GEOG 106: ENVIRONMENTAL GEOGRAPHYChapter 5: Ecosystems and the Bioclimatic Environment

Pages 67-91

6 and 8 October 2009

Chapter 5 Outline:• Evolution of Earth’s atmosphere,

biosphere, hydrosphere, and lithosphere,

• Organization of food chains and food webs,

• Biogeography,• Climate regions, biomes, and plant

productivity,

Chapter 5 Outline:• Terrestrial ecosystems,• Marine ecosystems,• Altitudinal zonation,• Ecological succession,• Land use: intersection of physical

and natural systems, and• Human impact upon ecosystems.

5.1: Introduction:• Our Solar System formed

approximately 4.5 to 5 billion years ago,

• Life in Earth’s oceans has been evolving for the past 3 billion years,

• Life on Earth’s land has been evolving for the past 500 million years,

• Terrestrial plants have been evolving for approximately 100 million years,

5.1: Introduction:• Plants (producers) remain the

dominant organisms on Earth, in terms of total biomass,

• Of the terrestrial animals, insects are the dominant species, with millions of species identified so far, and

• Reptiles, birds, and mammals (that’s us!) represent the smallest group of life on Earth.

Fig. 5.1: Example of three simple food chains (top) and food webs (bottom). Food chains describe energy flow through an ecosystem.

Where is the Biosphere?

Where is the Biosphere?

5.2: Form and Function of an Ecosystem:

• All ecosystems are comprised of food chains,

• Insolation is the energy source that drives ecosystems and food chains, and

• Food chains are…

Food Chain/Food Web:• Describes NRG transformations

within an ecosystem.• These transformations occur in a

series of steps or trophic levels.

Food Chain/Food Web:• First Trophic Level: Producers (otherwise

known as plants… photosynthesis!).• Second Trophic Level: Primary Consumers

(otherwise known as herbivores).• Third Trophic Level: Secondary Consumers

(otherwise known as carnivores).• Fourth Trophic Level: Tertiary Consumers

(otherwise known as “top carnivores”).• Decomposers: Include bacteria and fungi that

break down organic material and recycle nutrients back into the ecosystem.

Food Chain/Food

Web:

Which trophic level(s) can

you identify in this image?

Food Chain/Food Web:

Energy Pyramid:

Ecology:• The study of the interrelationships

of organisms to one another and to the environment.

Ecosystem:• Interaction of living and non-living

components of the environment.

Ecosystem:• Organism,• Population,• Community,• Ecosystem, and• Ecosphere.

Ecosystem:

Can you identify both

living and non-living

components of this

ecosystem?

NRG flow in the Biosphere:

Energy Pyramid

Fig. 5.2: An energy pyramid showing the 90 percent energy attenuation between each trophic level. Note the importance of the detrivores within the food chain and energy pyramid.

5.3: Plant Productivity:Feeding Ecosystems:

• Photosynthesis,• Plant productivity,• Efficiency,• Principle of five limiting factors,• Climatic limitations, and• Human impacts on plant

productivity.

Insolation receipt by vegetation:

Fig. 5.3

Climatic Limitations on Plant Productivity:

Fig. 5.4: Environments with no limitations, seasonal limitations, and permanent limitations.

Productivity of Terrestrial Vegetation:

Fig. 5.5: Productivity per square meter for seven major climatic zones. Note the extreme productivity within tropical forest climate regions.

5.4: Types of Ecosystems and Their Characteristics:

• Terrestrial, saltwater, and freshwater ecosystems,

• Biomes and ecotones,• Biological organization,• Biomass,• Symbiosis, and• Biogeography.

Biomes:• Includes the total assemblage of

plant and animal life interacting within an ecosystem (similar to a community).

• We will focus on selected plant/vegetative biomes.

Major Biomes on Earth:

Major Biomes on Earth:• Tropical rainforest,• Tropical deciduous forest,• Tropical scrub,• Tropical savanna,• Desert,• Mediterranean woodland and

shrub,

Major Biomes on Earth:• Midlatitude grassland,• Midlatitude deciduous forest,• Boreal forest,• Tundra, and• Mountains and ice caps.

Tropical Rainforest Biome:

Tropical Deciduous Forest Biome:

Tropical Scrub Biome:

Tropical Savanna Biome:

Desert Biome:

Mediterranean Woodland and Shrub Biome:

Midlatitude Grassland Biome:

Midlatitude (Deciduous) Forest Biome:

Midlatitude (Deciduous) Forest Biome:

Boreal Forest Biome: