Why are there so many types of species? One
reason is that the types of environments differ in different parts of
the world. Even in one region
of a single continent, southern
the thorn forest-scrubland of the
the coastal environments of
and Paraguayan subtropical rainforests.
The aquatic environments
have very different species than the those found in the aquatic
Throughout the world, there are classes of ecosystems referred to as biomes. A biome is a major type of physical environment that is inhabited by characteristic plants and animals. Temperature and annual precipitation determine the nature of many of these biomes.
a) deserts: Deserts actually contain a diversity of organisms. Some are dormant until the rains come and others are nocturnal.
b) grasslands: In grasslands, the amount of rainfall is less than that needed to support trees. Herbivorous mammals and the insects they attract are important components of the animal life.
c) savanna: Savannas are extensive grasslands with occasional trees. They are often tropical with rainy and dry seasons.
d) tropical rain forests: Tropical rainforests have high temperatures and a great
amount of annual rainfall. There
is little seasonal change and, as a result, trees do not drop their leaves.
Because the trees do not drop their leaves and because insects
and decomposers quickly make use of the organic matter on the forest floor,
the soils are relatively poor with very few nutrients.
Tropical rainforests have an incredible biodiversity—an estimated
half of all the plant and animal species on earth live here.
The following images are of a Brazilian rainforest (just south
e) temperate deciduous forests: The dominant type of tree in temperate deciduous forests are the broad-leafed flowering plants which drop their leaves in colder seasons. There is a lesser diversity of species than that found in tropical rainforests.
f) coniferous forests: Conifers have thin leaves (which we often call needles). These needles allow them to lose less water which is especially an advantage in areas with harsh winters such as northern latitudes and higher altitudes
g) tundra: The tundra has a permanently
frozen soil layer and short plants. It
can be found in polar regions and at high altitudes
(such as in the