Posted by: swinemoor | January 2, 2014

The Dangers of Encroachment


Swinemoor Common is under threat from encroachment but, providing that this does not actually cross the boundary onto the common itself, does this actually matter?

The short answer to this is YES and this is one of the main reasons (along with flooding) that NSH has objected to the construction of the ‘cottage’ hospital on three of the Medieval fields on the western edge of the Common. The long answer is also yes but the reasons for this are not always clear.  The main risks from encroachment arise from:

  • Habitat fragmentation: This is well known from places like the Amazon rainforest where species become threatened within the forest due to it being sliced-up by new roads along which ribbon development and forest clearance takes place.  These areas then gradually become larger whilst the remaining areas of forest become ever smaller, isolating the species within them. This can affect the chances of individuals finding a mate and, since certain  species need a large area over which to forage (territories), it can eliminate those species that require larger territories than the remaining habitat fragments.
  • Edge effects: If you enter a British woodland you will notice that around the edges there is typically a lot of brambles and perhaps thorn bushes. These extend some way into the woodland, however, if the woodland is large enough, they will disappear to be replaced in turn by woodland floor species such as ferns and perhaps bluebells, dog’s mercury and wood anemones. If the wood is small then the woodland flora may not be present at all: in other words it is all woodland edge and not really a woodland habitat. This is what is meant by edge effect. The key point about this effect is that it affects smaller areas of habitat more acutely than larger areas and, as the contiguous area of habitat is reduced, its effects become ever more influential.
  • Island Biogeography: This idea comes from the seminal work of McArthur and Wilson in 1967 where they looked at a number of islands to determine the number of species they contained. They noticed that islands of roughly the same size contained roughly the same number of species, however, this number varied depending on the distance the island was from the mainland.
    Island Biogeography: Species: Area and Species: Distance effects

    Island Biogeography: Species: Area and Species: Distance effects

    Specifically they discovered that small islands near the mainland had more species than small islands further away but had less species than larger islands at the same distance. McArthur and Wilson, noticing that the species composition on each island was different, hypothesised that species were being lost and gained from islands all the time but those nearer to the mainland had a better chance of re-colonisation and so contained a greater number of species. Larger islands contained more ecological niches and so could hold a greater number of species. This is the foundation of the so-called area-effect and distance-effect that has influenced ecological thinking around the subject of meta-populations.

  • Non-native Invasive Species: This is related to edge effect as it initially affects the edge of the habitat area, damaging it. This damage, depending on the nature of the species, can be extensive if the infestation is not treated. However, it is the direct result of habitat fragmentation and the introduction of these damaging species, that increases this risk.

Swinemoor Common

Spreading Japanese Knotweed on the edge of Swinemoor Common

Spreading Japanese Knotweed on the edge of Swinemoor Common

Extrapolating from the above, we can see that, as the area of old semi-natural grassland that makes up Swinemoor Common and its surroundings is reduced by encroachments such as the industrial estate and now the ‘cottage’ hospital, the edge effect on the remaining habitat increases and its value to the species that currently live there decreases. This means that the inevitable result of the developments that have already taken place will have been local extinctions – it is interesting to note that no invertebrate surveys were carried out prior to the construction of the Folly on the Lane and there are no proposals to undertake any now. The remaining species are now under threat as a result of the increased fragmentation of the habitat that has taken place and the from the proximity of invasive alien species on the adjacent, non-sympathetic land-use types that have replaced the former grasslands.

Westwood, Hurn, Swinemoor and Lund

All of these areas are under the same threat that is why any access to the old Westwood Hospital site should be opposed as it will involve the loss of sections of hedgerow and damage to unploughed pasture as well as potentially a  number of trees, further fragmenting the habitat here. Lund has already suffered from the widening of the road through it in the past and is now becoming more isolated (a more distant island in effect) from the grasslands to the South as a result of the construction of the new Southern Relief Road (which itself has fragmented a large area of semi-natural grassland to the south of the town). Hurn is always under threat from the racecourse and Figham has suffered damage from the construction of the gas pipeline through the centre, fragmenting the semi-natural grasslands here.

There are many plaintive letters in the Beverley Guardian bemoaning the loss of the town’s cultural heritage, however, our natural heritage is also being lost at an ever-increasing rate. This cannot be allowed to continue if we are to keep hold of what we have for future generations. Whatever happened to sustainable development? In spite of it being a key component of the National Planning Policy Framework (NPPF), we at NSH cannot see any evidence of it around Beverley.


  1. […] on flood-prone land, the loss of street trees, the building of a new bypass nobody wants and the piece by piece damage to the countryside and wildlife surrounding the town. All of this under the watchful eye of ERYC whose job it is to preserve Beverley as one of the best […]

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