I. Climate largely determines where species live

A. Climate = prevailing weather conditions, most importantly temperature and moisture, which help determine biological communities

B. Biomes = major biological communities that occur over a large area of land

C. Additional factors play important roles in determining where biomes are located

• soil type
• wind
• latitude
• elevation

II. There are seven major biomes

A. Tropical rain forests

• abundant rainfall (200-450 cm/year), little seasonal variation
• high productivity, dominated by large trees
• infertile soil, most of the nutrients are held in the plants
• decomposition occurs quickly
• at least 50% of all terrestrial species

B. Deserts

• sparse precipitation (less than 25 cm/year)
• sparse vegetation, which is drought resistant, such as cacti
• covers large areas of continental interiors

C. Savannas

• low precipitation (90-150 cm/year), with long dry seasons
• tropical grasslands, with widely spaced trees
• located between tropical forests and deserts

D. Temperate deciduous forests

• plentiful precipitation (75-250 cm/year), distributed throughout the year
• temperate regions are about half way between equator and poles
• dominated by large trees, which usually shed leaves during cold winter
• drier regions, different soils favor evergreen forests
• very dry summers favor shrubs, chaparral

E. Temperate grasslands

• moderate climates with less precipitation than temperate deciduous forests
• temperate regions are about half way between equator and poles
• prairies, or open grasslands, with deep, thick roots
• highly fertile soil, usually converted to agriculture

F. Taiga

• cold, wet climates, with long winters, and most precipitation in summer
• closer to poles than equator
• dominated by large coniferous trees
• large mammals are common

G. Tundra

• very low precipitation (less than 25 cm/year)
• between taiga and poles
• brief summers, long very cold winters
• soil often boggy, permafrost (permanently frozen soil at depths greater than 1 meter)
• mostly low growing plants

III. Aquatic communities are linked to terrestrial communities

A. Organic & inorganic materials continuously enter bodies of water via streams and runoff

B. Freshwater communities

• lakes cover about 1.8% of Earth's surface; streams about 0.3%
• ponds and lakes have three main zones:

     a. littoral zone = shallow, near shore, with aquatic plants and smaller animals
     b. limnetic zone = surface waters away from shore, with algae, zooplankton, fish
     c. profundal zone = deep water, limited light, with bacteria and decomposers

C. Marine communites

• nearly 75% of Earth's surface
• oceans have three main zones:

     a. shallow ocean waters = shallow, near shore, rich communities with aquatic plants
          and many animals
     b. surface of the open ocean = surface waters away from shore, rich with 
          phytoplankton (40% of all producers on Earth), zooplankton, many fish, invertebrates
     c. depths of the ocean = deep water, limited light, with bacteria, decomposers,
          unusual carnivores, and occasional deep sea vents

D. Estuaries = saltwater marshes

• very productive, collecting organic and inorganic materials via streams and runoff
• aquatic plants shelter developing fish, birds, invertebrates
• endangered by human development