Work package 3

In WP3, the orthogonality and experimental control of canopy disturbance and drought is elevated even more to increase the mechanistic understanding on the relative importance of canopy opening vs drought on below-canopy biodiversity. There is a need to better understand species-specific responses and assess, for instance, why particular species decline.

The major objective of WP3 is to create artificially disturbed canopies and no-analog light regimes brought about by experimental clipping of tree branches and foliage – in hitherto undisturbed forest – that reflect the actual disturbance regimes occurring across temperate European forests, in interaction with a drought treatment in hydrologically isolated mesocosms.

Indeed, although 186 plots are being surveyed in WP1 and 74 in WP2 across Europe, there might be undetected co-variation of other environmental drivers with drought and light (e.g. due to soil nutrient co-variation). To increase orthogonality, but at the expense of spatiotemporal representativeness and comprehensiveness, a highly controlled full-factorial mesocosm experiment is needed.

At the WP3 experimental forest site in the Vagevuurbossen (Wingene, BE), clipping treatments are conducted in 12 circular plots that will each contain ambient and drought mesocosms (432 mesocosms in total). Different plant communities will be exposed to this combined drought x canopy disturbance treatment. The question here is again how biodiversity at different levels of biological organisation responds to different forms of novel light regimes in interaction with drought.