There are so many species living on this planet.
But where do they all live?
What kinds of environments do they thrive in, and how are they adapted to those environments?
We can refer to these different types of regions as biomes, and it will be important to understand
their ecological characteristics, so let’s begin a survey of all the different types
of biomes now.
Terrestrial biomes can be defined as ecosystems with similar climates in regions that need
not be located in proximity but can span across the Earth.
For example, tropical rainforests aren’t constricted to a single continent, they can
be found in different continents, but their characteristics will be very similar, such
as temperature, precipitation, and latitudinal location.
Let’s start by examining rainforests.
As one might guess, rainforests receive the most rain of all of the biomes.
A typical year can see anywhere from 80 to nearly 400 inches of rain.
Tropical rainforests are found closer to the equator, between the Tropic of Cancer and
the Tropic of Capricorn.
This hot, moist biome, where it rains all year long, is known for its dense canopies
of vegetation that form three layers.
The top layer, also called the canopy, contains tall trees that prevent much of the sunlight
from reaching the ground.
The middle layer, or understory, is made up of vines, smaller trees, ferns, and palms.
A lot of plants from this level are used as common houseplants.
The bottom layer, or floor, is covered with wet leaves and leaf litter that decomposes
rapidly in the wet, warm conditions, like a compost pile, sending nutrients back into
the soil.
Few plants are found on the floor of the forest due to lack of sunlight.
But the hot, moist environment and all the dead plant material creates the perfect conditions
in which bacteria and other microorganisms can thrive.
Now let’s examine the hot desert biome.
We can find these between 15° and 35° latitude both north and south of the equator.
Examples include the Mojave, Sonoran, Chihuahuan, and Great Basin deserts of North America.
There is the Sahara in Africa, the Negev in the Middle East, and the Gobi in Asia.
In contrast with rainforests, deserts are the driest of all the biomes.
In fact, the most important characteristic of a desert is that it receives very little
rainfall.
Most deserts receive less than 300 millimeters a year, compared with rainforests which receive
over 2,000 millimeters.
This means that the desert only gets around 10 percent of the rain that a rainforest receives.
The temperature in the desert can change dramatically from day to night because the air is so dry
that heat escapes rapidly in the sun’s absence.
The daytime temperature averages 38°C while in some deserts it can get down to -4°C at
night.
The temperature also varies greatly depending on the location of the desert.
Since desert conditions are so severe, the plants that live there need to have adaptations
to compensate for the lack of water.
Some plants, such as cacti, store water in their stems and use it very slowly, while
others like bushes conserve water by growing few leaves or by having large root systems
to gather water.
Some desert plant species have a short life cycle of a few weeks that lasts only during
periods of rain.
If we keep moving away from the equator we will encounter temperate grasslands.
Grasslands receive about 20 - 35 inches of rain per year.
The vegetation includes prairie clover, oats, wheat, and barley, and these can be found
in the prairies of the Great Plains of North America, the pampas of South America, the
veld of South Africa, the steppes of Central Eurasia, and surrounding the deserts in Australia.
In other words, these biomes are found on every continent except Antarctica.
Grasslands are generally open and continuous, fairly flat areas of grass.
They are often located between temperate forests at high latitudes and deserts at subtropical
latitudes.
Grasses vary in size from 2.1 meters tall with roots extending down into the soil 1.8
meters, to the short grasses growing to a height of only 20 to 25 centimeters tall.
These short grasses can have roots that extend 1 meter deep.
The height of grass correlates with the amount of rainfall it receives.
While temperatures are often extreme in some grasslands, the average temperatures are about
-20°C to 30°C. Tropical grasslands have dry and wet seasons but remain warm all the
time.
In contrast, temperate grasslands have cold winters and warm summers with some rain.
The grasses die back to their roots annually, while the soil and the sod protect the roots
and the new buds from the cold of winter or arid conditions.
A few trees may be found in this biome along the streams, but not many due to the lack
of rainfall.
Next up are the temperate shrublands, found in west coastal regions between 30° and 40°
north and south of the equator.
Here we find aromatic herbs like sage, rosemary, thyme, and oregano; shrubs, acacia, chamise,
and grasses.
Shrublands include regions such as chaparral, woodland, and savanna.
Some examples can be found in southern California, Chile, Mexico, areas surrounding the Mediterranean
Sea, and southwest parts of Africa and Australia.
These regions are usually found surrounding deserts and grasslands.
Shrublands usually get more rain than deserts and grasslands but less than forested areas,
typically receiving between 200 and 1,000 millimeters of rain per year.
This rain is unpredictable, varying from month to month, with a noticeable dry season and
wet season.
The shrublands are made up of shrubs or short trees.
Many shrubs thrive on steep, rocky slopes, and there is usually not enough rain to support
tall trees.
Shrublands are usually fairly open so grasses and other short plants grow between the shrubs.
In the areas with little rainfall, plants have adapted to drought-like conditions.
Many plants have small, needle-like leaves that help to conserve water.
Some have leaves with waxy coatings and leaves that reflect the sunlight.
Several plants have developed fire-resistant adaptations to survive the frequent fires
that occur during the dry season.
Now that we have these first four biomes covered, let’s move forward and check out just a
few more.