T1Bx Mixed forests on acid soils

Description

An acidophilous analogue of T1E1, these communities, usually dominated by pedunculate oak with a pretty diverse tree layer, are the zonal forests on acid susbtrates in the lowlands of the northern, maritime territories of the ecoregion, where summer-droughts are rare and mild, so deciduous broadleaved trees can supply enough water to support the high transpiration rates of their competitive light-capturing apparatus. In the lowest areas, where severe frosts and snowfalls are a rare occurrence, they may transition towards T22x. At somewhat higher elevations or in particularly well-oriented valleys, rainier and cooler summers reduce even further the risk and severity of droughts and lead to the predominance T182. In southern Galician and northern Portuguese coastal areas, on their part, sunny and dry summers lead to somewhat complex transitions towards T211. A new regional level IV unit is created, since its fusion with the montane forests of T1By is, for deep floristic and ecological reasons, quite unsatisfactory at that level. It encompasses a number of higher level units recognised by EUNIS, some of which intend to capture the above alluded transitions: T1B621 ("Eastern Cantabrian acidophilous oak forests); T1B622 ("Western Cantabrian acidophilous oak forests); T1B631 ("Mesophile Luso-Galician collinar oak forests); T1B632 ("Humid Luso-Galician collinar oak forests; T1B64 ("Luso-Galician montane acidophilous oak forests). Traditional, centuries-old management have often transformed these communities into chestnut-enriched woodlands exploited for timber or fruit.

Phytosociology i

• Blechno spicant-Quercetum roboris
• Hyperico pulchri-Quercetum roboris
• Lonicero periclymeni-Quercetum pyrenaicae
• Rusco aculeati-Quercetum roboris
• Vaccinio myrtilli-Quercetum roboris
• Viburno tini-Quercetum roboris