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Source: Earth PD Rainforest PD Temperate Forest CC Grasslands CC Tundra CC Desert CC Biome Comparison CC

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Hi. I'm Jensen Morgan. We're going to talk about some great concepts in environmental science. Today's topic is biomes. So let's get started.

We're going to talk about major biome types and our three key terms for this tutorial. Our first key term is actually a review, "biome," which are areas of the Earth with similar climatic conditions, plant life, and animal life. The primary characteristics of a biome is its level of precipitation and range of temperature.

Our next key term is "biodiversity," which is the number and relative abundance of species in a given area. And our last key term for this tutorial is "biomass," the total weight of plants, animals, and other organisms in a given area. All three are important concepts for today's topic.

There are a wide variety of biome classifications, as you can see in this chart here. But we're going to cover six main categories. This biome map here shows all the different types of biomes on earth. Note that the same biome type exists at various locations on earth. For example, the arid desert is here, in Mexico, and also here, in North Africa.

The first biome type we're going to discuss is tropical rain forest. They are hot and humid and generally appear near the equator. They have high levels of both biodiversity and biomass. Vegetation grows in different layers going up, so various forms and groupings of life exist at each layer. Because rain forests tend to be so dense, the top canopy layers receive the most sunlight, while the forest floor receives very little.

Temperate forests receive less rainfall than tropical ones, and are generally cooler. They are filled with deciduous trees that can lose their leaves in autumn and go dormant in the winter, though there are evergreens in the mix as well. They are found in temperate zones in both hemispheres and experience the four seasons. Most of the human population lives in this biome.

The taiga biome is filled with cool conifer tree forests in both hemispheres. Many of the animals in this biome hibernate during the long, cold winters. The growing season tends to be short as well.

Grasslands are primarily made up of grasses without many trees. This is largely the result of lower levels of precipitation. Within this group are savannas, which are tropical grasslands near the equator which can support tall grasses, but still no trees. The majority of grazing animals on Earth actually live in savannas. Savannas have a wet and dry season and frequent natural fires play a large role keeping a savanna healthy.

Steppes are another grassland group. They're the opposites of savannas. They're cold grasslands with little precipitation. And the last subgroup here is the temperate grasslands, which are in the dryer areas of the temperate biome latitude.

Tundra is the coldest biome category, and receives very little rainfall. There is a layer of permafrost where the ground is actually frozen year round which, when combined with a very short growing season of this biome, makes for low biodiversity. The sparse flora and fauna that do live here have adapted to the harsh conditions.

The desert biome has very little precipitation, low biodiversity, and tends to be sandy and rocky. Deserts can both be cold and hot, but always have low levels of precipitation. High winds leave deserts with little topsoil and nutrients to grow plant life. Those that can survive grow spines, shallow roots, and evolved waxy surfaces to retain and protect their water. Desert animals tend to be small, nocturnal to avoid the heat of the day, and get most of their water from what they eat.

This graph here can give you an idea of how each of the biomes are distributed in relation to temperature and precipitation. At the top of both heat and high precipitation sits the tropical rain forest biome. And at the bottom of both temperature and precipitation is the tundra biome.

Aquatic biomes exists as well, and fall into three main categories-- freshwater, estuary, and marine. Freshwater includes lakes, rivers, and streams. Estuaries are known for their high levels of biodiversity, because they tend to be along shorelines where saltwater and freshwater sources meet. And marine includes all oceanic environments. The marine group tends to have lower levels of biodiversity and the colder the water, the larger the fish.

Now let's have a recap. We talked about the six main biome types and our three key terms, which are-- biome, areas of the Earth with similar climatic conditions, plant life, and animal life; biodiversity, the number and relative abundance of species in a given area; and biomass, the total weight of plants, animals, and other organisms in a given area. Well, that's all for this tutorial. I look forward to next time. Bye.

Terms to Know

the number and relative abundance of species in a given area


the total weight of plants, animals, and other organisms in a given area


areas of the earth with similar climatic conditions, plant life, and animal life