CASE STUDIES
RESTORATION OF GRASSLAND ON CLAY SUBSOILS FOLLOWING CONSTRUCTION OF THE SECOND RUNWAY AT MANCHESTER AIRPORT
A case study of selected mitigation measures can be viewed by clicking here.
As part of the approval and planning permission for the second runway a
Landscape and Habitat Management Plan (with a 15-year lifespan) was developed to
protect and improve semi-natural habitats around Manchester Airport. A part of
the action programme involved mitigation measures to create new grasslands in
the vicinity of the airport.
The creation of visually attractive, species rich grasslands which, as far as
possible, resemble locally indigenous mesotrophic grassland communities (NVC MG
5) was a key requirement of Planning Agreements with Cheshire County Council and
Manchester City Council. On sites where the topsoil was completely removed, the
exposed dense clay subsoils were very inhospitable for germination and
establishment of seedlings, being waterlogged in winter and with a dense
impenetrable surface in summer. Mineral nutrient content was extremely low in
nitrogen and phosphorus. After three years, new grasslands sown with wildflower
species seed mixtures, failed to establish a diversity of plant species and a
near 100% of re-seeded sites had an inadequate vegetation cover at least in part
of the site, with much bare ground and only a small proportion of species
included in the original sown seed mixture having established.
In order to achieve long-term management objectives to develop attractive swards
of locally native wildflowers within a target mesotrophic grassland (MG5c),
which are useful habitats for a variety of animals, combinations of slow and
fast release fertiliser, sowing of wildflower seed typical of MG5 grassland
communities and incorporation of composted greenwaste to reduce bulk density and
increase porosity, were tested.
