▁that ▁plants ▁profit ▁from ▁a ▁rising ▁atmos pher ic ▁CO 2 ▁concentration ▁with ▁a ▁mean ▁bi om ass ▁stim ulation ▁of ▁ 3 0 %, ▁but ▁also ▁indicated ▁that ▁acc lim ation ▁counter act s ▁and ▁mit ig ates ▁most ▁of ▁this ▁stim ulation ▁ ▁B ios phere ▁– ▁atmosphere ▁flux es ▁ ▁Since ▁ 1 9 9 6 ▁his ▁research ▁group ▁got ▁act ively ▁involved ▁in ▁the ▁quant ification ▁of ▁flux es ▁between ▁e cos ystem s ▁and ▁the ▁atmosphere ▁for ▁a ▁better ▁understanding ▁of ▁e cos ystem ▁responses ▁to ▁global ▁changes . ▁He ▁was ▁an ▁active ▁particip ant ▁in ▁various ▁European ▁flux ▁programs , ▁incl . ▁C AR BO - E U RO PE ▁IP . ▁From ▁ 2 0 1 3 - 2 0 1 9 ▁Ce ule mans ▁was ▁the ▁Belg ian ▁F ocal ▁Point ▁of ▁the ▁Integr ated ▁Car bon ▁Observ ation ▁System ▁research ▁infrastr ucture ▁and ▁coordin ated ▁the ▁Belg ian ▁network ▁of ▁observation ▁stations . ▁ ▁Le ad ership ▁and ▁director ▁of ▁Research ▁Center ▁of ▁Ex cell ence ▁ ▁From ▁ 2 0 0 0 - 2 0 1 9 ▁Ce ule mans ▁led ▁the ▁Research ▁Group ▁of ▁Plant ▁and ▁Veg et ation ▁E col ogy ▁( P LE CO , ▁Department ▁of ▁Bi ology , ▁University ▁of ▁Ant werp ). ▁In ▁ 2 0 0 7 ▁the ▁research ▁group ▁was ▁recognized ▁as ▁a ▁Research ▁Center ▁of ▁Ex cell ence ▁at ▁the ▁University ▁of ▁Ant werp . ▁As ▁the ▁Director ▁of ▁the ▁Research ▁Center , ▁he