Physical Geography Chapter 16

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Transcript Physical Geography Chapter 16

Chapter 16
Ecosystems and Biomes
Biogeography studies the ecology of a spatial
location across time
Ecology examines the interaction of a location’s
abiotic (non-living) and biotic (living)
[an open system]
Ecology was coined/started about 100 years ago
by Ellen Swallow at M.I.T.
Biotic structure can be hypothesized as a
hierarchy of complexity and energy demand
within an even greater hierarchy of living and
non-living elements of scientific study
Ecology Studies Living / Non-Living
Feedback Among
Ecosphere (Biosphere)
Laws of the Biosphere
(1) Law of Production
- Biotic Potential [BP]
- carrying capacity
(2) Law of Adaptation
- Darwin’s Natural Selection
(3) Law of Fertility
- progression of
Laws of the Biosphere, cont
(4) Law of Succession
- orderly and progressive sequence of
vegetation introduction into newly created
or recently modified landscapes
- progression to climax vegetation
Laws of the Biosphere, cont
(5) Law of Control
- Limiting Factor Principle
- Environmental Resistance [ER]
--- density dependent (ex:disease; parasites)
--- density independent (ex: climate; soil; human
activity; catastrophe)
----- predation
Connections: Energy Flow, Matter Cycling
and Gravity
Life on Earth is dependent on three connected factors:
(1) One-way flow of high-quality (useable) energy from
the sun
(recognizing existence of chemosynthesis)
(2) Cycling of matter and energy by living organisms
through ecosystems
(3) Gravity – constrains atmosphere and creates
downward movement of matter / energy cycles
(ex: rock cycle; gaseous cycle; biochemical cycle)
Carbon and Oxygen Cycles
Figure 16.8
The Nitrogen Cycle
Figure 16.9
The Sun: Source of Energy for Life
Sun supplies radiant energy, visible light, energy
for photosynthesis
… primary productivity or biomass (C/sq. m/yr)
[6H2O+6CO2+energy --- C6H12O6+6O2];
factor behind unequal heating that creates
temperature zones and winds
--- 72% hydrogen; 28% helium
--- an immense fusion reactor
The Sun: Source of Energy for Life
- A tiny percentage of solar ejected solar energy
reaches the Earth [.0000001%]
--- 34% of this insolation is reflected by the
atmosphere; remaining 66% warms the
atmosphere/Earth surface
- Most of this energy will inturn become long wave
infrared radiation to heat the atmosphere –
natural greenhouse effect
Functional Format: Chains/Webs
(1) Abiotic
(including Law of Tolerance/range of tolerance)
(2) Autotrophs
--- net primary productivity
terrestrials: insolation; soil moisture and
nutrients; atmospheric CO2 / O2 / O3;
plant age/species; etc
marine: water depth; turbidity; nutrient
load; pollution; etc
Functional Format: Chains/Webs, cont
(3) Heterotrophs (secondary productivity)
Functional Format: Chains/Webs
(4) Decomposers
Ecological Pyramids
- pyramid of organism numbers
- biomass pyramid
- productivity
A species occupies a habitat and operates within
an ecological niche (niche)
- by niche, a species can be classified as a
specialist or a generalist
And within an ecosystem will develop biotic
associations between plant and animal
Species in an Ecosystem
(1) Native Species
(2) Alien (or Immigrant) Species
(3) Indicator Species
(4) Keystone Species
Traits of Vulnerable Species
Restricted Range and Habitat
Low Biotic Potential
Non-Adaptative Behavior
Specialized Diet
Classification of Terrestrial Ecosystems
(1) Forest- moderate-to-high annual
precipitation; tree and smaller mass
vegetation patterns
--- classes: tropical rainforest
tropical deciduous
tropical shrub
temperate deciduous
evergreen coniferous
Restatement of Table 16.2, p. 542
Classification of Terrestrial Ecosystems, cont
(2) Grasslands – average annual precipitation
patterns sufficient to support grass/shrub
vegetation; drought may be common;
vegetation bordering on xerophytic
--- classes: tropical
arctic tundra
Classification of Terrestrial Ecosystems, cont
(3) Deserts and semi-deserts- locations where
evaporation exceeds precipitation; annual
average precipitation < 10”; often nutrientrich soil; frequently saltpan; true xerophytic
--- classes: tropical
Classification of Marine Ecosystems
Why are the oceans important?
(1) the Earth surface is approximately
72% water
(2) Their role in: hydrologic cycle;
distribution of solar energy; CO2 sink;
generation of pressure systems; food
source; habitat; minerals; pollution
dispersion; etc
Classification of Marine Ecosystems, cont
Ocean Zones
Oceans have two major life zones
(1) Coastal - relatively warm; nutrient rich;
high-water mark to continental shelf;
<10% of ocean area, contains 90% of
marine species; high net primary
productivity per unit of area
(1) Coastal, cont
--- coral reefs – most threatened ecosystem
in coastal zone
We’ve mentioned:
--- estuaries
--- coastal wetlands
--- beaches – barrier and rocky
--- barrier islands
(2) Open Ocean-vast area of Earth oceans;
only about 10% of marine species inhabit;
average net primary productivity per unit
is low
-comprised by three vertical zones
--- euphotic
--- bathyl
--- abyssal