Jeune peuplier (Populus sp.) colonisant un tas de pouzzolane (Puy-de-Dôme (63), France). Tags: pouzzolane; roche volcanique; projection volcanique scoriacée; gravier; arbuste; arbre; peuplier; Populus sp.; coloniser; colonisation; plante; colonisatrice; feuille; tas; nature; naturel; pozzolana; volcanic rock; scoriaceous; volcanic; ejection; gravel; shrub; tree; poplar; colonise; colonize; leaves; leaf; heap; naturalness; colonization; plant;