The World’s 5
Biomes
Environmental Science
Jesi Lee
Mrs. Leggio
Period 1*
January 11,2005
Biomes Project
Tundra
The Tundra is the coldest Biome. The name tundra comes from the
word Tunturia, meaning treeless plain. It has frost-molded
landscapes, extremely low temperatures, little precipitation, poor
nutrients, and short growing seasons. Dead organic material function
as a nutrient pool. The two major nutrients are nitrogen and
phosphorus. Nitrogen is created by biological fixation, and
phosphorus is created by precipitation. The tundra is seperated by
two types: arctic tundra and alpine tundra.
Characteristics of Tundra
- Low Biotic diversity
- Simple vegetation structure
- Extremely Cold Climate
- Limitation of drainage
- Short season of growth and reproduction
- Large Population oscillations
- Energy and nutrients in the form of dead organic material
Arctic - Located in the northern hemisphere, encircling the north
pole. Cold- desert like conditions. Rainfall may vary in
different regions. Soil is formed slowly. Low shrubs, sedges,
reindeer, mosses, liverworts, and grasses. There are 400 types
of flowers. Herbivorous mammals and carnivorous mammals,
migrating birds.
Alpine - located on mountains through out the world at high altitude
where trees cannot grow. The growing season is about 180 days.
The plant and animal life are familiar to the Arctic.
Grasslands
Grasslands are characterized as lands dominated by grasses
rather than large shrubs or trees. In the Miocene and Pliocene Epochs,
which spanned a period of twenty five million years, mountains rose
in western north America and created a continental climate favorable
to grasslands. There are two main divisions of Grasslands: (1)
tropical grasslands, called Savannas (2) temperate grasslands.
The Savanna:
The Savanna is a grassland with scattered individual trees. The
Savanna covers almost half of the surface of Africa, about five
million square miles (generally central Africa) and in
Australia, South America, and India. Climate is the most
important factor in creating a Savanna. Savanna’s are sometimes
classified as forests.
Temperate Grasslands:
Temperate Grasslands are characterized as having grasses as the
dominant vegetation. Trees and shrubs are absent. Temperatures
vary more from summer to winter, and the amount of rainfall is
less in temperate grasslands than in Savannas. Temperate
grasslands have hot summers and cold winters. Trees grow hear
river valleys and a few hundred flowers grow in the grasses.
Precipitation in the temperature grasslands usually occur in
the late spring and early summer.
Desert
The desert covers about one fifth of the Earth’s surface and
occur where rainfall is less than 50 cm/year. Are caused by extremely
low rainfall over an area. Theses biomes are nonetheless home to many
plants and animals which have through the course of their evolution
adapted to this dry environment.
Coastal and Cold Deserts
Coastal deserts are found in areas that are moderately warm to cool,
such as the Neotropic and Nearctic realm. The winters are usually
cool and short, while the summers are long and warm The soil is mostly
sandy with a high alkaline content, it is also very porous, so rain
seeps quite rapidly into the ground. Most of the flora in the coastal
desert features thick foliage, with good water retention, and their
roots are close to the surface of the ground in order to get enough
water before it drains into the soil.
Animals of the coastal desert include rough skinned amphibians, birds
of prey, scavenger mammals reptiles and insects; most have adapted
quite well to the climate, and again, they are largely nocturnal
during the warmer months.
Perhaps the strangest of all desert biomes is the cold desert, as
our perception of the desert is usually associated with the heat of
the sun. But even if there is a moderately high amount of snow and
rainfall during the wintertime, the soil is too heavy and alkaline.
Alluvial fans pull some of the salt through the porous soil, so plant
life can survive, but then again, as with its arid counterparts, the
cold desert offers less than ideal conditions for sustaining delicate
plants and animals.
Most of the animals in the cold desert are burrowers, even the
carnivores and reptiles which even though cold-blooded, have made
their homes in the cold desert.
Deer and other larger herbivores are only found during the winter,
as the supply of grass is more abundant during that period.
Arid, and Semi-Arid Desert
Arid deserts generally occur at low latitudes, and can be found in
North-America, South-America, Africa, and Southern Asia.
Seasons in the arid desert are generally dry and hot, with few
occurrences of rain during the winter. The heat peaks to extremes
during the daytime because there are no clouds to shield the earth
from the sun's rays.
When it does rain, it is not uncommon for the rain to evaporate before
hitting the ground. The soil is usually either sand or coarse, and
rocky. Vegetation consists mainly of shrubs and small trees of which
the leaves have evolved to retain water. Most desert life forms have
followed this train of evolution, with animals species being mostly
active at night.
Semi-arid deserts are found in North-America, Europe, Russia, and
Northern Asia.
Seasons are generally more defined than in the Arid desert, with low
rainfalls during the winter. Even if the rainfall is kept at a bare
minimum, several species of animals and plants thrive in this
climate, the animals, while nocturnal, can still be found during the
day, mostly in the shade of the various trees and plants.
AQUATIC
Water covers about three quarters of our planet. From oceans to
rivulets, aquatic biomes are host to a wide variety of life-forms,
and minerals, from the most common algae to the most mysterious
deep-sea creature.
Life began in the ocean billions of years ago. Most of the life forms
which currently occupy the earth had their start as single-celled
organisms, forced into evolution by an ever-changing environment.
Even now, species are disappearing and appearing without us knowing.
There two types of aquatic biome, the marine regions, and the
freshwater regions.
The marine regions
The marine regions are divided between coral reefs, estuaries, and
oceans. Oceans represent the largest and most diverse of the
ecosystems; salt water evaporates and turns to rain which falls on
the land regions, while most of the oxygen in our atmosphere is
generated by algae. Algae is also responsible for the absorption of
large amounts of carbon dioxide from our atmosphere.
The ocean connect to the land via what is called the inter-tidal zone.
Because of rising and falling tides, coastal areas are constantly
changing, with various animals and marine plants living at the
bottom, and on the seashore. Rocky coastal areas are host to fewer
species due to the fact that only the highest of tides will reach
the top of the cliffs.
In the warm shallow waters which line the continents and surrounding
islands lie barriers called coral reefs. Coral is a living organism
consisting of animal and algae tissues. Corals feed like plants
through the process of photosynthesis, and like animals, they also
use their tentacles to catch micro-organisms. The coral reef is also
host to other species such as starfish, octopi, and other mollusks.
Freshwater Regions
Freshwater is so called because of its extremely low salt content.
It exists in various forms such as lakes, rivers, ponds, swamps, or
wetlands such as the Florida everglades, and is host to a wide variety
of plants and animals.
Lakes and ponds, are like the oceans, in that they are divided into
separate zones which are defined by their distance from the shore.
The littoral zone, which is closet to the shore is host to a wide
variety of species due to its warm, shallow environment. Various
species of invertebrates, crustaceans, plants and amphibians thrive
in this environment, and in turn provide food for predators such as
birds, reptiles and other creatures inhabiting the shoreline.
As the Earth warmed up following the Pleistocene era, or ice-age,
the accumulation of melted ice went on to form the various lakes which
are found around the globe. Because lakes are generally separated
from one another, they are home to few species and plant life. While
lakes can exist for centuries, other inland bodies of water such as
ponds tend to dry up fairly quicker. Because of that factor, the
species which breed and inhabit these areas are often threatened by
extinction, especially when major change is brought on my human
expansion.
The limnetic zone, the open water near the surface of a lake or pond,
is home to a variety of phytoplankton, and zooplankton, which play
an important role in the food chain. Several species of freshwater
fish such as bass and lake trout can also be found this area, mainly
feeding on insects and plankton. The deeper region of a lake or pond
is called the profundal zone. This zone, shrouded in darkness, and
serves as a repository for dead plankton, and is inhabited by
creatures which feed mostly on decaying organisms. Because
freshwater biomes are inland, they are more subject to seasonal
changes
Other areas of still waters, or wetlands, such as glades, swamps,
and marshes support a large variety of aquatic flora and fauna.
FOREST
Forest Biomes represent the largest and most ecologically complex
systems. They contain a wide assortment of trees, plants, mammals,
reptiles, amphibians, invertebrates, insects and micro-organisms
which vary depending on the zone's climates. Sadly, boreal and
rainforest biomes are being cut down at an alarming rate, with
hundreds of species of plants and animals disappearing from the
planet on a daily basis.
Temperate Deciduous
Temperate deciduous forest are a close relative of the Taiga biome,
and can be found in areas with a milder, shorter winter season. In
addition to evergreens, trees in the temperate forest include maple,
elm, oak, cedar and other trees which shed their leaves in the fall.
The temperate forest's soil in richer than that of the boreal forests'
and features a larger assortment of forest floor plan life; this is
also due to the fact that the forests' canopy is thinner, allowing
more light and heat to penetrate, permitting photosynthesis in the
forest floor plants, and the survival of smaller, and cold blooded
animals such as garter snakes, turtles, and a few amphibians. Again,
several of the temperate forests' species hibernate, and/or burrow
in the ground to pass the winter months.
Other forests which fall between the boreal and temperate
classification include moist evergreen forests, moist evergreen and
broad-leaf forests, dry evergreen forests, mediterranean forests,
temperate evergreen forests, and temperate broad-leaf forests.
Boreal, or Taiga biomes
The largest of the land biomes is the boreal, or Taiga biome. Taiga
biomes can be found in areas with shorter, warm summers and long
winters; there are Taiga Biomes in Europe, Asia, Siberia, and
North-America. Because of the cold climates, plant life in the boreal
forest is sturdy, consisting mainly of evergreens and other resilient
vegetation. Because the forests' canopy is dense, forest floor
vegetation is thin. Animal life in the boreal forest consists mainly
of birds and mammals, such as deer, wolves, and various rodents, and
very few reptiles. Most of the boreal forests' creatures are well
adapted to the cold climate, and hibernate during the long winters.
Forests represent a third of the earth's land, and are found in the
four corners of the globe. The major attribute of the forest biome
is its trees. While they are different from animals in many ways,
they share one common characteristic: they breathe. While humans and
animals breathe in oxygen and exhale carbon dioxide, trees take in
carbon dioxide and produce oxygen. Deforestation represents a great
threat to the future of the earth's atmosphere, and the only way this
can be avoided is by careful management of this resource. Once a tree
is cut down, another should take its place, but there is still too
large a number of trees being cut down as opposed to the number of
trees being planted.