Mount Capanne, a mountainous massif albeit of modest size when compared with the nearby elevations of Corsica, is, in climatic terms, an island within an island. The mountain forms a barrier to clouds coming from the north, accumulating a good quantity of precipitation on its northern side. Indeed, most rain is recorded on the slopes of Mount Capanne, particularly on the northern side of the massif where the average annual rainfall reaches around 950 mm.

This phenomenon led to the development of waterways, today having a clear seasonal pattern, which have deeply furrowed the slopes of the elevation over the millennia, creating distinctive cool, moist habitats. The valley floor generally features a widespread presence of common alder (Alnus glutinosa), a tree growing up to 25 metres tall which loves moist soil, creating riparian formations of small, linear alder shrubwoods whose shade helps maintain a cool microclimate along the natural geological furrows in summer. The alders, with their distinctive pendulous catkin blossoms appearing before the first leaves, from February to April, are often swathed in vines of old man's beard (Clematis vitalba), a hardy climbing plant.

Another tree species found in the damp valleys, although less common than the alder, is the willow (Salix sp.). Ferns (Dryopteris sp.) abound along the waterways, most notably the royal fern (Osmunda regalis), an important thermophilous plant from the tertiary era, still moderately widespread on Elba, particularly on the northern slopes of Mount Capanne but increasingly rare on the mainland. The small pools that form along the gullies provide homes for other moisture-loving species such as fool's watercress (Apium nodiflorum), known on Elba as gargalastro, common duckweed (Lemna minor) and several species of mint (Mentha sp.) whose fragrant blooms attract dozens of butterflies, moths and other pollinating insects.