EVSC30006 Lecture Notes - Lecture 2: Light Pollution, Transect
1 Jun 2018
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LECTURE 2: URBAN-RURAL GRADIENTS
• Environmental Gradient: change in environmental variable as you move along a gradient
o Concept introduced in 1967 and observed in nature
o Gradient: environmental abiotic variation is ordered in space
▪ Resulting pattern of environmental variation influences the distribution of organisms
• Zones from rural to urban – level of development to the environment – gradual change
Melbourne: centre of Melbourne very green due to green space in CBD
• Gradient depends on where you are located in the urban area = highly variable suburb to suburb
• Hahs & McDonnell (2006):
o N/S transect: percent cover of urbanity decreases as you move north
o W/E transect: percent cover of urbanity increases as you go east – almost as high as CBD
• Studies on urban-rural gradients are mostly around presence of
organisms
o Other ways to measure: air quality, light pollution,
population density
• How to read (graph to right):
o A. Organisms presence is same throughout the gradient
o C. Organisms remains high for a while, then urbanity is too
much and pop drops out
o E. Low abundance in rural area, then high in urban area
(Feral cats, Indian Minors)
Urban-Rural Gradient: proposed in 1990, applied env gradients to cities to show a continuum of variation
between rural and urban areas, categories depend on the study/author
