial. In this project, I participated to the development of HETEROFOR, an individual-based and spatially explicit tree growth model through the integration of a phenological and a water cycle module, two processes key to assessing how climate change will affect forests. Using this model, I realised projections of the future forest productivity according to different climate models and scenarios with the objective of assessing how climate change will affect oak and beech tree growth in European temperate forests and how this response will be modulated by the local soil, stand and climate conditions. The results show that under the hypothesis of a constrained CO2 fertilizing effect, the forest productivity would increase on average in the temperate continental and mountainous regions but would decrease in the oceanic area due to higher hydraulic stress exceeding the effect of the longer vegetation period. When accounting for the CO2 fertilizing effect, a generalized increase in productivity was simulated. The climate, stand and soil
(AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2021