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
Answers to many of these questions can be found on the "Answers to End-of-Chapter Questions" page at the text website.
For feedback, post possible answers and ideas in the folder "Text 'Review' and 'To Think About' Questions" in the Biology Chat Section of Web Crossing.
General Biome Web Resources
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 why no two species can occupy the same niche in a biological community.
- 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.
- Explain how latitude, altitude, tilt of the axis of the Earth,
global air circulation patterns, global wind patterns, and mountain ranges affect temperature, rainfall and the geography of biomes.
- Explain which biomes are the most and least productive and
why.
- Describe some adaptations found in various plants and
animals that allow them to survive in a particular biome.
Key Terms:
| population |
| biological community |
| ecosystem |
| biosphere |
| biome |
| niche |
| tundra |
| desert |
| prairie (grassland) |
| temperate rain forest |
| tropical rain forest |
| temperate deciduous forest |
What is your biological community like?
How would you distinguish your biological community from your population?
Biological Populations are made up of individuals of the same species (interbreeding organisms) living in the same geographic area.
Biological Community a group of interacting organisms of different species in a given area or a group of interacting populations in the same area.
- biological community in CU?
- biological community in your home (apt. or dorm)?
- dust mites
What is an ecosystem? How would we describe the ecosystem of CU?
Ecosystem A biological community in combination with its physical environment. An ecosystem can be small (a leaf, your bathtub, or kitchen sink with resident community of microorganisms) or it can be large (house, yard, city, watershed, the entire planet).
- a lake or pond (p. 880 of 'Life')- boundaries are distinct between aquatic and terrestrial ecosystem.
- two adjacent ecosystems on N and S facing sides of valley. Boundaries are not always easily drawn between ecosystems.
Habitat and Niche
Within an ecosystem, species occupy different habitats or places in the environment. Because resources like water, food, and shelter may be limiting, species are often competing with one another. The only way that they will be able to coexist is if they occupy slightly different niches (different ecological occupations in the community). No two species can occupy exactly the same niche.
- warbler niches on spruce (fig. 41.2, p.837 in 'Life' text)
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 part of the planet where life exists, about 6 miles up into the atmosphere and to the same distance into deep ocean trenches
What biome does CU exist in?
Major terrestrial biomes (from the Missouri Botanic Gardens)
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
- Prior to settlement, more than 60% of Illinois, approximately 22 million acres, were covered with prairie. Today, just over 2,000 acres remain, less than one-hundredth of one percent. Tall grass prairies are endangered ecosystems in Illinois.
Temperate Deciduous Forest
- south of the northern boreal forest (taiga) in eastern North America, eastern Asia, and much of Europe.
- 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
Where are these biomes located?
- Biome Map from Missouri Bot. Garden
- See map in your textbook Fig. 43.2, page 874-875,
Why are biomes located where they are?
Similar types of biomes appear at corresponding latitudes because they have similar climates (temperature and precipitation).
- Global air circulation and precipitation
- Global Ocean Currents and Climate
- Mountains and the rain shadow effect (from Plant Bio 102, UIUC)
- Local climate patterns affected by proximity to bodies of water (Great Lakes) and topography (canyons)
Why are some biomes more productive than others?
Productive potential of the Earth's vegetative biomass NASA
Why are certain organisms found in particular biomes?
The major objective of all species is to survive long enough to reproduce. To achieve that objective organisms have evolved some astounding adaptations.
Deserts:
Tropical Rain Forests:
Grasslands:
Tundra:
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