The Urban Green Plan

PBL Project
The Urban Green Plan
Bio 1M03 L32 - 05

The Urban Green Plan

      The existence of many species being threatened since human expansion has become a major issue on both a local and a global scale. Endangerment and extinction of numerous organisms have strained the biodiversity within urban cities. Expansion of land use by humans have left a minimal amount of fragmented natural habitats that can only support a limited number of species, most of which seem to be small. Moving into the city, there is a consistent trend of physical changes that occur towards the city core (McKinney, 2002). These trends are “heat, air pollution, soil densities, soil alkalinity, and rainfall (McKinney, 2002).” These factors contribute to the overall environment around the city. According to McKinney (2002), as the city transitions towards the core of the city, the loss of habitats increases which demonstrates a direct relationship between expansion and loss of biodiversity. Not all habitats are lost, rather they are split into four different sub categories of significantly smaller habitats which are: built habitats, managed vegetation, ruderal vegetation and natural remnant vegetation (McKinney, 2002).
      The number of species found in the center core of cities is less than half the species found in more rural and even wild environments. McKinney (2002) uses an example cited to Blair (2001) which was on the study of birds in Palo Alto, California as a compare and contrast of the number of species in the area. This research showed that there were seven summer resident birds in the city core compared to twenty-one that are found outside the city core. The urbanization causes a homogenization of species because non-native species have out-competed and therefore replaced native species (Alvey, A. 2006). This has many adverse biological ramifications because the loss of biodiversity is related to the loss of genetic diversity. If one local population becomes extinct,...