Terrestrial Biomes
Biome – defined
Concept of “climate space”
Climate diagrams
Potential vs. actual vegetation
A brief biome tour
Readings: Chapter 2 – esp. pages 14-18
Terrestrial Biome defined
• Major division of the terrestrial biosphere
(broader than “ecosystem” or “landscape”)
• Large-scale classification of the terrestrial habitat,
distinguished by predominant plants, and
associated with particular climates.
– Examples include: desert, rain forest, tundra
• Globally, there are about 6-9 major terrestrial
biomes (depending upon who’s counting)
• Similar terms: life zone, ecoregion, biogeographic
province
Terrestrial Biomes
Campbell
What determines the distribution of the
terrestrial biomes?
Distribution of annual temperature ranges
Krebs 2001, Figure 7.2
Annual precipitation - a function of temperature and moisture patterns.
Krebs 2001, Figure 7.3
What determines the global distribution
of temperature and precipitation?
Atmospheric circulation patterns (e.g. “cells”) create zones of temperature
and precipitation
Distribution of Earth’s major dry & wet
areas
Related to Hadley cells of air circulation
• These circulation patterns are further
modified by the Coriolis effect due to the
spinning of the Earth.
• Note the distribution of land and ocean
masses also affect temperature and moisture
At a regional scale, topography and distance from water bodies influence vegetation distribution
(California)
Bakker 1971
Temperature (energy) and moisture (precipitation) are
primary determinants of terrestrial biome distribution
Additional phenomenon and processes determine
vegetation distribution at smaller scales (e.g.
topography, distance from water bodies, ElNino/Southern Oscillation and other periodic climate
phenomena).
Convergent evolution
Unrelated plants from different parts of the world often show
similar appearances when exposed to similar climates
Senecio sp. on Mt. Kilimanjaro
Espeletia sp., Andes Mts.
Molles & Cahill
Fig. 2.40
…This introduces the concept of “potential vegetation” according to “climate space”
Campbell & Reece 2002
Biomes
“Climate Space”
• Each region of the Earth can be defined by it’s
particular “climate diagram” or location in
“climate space.”
• Temperature and moisture are primary
determinants of distribution.
• Local organisms are adapted to that particular
climate (temperature-moisture space).
Climate diagram for Blythe, California (Sonoran Desert)
Krebs 2001, Figure 7.4a
Climate diagram for Great Smoky Mountain National Park, Tennessee
Krebs 2001, Figure 7.4b
Terrestrial Biomes:
distribution of “potential” vegetation according to climate space
Campbell
Problems with this concept:
• Rapid climate change poses problems – can
species distribution keep up?
• Humans also alter vegetation, transforming
“potential” vegetation to “actual” vegetation –
how do we measure this?
Deforestation in Rondonia, Brazil
wet
precipitation
7
4
2
dry
6
5
1
cold
3
temperature
warm