Habitat Management – Grasslands
The type of grassland depends on the type of soil and the way it is managed. Nutrient rich soils tend to produce a sward which is relatively species poor – one or two species act as “bully boys” and take over. Chalk graslands are amongst the richest but as soon as nutrients are added, such as fertilizers, then the species diversity and floral richness is lost. The key to creating a floristically rich grassland is to either to graze the land or to mow at particular times of the year and, traditionally, take a hay crop.
The choice of grazing also affects the grassland structure. For instance cattle eat by gripping the grass with their tongues and pulling whereas sheep cut the grass by biting with their teeth.Cattle are heavy and can create bare soil patches, or “poaching”. These bare areas can themselves provide a valuable habitat for some species of invertebrates and opportunities for other plants to seed.
Traditionally mowing would have been done by hand with a scythe. Today mowers and tractors are used. But the principles are the same.
Hay cuts were traditionally done in late June/July. The cut sward being left to dry in the sun (tedding or raking to turn the grass over to ensure it dried evenly) before being raked and baled for storage and eventual winter feed for the farm animals.
An early cut will favour those plants which seed early whilst a later, autumn cut will allow later flowering species such as scabious to set seed.
Thus the floral diversity of the grassland will be dependent upon the time of cutting. Raking also clears out any “thatch” which builds up over time and which can reduce floral diversity. However thatch is important shelter for field voles (Microtus agrestis) which nest in thick grass and in turn provide food for Barn owls (Tyto alba). Patches of taller grasses such as Cock’s-foot (Dactylis glomerata). False Brome (Brachypodium sylvaticum), Purple Moor-grass (Molinia caerulea) and Tor-grass (Brachypodium pinnatum) provide the main egg laying sites and larval foodplants for the Large Skipper (Ochlodes faunus) butterfly.
Therefore if you wish to promote as wide a diversity of wildlife as possible a variety of regimes need to be considered to deliver the maximun diversity of structure.
Creation of grasslands
There are several ways to create a wildflower rich meadow. One is by planting “plugs” of suitable flower mixtures. Another is by spreading flower rich hay over the area in the autumn. The most intensive is to scrape off the first few inches of topsoil to remove any nutient rich soils and to cover with hay from a flower rich meadow.
Natural England provide a range of information leaflets downloadable from their website which provide detailed advice about various aspects of meadows and grassland restoration and creation. For a simpler overview, aimed more at the gardener try wild wild flower meadows.