Transcript Terrestrial Biomes

Chapter 20
Terrestrial
Biomes
Robert W. Christopherson
Charlie Thomsen
Spatial Patterns of Vegetation
Biogeographer: A geographer who studies
the spatial distribution of natural vegetation
and its relationship to abiotic conditions.
Structure: The growth forms of the dominant
plants and their organization and arrangement
in space.
Flora: List of plants found in a region
Vegetation Structure
Life Forms
Size and stratification
Coverage: the degree to which the foliage of plants cover the ground
beneath them.
Barren
Very sparse
Discontinuous
Continuous
Periodicity: response of plant foliage to annual climatic cycle.
Deciduous
Evergreen
Leaf Shape and Size:
Broad leaf
Needle leaf
Leaf Texture
Membranous: average thickness
Filmy: thin and delicate
Sclerophyllous: hard, thick and leathery
Vegetation Structure
Life Forms
Trees: A perennial woody plant having a
single upright main trunk.
Shrubs: a woody plant having several stems
branching near the ground
Lianas: woody vines that climb on trees.
Herbs: small tender plants lacking woody
stems. Broadleaved herbs are termed forbs
in distinction with grass.
Epiphytes: plants using other plants as
supporting structures and thus live above
ground level.
Life Forms
Forbs
Grass
Trees
Epiphytes
Shrub
Lianas
The Major Biomes
Biome: a broad major grouping of natural
ecosystems that include animal life as well as
plants. The major biomes are recognized
primarily based on vegetation.
Forest
Savanna
Grassland
Desert
Tundra
Forest Biome
Tropical Rainforest
(1) Trees are smooth barked and unbranched in the lower 2/3, and
trunks commonly buttressed at the base;
(2) Broadleaf evergreen trees dominate the forest;
(3) Crowns form two or more layers of trees
(4) large number of species of trees coexist (up to 300 species/ha).
Subtropical Evergreen Forest
(1) compared to tropical rainforest, BEF has fewer species, smaller
leaves and more leathery, and canopy is less dense
(2) Annual range of temperature is small or moderate, and rain fall is
abundant and well distributed throughout the year.
(3) Includes both broad and needleleaf evergreen trees.
Midlatitude Deciduous Forest
(1) Almost entirely limited to the midlatitude landmasses of the
northern hemisphere.
(2) dominated by tall, broadleaf trees that provide a continuous canopy
in summer but shed leaves completely in winter.
Forest Biome-2
Needleleaf Evergreen Forest
(1) straight-trunked, conical trees with relatively short branches and
small narrow needlelike leaves.
(2) leaves are evergreen.
(3) species are few, thus one or two species can make a large tracts of
forest.
Needleleaf Deciduous Forest
(1) straight-trunked, conical trees with relatively short branches and
small narrow needlelike leaves.
(2) trees shed needles during the winter.
(3) primarily distributed in central and eastern Siberia.
Sclerophyll Forest
(1) low tree with short, hard, leathery leaves
(2) Associated with Mediterranean Climate
(3) California coastal ranges, Chaparral.
Rainforest Canopy
Figure 20.5
Buttressed Trees
Figure 20.6
Amazonian Rain Forest
Figure 20.6
Rainforest
Canopy
Figure 20.5
Mixed Broadleaf Forest
Figure 20.10
Mediterranean Chaparral
Figure 20.16
The Savanna Biome
Savanna woodland
(1) Consists of trees spaced rather widely apart, permitting
development of dense lower layer grasses.
(2) Primarily distributed in wet-dry tropical climate;
(3) Crowns are flattened or umbrella-shaped
(4) Fire is frequent during the dry season
Thorntree-tall grass Savanna
(1) A transition to the desert biome.
(2) Trees are larges thorny species, and more widely scattered than
savanna woodland.
Grassland Biome
Prairie
(1) Consists of dominant herb and subdominant forbs.
(2) Trees and shrubs are almost totally absent.
Steppe
(1) also called short-grass prairie.
(2) short-grass occurring in sparsely distributed clumps or bunches.
(3) Ground coverage is low and much bare soil is exposed.
Midlatitude Grasslands
Figure 20.17
Figure 20.18
Desert Biome
Thorntree semidesert
(1) found in low latitude region associated with tropical and
subtropical climates.
(2) xerophytic trees and shrubs adapted to a climate with a very long,
hot dry season and only a very brief but intense rainy season.
(3) the thorntrees shed leaves during dry season.
Semidesert
(1) xerophytic shrub vegetation with poorly developed herbaceous
lower layer.
(2) the middle and southern Rocky Mountain region and Colorado
Plateau have seen expansion of semidesert into previously steppe
grassland due to over grazing.
Dry Desert
(1) Xerophytic plants widely dispersed and providing no important
degree of ground cover..
(2) Small hardleaved or spiny shrubs, succulent plants or hard grasses..
Grassland Biome
Prairie
(1) Consists of dominant herb and subdominant forbs.
(2) Trees and shrubs are almost totally absent.
Steppe
(1) also called short-grass prairie.
(2) short-grass occurring in sparsely distributed clumps or bunches.
(3) Ground coverage is low and much bare soil is exposed.
Sonoran
Desert
Figure 20.19
Tundra Biome
Arctic tundra
(1) Arctic tundra has long daytime in the summer, melting top layer
ice.
(2) Plants are low and mostly herbaceous though dwarf willow occurs.
(3) Sedge, grasses, mosses, and lichens dominate the low layer.
Alpine tundra
(1) resembles arctic tundra.
(2) can develop in any latitude given sufficient altitude.
Tundra Sedge
Arctic Tundra
Figure 20.20
Alpine Tundra
Figure 20.21
Major Terrestrial Biomes
Figure 20.4