1. Chapter 10: Cycles and
Patterns in the Biosphere
McKnight’s Physical Geography:
A Landscape Appreciation,
Tenth Edition, Hess

2. Cycles and Patterns in the
Biosphere
• The Impact of Plants and Animals on the
Landscape
• The Geographic Approach to the Study of
Organisms
• Biogeochemical Cycles
• Food Chains
• Natural Distributions
• Environmental Relationships
2© 2011 Pearson Education, Inc.

3. The Impact of Plants and Animals
on the Landscape
• Vegetation grew profusely
at one time
• Human modification of
vegetation
• Animal life less apparent
• Both interact with
components of the
landscape
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Figure 10-1b

4. The Geographic Approach to the
Study of Organisms
• Simplest organisms still extraordinarily complex
• Seek patterns of distribution of living organisms—
biogeography
• Several biological classification schemes
– Most common, binomial, “two name”
• 600,000 species of plants; twice that of animals
• Biota—total complex of plant and animal life
– Flora: plant life
– Fauna: animal life
• Ocean biota—plankton, nekton, and benthos
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5. Biogeochemical Cycles
• Organisms survive through
complex of systemic flows
of energy, water, and
nutrients
• Cycles through which
Earth’s chemical elements
are absorbed by
organisms and returned to
Earth through
decomposition—
biogeochemical cycles
5© 2011 Pearson Education, Inc.
Figure 10-2

6. Biogeochemical Cycles
• The flow of energy
– Sun is source on which all
life depends
– Photosynthesis and
respiration
– Food chain
– Energy must be converted
to a usable form and
recycled
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Figure 10-3

7. Biogeochemical Cycles
• Photosynthesis
– Biosphere receives solar energy
– Chlorophyll
– Chemical equation
• CO2 + H2O = Carbohydrates + O2
– Energy distributed by animals eating plants or each
other
– Energy distributed in the plants through respiration
– Plant respiration equation
• Carbohydrates + O2 = CO2 + H2O + Energy (heat)
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8. Biogeochemical Cycles
• Net primary production
– Net photosynthesis—
difference in
carbohydrates produced
to those lost to respiration
– Net primary production is
the net photosynthesis
over a year (Figure 10-4)
– Measure of chemical
energy in a plant
– Reflected in the dry
weight, or biomass, of the
material
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Figure 10-4

9. Biogeochemical Cycles
• The Hydrologic Cycle
– Every living thing
depends on water supply
– Water dissolves nutrients
and carries them to all
parts of the organism
– Two ways water is found
in biosphere
• In residence: chemically
bound to plant and animal
tissue
• In transit: part of
transpiration-respiration
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10. Biogeochemical Cycles
• The Carbon Cycle
– Biosphere contains
complex mixture of carbon
compounds
– Main components
• Transfer of carbon from CO2 to
living matter and back to CO2
– Rapid process (years not
centuries)
– Gradual incorporation of
stored carbon in rock
– Fossil fuels increase CO2
10© 2011 Pearson Education, Inc.
Figure 10-6

11. Biogeochemical Cycles
• The Oxygen Cycle
– Building block in most
organic molecules
– By-product of plant life
– Occurs in many forms
and is released in many
ways
– Sources include water,
carbon dioxide, ozone,
oxygen stored in rocks
11© 2011 Pearson Education, Inc.
Figure 10-7

12. Biogeochemical Cycles
• The Nitrogen Cycle
– Nitrogen only usable in gas
form by a few bacteria
– Nitrogen usable by other
organisms as nitrates that
are used in plants—nitrogen
fixation
– Waste converts nitrates to
waste nitrites
– Bacteria convert nitrites
back to nitrates and nitrogen
gas (denitrification)
12© 2011 Pearson Education, Inc.
Figure 10-8

13. Biogeochemical Cycles
• Other mineral cycles—other minerals critical to the
biosphere
– Phosphorous
– Sulfur
– Calcium
• Gaseous pathways—interchange between biota and
atmosphere-ocean environment
• Sedimentary pathways—element is weathered and
reaches the groundwater; returned to the ocean and is
consumed by ocean organisms
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14. Food Chains
• Food chain—direct
passage from one
organism to another of
nutrients
• More complex—food
“web”
• Primary energy
transformation
mechanism
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Figure 10-9

15. Food Chains
• Fundamental unit: producers
(autotrophs), self feeders
• Producers eaten by
consumers (heterotrophs)
– Primary consumers:
herbivores
– Secondary consumers:
carnivores
• Food pyramid
• Decomposers begin the food
pyramid again
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Figure 10-10

16. Food Chains
• Energy is inefficiently
consumed between different
food pyramid levels
• Pollutants in the food chain
– Biological amplification
– Chemical pesticides and
heavy metals (mercury, lead)
– Irrigation-related issues
16© 2011 Pearson Education, Inc.
Figure 10-11

17. Natural Distributions
• Four basic conditions
• Evolutionary development
– Survival of the fittest
– Where did the genus
(closely related organism
group) evolve?
• Some localized
• Several scattered localities of
the same genus
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Figure 10-12

18. Natural Distributions
• Migration and dispersal
– Animals move from one
place to another
– Plants move through seed
dispersal
– Distribution pattern of
organisms results from
natural migration or
dispersal from the original
development center
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Figure 10-14

19. Natural Distributions
• Reproductive success
– Ability for organisms to
reproduce affects
distribution
– Factors resulting in poor
reproductive success
• Heavy predation
• Climate change
• Food supply failure
• Changing environmental
conditions
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Figure 10-16

20. Natural Distributions
• Extinction and die-off
– Range diminution
• Small areal changes
• Mass extinction
– Plant succession—one
vegetation type replaced by
another (Figure 10-17)
• Occur after catastrophic events
• Primary succession—pioneer
community
• Secondary succession
– Extinction versus succession
20© 2011 Pearson Education, Inc.
Figure 10-17

21. Environmental Relationships
• Relationships of plants and animals depends on
environment
• Influences depend on the area of interest
– Large area: seasonal characteristics, location
– Small area: localized terrain, topsoil
• Interspecific versus intraspecific competition
• Limiting factor: most important variable for the
survival of an organism
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22. Environmental Relationships
• The influence of climate
– Light
• green plants need light to survive
• Light changes shapes of plants
(Figure 10-19)
• Photoperiodism: stimulates
seasonal plant behavior
– Moisture
• Distribution of biota governed
more by moisture than any other
factor
• Biota evolution dictated by
adaptation to moisture conditions
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Figure 10-19
Figure 10-20

23. Environmental Relationships
• The influence of climate
– Temperature
• Different species can survive in
different temperatures
• Plants have limited cold
temperature tolerance
– Wind
• Wind effects generally limited
• Persistent winds can have
limiting effects through increased
drying
• Strong winds can be destructive
to biota
23© 2011 Pearson Education, Inc.
Figure 10-21

24. Environmental Relationships
• Topographic influences
– Plants and animals in a plains
region vastly different from a
mountainous region
– Slope and drainage
• Wildfires
– Result in complete or partial
devastation of plant live and
death or driving away of animals
– Can be helpful for regrowth and
maintaining of plant type
24© 2011 Pearson Education, Inc.
Figure 10-22

25. Environmental Relationships
• Example of selva (rainforest)
– Occurs when climate is warm and
has abundant precipitation
– Abundance of precipitation and
warmth leads to abundance of
natural vegetation (flora), jungle
– Numerous plants allow for fauna
– Leaves, trees, branches
decomposed by abundant fauna
on floor, put into soil
– Water runoff
25© 2011 Pearson Education, Inc.
Figure 10-24

26. Summary
• Plants and animals impact and interact with the
landscape in numerous ways
• Need a classification scheme for biota to understand
geographically
• Flora and fauna refer to plants and animals,
respectively
• Energy originates from the Sun and flows to organisms
through photosynthesis
• The hydrologic cycle describes the transition of water
through the biosphere
• The interaction of carbon with the biosphere is the
carbon cycle 26© 2011 Pearson Education, Inc.

27. Summary
• Oxygen and nitrogen cycle through the biosphere
through the oxygen and nitrogen cycles, respectively
• Other minerals cycle through the biosphere as well, but
they are not as commonly observed
• Food chains describe the passage of energy from one
organism to another
• There are four primary components to the natural
distributions of biota
• Numerous environmental relationships affect which
biota exist in which regions
27© 2011 Pearson Education, Inc.