The study of inter-relationships of organisms with each other and their physical environment.

A Biome is a terrestrial ecosystem occupying an extensive geographical area and is characterized by a particular plant community.

Biomes: Physical factors that can effect the location of biomes include: Temperature Rainfall Altitude and Latitude Mountain Chains Air currents Ocean currents These categories of plant life are called biomes. Often biomes are thought of as climatic regions E.g. grassland, savanna, temperate forest, desert, boreal forest, tropical rain forest, tundra The land surface of the Earth is divided into a number of geographic areas distinguished by particular types of dominant vegetation.

Temperature and Rainfall: Terrestrial Biomes are greatly influenced by rainfall and temperature. Temperature influences the availability of water to plants, soil & animals. The hotter it is the faster water evaporates Cold temperatures can lock the water up in ice Latitude: Latitude measured in degrees, is the distance north or south from the equator, which is at 0  latitude. Latitude effects the angle at which the sun strikes the Earth’s surface. This is due to the tilt of the Earth’s Axis.

Mountains have an important impact on climate. thinning air retaining less heat As elevation increases temperature decreases due to The temperature drops 2  C (3.5  F) for every 305 meters (1000 feet) Mountains also create a local dry area called a rain shadow on the leeward side

In general the world can be divided into biomes based on latitude. The Major Terrestrial Biomes

Tundra: Between high latitude tree line and deep snow of polar regions. Severe conditions -55 °C (-40 ° F) in winter. Makes up 1/5th of the Earth’s total land. Permafrost which stunts growth. (1.5 feet below surface) Growing season of 2 months, harsh cold winters. Largest animals: Caribou, musk oxen, reindeer. Top predators: include wolves, grizzly bears, white fox and snowy owl. Herbivores: Grouse and lemmings. Summer sees migrations of birds to feed on insect hordes. Vegetation: Tree-less, grasses,herbaceous plants, mosses, lichens.

Conifer (boreal) Forests or Taiga: 45  – 60  north latitude, along the low-latitude borders of Tundra. Long winters and short summers. Short growing season. Low diversity of life due to harsh climate. Ground layer has less invertebrates and leaf litter is slower to decompose. Animals: Elk, moose, deer, black bears, grizzly, porcupines, hares, lynxes, grouse, wolf, fox. Vegetation: Evergreen trees, small compact, wax coated leaves. Can’t compete with deciduous trees in temperate zones. The Pacific coast forests have adapted to dry summers and can store water and nutrients due to massive size.Thick bark protects from fires.

Temperate forest: Plenty of rain fall, temperate climate, broad leaf trees (deciduous & evergreen), cool winters. Growing season of at least 4 months. Cover most of eastern America. Vegetation: 4 layers of plant growth, tree layer, shrub layer, field layer and ground layer. Main trees in the north are oak, birch, beech, and maple. Further south oak and hickory. Animals: Chipmunks, squirrels, raccoons, opossums and mice feed on nuts, fruits and insects. Deer feed on shrubs and seedlings Wolves, bobcats, foxes, and mountain lions feed on the other mammals. Rich top soil supports a large population of decomposers.

Temperate Grassland: (Prairie) Continental interiors, seasonal variations in rainfall. Transition zones between temperate forests and deserts. Rolling to flat terrain, hot-cold seasons, periodic droughts and fires. Vegetation: Mainly grasses mixed with legumes and some annuals. Water and fire are the main factors in vegetation type Animals: Seed eating rodents, large herbivores like bison, gazelles, zebra, horses etc. Large predators like Lions,Wolves, dogs etc.

Soil formation and Biomes Different climates produce different soils. Soil is formed from the weathering of rock and breakdown of organic material like leaf litter.

The Oceans Oceans cover 71% of the Earth’s surface But oceans are only about 1/3 as productive as land.

photic zone Supports photosynthesis aphotic zone Supports chemosynthesis only Ocean Life Zones

The life in the oceans is divided into two main groups: Benthic (bottom dwelling). Pelagic (free floating)

Along the continental shelves life is much denser than in the open ocean because nutrients are washed out from the land. The most important factors in marine ecosystems are sunlight and nutrients The Oceans But although water appears to be transparent it blocks light energy. Light can only go about 200m. Most of the nutrients are concentrated near the bottom!

Most nutrients are concentrated near the bottom sediments where light is too low for photosynthesis. Upwelling transports these sediments to the surface

Consisting of algae, protists, shrimp and other crustaceans. They are the basis of the food web for most pelagic organisms. The start of the food chain in oceans are the free floating phytoplankton Next in the food chain are the free floating Zooplankton

Coastal wetlands are rich in nutrients, water is shallow and plants can attach to the bottom. Breeding grounds for a range of organisms including most commercially important fish species. Estuaries