Lecture 3
Biomes
I. Definitions and the Community Concept
II. Ecological Equivalents, Life Zones, and Biomes
A. Tropical Rainforest
B. Tropical Seasonal Forest
C. Tropical Savanna
D. Desert
E. The Mediterranean Biome
F. Temperate Grassland
G. Temperate Forest
H. Temperate Rainforest
I. Coniferous Boreal and Montane Forests
J. Tundra
Lecture 3
I. Definitions and the Community Concept
Community:
All the populations of organisms that live and interact within a
prescribed place or habitat.
Community Concepts:
• Superorganism Community Concept (S.A. Forbes 1887, Clements 1916)
• Individualistic Community Concept (H.A. Gleason 1920’s)
(F. E. Clements)
(H. A. Gleason)
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Lecture 3
I. Definitions and the Community Concept
Classifying and Mapping Communities:
• Unit of description:
• Stand (area of homogeneous associations, usually trees)
• Dominance types (dominant species within an association)
• Important properties of community structure:
• Species composition
• Overall species diversity
• Most abundant species
• Most dominant species in terms of biomass or structure
• Species eveness
• General growth form or structure
• Number of trophic levels
• Primary productivity
Lecture 3
I. Definitions and the Community Concept
Comparing Vegetation Communities:
Line transect
sampling
Quadrat sampling
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Lecture 3
I. Definitions and the Community Concept
Comparing similarity and dissimilarity of communities:
• Variables assessed:
Relative Density =
individuals of species x
x 100
total individuals of all species
Relative Frequency =
frequency of species x
x 100
sum of frequency of all species
Relative Dominance =
basal area of species x
x 100
total basal area of all species
Importance Value = Relative Density x Relative Frequency x Relative Dominance of Species x
Lecture 3
I. Definitions and the Community Concept
Comparing between stands in different communities:
• Alpha diversity: The degree of difference in the species composition
between stands of the same community.
• Beta diversity: The degree of difference in the species composition
of two different communities.
• Gamma diversity: The degree of difference in species composition
across an entire landscape.
• Index of similarity:
Index of similarity =
2 x the no. of species that occur in both stands
total species in stand 1 + the total species in stand 2
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Lecture 3
I. Definitions and the Community Concept
Community Structure Types:
• Forest: Sites dominated by trees and a generally continuous
canopy.
• Woodland: Sites typified by widely spaced trees allowing for
substantial areas dominated by shrubs, grasses, or herbs.
• Shrubland: Sites dominated by a relatively continuous cover of
shrubs.
• Grassland: Sites dominated by grasses and herbs.
• Scrub: Sites dominated by widely spaced shrubs.
• Desert: Sites dominated by sparse xerophytic plant cover with
mostly bare ground.
Lecture 3
II. Biomes
Biomes:
Large areas of the earth that have the same vegetation and climate.
Alexander von Humboldt (1769 – 1859)
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Lecture 3
I. Definitions and the Community Concept
C. H. Merriam (1886)
Lecture 3
I. Definitions and the Community Concept
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Lecture 3
II. Biomes
Lecture 3
II. Biomes
1. Tropical Rain Forests
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Lecture 3
II. Biomes
(Ficus virens)
(Koompasia excelsa)
Lecture 3
II. Biomes
Mangroves
(Rhizophora spp.)
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Lecture 3
II. Biomes
Deforestation of
the Tropics
B. Tropical Savanna
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C. Temperate Forests
D. Coniferous Boreal and Montane Forests
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E. Temperate Rainforests
F. Mediterranean Biome
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G. Temperate Grasslands
H. Desert Biome
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H. Desert Biome
I. Tundra
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J. Tundra
Siberian
Tundra
J. Tundra
Alpine
Tundra
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