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Lecture 3Biomes

I. Definitions and the Community ConceptII. Ecological Equivalents, Life Zones, and Biomes

A. Tropical RainforestB. Tropical Seasonal ForestC. Tropical SavannaD. DesertE. The Mediterranean BiomeF. Temperate GrasslandG. Temperate ForestH. Temperate RainforestI. Coniferous Boreal and Montane ForestsJ. Tundra

Lecture 3I. Definitions and the Community Concept

Community:All the populations of organisms that live and interact within aprescribed place or habitat.

Community Concepts:

• Superorganism Community Concept (S.A. Forbes 1887, Clements 1916)

• Individualistic Community Concept (H.A. Gleason 1920’s)

(H. A. Gleason)(F. E. Clements)

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Lecture 3I. 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 3I. Definitions and the Community Concept

Comparing Vegetation Communities:

Line transectsampling

Quadrat sampling

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Lecture 3I. Definitions and the Community Concept

Comparing similarity and dissimilarity of communities:• Variables assessed:

100 species all of sindividual total

xspecies of sindividual Density Relative x=

100 x species all offrequency of sum xspecies offrequency Frequency Relative =

100 x species all of area basal total

xspecies of area basal Dominance Relative =

x Species of Dominance Relativex Frequency RelativeDensity x Relative Value Importance =

Lecture 3I. 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:

2 standin species total the 1 standin species totalstandsboth in occur that species of no. x the2 similarity ofIndex

+=

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Lecture 3I. 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 3II. Biomes

Biomes:Large areas of the earth that have the same vegetation and climate.

Alexander von Humboldt (1769 – 1859)

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Lecture 3I. Definitions and the Community Concept

C. H. Merriam (1886)

Lecture 3I. Definitions and the Community Concept

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Lecture 3II. Biomes

Lecture 3II. Biomes

1. Tropical Rain Forests

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Lecture 3II. Biomes

(Koompasia excelsa)(Ficus virens)

Lecture 3II. Biomes

Mangroves

(Rhizophora spp.)

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Lecture 3II. 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