Terrestrial Biomes
Tropical Rainforests
In order for a biome to be tropical it has to fall somewhere between the Tropic of Cancer and the Tropic of Capricorn.
-Any biome between the two tropics can be referred to as tropical. For example; tropical deserts, tropical savanna, etc.
-To be considered a rain forest there needs to be between 250-450cm (98-177in) of annual rainfall.
Tropical rainforests are one of our most important biomes in regards to biomass
-Biomass is the density or amount of living material in a given area
-Biomass can refer to plant mass, fungi mass, animal mass, bacteria mass, or even protist mass
-Only 7% of the world is covered in rain forest but they house 50% of all living things on the planet
-One Acre of rain forest a second is destroyed. An acre is almost the size of a football field.
-One species of animal goes extinct every year. Soon it will be three or four species every year.
Savannas
A Savanna is a tropical grassland
-A Savanna is usually characterized by lots of grass, a few bushes, and spars trees
-Because a Savanna is tropical it does not experience seasons
-The temperature is relatively the same all year
-Savannas are also known for having large amounts of biomass
-Savannas are also home to many of the worlds large mammals
-The abundance of grass provides food for large herbivores and insects
-The large herbivores provides food for the many carnivores
Deserts
A desert is a biome where there is little precipitation. If a biome receives only 50cm or less of rain a year it is usually categorized as a desert.
-About 1/5 of the earths surface is covered in desert
-The arctics and sometimes the tundras receive as little precipitation as the deserts so they can be referred to as "Cold Deserts"
-The lack of water creates a large amount of strain on any plant life because of this plant life is very sparse in the desert. Plant life in a biome usually holds soil together. Because there is little plant life, deserts erode very quickly. The quick changes in temperature, extreme heat during the day and cold at night, cause rocks to crumble. The water of flash floods can also cause the sun backed rocks to shatter. Along with these geological forces and wind is how deserts acquire their large amounts of sand.
-Because of the wind and high amounts of erosion a process known as denudation takes place in most deserts. Denudation is where the earth erodes away creating a basin. This is why deserts tend to be the lowest points on earth.
-Just because a desert has a lack of water, represents the hottest places on earth, and has very little plant life, does not mean that there are no animals. Deserts have a large diversity of animals well adapted to these harsh environments.
-The majority of desert animals are nocturnal to avoid the heat and water loss. In other biomes there is usually a mix of diurnal and nocturnal animals to avoid predation and niche
Chaparral
-A Chaparral is defined as a shrub land that has hot dry summers and mild wet winters. Wildfires is an important feature for most chaparrals.
-The plant life that lives in a chaparral is usually drought tolerant due to the long drought periods that sometimes affect chaparral
-There is not much chaparral in the world
Temperate Grasslands
-A Temperate grassland is a grassland that experiences the four seasons. This is different than the tropical grasslands known as Savannas. Savannas do not experience seasons, they stay relatively the same temperature all year.
-Like most biomes, it is the amount of precipitation that defines grasslands
-Grasslands receive enough precipitation to grow grass but not enough to sustain a forest. There are usually few trees growing in the grasslands.
-Dry thin soil is also a contributing factor to the lack of trees in a grassland
-Grasslands also suffer from fires
-The hot dry ground and dry grass easily leads to large fires. The grass recovers quickly from fires since grass grows from the bottom. Trees do not recover from fires because they grow from the top.
Grass is the most successful plant on the planet and it has helped humans survive all over the world.
-A large part of human societies where based on either rice or wheat crops
Deciduous Forest/ Temperate Broadleaf Forests
-A temperate forest is a forest that experiences all fours seasons
-The temperate forest is full of deciduous trees
-These are trees that change color in the fall, lose their leaves in the winter and grow bright green leaves in the spring and summer
-Temperate forests receive a lot of rainfall, not enough to be considered a rainforest but enough to support the abundant biomass of trees
Coniferous Forests
-Coniferous forests are temperate forests that experience all four seasons but the difference between a broadleaf temperate forests and a coniferous temperate forest is that the coniferous forests usually experience a more severe winter and the dominant tree type is pine trees.
-A conifer is another name for a pine tree. Pine trees have special adaptations that allow them to live in extremely cold weather. Conifers are "evergreens" they never lose their leaves.
-Conifers have a sugar sap inside their trunk that acts like an antifreeze and prevents freezing during the winter. The leaves of conifers are needle shaped and coated in a wax that prevents water loss.
-Even though coniferous forests have very cold winters they still have warm summers. The animals that live in coniferous forests are adapted to survive the cold winter either through food storage, thick fur, or even hibernation.
Taiga
-A Taiga is very similar to a coniferous forest. The difference is that a taiga spends the majority of the year in winter conditions. There might be only 2 months out of the year where there is no snow.
-Very few trees other than conifers can survive in a taiga
-Because of the cold there are few reptiles and amphibians that live in the taiga
-Mammals can survive in these conditions because of their fur and fat reserves
The Tundra
Tundra is the coldest of all the biomes. Tundra comes from the Finnish word tunturia, meaning treeless plain.
-The main characteristics of a tundra are the constant ice, extremely low temperatures, little precipitation, and short growing season
-Tundra is separated into two types: arctic tundra and alpine tundra.
Characteristics of Tundra
Extremely cold climate
Low biotic diversity
Simple vegetation structure
Limitation of drainage
Short season of growth and reproduction
Energy and nutrients in the form of dead organic material
Large population oscillations
Arctic
Arctic tundra is located in the northern hemisphere, encircling the north pole and extending south to the coniferous forests of the taiga.
-The Arctic is known as a cold desert since it only receives 15-25cm (6-10in) of precipitation each year and that includes melting snow.
-The average winter temperature is -34C (-30F) and the summers are between 3-12C (37-54F)
-So the summers get just warm enough to sustain life
-The growing season is only 50 to 60 days
-There are no deep root systems in the arctic mainly because of the permafrost (a permanently frozen layer of soil)
-But there are 1700 types of plants that can live in the arctic including
low shrubs, sedges, reindeer mosses, liverworts, and grasses
400 varieties of flowers
crustose and foliose lichen