Biology 100/101
Lecture 4: Ecosystems in Space
Text readings in Life by Ricki Lewis:
Chapter 42 (Communities and Ecosystems)
Chapter 43 (Biomes)
Review questions:
Questions 1 and 5, page 870
Questions 2a, e, h, and 6, page 887
"To think about":
Question 2, page 870
Questions 1, 4, and 5, page 887
Web Resources:
Chapter 42 Web Links
Chapter 43 Web Links
Illinois ecosystems
Biomes of the World
Objectives:
After studying this material you should be able to:
- Explain the relationship between populations and biological communities.
- Explain the relationship between biological communities and ecosystems.
- Explain the meanings of the terms biome and biosphere.
- Describe the characteristics of the following major terrestrial biomes: tundra, desert, prairie (grassland), temperate deciduous forest, temperate rain forest, tropical rain forest.
- Discuss the role of climate in distinguishing different biomes.
- Explain which biomes are the most and least productive and why.
- Describe some adaptations found in the various plants and animals that live in a particular biome (that is, desert, tropical rain forests, grasslands, and tundra).
Key Terms:
| population |
| biological community |
| ecosystem |
| biosphere |
| biome |
| desert |
| tundra |
| adaptation |
| prairie (grassland) |
| temperate rain forest |
| tropical rain forest |
| temperate deciduous forest |
What is the relationship between populations and biological communities?
- A population is a group of interbreeding organisms living in the same area.
- A biotic community includes all of the organisms (that is, all of the different and interacting species) in a given area.
What is the relationship between biological communities and ecosystems?
- A biotic community in combination with its physical and climatic environment is called an ecosystem. In other words, all the living and nonliving things within a defined area.
- Ecosystem boundaries are not always clear; they interact with one another and can change.
- An ecosystem can be small (a leaf) or large (the entire planet).
What is a biome?
A group of interacting terrestrial ecosystems characterized by its own type of vegetation, largely determined by temperature and rainfall
OR
a group of interacting aquatic ecosystems with similar physical and chemical conditions (e.g., salinity).
- Terrestrial biomes are spread over large geographic areas.
- Terrestrial biomes are often not sharply separated, but merge gradually into one another.
-
Aquatic communities can be divided into two types: freshwater (e.g., lakes, ponds, rivers) and marine (e.g., coastal and oceans).
What is the biosphere?
Gk; bio, life and spher, ball
- the global ecosystem
- the thin shell (?) of air, land, and water around the earth that supports all life
Major terrestrial biomes
Examples of biomes. Which one am I?
Where are these biomes located?
- Biome Map
- See map in your textbook, page 874-875,
- or refer to this
map instead.
What is the relationship between biomes and climate?
- if you knew the mean temperature and rainfall of a region, and especially if you had some measure of their variability and seasonality, you could predict the type of biotic communities that would be found there.
-
and even if you didn't know the exact species of plants and animals that might live in the region, you could predict adaptations they might have that would allow them to live there.
Examples of how various physical factors influence climate
Tundra
- Northern North America, Europe and Asia below ice-cap
- bitterly cold winters, short summers, growing season <60 days
- low rainfall (20 cm/yr) but lots of melting snow in summer
- permafrost
- high elevations above timberline (alpine tundra)
Desert
- regions where rainfall is less than 20 cm/yr
- cold (Great Basin desert between Sierra Nevadas and Rockies) and hot (Sahara and Sonoran desert in Arizona)
- not all deserts have sandy soils
Grasslands
- 10 to 30 inches/yr (25-75 cm/yr) of rainfall, but not enough to support trees (or trees widely scattered)
- relatively cold winters
- variety of names (e.g., savanna in tropical/subtropical regions, prairie in temperate regions)
- height of the grasses reflects local moisture
- extensive root systems
- rich soil
- maintained by grazing and fire
Temperate Deciduous Forest
- south of the northern boreal forest (taiga) in eastern North America, eastern Asia, and much of Europe (and in equivalent zones in the southern hemisphere)
- moderate climate with relatively high rainfall (distributed over entire year)
- well-defined seasons, with growing season between 120 and 300 days
- rich soil from decomposed leaf litter
- temperate areas with poor soil and little water support coniferous forests
Temperate Rain Forests
- wet and cool climates where marine air meets coastal mountains
- very limited distribution; Chile and the Pacific Northwest
- sustain highest standing biomass of all terrestrial ecosystems
Tropical Rain Forests
- South America, Africa, and the Indo-Malayan region near equator
- warm/hot weather with plentiful rainfall (200-400 cm/yr)
- growing season is year-long (dry season may be 2-3 months)
- richest and most complex biome
- rapid recycling of nutrients, poor soil for agriculture
- competition for light leads to vertical stratification of species
Biome Productivity
Net primary productivity is influenced by temperature, rainfall, and other factors (availability of sunlight, nutrients, and length of growing season). The more productive a community, the more life it can support per unit area.
Terrestrial biome(s) with highest net primary productivity:
Terrestrial biome(s) with lowest net primary productivity:
Adaptations of Organisms
Working in groups and, later, consulting your textbook and using the links above and below, list some adaptations (in structure, function, behavior, etc.) found in the various plants and animals that increases their likelihood of existing in these biomes.
Deserts:
Tropical Rain Forests:
Grasslands:
Tundra:
Biology 100/101 Home Page
