Monodominance at the rainforest edge: case study of Codia mackeeana (Cunoniaceae) in New Caledonia
Ibanez T. | Birnbaum P.
Monodominance is unexpected in tropical forests, which usually exhibit rich and diverse flora. Mechanisms leading to monodominant forest are commonly discussed within the theoretical framework of forest succession. One of the central issues for managers is to determine whether monodominance is a non-persistent step in the succession of mixed forest, or a late successional state that persists for several generations. Early successional (post-external disturbance) monodominant forests are likely to be the most common, but studies have focussed on late successional ones (without external disturbance). Here, we investigate monodominance in Codia J.R.Forster & G.Forester (Cunoniaceae) in New Caledonia. Codia forests characteristically occur either as patches within a matrix of mixed forests or as a narrow belt located at the interface between mixed forest and open vegetation. We test the hypothesis that monodominance in Codia is an early and non-persistent step in the secondary succession towards mixed forest through a case study of C. mackeeana. Spatial patterns of canopy level dominance and the regeneration pool in a large C. mackeeana population, as well as along five transects from savanna to mixed forest, support our hypothesis. Establishment of C. mackeeana likely allowed a quick closure of anthropogenic savannas followed by a slow recovery of diversity towards mixed rainforest. (Résumé d'auteur)
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