LECTURE 2 CH 5 THE BIOME CONCEPT
pg. 99-101.5, 104.5-109; 110-118 (Figures only); 122
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 and
oxygen.
5. Unrelated organisms in similar environments evolve a resemblance to each other.
Biome: Large-scale distributions of life forms
Concept map based on physical factors: Which major factor distinguishes habitats?
Aquatic: rivers, lakes, oceans
Variation in aquatic habitats due to variation in:
physical factors (light, temperature, water movement)
chemical factors (salinity, oxygen)
Terrestrial-aquatic interface
Estuary, mangrove, salt marsh, swamp, bog/fen, marsh
Concept map of features that distinguish these habitats:
salinity, woody vs. herbaceous, tropical vs. temperate
Land and water habitats not isolated; dynamic exchange of energy and matter
Terrestrial
Concept map: 4 variables that distinguish biomes:
growth form, seasonality of leaves, leaf morphology, latitude
ID biomes encountered E to W in North America
ID pictures of biomes worldwide
ID locations of biomes worldwide
Proximal causes of distributions of biomes
Major cause: climate (precipitation, temperature, and their seasonality)
Additional causes: soil, fire, grazing, topography
Climate (Precipitation and Temperature) and Biomes
Whittaker: scheme of average P and T predicts biomes
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
Localities worldwide with similar climates have similar biomes.
Convergent evolution
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.