Finding the green in Cities
The Botanical Biodiversity of Urban Greenspaces
Latisha T. Williams
Abstract:
Cities represent the most extreme form of human influence on an
ecosystem and hold within them the faith of nature, the ability to
conserve or destroy it. The wide spread belief (myth) that urban
environments are disconnected from the natural world and lacking in
biodiversity has been widely explored and it has been determined by
some that biodiversity is indeed preserved in cities. Where this diversity
is actually located is a matter of less clarity because much of the study
on the urban biodiversity has historically focused on the wilderness
surrounding the city, not within a city, creating a gap in information about
city-biodiversity interactions (Oliveira et al. 2011). It has been extensively
acknowledged and well documented that species diversity, or
biodiversity, in urban areas is an important ecological factor. Yet there is
little clarity about where this diversity can be found, partly because there
is no unified understanding of what is urban nature. A space classified
as an urban green space includes man-made plant communities
throughout the landscape as well as natural areas, that when combined
create the green urban infrastructure of the urban fabric. Identifying
urban green space and the biodiversity within these spaces is important
to preserve biodiversity of nature within urban environments. This study
represents a pioneering effort to classify the types of urban greenspaces
and works to identify the spatial distribution and species abundance of
plant diversity throughout urban green spaces, allowing patterns of
diversity to be recognized that could later be built upon in conservation
and preservation efforts by addressing the following:
1. What are the different types of urban greenspaces located with
the built environment of a city?
For the purpose of mapping, an urban green space was defined as any public
area containing vegetation and accessible to the pubic for physical or
aesthetic purposes. This vegetation did not need to be landscaped or
maintained. Once the areas were mapped they were then divided into nine
categories: parks, sports fields, playgrounds, grassy lots, over grown lots,
green streets, traffic circles, cemeteries and natural areas.
Of the nine categories the five chosen as study sites were parks, cemeteries,
green streets, traffic circles, and natural/undeveloped areas. These
categories were chosen because they represented green spaces that people
could come in contact with on a daily basis, either by actually using them or
through observation. Two sites for each of the selected categories were used
for species survey/diversity analysis, because that was the maximum
available for the area, and then sampled during the Spring-Fall growing
season over the course of two years. Linear transects and circular quadrate
were used to collect species information. Stratified linear transects measured
12.5meters long and at the end of this distance the type and number of trees,
shrubs, and herbs in circular transects of 10meters, 5meters and 2.5meters
respectively were determined. The size for circular transects was determined
by the maximum width of the smallest green-space included in the study,
green streets.
2. Of the greenspaces present, which has the highest level of
diversity (what is the abundance and distribution of the botanical
species present)?
3. How does the level of diversity for various urban greenspaces,
compare across botanical categories (herbs, shrubs and trees)?
What effect does human impact, through the frequency and level
of maintenance, have on the diversity of urban greenspaces?
It is expected that, diversity will be higher at locations that are more
managed and easily accessed by the public and that exotic species will
not inhibit the diversity of an area. At the same time the presence of
native species is not expected to guarantee greater diversity.
Diveristy Across Botanical Category & Area
2.5000
2.0000
D ive rs ity
Herbs
1.5000
Shrubs
Trees
Non-Native
1.0000
Natives
0.5000
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Preliminary Conclusions:
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The results are still being analyzed, however it appears that managed areas
may be slightly more diverse than the natural greenspaces, in Binghamton, but it
is those greespaces with both a natural component as well as human influence
that maintain the highest botanical diversity. Nonetheless, there may be some
native species that refer� managed greenspaces. Thus, it may be optimum to
have both natural and managed greenspaces within an urban environment.
Also, it appears possible that particular types of management, especially close
mowing of lawns, is inimical to biodiversity, while allowing some messy�
spaces within managed greenspaces might increase diversity. Another aspect
of this research, not reported here, was a survey of Binghamton residents to
determine preferences and attitudes towards greenspace and the environmental
attributes in these spaces, which may help to determine to what extent the
public would support changes in management intended to increase biodiversity
and conservation.
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Table 1: The organizations of urban green spaces in the City of Binghamton according
to management level (1= least managed, 9=most managed) and frequency of
maintenance (1=no maintenance, 9= frequent maintenance). Maintenance is
different from management in that management is the act of establishing the green
space and the measure of how much effort goes into the up keep, while the
frequency of maintenance is how often this effort has to be exerted. Vegetation
observations are made according to the general observations of most of the green
spaces in that particular category (T=trees, G=grass, F=flowering plants, S=shrubs)
Future Research
This initial study concentrated on formatted� greenspaces that are incorporated
into the social sphere as space that is physically used or visually enjoyed, and
now is being extended by other students to unformatted� less accessible
greenspaces such as overgrown lots, railroad rights of way, and islands and
other streamside vegetation, that were identified through the greenspace
mapping. There is also a need to study private yards. Once the data are
analyzed, policy prescriptions will be developed that hopefully maximize
conservation of biodiversity in Binghamton, as well as other urban environments.