Friday, 15 March 2013

Gatwick’s habitat mosaic: The science stuff

The names of our two conservation sites reflect the (sometimes infuriating) tradition of airport acronyms...

NWZ: situated just above the western end of the airfield

 LERL: to the south-east of the South Terminal

However they are usefully descriptive names and 'ell', 'ee', 'arr', 'ell' (LERL) rolls off the tongue after a while. These two areas are made up of mixed habitats containing their own related niches of wildlife. Our aims are to conserve all of these habitats and enhance them. Were it not for the airport then these buffering pockets of land would probably not be here, instead being given over to housing development or agriculture.

Brockley Wood’s south-eastern edge

I am often asked why we go in and carry out such heavy duty habitat management; it can seem counter-productive hacking back the brush and young woodland instead of just leaving it up to nature. In the simplest terms, changes in land use and development by people have caused our landscape to become very fragmented. Ecosystems no longer function in the usual way and the isolation of habitats such as woodlands, lakes and grasslands tends to result in their containing fewer species and a less diverse structure. For example, if the last remaining field maple in a small woodland fragment died out, there would be less chance of re-colonisation from the surrounding area if there is no other nearby woodland. A few dominating species in a small area are also more likely to take over and out-compete others. So we intervene to maximise the diversity of the land we have left and prevent a few species from becoming overly dominant (in the context of the wider landscape).

Bankside coppicing along Man’s Brook, North West Zone

Recently we have begun rotational coppicing of shrubs and trees (ie. cutting back to ground level) to provide a range of different-aged scrub as it regrows. A richer variety of habitats is beneficial for biodiversity as it will suit a wider assortment of species. However, if coppice stands are neglected they can grow up again into tall canopy cover, shading out the smaller ground flora. If hedgerows are left uncut, they can grow out and become straggly, dying off in the centre and eventually becoming lines of large trees. Coppicing helps to keep the integrity of a habitat and maintain it in a medium-aged state.

Coppicing can affect environmental conditions such as ground temperature and light levels

With conservation pressures ranging from small scale to large, our best course of action is to maintain a high level of structural diversity in a dynamic system, so that these many small havens will make up a healthier whole and as many organisms will benefit as possible.

There are many very good reasons for preserving the biodiversity of our planet … I am not going to list them all here, instead I will refer you to this link (though I honestly don’t mind if you want to skip over point no.9):

The thing which resonates the most with me about conserving biodiversity is Aldo Leopold's statement in ‘A Sand Country Almanac’:
   “ - if a missing cog or belt can render a car’s engine useless—how much more might a missing organism affect the health of an ecosystem whose complexity is overwhelming?”