LECTURE 2
CH 5 THE BIOME CONCEPT
MAJOR CONCEPTS
1. Land plant (and animal) life have predictable distributions across the earth.
2. Climate, especially prevailing temperature and precipitation, is the major determinant
of plant distributions.
3. Variation in topography and soils influence local distributions of plants.
4. Life in aquatic habitats corresponds to variation in physical factors, such as light,
temperature, and water movements, and to chemical factors, such as salinity, nutrients,
and oxygen.
5. Unrelated organisms in similar environments evolve a resemblance to each other.
Biome: Large-scale distributions of life forms
(ICA) Concept map based on physical factors: What factor distinguishes habitats?
Aquatic: streams + rivers, lakes, oceans
Variation in aquatic habitats due to variation in:
physical factors (light, temperature, water movement/depth) 5.20, 5.22
chemical factors (salinity, nutrients oxygen)
Human inputs( acid rain; nutrients + eutrophication) 108
Terrestrial-aquatic interface
Mangrove, salt marsh, estuary, swamp, marsh, bog/fen
(ICA) Concept map of features that distinguish these habitats:
salinity, woody vs. herbaceous, tropical vs. temperate, drainage, pH
Land and water habitats not isolated; dynamic exchange of energy and matter
Terrestrial
(ICA) Concept map: 4 variables that distinguish biomes:
growth form, seasonality of leaves, leaf morphology, latitude
ID biomes encountered E to W in North America 5.8
ID pictures of biomes worldwide 5.9-5.17
ID locations of biomes worldwide 5.8
Proximal causes of distributions of biomes
Major cause: climate (temperature, precipitation, and their seasonality) 5.2, 5.3
(ICA) Additional causes: soil, fire, grazing, topography affect local-scale distribution
Climate (Precipitation and Temperature) and Biomes
Whittaker: scheme of average P and T predicts biomes 5.5
Walter’s climagrams of P and T for
Boreal polar: average annual T = < 5C
Temperate: 5-20C
Tropical: > 20C
Each climate zone has typical seasonal pattern of P and T
Biome determined first by T, then P, then seasonality
ID biome from climagram 5.6, 5.7
Localities worldwide with similar climates have similar biomes 5.8
Convergent evolution 87; 5.1; 21.11
If form and function match climatic environment,
then unrelated organisms in similar environments evolve similar form and function.
Assume: Genetic variation exists for such evolution.
Summary 110-111
Review Questions 1-8