Biomes

Biomes: The land surface of the Earth is divided into a number of geographic areas distinguished by particular types of dominant vegetation. 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 Factors that can effect the location of biomes include: Temperature Rainfall Altitude and Latitude This means that plants characteristic of arctic regions may also be found in mountain ranges

In general the world can be divided into biomes based on latitude. Tundra: Between high latitude tree line and deep snow of polar regions Tree-less, harsh cold winters, grasses,herbaceous plants, mosses, lichens. 1/5th of earth’s land. Permafrost which stunts growth. Growing season of 2 months Largest animals are the caribou, musk oxen, reindeer. Top predators include white fox and snowy owl. Grouse and lemmings are some of the herbivores. Summer sees migrations of birds to feed on insect hordes.

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. 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. 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.

Conifer (boreal) Forests or Taiga: 45 – 60 north latitude, along the low-latitude borders of Tundra Evergreen trees, small compact leaves, cant compete with deciduous trees in temperate zones. Pacific coast forests adapted to dry summers, can store water and nutrients due to massive size. Thick bark protects from fires. Elk, moose, deer, black bears, grizzlies. Porcpines, hares, lynxes, grouse. Ground layer has less invertebrates and leaf litter is slower to decompose.

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

Temperate (Mediterranean) Shrub lands or chaparral: Mild moist winters, long, dry summers: Mediterranean climate Dense stands of shrubs, small trees Mule deer, lizards, rabbits, rodents are often small and dull colored to match environment. California is considered to have a Mediterranean scrub biome.

Deserts: Subtropics , low levels of rainfall Less than 25 cm of rainfall a year. Nights are cold Brief growing seasons. Succulents adapted to store water. Reptiles, insects. Many animals are small and nocturnal

Tropical forests: Humid equatorial regions, uniform temperature, lots of rain. Seasonal rainfall Tropical rain forests get 200-400 cm of rainfall per year. Complex ecosystem, has more plant and animal species than all the other biomes put together. Competition among plants for light. Upper canopy of solitary tall trees, can be 50-60m tall. Lower story canopy is continuous. Many vines and epiphytes growing on the trees. Few plants on forest floor, little leaf litter. Soil is infertile,low in nutrients, mostly red clay.

Soil formation and Climate Different climates produce different soils

Tropical regions with high rainfall and warm temperatures. Climate and the speed of weathering of rock The wetter and warmer the climate the faster chemical weathering will occur. So the faster the build up of soil So where in the world we you find the fastest weathering? Tropical regions with high rainfall and warm temperatures. Weathering here can extend to depths of several tens of meters. In cold areas and deserts it will only go down a few centimeters!

Soil: What is soil? Soil is a mixture of: Air, water and its solutes, mineral particles from parent bedrock, decaying organic matter, And organism responsible for its decay. Soil is a living skin!

The Oceans

The life in the oceans is divided into open ocean: pelagic (free floating) and benthic (bottom dwelling). The main component of the free floating division is plankton, which is composed of algae, protists, shrimp and other crustaceans. It is the basis of the food web for most pelagic organisms. The oceans are only about 1/3 as productive as land. The open oceans are only slightly more productive than desert. Along the continental shelves life is much denser than in the opean ocean. Nutrients are washed out from the land. In temperate latitudes the main producers are brown algae like rockweed (fucus), and kelp.