PLANT DIVERSITY IN URBAN COMMUNITY GARDENS

As the human population expands rapidly, more and more people move into urban centers and the proportion of urban landscape also increases. In 1950 about 30% of the worlds population lived in urban centers, but this increased to about 50% by the end of 2011. The biology of urban landscapes are interesting since they can be vastly different from the more widely studied “natural” environments. Furthermore, if a larger portion of the human population will occupy urban landscapes we need to understand how these landscapes work and the ecosystem services at play if we are to make urban centers sustainable.


There is a growing body of evidence that biodiversity changes in urban areas. For the most part it seems that unplanned urbanization severely decreases biodiversity. Urbanized landscapes often have fewer insect species and species richness and composition may be altered when compared to less disturbed habitats.  This is very concerning since biodiversity has important functions to play in biological systems, including those found in urban areas.  While there is growing evidence that urban landscapes support different insect communities, we know little about the qualities of the urban landscape that determine which species thrive and which do not. Some of these factors include the heat island effect, permeability of the urban matrix, and resource availability. We can begin to understand how the permeability of the urban matrix, i.e. to what extent insects can move from point A to point B in an urban area, and the availability of resources affects insects by examining plant biodiversity at different landscape scales. In particular, urban community gardens offer an excellent system to examine biodiversity at different spatial scales: the individual plot, the garden, and the larger burgh/landscape context. In addition, since urban community gardens offer food and green space, biodiversity in such spaces can provide direct ecosystem services for residents.



We examined plant diversity and insect abundance at 18 community gardens in New York City to ask:

(i) How does plant diversity in urban community gardens affect insect abundance in gardens? How does plant diversity at different spatial scales (plot, versus garden, versus landscape scale) affect insect abundance in community gardens?

(ii) How is biodiversity in gardens related to socio-economic indicators of neighborhoods?

(iii) How does plant diversity in gardens influence dietary/nutritional diversity of gardeners?

(iv) How does the cultural (specifically culinary) diversity of gardeners affect the diversity of plants grown in gardens? And in turn diversity of insects present in gardens?