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

Chapter 10: Cycles and Patterns in the Biosphere

McKnight’s Physical Geography: A Landscape Appreciation,

Tenth Edition, Hess

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.

The Impact of Plants and Animals on the Landscape

• Vegetation grew profusely at one time (native plants)

• Human modification of vegetation, where?

• Animal life less apparent

• Both interact with components of the landscape: soil, landforms, water


Figure 10-1b

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


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


Figure 10-2


• 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


Figure 10-3


• Photosynthesis– Biosphere receives solar energy– Chlorophyll: a light- sensitive pigment in leaf cells– 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)



• 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


Figure 10-4


• 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 stream



• 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


Figure 10-6


• 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


Figure 10-7


• 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)


Figure 10-8


• 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


Food Chains

• Food chain—direct passage from one organism to another of nutrients

• More complex—food “web”

• Primary energy transformation mechanism


Figure 10-9

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


Figure 10-10

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


Figure 10-11

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


Figure 10-12


• 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


Figure 10-14


• 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


Figure 10-16


• 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


Figure 10-17

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



• 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


Figure 10-19

Figure 10-20


• 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


Figure 10-21


• 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


Figure 10-22


• 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


Figure 10-24

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


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


Documents

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