Essai sur la dynamique des peuplements de lianes ligneuses d’une forêt du Nord-Est du Gabon

Abstract

The dynamics of two woody liana communities has been studied in two rain forest plots on the M’Passa plateau, North-East Gabon. The forest structure was different in the two areas studied. The first plot (2.4 ha) was set up at ground level on the forest edge, along a track opened ten years earlier. The second plot (3.2 ha) was located within the mature rain forest itself, a few hundred metres away, on uneven ground with a slope leaning towards a small river valley. The pattern of distribution of the woody climbers whose diameter at breast height (DBH) was ≧ 5 cm is described on the two plots. The distribution of these liana communities was always clumped. The density of woody climbers was higher in the forest edge plot than in the mature forest plot (145 ind/ha vs. 114 ind/ha). However, the percentage of older lianas, i.e. those whose DBH was ≧ 10 cm, was higher in the mature forest than at the forest edge (20.6 % vs. 7.8 %). The role of tree falls at the settlement stage of a woody liana community is discussed, and the importance of the supporting trees surrounding the gap is stressed. Woody lianas thrive during the first stages of the forest growth cycle, competing for light with the trees. Later on, woody climber communities age and regress when the forest mosaic matures.