Chapter 20 Terrestrial Biomes 1

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 3

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. 4

Life Forms Forbs Shrub Trees Grass Epiphytes Lianas 5

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 6

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. 7

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 (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. 8

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. 15

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. 16

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.. 18

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. 19

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 21

Arctic Tundra Figure 20.20

Alpine Tundra Figure 20.21

Major Terrestrial Biomes Figure 20.4