With increasing human populations and a rise in people migrating to urban areas there
will be a corresponding rise in urbanisation across the globe. Urban green spaces are
therefore becoming increasingly important for biodiversity as reserves and movement
corridors. This thesis aimed to understand the impacts of traffic and environmental
related factors on the ability of green space to be wildlife reserves using the town of
Bracknell, Berkshire, UK, as a model urban area.
Concentrations of NO2 declined with distance from the road but urban green spaces
showed many exceedances of NO2 and NOx critical levels. There were decreases in
soil moisture and total C and N at the road edge but increases in soil pH, C:N,
titanium, chromium, nickel, copper, zinc, cadmium and lead. Some protection of
urban green spaces from the road could be achieved with the use of tree shelterbelts.
It was found that roads had a significant affect on plant communities; with more bare
ground, moss, herbs and stress-tolerator species and less grass and competitive species
near to the road edge. These changes are related to differences in the environmental
conditions at the roadside. Carabid species richness, abundance and diversity and
invertebrate abundance and plant diversity were all higher at the road edge than the
site centres, indicating that these groups are able to take advantage of the road edge
habitat.
Overall, sites with decreased mowing had more invertebrates and the bioindicators
carabids and woodlice. Reducing mowing frequency therefore provides a simple
method to improve urban green spaces for biodiversity. Furthermore, older and larger
sites had greater biodiversity.
This thesis has demonstrated that environmental and traffic related factors have
significant effects on urban biodiversity. There are methods which could be
employed, however, to lessen these impacts to allow urban green space to act as
effective wildlife reserves.