Stratégies de défense et de compétition de peupliers forestiers et de peupliers pionniers

Among the genetically improved poplars, Populus nigra and Populus deltoides are pioneer poplars, while Populus trichocarpa is more a forest species. The biochemistry of the Populus trichocarpa is more successful in controlling general pests, but its already significant defences are less responsive in the event of attacks. The galleries of the miner moth Phyllocnistis unipunctella are longer when polyphenols increase, but there are fewer insects that develop more slowly, attain a lower weight – all factors in favour of the forest poplar. Compared to pioneers, this forest poplar has many characteristics of “non apparent trees” (Feeny, 1976). The growing season for the forest poplar is longer, its basal area increment greater and it grows proportionally more in May and in September – characteristics that all give it a competitive edge over other surrounding trees. It is more tolerant to shade, but more vulnerable to limb snapping.