Several decades of research have shown that canopy gaps drive tree renewal processes in the temperate deciduous forest biome. In the literature, canopy gaps are usually defined as canopy openings that are created by partial or total tree death of one or more canopy trees. In this study, we investigate linkages between tree damage mechanisms and the formation or not of new canopy gaps in northern temperate deciduous forests. We studied height loss processes in unmanaged and managed forests recovering from partial cutting with multi-temporal airborne Lidar data. The Lidar dataset was used to detect areas where canopy height reduction occurred, which were then field-studied to identify the tree damage mechanisms implicated. We also sampled the density of leaf material along transects to characterize canopy structure. We used the dataset of the canopy height reduction areas in a multi-model inference analysis to determine whether canopy structures or tree damage mechanisms most influenced the creation of new canopy gaps within canopy height reduction areas. According to our model, new canopy gaps are created mainly when canopy damage enlarges existing gaps or when height is reduced over areas without an already established dense sub-canopy tree layer.
Résumé
39L'utilisation du LiDAR pour l'étude des régimes des trouées a connu une importante progression 40 au cours des dernières années. Généralement, les chercheurs ont adopté de façon implicite la 41 prémisse que les trouées détectées ainsi étaient équivalentes, sur la base de leur écologie, aux 42 trouées échantillonnées in situ selon des méthodes plus traditionnelles. Cependant, ces dernières 43 tiennent seulement compte des trouées dans la canopée créées par la mort d'au moins un arbre 44 mais non des ouvertures édaphiques qui sont produites par certaines conditions de site empêchant 45 l'établissement et la croissance d'arbres. Nous avons produit un modèle prédictif capable de 46
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