Lecture Notes: Urban Environmental Geography –

March 29, 2010

 

Today… some announcements

FIELD TRIP… IMPORTANT… sign up for field trip times, yellow sheet is the master. LINK to field trip information. Note: the link to the handout is just for your information, it’s from a couple years ago. I’ll update and post 2010 a week from now.

MIDTERM: as expected, there was no way for me to grade them during Spring Break. Incidently the field course went great… not even bad weather. I’ll return your midterms next Monday. So far, so good.  

For WEDNESDAY: Amina, Daniele, and Luis… please see me

 

WELCOME BACK. Where are we in the course… LINK to schedule

 

REVIEW – 5 subsystems of Earth systems and 5 big concepts… relate at least one each to your Spring Break. GREEN SHEET.

 

HW07 LINK... forge our way through it... Emigration Canyon.

 

BIOSPHERE – a subsystem of Earth systems... probably we won't get to this but I can summarize later. 

THEMES of your workbook:

 

Chapter 15. SOILS – what do they say, why does it matter to cities

Sediments versus soils:

Soils are sediment (versus bedrock); virtually all soils are sediment, but not all sediments are soils. Soils have been altered by life… organic matter.

 

Chapter 16.... BIOSPHERE BASICS … from Christoperson to Urban Environmental Geography

Life zone or life band. We call Earth the Blue Planet. Life is very special.

 

1.     It’s a system… a sub-system of Earth systems

v    Open versus closed systems. Earth systems virtually a closed system, biosphere an open system.

v    Negative versus positive feedback loops. Biosphere makes atmosphere what it is today and appears to stabilize some perturbations such as CO2 production. Self regulate.

v    Primarily powered by energy from the sun. Light from the sun is transformed into plant matter. Animals get their energy ultimately from plants and the sun.

v    Interactions involve cycling of substances, biogeochemical cycles. Nutrient cycling: CHONSP (carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorous). Complex… but take-away message it that it is a system, with cycling and recycling in different forms. For example: water provides the only form of hydrogen that plants can use Mackenzie.

v    Interactions: Earth is very different because of biosphere as well as influencing biosphere

v    Ecosystems… from simple to complex. Example: Great Salt Lake . Consumers, producers, and decomposers. How can we tell if an ecosystem is “sick?” Hierarchy… from atoms… through individuals, to populations (individuals interacting with other individuals), to communities  (populations interacting with other populations); to ecosystems (communities interacting with other communities), to biosphere/ecosphere (all the ecosystems interacting with each other); to Earth systems (all sub-systems interacting with each other). 

v    Basic structural unit of all living organisms is the cell.

v    Four essential properties of living organisms (from Skinner):

Ø     metabolize (chemical reactions by which energy is provided for life processes);

Ø     grow (ordering of atoms and molecules to make bigger molecules);

Ø     reproduce (for single-celled organisms they divide; for multi-celled organisms they have sexual or asexual reproduction);

Ø     evolve (change over time as certain individuals in a population leave more offspring than others).

v    Biome: (Mackenzie) a group of ecosystems within a geographical region exposed to the same climate conditions and having dominant organisms with a similar life cycle, climatic adaptations, and physical structure. Biomes = ecosystems… sort of. But biome is the geographic area. Ecosystem stresses the webs of relationships.

 

2.     Humans have had major impacts on biosphere. Urbanization is a impacts the biosphere … directly and indirectly

“the human footprint.” More on this in our labs.

Tinkering with the CHONSP biogeochemical balances.

 

 

3.     Planetary perspectives of life.

Increased diversity with time.

Geological evidence of life and changing life forms.

Evidence of extinctions.

 

 

4.     Biodiversity.

Biological diversity Skinner

Results from speciation Hierarchy (Skinner) and extinction Skinner

Species are born by speciation and die through extinction.

Individuals adapt

Extinction

Human activities have affected rates of extinction.

Predator – prey relationships can eliminate a species. Humans have hunted species into extinction or weakened them so that climate change caused extinction.

Extinction of one species may be downfall of another, concept of climax species.

Changes in environment can result in extinctions of species that cannot adapt or migrate.

Adaptation.

Human activities have affected land use and land use affects adaptation and migration

Speciation.

In general, human activities do not affect rates of speciation.

A species consists of biologically similar organisms. If they reproduce sexually, a species consists of those individuals capable of breeding with each other.

What happens: offspring have change in allele frequency… characteristics determined by genetic makeup such as blue eyes, hoofs of horses.

Several types of speciation: Geographic isolation (allopatric); time drift (anagenesis); splitting into two daughter species (cladogenesis);

 

5.     Urban Ecosystems.

 

Niche.

·        How an organism interacts with its environment. What it does (Mackenzie). How it lives and what it eats. The role an organism plays in an ecosystem ( Adams ). The range of environmental factors over which an individual can have positive fitness including biotic relationships with other organisms, and abiotic factors, meaning relationships with physical factors of environment (Ernst).

·        Keystone concept discussed in Hengesbaugh’s Creatures of Habitat… prairie dog is keystone to community… supports several relationships

 

Habitat.

·        Where an organism lives. A place where an animal or plant finds food, water, cover, and space to grow and reproduce ( Adams ).

·        Changes of land use associated with urbanization affect ecosystems.

 

 

  From Adams : urban wildlife habitats.

Species that use buildings: pigeons.

Sparrows that open automatic sliding doors.

Squirrels need large trees, but don’t need forests.

Salt Lake City cemetery for hawks and deer.

Ski runs… fragmentation and interfaces.

 

 

Is an urban ecosystem really an ecosystem? (Adapted from Adams )

Self-contained?

Complete food chains?

Recycle nutrients?

Solar energy drives the ecosystem?

Food supply based on food chain?

Balanced productivity?

Sustainable?

Succession of vegetation?

Climax community(ies)?

GREAT SALT LAKE Stephens (from Don Paul)

Are cities ecosystems? Yes and no.

Is a city an ecosystem? "Cities are living systems, made, transformed, and experience by people. Urban forms and functions are produced and managed by the interaction between space and society, that is, by their historic relationship; between human consciousness, matter, energy and information." (Castells, 1983)

Ecosystems and their dynamics to urban areas. LINK to portrayal of ecosystem. LINK to portrayal of urban system.

Energy flows. Transformations. food chains, food webs. Nutrient recycling. CHONSP (carbon, hydrogen, oxygen, sulfur, phosphorus). Aldo Leopold story of molecule-X and molecule-Y. Relationships of abiotic and biotic components. The interrelatedness of ecosystems and their subsystems. A change in the abiotic environment can have mixed responses in the ecosystem, some positive feedback loops, and some negative feedback loops. The relationships are complex, and nonlinear.

Urbanization affects land use and ecosystems. Ecological consequences of change: Species density. Species mix. Urban ecosystems. adaptability. biodiversity. Winners and losers LINK adapted from AdamsUrbanWildlife. Birds. Mammals and others Biodiversity (speciation, extinction, and migration). Biodiversity is considered healthy. Niche. Habitat. Changes in habitat shape, size, location, fragmentaiton, coridors, seasonality... Interactions with physical environment (abiotic factors) AND Interaction with other organisms (biotic factors). Spirn Spirn Spirn

HEALTHY versus STRESSED versus SICK. Stable systems. Sustainable "a system's ability to maintain its structure (organization) and function (vigor) over time in the face of external stress (resilience)" Costanza, 1992. How a system responds to stress depends on the system and on the stress. (Smol, 1995). One definition of healthy: A system that existed before significant anthropogenic impact. (Smol, 1995). Is a system stressed beyond the natural range of fluctuations?

 

 

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