Situated in the north of the island, between the Old Rhine and the high water dyke, the alluvial meadow is an open area where woodland groves alternate with areas of tall plants. It presents a huge diversity of vegetation. This meadow biotope, which is rare in the Rhine Valley, should be protected by keeping it open.

http://rn-rohrschollen.strasbourg.eu/uploads/images/Ophrys abeille ©C.HELLIO.JPG http://rn-rohrschollen.strasbourg.eu/uploads/images/epipactis_des_marais-C-HELLIO.JPG http://rn-rohrschollen.strasbourg.eu/uploads/images/cornouiller_male.JPG

Dry grassland

Grassland is characterised by low-growing vegetation suited to high temperatures (thermophilous) and drought (xerophilous). Such grassland can be found in various places on the meadowland and on the dyke and it occupies the gravel outcrop sectors. These sectors remind one of Mediterranean fragrances thanks to the clumps of Thyme (Thymus pulegioides) and Oregano (Origanum vulgare) accompanied by other species such as Viper's Bugloss (Echium vulgare) and Bee Orchid (Ophrys apifera). This orchid, registered on the Red List Alsace of threatened species, grows on dykes and meadows.

The red lists of threatened habitats in Alsace (Odonat - 2003) assess the state of conservation and vulnerability of animal and plant species, and even of natural habitats. They help to establish priorities according to criteria of rarity, vulnerability, threats...

Hay meadows

Hay meadows have higher, denser vegetation than grassland. They are characterised by a considerable wealth of Graminaceae, including Tall Oat Grass (Arrhenatherum elatius) and a range of flowering plants, the most well known of which is no doubt the Oxeye Daisy (Leucanthemum vulgare).

Humid meadows

This habitat can be found covering small areas in the reserve. It presents an aspect of tall herbs, including Purple Moor Grass (Molinia caerulea) accompanied by sedge grasses (also called Carex). The most well known plant found in humid meadows along the Rhine is no doubt Valerian (Valeriana officinalis); it is accompanied by Willowleaf Yellowhead (Inula salicina), which forms large yellow tufts in the meadow, and the beautiful and protected Marsh Helleborine (Epipactis palustris), that shy orchid that grows in the month of July.

 

Woodland groves

The majority of the woodland groves found on the alluvial meadowland are composed of Blackthorn (Prunus spinosa), Dog Rose (Rosa canina), Hawthorn (Crataegus monogyna) and Common Dogwood (Cornus sanguinea). The majority of these shrubs are thorny and are used essentially as refuges and feeding sites for the fauna (mammals or birds).

Scientific survey

The reserve's alluvial meadowland too is regularly surveyed. The purpose of the surveys is to characterise the habitats present and assess the management methods employed.

Surveys are carried out every 2 years. A network of 32 permanent georeferenced sample plots has been set up throughout the meadowland. Each sample plot covers a surface area of 25 m².

A sample plot is a delimited, precisely located area in which vegetation inventories are made. The permanent sample plots enable long-term surveys of the development of vegetation. The size and shape of the sample plot varies depending on the purpose of the study.

A phytosociological survey is carried out for each sample plot. Phytosociology is the study of the relationships between plants and is used to examine and differentiate between the plant communities present on a site. A phytosociological survey consists in compiling a floristic inventory of the sample plot (all species found are recorded). Each species is then given a so-called cover coefficient according to the surface area that it occupies on the sample site. All data recorded are then input into a computer and compared with previous surveys. The resulting survey comparison with previous surveys is adapted to management operations follow-up such as mowing in our case. Analysis of these data helps the managing authority to assess the management method used.

Photographs:
Bee orchid © Camille HELLIO
Marsh Helleborine © Camille HELLIO
European cornel © Camille HELLIO