![]() excelsior, Ulmus montana (fine sand and silt, deep water table), Ulmus minor and Prunus avium are distributed in braided sections upstream of Lyon, (3) in some meandering sections upstream of Lyon, a decrease in agriculture in the early 20th century allowed the development of oak forests of Quercus robur this forest was destroyed in the 1980s for the Sault-Brénaz dam, (4) between Lyon and Montélimar and in the Saône floodplain, Populus alba and Fraxinus angustifolia replace P. ![]() incana (fine sand, mid-depth water table), F. nigra (gravels, coarse sand, deep water table), A. daphnoïdes (sand, proximity of water table), P. germanica, Hippophae rhamnoides (gravels, proximity of water table, only upstream from Seyssel), Phalaris arundicea, Equisetum hiemale, Aegopodium podagraria, Salix triandra, S. minima (fine sand, proximity of water table), Salix eleagnos, Salix purpurea, M. rosmarinifolium are still present in the Swiss Upper Rhône, (2) Calamagrostis epigeios (sand, gravels, proximity of water table), T. Longitudinally, the following species are representative: (1) limited populations of T. incana by more tolerant species such as Salix cinerea and Alnus glutinosa. Along reservoirs, the increase in water table and decrease in current velocity have led to the replacement of species requiring well-oxygenated water such as A. River embankment and impoundment have reduced or eliminated ‘alpin’ pioneer species as Myricaria germanica and Typha minima, a protected species in the Swiss upper Rhône. Senecio inaequidens has been found recently in the Drac and Isère valleys. The creation of new areas by engineering works has favoured the establishment of non-native species such as Reynoutria sachalinense, Buddleia variabilis, Buddleia davidii, Ambrosia artemiaefolia, Acer negudo, Amorpha fruticosa (in tributaries), Aster novi-belgii and Galega officinalis (downstream from Lyon), Impatiens roylei (upstream from Lyon on sandy beaches), Solidago canadensis and Phytolacca americana. ![]() nigra, Robinia pseudacacia (non-native species) and Q. betulus ( Vinca minor, Mercurialis perennis, Phyteuma spicatum, Melica uniflora, Euphorbia sylvatica, Lamium galeobdolon), (5) the development of new types of plant communities as open poplar woods made up of P. sylvatica), (3) a progression of monopolistic species in open gaps ( Impatiens glandulifolia, Solidago gigantea, Palaris arundinacea, Urtica dioïca, Rubus fruticosus, Crataegus monogyna, Prunus spinosa, Berberis vulgaris, Humulus lupulus, Clematis vitalba, Parathenocissus quinquefolia), (4) an arrival of new species usually associated with Q. platanoïdes, Tilia cordata, Coryllus avellana, Carpinus betulus, Quercus pubescens, Buxus sempervirens, F. incana), (2) a progression of hardwoods ( F. The main effects of the hydrological change were: (1) a regression in softwoods ( S. More recently, hydroelectric development of the Rhône valley has led to severe changes in by-pass sections, causing a reduction in wetted areas and lowering of the water table by up to 1 m in some areas. From the middle of the 19th century, anthropogenic pressure began to increase along the river corridor, and hard wood species such as Fraxinus excelsior progressively colonized river margins ( Marigo et al. Plant succession was usually reset at a softwood stage ( Salix daphnoïdes, Salix purpurea, Salix eleagnos, Salix viminalis, Salix alba, Alnus incana), with the more mature species being poplars ( Populus nigra). Coarse sediments (sand, gravels and pebbles) were displaced by floods and constituted unstable bars. ![]() During the 18th century, allogenic successions occurred in braided sections with a strong rejuvenation process of fluvial landforms. The ecological features of alluvial forests depend on geomorphology (braided, meandering, anastomosing). Upper terraces were used for agriculture and lower terraces as grassland. During the 18th century, forests were limited to the riverbanks (riparian forest) and islands. Jean-Paul Bravard, in Rivers of Europe, 2009 7.5.3 Floodplain ForestsĪlluvial forests have decreased by ∼50–80% during the past 50 years, being replaced by agriculture and other human activities.
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