From rurality to ferality: A case study from the upper Moselle valley, France
Authors: Schnitzler-Lenoble Annik , Aumaître Damien , Schnitzler Christophe 
Published: November 2022

In this paper we present the woodland dynamics of the Moselle valley, upstream from Nancy in north-eastern France. The Moselle flow regime has been partly preserved, although the valley underwent extensive land-uses in the past, with two periods of abandonment of agriculture practices since the 1870s. In the 2377 hectares of the Natura 2000 zone, the surface areas of all woodland patches of more than 0.1 ha were quantified by GIS (Arcview 3.3R), on the scale of 1 : 50.000 from aerial photographs from 1950 and 2003. One hundred and thirty-six phytosociological surveys were performed on vascular plants, and abundance – dominance was estimated by eye using the phytosociological scale. Human impact (cuttings, plantations, presence of ancient orchards) was evaluated by field trip. Woodlands were separated into two categories of conservation : high (i. e. natural character of forest architecture) and low (with human impacts). From these data, we quantified the surface areas of each forest community defined by phytosociology, as well as their conservation value. Fallopia x bohemica Chrtek & Chrtkova and Impatiens glandulifera

Royle were tested with regard to the following factors : forest type, shape (perimeter), size (surface area), and age (more or less than 50 years old), and the frequency of flooding. Data were analysed using the Kruskall-Wallis test. The total forest surface was 546.6 ha, split into 397 patches of various areas (ranging from 0.1 to 16.6 ha). On the current wooded forest surface, 11.1% was less than 50 years old. Four forest types were identified : willow bush (Salicetum triandrae) and willow tree (Salicetum albae) forest communities, both on river banks close to the river ; ash-alder (Pruno-Fraxinetum) on more elevated sites ; and marsh alder (Alnetum glutinosae) in old channels. The total species richness was 126. Ash-alder patches were the richest in species, and the most complex in architecture when not influenced by human activities. Communities of high conservation value were found in all forest types but in lower proportion than those of lower conservation value (28.4 versus 71.6%, respectively). Compared with other floodplain forests of similar ecology in the Rhine plain, the woodlands of the upper Moselle valley were more fragmented, but more natural because of the lack of recent silvicultural activities. Their relative youth explains why they lack native species of trees and some geophytes that are typical of mid-or late successional stages. Willow forests showed greater invasion by exotic species, and younger forests were invaded to a greater extent than forests over 50 years old by Fallopia x bohemica Chrtek & Khrtkova and Impatiens glandulifera Royle. The increase of woodlands in willow stands can be considered as a sign of modestly successful recovery from long-term deforestation. Of course, these fallows will never return to pristine old-growth forests. They could be defined as “feral” or “ dedomesticated” landscapes because succession processes will take different courses and different lengths of time compared with natural processes. Such “dedomesticated” landscapes would however provide interesting evolutionary perspectives for the long term and suggest the interest of research in the context of changing uses. Forests should be therefore allowed to continue their expansion so that the entire range of natural habitats, as well as novel habitats, are re-created and full functional links can be established between terrestrial and aquatic communities.