La dynamique d'évolution du pic mar et du chêne dans le canton de Vaud

Evolutionary dynamics of the Middle Spotted Woodpecker and the oak in the Canton of Vaud In the Canton of Vaud, the Middle Spotted Woodpecker (Dendrocopos medius) has shown a considerable increase in population over recent decades: in 2015, there were about 170 nesting territories. A census of the woodpecker, by its song, and a dendrometric inventory, taken together, made it possible to map the forest environment favourable to this bird, and to estimate present trends. Standing volume of oak in territories occupied by the Middle Spotted Woodpecker is, on average 124 m3/ha, of a total standing volume of 302 m3/ha. In more than 90% of territories of the Middle Spotted Woodpecker, standing volume of conifers is less 150 m3/ha, and of non-coniferous other than oak 269 m3/ha. These forests show a strong deficit in young stands capable of succeeding the mature oaks; this situation represents a long term threat to the oak and, as a result, to the populations of the Middle Spotted Woodpecker. A logical consequence of this situation is the need for a policy based on a strong political will to encourage oak-rich forests; the high genetic variability of the oak gives it an advantage compared to other species with regard to adaptation to climate change, but also with regard to the maintenance of biodiversity, the result of a heritage of several thousand years, of which the Middle Spotted Woodpecker is an integral part.