introductiontothemanagementofgrasslandandwetlandhabitats...
TRANSCRIPT
Introduction to the management of Grassland and Wetland habitats
Mark Webster 14/9/15 Pott Row Village Hall for GVCG
A Summary of presentation with additional reference to The History of the Countryside Oliver Rackham 1986 J.M.Dent; Fens, Bogs and Marshes: their flowers and vegetation a presentation at Wicken Fen by Owen Mountford 2015; http://www.wildlifetrusts.org/wildlife/habitats/lowland-‐meadows
Meadow is Grassland created by cutting or Mowing by humans for hay.
Pasture is grassland grazed by Farm animals.
Trees are the natural vegetation in our latitude round most of the world. Grassland occurs in places that are too dry or too high for trees or are grazed too much by wild animals. Pollen studies suggest grassland was rare before civilization. The landscape appeared to transform to grassland beginning with the arrival of Neolithic man in 4000 BC. Meadows and pastures though now a well-‐defined plant communities appear to have assembled together from a selection of plants that once grew in places too high or too far north for the wild wood.
Meadows tend to grow on fairly neutral soils. Acid-‐sandy soils tend to become a heathland population. Pasture is often wet marshy grassland or fen and tends to be acid and chalk grassland. Grazing farm animals on pastures are often sheep goats and Highland cattle.
Churchyards are sometimes the best piece of ancient grassland in any locality
Broadly there are 3 types of meadow.
• Unimproved or nutrient poor or non-‐fertilized; is best or the most bio diverse and is dominated by thinner grasses which allow other herb species to coexist. Less than 15,000 hectares of unimproved neutral grassland remains in the UK
• Semi-‐ improved meadow Semi-‐improved grasslands still retain a good number of grasses and valuable wildflowers such as Red Clover, Bird's-‐foot Trefoil, Ox-‐eye Daisy and Knapweed which are important for Bumblebees and many other insects. Under traditional management these also have the potential for supporting more species.
• Improved or fertilized meadow dominated by thicker grasses which tend to outcompete other species by creating dense shade.
Churchyards are sometimes the best piece of ancient grassland in any locality as they may as old as the oldest fragment of the church and will often have been grazed or mown. However even Churchyard meadows can be altered by too much tidiness or excessive mowing.
There has been a loss of meadows during the twentieth century. Up to 98% of lowland meadows have been lost since 1945 according to the Countryside Commission 1984. This has been caused by a number of factors including changes in farming practice, imported feeds, silage and urbanization.
Why manage meadows?
In order to hold back succession. For example historically in the North America prairies or pastures were maintained by the dry climate, grazing by large herds of buffalo and burning. Since the extermination of buffalo trees have advanced into the prairie land. Britain is too wet for grassland to avoid invasion without grazing or mowing. Accordingly the habitat will succeed into woodland.
Each part of the UK boasts its own specialities, but the one characteristic shared by traditionally managed lowland meadows is the high number of herbs and grasses – they can frequently boast up to 30 grasses and 100 or more wildflower species. Grasses include quaking-‐grass, sweet vernal-‐grass, crested dog's-‐tail and red fescue, while flowers include devil's-‐bit Scabious, pepper saxifrage, green-‐winged orchid, snake’s-‐head fritillary and adder’s-‐tongue fern. In damper areas, cuckooflower, ragged-‐Robin and yellow iris can be found, as well as rarer species like narrow-‐leaved water dropwort.
How to manage meadow?
In order to maintain a meadow cutting and raking needs to be undertaken. On unimproved meadow x1 per year is sufficient. Less unimproved meadow may require x 2 cuts per year. The cutting is undertaken mid to late summer (Late June and September) and the second cut in early autumn (late September or October).
Cutting can be undertaken with a hand scythe or an Allen Scythe or reciprocating mower which is a toothed blade sliding back and forth horizontally across stationary teeth to produce a scissor action, and also drives two large wheels for forward travel.
In order to render the habitat nutrient poor it is essential that the cut vegetation is raked off.
Problems Faced when managing meadows.
These include:
• Scrub: this includes a variety of woody species such as Hawthorn, Bramble, Oak and Silver Birch which sometimes grows very densely, shading out other low growing herb or grass species. Scrub will mature into secondary woodland if left unmanaged
• Nettles, Thistles, Brambles and Ragwort, invasive species, sites that have been neglected or over managed.
• Inappropriate Management includes over mowing, topping and not removing the cuttings, fertilizers, tree planning broad spectrum weed killers, pond dredging and overgrazing.
Mark suggested avoiding being tempted to create meadows from scratch. The creation of meadows was dependent upon having poor soil in the first place. However this may be a practical solution in urban settings. However it does need ongoing management to ensure the new annual seeds have bare ground in which to germinate.
Wetland Habitats
The word Fen is used to mean different habitats in a vernacular (native language or dialect) sense but also is used in a scientific sense. So here is an attempt to clarify the scientific meanings:
Expressed simply
• a mire is vegetation on waterlogged peat • A Bog is a mire where Sphagnum (bog-‐moss), Heathers (ericaceous shrubs) and cotton grass
dominate and where the water is acidic. The best example of this locally is Roydon Common. This is unusual habitat to be found in East Anglia because bogs are generally found in Northern and Western Britain.
• A Fen is a mire dominated by tall grasses, sedges, rushes and forbs where the water may be mildly acidic but is probably around neutral or even alkaline.
A fen
Reed beds require cutting every 3 years and this is generally undertaken in the winter, Sedge beds in the summer.
KR 15/9/15