C'est ma place : caractéristiques des arbres porteurs de cavités de Pic noir

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVINInternational audienceThe Black Woodpecker is considered both an ecosystem engineer and an umbrella species: it has the capacity to modify its environment through cavity excavation which in turn favors a large range of species that depend on cavities but are unable to dig them (secondary cavity nesters). However,the factors that affect cavity excavation by Black woodpecker at the tree scale remain poorly known. We analyzed characteristics of trees bearing Black Woodpecker cavities to assess its local habitat preferences. We compared tree-traits between trees bearing Black Woodpecker cavity (n=60) and trees devoid of it (n=56) in two French lowland forests. We hypothesized that: i. Cavity-trees would have a lower wood density and display more conks of fungi than control-trees; ii. The local environment of cavity-trees would be less crowded than those of control trees. In particular, the first branch would be higher on, and their first tree neighbor tree further away from, cavity-trees than controltrees; iii. Cavity-trees would display more other woodpecker cavities and saproxylic microhabitat than control-trees. We validated most of our hypotheses and showed that cavity-trees differed significantly from their control counterparts according to analyzed factors. Black Woodpeckers excavate softer trees with a higher first branch in a less crowded environment, and thus, at the same time, minimize both the energy dedicated to cavity excavation and the predation risk. Second, cavity-trees bear more microhabitats, supporting a more important engineer role than previously proposed. In terms of biodiversity-friendly management measures, it would be beneficial to favor large standing beech trees with a trunk free of low branches and locally apart from others, especially in stands dominated by other tree species