Biological Communities: The Biome Concept

Assignment: Read Chapter 4:Variations in the Physical EnvironmentNext week ONLY: Monday AM lab = Tues 5-8 Monday PM lab = Wed 5-8Please turn cell phones off + put away. 1st row seats = saved for later-comers…

Biological Communities: The Biome Concept

OBJECTIVES• What are large-scale distributions of plant

life forms?• aquatic• terrestrial• What is the proximal cause of their

distribution?• How does climate differ among biomes?• Whittaker’s scheme• Walter’s climagrams• Do form and function converge in regions

with similar climate?

Concept Map… *** Which physical factor separates habitats?

A water availability B movement of water USE EACH ONCE C medium of gas exchange D amount of salinity

Biome

Terrestrial Aquatic

Wetlands Desert Freshwater Marine

Rivers Lakes

1

2

3

4

Aquatic habitats

River continuumDownstream drift

High gradient vs.Low gradient

River: where precipitation > evaporation

photic

aphotic

A lake can be divided into vertical and horizontal zones.

Lakes can be poor or rich in nutrients.

Oligotrophic Eutrophic

Limnology = study of freshwater habitats

Abyssal zone

Ocean zones differ in temperature, depth, light, and tides.

Ocean habitats

OceanographyMarine biology

Estuary: where ariverreaches the ocean but isimpeded bylandforms

The terrestrial-aquatic interface…

The terrestrial-aquatic interface

rocky freshwater estuary marine

woody herbaceous woody herbaceous

swamp bog/fen marsh mangrove salt marsh

tropical temperate

Another concept map…

Concept map *** What 4 variables distinguish biomes?

Herbaceous/graminoids Shrubs Trees (grasses, sedges)

Shrublands Forests Grasslands Deserts

Tundra Evergreen Deciduous

Conifers Broadleaf Temperate Trop.

Temperate Tropical

Biome: a major type of terrestrial community categorized by its 1) dominant plant form, 2) seasonality of leaves, 3) leaf morphology, 4) location.

Tropical rain forestTropical seasonal (deciduous) forest / savannaSubtropical desertWoodland/shrublandTemperate rain forestTemperate seasonal (deciduous) forestTemperate grasslandBoreal forest (taiga)Tundra

***Review of major biomes…(write these down)

***What biomes do

you see in a cross-

country trip from E to W?

***Write down the letter that corresponds to the name of the biome:

Pictures not in this PP…go to book to see them.

A Tropical rain forestB Tropical seasonal forest/savannaC Subtropical desertD Woodland/shrubland Temperate rain forestE Temperate grassland/desert F Temperate seasonal forest G Boreal forestH Tundra

Answers

A

BC

D E

FG

H

I*** Which biome is found at each indicated

letter?

H Tropical rain forestG Tropical seasonal forest/savannaF Subtropical desertD Woodland/shrublandI Temperate rain forestC Temperate seasonal forestE Temperate grasslandB Boreal forestA Tundra

Answers

***Proximate/functional approach…

• What is the major factor determining biomes?

• In one sentence: Why isn’t there a single biome for the

earth?

Most species have limited tolerance; hence small ranges and biomes develop.

***In one sentence: Compare the ranges of birds/plants.

Climate is the major determinant of plantdistributions. Other factors are soil, fire, grazing, topography.

Whittaker’s scheme: biomes delineated by average temperature and precipitation.

Walter’s climate diagrams allow comparisons among localities.

20 mm monthly rainFor each 10ºC in temp= enough water for growth

(wherever precip line is above temp line)

growing season

What is clue that this is a desert?

Climatic zones and biomes separated first on basis oftemperature, then precipitation and its seasonality.

Boreal + polar climate zones:average annual T=< 5C

Temperate climate zones: average annual T = 5-20C

Equatorial + tropical climate zones: average T = > 20C.

Each climate zone has a typical seasonal pattern of temperature and precipitation.

When is itsdry season?

***What type of biome would you expect to develop with each climate?

Explain.

A B

***What type of vegetation would you expect at each locality? Explain.

A B

***Summarize in one sentence the main conclusion about biomes based on these figures and legends.

Localities worldwide with similar climate have the same biome.

Observation:Plant growth form is similar in widely separated areas. I wonder why?

Mexico Kenya

***Hypothesis:If form and function match the environment,then…?

Prediction: then unrelated organisms in similar environments will evolve similar form and function = Convergent evolution

Mexico Kenya

Unrelated African and South American rainforest mammals show striking convergence.

Example of exam question…A. Which biome would occur in each climate?

B. What is the limiting climatic factor(s) for each biome?

C. Where is each biome located in the Western (New World) and Eastern (Old World) hemisphere? Put letters on map.

OBJECTIVES• What are large-scale distributions of plant

life forms?• aquatic• terrestrial• What is the proximal cause of their

distribution?• How does climate differ among biomes?• Whittaker’s scheme• Walter’s climagrams• Do form and function converge in regions

with similar climate?

Chapter 5 Biological Communities: The Biome Concept

biomes* growth form forbsecological tolerances edaphic optimumspecializations specialists generalistsclimate zone growing season prairiessteppes rhizomes sclerophylloustaiga permafrost canopyemergent trees understory lianasepiphytes streams rifflespools allochthonous riparian zoneautochthonous river continuum lakeslittoral zone limnetic zone benthic zoneestuaries littoral zone zonationneritic oceanic zone benthic zonephotic zone aphotic zone coral reefs

Vocabulary

lotic lentic plant formherbaceous graminoids topographycontinental drift rain shadow middenecotone marine swampcypress mangrove bog/fenmarsh salt marsh estuaryoligotrophic eutrophic oxbow lakedeep sea vent kelp forest inter-tidal community zone

More vocabulary…Chaper 5/ Lecture 2: