How does a shift in forest tree species composition affect soil organic carbon storage in ancient forests of Wallonia: site conditions, biotic interactions, and reversibility

As in many countries worldwide, Wallonia has witnessed a conversion of semi-natural ancient forests to coniferous forests, some of which have been subsequently restored by planting indigenous broadleaved species. Understanding the effects of these consecutive conversions and restorations on soil organic carbon (SOC) storage, soil biodiversity, and ecosystem functioning is of paramount importance, as unconverted ancient forests may serve as benchmarks for assessing the effects and reversibility of changes in tree species composition on soil C storage and functioning in other similar systems.
The general objective of SHIFT is therefore to gain a mechanistic understanding of how shifts in tree species composition affect SOC storage, soil biodiversity, and ecosystem function, using the ancient forests of Wallonia as a case study. To test the generality of these effects, we will deploy a sampling design that captures a variety of soil conditions, representing a gradient of inherent soil properties.