This document discusses urban ecology and the importance of integrating ecology into cities for sustainability. It describes how urbanization can disrupt ecological functions and habitats. Green networks of interconnected natural areas can help mitigate these impacts by preserving biodiversity and ecosystem services. Examples of green network elements are provided, including river restoration, urban nature preserves, wildlife crossings, and converting vacant lands and brownfields into natural areas. The document uses case studies like the Enz River in Germany and BP Park in Australia to illustrate successful green network projects.

1. PLAN 1900: Sustainable Cities
Week 14: Urban Ecology
Anuradha Mukherji
Assistant Professor of Urban and Regional Planning

2. URBAN ECOLOGY
• Study of human dominated eco-systems, i.e., cities –
system where human species is a central agent
• Urbanization ‘fragments, isolates, and degrades natural
habitat, disrupts hydrological systems, modifies nutrient
cycling”
• Cities and rapid urbanization impact ecological
functions – Ecological functions are the building blocks
of specific habitat types on which species depend.
• Disruption to ecological functions including physical
habitat results in a change or loss in habitat type.

3. INTEGRATING ECOLOGY
• Integrating ecology into cities is essential to sustainability
• Can help mitigate human impact on ecosystems
• Enhances ecosystem services (i.e., the combined
actions of species in an ecosystem that perform
functions of value to society, such as production of
oxygen, decomposition of waste, pollination)
• Protects biodiversity (i.e., the variety of life forms
indicated by numbers of different species of plants and
animals in an ecosystem)
• Maintains a healthy functioning planet for future
generations

4. GREEN NETWORKS SYSTEM
System of interconnected or related patches and
corridors that provide and sustain ecological values within
a human dominated landscape.
Goal is to preserve or restore the ecological integrity of
critical natural systems while allowing for compatible
human activities within the network and productive use of
adjacent lands.
Ecological integrity is the health, structure and functioning
of an ecosystem consisting of near natural levels of
production, biodiversity, soil and water.

5. GREEN NETWORKS HIERARCHY
System linked at multiple scales:
1. Mega – significance at continental level
2. Macro – National and regional levels
3. Meso – City level
4. Micro – Individual projects and sites
Linking scales creates possibility for connectivity and flows
between levels that are essential for sustainability

6. EUROPEAN GREEN BELT
This image is attributed to Smaack @ 2011 (CC BY-SA 3.0)
Old forest area along eastern European borders
Multinational movement to conserve & protect
Connects national parks, nature parks, biosphere reserves

7. GREEN NETWORK EXAMPLE
Lifelines: Rivers, Streams, and Riparian Areas
1. Biologically most diverse and rich
2. Critical lifelines for providing connectivity that
facilitates flows
3. Important to preserve these critical corridors
4. Most places, rivers, streams and their drainage basins
are modified from their original condition
5. Sometimes channelized or straightened to manage
flooding or maximize land for urban development
6. In the long-term this increases the speed of water flow,
in turn the force causing erosion of stream banks, thus
carrying more sediment & reducing water quality.
7. The sediment load drops downstream, filling the
channel, reducing carrying capacity for water,
resulting in flooding beyond historical flood zones.

8. Enz River, Pforzheim, Germany
This image is attributed to

9. Enz River, Pforzheim, Germany
City of 120,000 at the edge of Germany’s Black Forest
River runs through center of town and was channelized and
straightened in early 1900s
Land adjacent to river developed through decades of urban housing,
industrial complexes, shops and other intense urbanization
A river restoration project as part of large scheme to create an urban
park following the natural course of the river for 15 km through the city
Re-naturalization process reintroduced the normal meander cycle of
river prior to channelizing, with trees and shrubs replanted
Now 20 years later, the river corridor is well established, vegetation has
matured providing species habitat, many ecological functions restored
Ecological corridor linking Black forest to other ecological zones

10. Enz River, Pforzheim, Germany
This image is attributed to

11. Enz River, Pforzheim, Germany
This image is attributed to

12. GREEN NETWORK EXAMPLE
Sources and Core Areas: Urban Nature Preserves
1. Large areas of natural or near natural landscapes
2. Prime habitat for various species
3. Improve air quality – supply oxygen & remove carbon
4. Mitigates urban heat island effect
5. Perform hydrological functions – water retention,
groundwater recharge, surface water filtration

13. The Phoenix Mountains Preserve, Arizona, USA
This image is attributed to
City of 120,000 at the edge of Germany’s Black Forest
River runs through center of town and was channelized and
straightened in early 1900s
Land adjacent to river developed through decades of urban housing,
industrial complexes, shops and other intense urbanization
A river restoration project as part of large scheme to create an urban
park following the natural course of the river for 15 km through the city
Re-naturalization process reintroduced the normal meander cycle of
river prior to channelizing, with trees and shrubs replanted
Now 20 years later, the river corridor is well established, vegetation has
matured providing species habitat, many ecological functions restored
Ecological corridor linking Black forest to other ecological zones
An example of open-space preserves that function as core areas
All natural or near-natural condition & part of the city of Phoenix Park System
Largest city park in the United States comprising – South Mountain Park, North
Mountain Range, and Sonoran Preserve

14. The Phoenix
Mountains Preserve,
Arizona, USA
This image is attributed to

15. The Phoenix Mountains Preserve, Arizona, USA
Downtown Phoenix from South Mountain
This image is attributed to
City of 120,000 at the edge of Germany’s Black Forest
River runs through center of town and was channelized and
straightened in early 1900s
Land adjacent to river developed through decades of urban housing,
industrial complexes, shops and other intense urbanization
A river restoration project as part of large scheme to create an urban
park following the natural course of the river for 15 km through the city
Re-naturalization process reintroduced the normal meander cycle of
river prior to channelizing, with trees and shrubs replanted
Now 20 years later, the river corridor is well established, vegetation has
matured providing species habitat, many ecological functions restored
Ecological corridor linking Black forest to other ecological zones

16. GREEN NETWORK EXAMPLE
Gray to Green Infrastructure: Transport & Utility Corridors
1. Roads, rail lines, and utility corridors form barriers,
interrupt flows & accelerate fragmentation
2. Ecological bridges & eco-ducts used to overcome the
barriers
3. Infrastructure travels through wide rights of ways –
residual space beside roads & rails or underneath utility
lines can be ecological corridors (e.g., for animal
migration corridor) – safer for motorists on roadways

17. Wildlife Overpass, Banff National Park, Canada
This image is attributed to Qyd @ 2006 (CC BY 2.5)

18. Watchung Reservation, I-78, New Jersey
Bridge for animal crossing
This image is attributed to Doug Kerr @ 2009 (CC BY-SA 2.0)

19. GREEN NETWORK EXAMPLE
Forgotten Space: Vacant Land, Underutilized Sites, and
Brownfields
1. Vacant, underutilized land and derelict or post-
industrial brownfield sites are a resource
2. Brownfield sites were previously occupied, often in
some industrial capacity, and are now abandoned
and may have contamination issues
3. A study of 70 cities in the United States showed that
15% of land on average is vacant
4. Often privately owned, these parcels can play a role in
establishing green networks or provide linkages
between other ecological zones
5. Example: BP Park in Waverton Peninsula, Sydney. A
former BP storage depot with 31 oil tanks carved into
sandstone bedrock. Bio-remediation carried out.

20. BP Park

21. Waverton Peninsula Strategic Master Plan

22. BP Park

23. BP Park