The departmental Wood of Kerio

Slightly less wooded than its neighbouring communes, Caudan has nearly 680 ha of forest, or nearly 16% of its surface, mainly on the slopes of natural valleys such as here. The Bois de Kerio belongs to the Departmental Council, with an area of 6.9 hectares, and has been listed as a classified woodland and "natural area of regional interest for mammals".

Managed by the Office National des Forêts, it is characteristic of the natural forest of Brittany, dominated by beech, oak and chestnut trees, under which holly and a vegetation of ferns and honeysuckle grow. The eastern part, which still comprised fields and meadows in the 1960s, reveals the former broom and gorse moors on the sparse heights.