Urban ecology studies communities where humans dominate the ecosystem, covering about 4% of the world's surface and exerting pressure on natural ecosystems. Urban ecosystems are characterized by built structures, low plant diversity, and reliance on external resources, unlike natural ecosystems which sustain themselves through natural cycles. The rapid urban growth projected to add 2 billion residents by 2030 presents significant environmental challenges, emphasizing the need for effective management and planning of urban green spaces for sustainability.

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Urban Ecology
 “A biological community where humans represent the dominant or
keystone species and the built environment is the dominant
element controlling the physical structure of the ecosystem.”
Why is Urban Ecology Important?
 People occupy only about 4% of the world’s land mass
 Almost half the world’s population live in urban areas
 Urban regions use or extract resources from all other regions
 Tremendous pressure is exerted on existing ecosystems worldwide
Urban Ecosystems

2. Urban ecosystem
 is simply the community of plants, animals, and humans that inhabit
the urban environment.
 is an area physically dominated by built structures like buildings,
roads, sewers, and power lines.
 also contains a rich patchwork of green spaces - parks, yards, street
plantings, greenways, urban streams, commercial landscaping, and
unbuilt lots - that provide the living heart of the urban ecosystem.
 Urban ecosystems are the most familiar of all ecosystems to
humans.
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urban ecosystem----con’d

3.  Cities are engineered ecosystems so they have many differences
from natural ecosystems
Feature Urban Ecosystems Natural Ecosystems
Surface
Features
•buildings, paved roads, &
parking areas
• plants
Plant
Species
• low density of plants • high diversity of
species
Animal
Species
• low diversity & abundance • high density & diversity
of species
Water
Cycle
• water enters sewers
• most surfaces cannot absorb
water
• surface water in ponds,
rivers, & lakes
• most rainfall absorbed
at surface
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urban ecosystem----con’d

4. Feature Urban Ecosystems Natural Ecosystems
Flow of
Materials
• massive deliveries of materials
to supply human demand for
consumer goods
• human body waste collected,
treated, & released
• household waste disposed of in
surrounding environment
• natural nutrient cycles
occur throughout
ecosystem
Food
Webs
• dependent on importing food
from outside agroecosystems
• natural food pyramids
with decomposition
occur throughout
ecosystem
Sustain-
ability
• cannot be sustained without
large deliveries of material from
outside
• completely
sustainable
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urban ecosystem----con’d

5.  also differences between urban ecosystems and natural ecosystems
(less dominated by humans).
o Urban ecosystems are generally highly disturbed systems,
• subject to rapid changes in soil and plant cover, as well as
temperature and water availability.
• The plant life in urban ecosystems is also different ,
characterized by many nonnative plants
• Even in the city's natural or seminatural areas, like parks, the
vegetation is often highly altered, with many nonnative and
invasive species.
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urban ecosystem----con’d

6. Set of Urban Ecosystem drivers
Biophysical drivers
• Flow of energy
• Cycling of matter
• Flow of information
Socio-economic drivers
• Information flow
• Cultural
values/institutions
• Economic systems
• Power hierarchies
• Land use & management
• Demographic patterns
• Designed & built environ.
Patterns/processes
Primary production
Populations
Organic matter
Nutrients
disturbance
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urban ecosystem----con’d

7. indicators of urban green spaces in cities and urban regions to
improve the quality of life
• Whole city scale indicators
– Fragmentation of urban green
• Size, shape isolation,
connectivity
– Level of nature protection
• Preparation for protected
green areas
– Biodiversity-species & habitat
• Diversity of breeding birds
& vascular plants
• Biotype diversity
• Site scale indicators
– Fragmentation
• Same measures
– Naturalness
• Degree of disturbance
• Exotica/rare species
– Biodiversity-species
• Diversity of birds,
vascular plants, carbid
beetles, butterflies
• Biotype diversity
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urban ecosystem----con’d

8. Extent of Urban Ecosystems
 Urban ecosystems currently cover about 4% of the world's surface.
 they are the only major ecosystem type that is expanding with the
rapid growth of cities worldwide, .
 New urban landscapes are being generated by the building of roads,
housing, power lines, and industrial and commercial sites
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urban ecosystem----con’d
 Cities are the heart of human commerce and industry
o the primary centers of
• employment,
• housing,
• transportation, and
• the range of social services from health care to education.

9.  the contribution of urban green spaces to the urban Ecosystems.
1. Shade and Temperature Control: Street trees and other green spaces help
to battle the urban heat island effect.
− Temperatures in the heart of a city are warmer than in rural areas due
to the large heat-absorbing surfaces of buildings and asphalt, as well as
high energy use.
−Trees provide shade and also transpire large amounts of water that
provide a cooling effect when evaporated.
−When combined, these effects can lower local temperatures
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urban ecosystem----con’d

10. 2. Air Filtering: City plants are efficient air pollution removers.
− In a park, trees can filter out as much as 85% of the ambient air
pollution - mostly particulates.
− Street trees can also be effective air purifiers, removing up to 70% of
particulates on a tree-lined street.
3. Noise reduction: Trees and shrubs can help filter out noise pollution
− A 30-meter belt of tall dense trees combined can reduce local noise
levels by 50%.
4. Storm water Control:
− Urban forests, wetlands, and streamside vegetation help to restore
some of the natural balance by buffering stormwater runoff,
absorbing pollutants, and recharging groundwater reservoirs.
5. Recreation, Aesthetic, and Spiritual Values: Parks and green spaces
provide city dwellers with invaluable recreational opportunities.
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urban ecosystem----con’d

11. 6. Biodiversity and Wildlife Habitat: Cities support a variety of plants and
animals.
 Urban ecosystems provide critical habitat to many migratory species.
For example, urban green spaces and parks are critical to many
migratory birds.
 In many instances, these wildlife provide us with recreational
opportunities.
7. Food Production: Although it is not so prevalent in the countries, urban
agriculture is very important on a global basis.
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urban ecosystem----con’d

12. Threatening the World's Urban Ecosystems
 Intensive and rapid urban growth is the greatest pressure on urban
ecosystems.
 Urban areas will add some 2 billion new residents worldwide by
2030, growing from the current urban population of 2.9 billion to
4.9 billion.
 In today's world, nearly all population growth is urban growth.
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urban ecosystem----con’d
 urban areas will be spread over a significantly larger area than today,
-changing natural areas like forests, grasslands, and farms into urban and
suburban environments.
-Within existing cities, more people will use parks and other green areas,
and development will gradually increase the stress on the remaining
green areas.

13.  Many communities still see green areas as more a luxury than
an essential component of the city's infrastructure like its roads
or sewers.
 There is a lack of planning and budgeting for the care of green
spaces.
• little attention is paid to the effects on the urban forest
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urban ecosystem----con’d

14.  Like all other ecosystems, urban ecosystems are not isolated
islands, but part of a larger web of life.
 What goes on in cities affects all the ecosystems that surround them
i.e. the nearby forests, farms, and waterways.
 More than any other ecosystem, cities are permeable in their
environmental effects.
• they draw resources from other ecosystems all around them
- food, water, building materials
• often export wastes and pollution.
- They can be a tremendous burden on the surrounding natural
ecosystems.
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urban ecosystem----con’d

15.  The management of urban ecosystems will remain a key challenge
for cities.
 The conflicts with urban development
• lack of knowledge and management capacity and
• too little understanding of the complex integration of the natural,
built and socio-economic systems into general urban
development.
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urban ecosystem----con’d

16.  All cities are not impacting the environment in similar ways.
 Developed world cities have largely overcome their env’tal problems
 waste water removal,
 sanitation,
 water supply,
 indoor air pollution,
 etc.
 Cities in the developing world are more concerned with other issues.
• Urban env’tal challenges have been divided into two categories:
Inefficient modes of resource use, such as in the water supply,
housing, or energy, and
 limited absorptive capacity of pollution and flooding
 The key urban env’tal challenges
• water pollution;
• air pollution;
• solid waste management; and
• inappropriate land use.
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urban ecosystem----con’d
Developed world cities Vs Developing world cities

17.  Urban environmental transition theory suggests that wealth can be
used to distinguish the env’tal performance of cities
 Dividing cities into three income categories,
1. The dominant env’tal problems in low-income cities are
localized health–threatening.
2. The environmental challenges in middle-income cities - threat
to both health and ecological sustainability.
3. Affluent cities must meet the challenges of global, inter–
generational, and environmental threats to ecological
sustainability.
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urban ecosystem----con’d

18.  the shifting burdens of cities are described in to three categories; “brown”, “gray”,
and “green” environmental agenda issues.
 Historically, western cities have first encountered the so–called “brown agenda”,
which encompasses such environmental health agenda as
• a concern for overcrowded housing,
• a lack of basic services,
• hazardous pollutants in urban air and waterways, and
• accumulation of solid waste.
 Once cities have overcome “brown” issues they have struggled with those of the
“gray agenda”,
• Industrialization concern and
• Motorization impacts (eg. chemical pollutants).
 As cities became highly developed, activities within their borders encouraged the
emergence of “green agenda” issues,
• Increases in consumption and waste generation that disrupted ecosystems
• Resource depletion and
• Global climate change.
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19.  The priority issues in the least developed cities of the developing world are:
Health, Water, and Sanitation (which we also term the “brown agenda”)
 The most important envir’tal issues in these poorer cities are:
oHousehold sanitation and
o Access to water
• a major problem - pollution of water with human excreta and
other wastes
o Indoor air pollution
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urban ecosystem----con’d

20.  Understanding the city as an ecosystem began with some types of studies.
e.g.
• Urban metabolism research view - city as a consumer and digester of
resources and a creator of waste products.
- the city as an organism with its own metabolic processes.
 Cities are increasingly linked to each other through flows of goods,
services, investment, finance, people, and knowledge.
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urban ecosystem----con’d
Cities within Regional and Global Ecosystems

21.  Global cities are also linked with and are increasingly impacting ecosystems
elsewhere at a larger scale.,
• “the web of connections linking one ecosystem and one country with
the next is escalating across all scales in both space and time.”.
 Cities are key to the promotion of global sustainability,
• Thus, it is important to understand the ways in which their activities
impact the local, regional, and global ecosystems
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urban ecosystem----con’d

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 interactions among socio–cultural and biophysical influences on the
development of urban areas
urban ecosystem----con’d

23. Urban ecosystems may be viewed in three ways
View 1
• As the built–up areas that are the habitat of urban people, their pets, their
garden plants, the adapted animals and organisms (birds, etc) and pests
(rats, weeds, etc).
• The survival of these areas depends on outside (external) support in the
form of energy, water, and materials inputs.
View 2
• As the immediate urban life-support system of the urban area and its
surroundings (the peri-urban area), providing ecological services such as
water supplies, areas for landfill, recreation zones, watershed protection,
greenhouse gas uptake, & biodiversity.
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View 3
• As the areas affected by urban activities as a driving force, on the
provision of life-support services to urban areas, including supplies of
food, energy, water, and materials.
• as those areas affected by the emissions and waste flow from urban areas.

25. Ecosystem Services in Urban Ecosystems(Green spaces )
 Green spaces in cities
• modify the urban heat island,
• absorb some of the emitted greenhouse gases,
• provide recreation,
• Aesthetics and recreation
• Connecting open space & habitat
• Air and water quality maintenance
• Urban climate amelioration
• add diversity to human life,
• may be of cultural value,
• may be part of flood control systems, and
• can contribute to wildlife corridors.
- creates a series of opportunities for biodiversity
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26. The traditional dev’t view pays attention to two kinds of UE function,
• Economic production &
• Social consumption,
 The production function in an urban ecosystem includes
• the production of material products,
• the application of labour and intelligence, and
• the generation of wastes.
The function of consumption in an urban ecosystem includes
• the consumption of commodities
• the utilization of infrastructure,
• the consumption of those resources and environments that have no
direct economic value like the atmosphere, watershed and hinterland
ecosystem.
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27.  The function of an urban ecosystem is the ecological regulation driven by
human production and consumption;
• i.e., the systematic feedback
 It includes
• the sustainability of resource supply,
• the sustainability of environmental carrying capacity,
• the sustainability of ecological buffering, and
• the vitality of self-organization and self-regulation in human society.
 It is just this type of specific function through which the economy, the
society and the physical environment interact with one another to sustain a
harmonious human ecosystem.
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28. The urban ecosystem approach raises critical needs:
1. Ecological footprints of cities needs to be identified
Ecological Footprint: a measure of the land area required to sustain a
given population of humans
i.e. understanding the dependence of urban residents on its immediate
hinterland and on far away places and resources for its everyday life
 It will assist in developing the concept of urban ecosystems i.e.
• where resources are used, and
• where wastes and pollution generated.
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29. 2. Global trends to develop local environment activities
 There must a clear need to link global env’tal problems to action at the
local level.
 Most global problems are a result of smaller, more local actions
e.g. increased use of cars at the local level leading to global warming.
 Thus, urban ecosystems need to be understood keeping global issues and
trends in mind.
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