BIOB50H3 Chapter 3: Chapter 3
Chapter 3 (Pg. 50-78)
Terrestrial Biomes
• Terrestrial biomes are characterized by the growth forms of the dominant vegetation
• Biomes are large-scale communities shaped by the physical environment, and particularly
climate variation.
• They are categorized by dominant plant forms and their characteristics, such as leaf
deciduousness (seasonal shedding of leaves) or succulence (Development of fleshy tissue for
water storage)
• Terrestrial biomes reflect global patterns of precipitation and temperature
• Temperature influences the distribution of plant growth forms directly through its effect on the
physiological functioning of plants.
• Precipitation and temperature act in concert to influence the availability of water and its rate of
loss by plants.
• Water availability and soil temperature are important in determining the supply of nutrients in
the soil, which is also an important control on plant growth form.
Plant growth forms
1) Sclerophyllous shrubs- have tough, leathery leaves and live in seasonally dry/moist and
warm/cool environment
2) Deciduous trees- drop their leaves during cold or dry periods and live in moist, seasonally
warm/cool or cool/cold on fertile soils or warm, seasonally wet/dry environment
3) Grasses, sedges- grow from the base of their leaves and live in moist seasonally warm/cool, with
fire environments
4) Cacti and shrubs- have succulent stems or leaves that contain water storage tissues that live in
dry, seasonally hot/cool environments
5) Evergreen broad-leaved trees- carry out photosynthesis year-round that live in wet warm
tropical regions
6) Needle-leaves evergreen trees – retain their photosynthesis tissues year-round that in live
moist, seasonally warm/cool or cool/cold on infertile soil environments
7) Forbs- are broad-leaved herbaceous (nonwoody) plants that live in seasonally cool/cols
environments
Terrestrial Biomes
1) Tropical Rainforests
• Found in low-latitude tropics (between 10 degrees N and S)
• Precipitation: 1,800mm| temperature: 24.6degreesC
• Hot, wet, seasonally invariant temperatures
• Contain broad-leaved evergreen and deciduous trees
• High biomass, high diversity—about 50% of Earth’s species. –
• Disappearing due to logging & conversion to pastures.
2) Tropical Seasonal Forests and Savannas
• Found @ 23 degrees N and S
• Precipitation: 1,493mm| temperature: 24.5
• Rainfall is seasonal, with pronounced wet and dry seasons
• Contain grasses, shrubs, drought deciduousness, with leaves dropping forms trees
during dry season.
• Fires & herbivory promote the formation of savannas
3) Deserts
• Found @ 30 degrees N and S
• Precipitation: 39mm | temperature: 22.3 degreesC
• High temperature and low moisture
• Sparse vegetation and animal populations but may have high diversity
• Many plants have succulent stems; also, drought deciduous shrubs, grasses, and short-
lived annual plants that are only active after rain
• In similar biomes plants can converge. For example the Cactus and Euphorb both have
succulent stems, water-conserving photosynthetic pathways, upright stems that
minimize midday sun exposure, and spines that protect them from herbivores. Despite
their similarities they are not closely related, thus these characteristics evolved
independently
4) Temperate Grasslands
• Found between 30 and 50 degrees N and some in the S
• Precipitation 727mm | temperature: 9.1 degreesC
• warm & moist summers, cold & dry winters
• High enough precipitation to support forests, but frequent fires and large herbivores
(e.g. bison) maintain grasslands.
• Humans use grasslands for agriculture because of fertile soils
5) Temperate Shrub lands and Woodlands
• Found @ 30-40 degrees N and S
• Precipitation: 747mm | temperature: 16.7degreesC
• Mediterranean-type climates (wet winters, hot & dry summers)
• Asynchrony between precipitation and summer growing season (when temperatures
are suitable for growth)
• Evergreen shrubs and trees dominate, frequent fires maintain biome
• Evergreen leaves allow plants to be active during cooler, wetter periods.
• Have nutrient poor soils
6) Temperate Deciduous Forests
• Found between 30-50 degrees N on the west and east side of Eurasia and North
America
• Precipitation: 848 | temperature: 7.6 degreesC
Document Summary
50-78: terrestrial biomes are characterized by the growth forms of the dominant vegetation. Biomes are large-scale communities shaped by the physical environment, and particularly climate variation. Sparse vegetation and animal populations but may have high diversity lived annual plants that are only active after rain. For example the cactus and euphorb both have succulent stems, water-conserving photosynthetic pathways, upright stems that minimize midday sun exposure, and spines that protect them from herbivores. America: precipitation: 848 | temperature: 7. 6 degreesc, enough rainfall for tree growth and fertile soils for trees when leaves fall off, oaks, maple, beech occur everywhere in this biome. Biological zones on mountains: on mountains, temperature and precipitation change with elevation, resulting in zones similar to biomes. Lower montane zone, montane zone, subalpine zone, alpine zone. Fresh water biological zones: biological zones in freshwater systems are associated with the velocity, depth, temperature, clarity, and chemistry of the water.
