CO2 fertilization, transpiration deficit and vegetation period drive the response of mixed broadleaved forests to a changing climate in Wallonia

Abstract

& Key message The change in forest productivity was simulated in six stands in Wallonia (Belgium) following different climate scenarios using a process-based and spatially explicit tree growth model. Simulations revealed a strong and positive impact of the CO 2 fertilization while the negative effect of the transpiration deficit was compensated by longer vegetation periods. The site modulated significantly the forest productivity, mainly through the stand and soil characteristics. & Context Forest net primary production (NPP) reflects forest vitality and is likely to be affected by climate change. & Aims Simulating the impact of changing environmental conditions on NPP and two of its main drivers (transpiration deficit and vegetation period) in six Belgian stands and decomposing the site effect. & Methods Based on the tree growth model HETEROFOR, simulations were performed for each stand between 2011 and 2100 using three climate scenarios and two CO 2 modalities (constant vs time dependent). Then, the climate conditions, soils and stands were interchanged to decompose the site effect in these three components.

Simulating tree growth response to climate change in structurally diverse oak and beech forests

“…Only the optimum response function during chilling (Eq. (1) in de Wergifosse et al, 2020aWergifosse et al, , 2020b was different and had to be adapted to correspond to that given in Duputié et al (2015) (itself based on Wang and Engel, 1998). Leaf yellowing and fall parameters were empirically fitted with the observations provided for 13 of the study sites located in Belgium, Germany, France and Romania.…”

“…The HETEROFOR model has been specifically designed to simulate individual tree growth in structurally complex stands based on a resource-sharing approach and to test the ability of innovative silvicultural systems to improve forest resilience to climate change (de Wergifosse et al, 2020a;Jonard et al, 2020). So far, it has been calibrated and used to simulate the impact of climate change on a couple of forests in Southern Belgium (de Wergifosse et al, 2020b). Yet, one can assume that calibrating a process-based model on a large range of ecological conditions will increase its generality and robustness (e.g.…”

Quantifying climate change effects on future forest biomass availability using yield tables improved by mechanistic scaling

“…However, overall growth trends remained positive regardless of the in-or exclusion of the CO2 fertilization effect (Table 2). In contrast, a similar study in the southern part of Belgium found more moderate growth changes when considering CO2 fertilization and found no significant change in growth when CO2 fertilization effects were excluded (de Wergifosse et al, 2020). The discrepancy between this and our simulation study can probably be partially explained by (i) the different soil conditions, (ii) the wetter climatic conditions in the southern part of Belgium, (iii) the consideration of four sites rather than the 302 sites considered in this study and (iv) the difference in the reference period (1975 -2005 compared to 1961 -1990 for this study).…”