BIOMES OF THE WORLD

OVERVIEW

Biomes are basic units of the biosphere and refer to the large
geographical region with a particular climax community. It organizes
the Earth's biological communities based on dominant vegetation,
geographic location, climate, and other factors.
Aspects of the physical environment include
precipitation, temperature, and water depth, which have a strong
influence on species' traits living in that environment. Geographically,
the same biome can occur in distinct areas with similar climates.

This chapter comprises two modules, which include terrestrial

and aquatic biomes, including learning activities.

Chapter Content:
❖ Terrestrial Biome
❖ Aquatic Biome
Terrestrial Biome

INTRODUCTION

Terrestrial Biomes are large-scale environments that are characterized by

temperature ranges and amounts of precipitation that affect the types of vegetation and
animal life that can exist in those areas. In this module, different types of terrestrial biomes
will be given emphasis.

OBJECTIVES
Upon completion of this module, you will be able to:
1. identify the two major abiotic factors that determine terrestrial biomes; and
2. recognize distinguishing characteristics of each of the eight major terrestrial
biomes.

LESSON PROPER
Watch the video clip 2020: The Year Everything Changes | Earth Hour 2020 at
the link https://www.youtube.com/watch?v=m9BHs-zj3tc.
Terrestrial Biomes are characterized ecosystems on land and are usually
identified by the growth form of the dominant vegetation, climate, and location on Earth.
The major terrestrial biomes include the tundra biome, the forest biome, the grassland
biome, and the desert biome.
The coldest of all the biomes is the Tundra Biome. It comes from the Finnish word
Tunturi which means “treeless plain." It is a region that lies south of the Arctic and extends
across North America, Europe, and Siberia. In the Northern Hemisphere, the areas that
would be tundra are oceans. It is divided into two: The arctic and alpine tundra. Arctic
tundra is a cold, desert-like condition and is located in the northern hemisphere, while
Alpine tundra is found on mountains throughout the world at high altitude where trees
cannot grow.
 (Photo Credit: earthobservatory.nasa.gov/biome)

A tundra biome is characterized by permafrost (permanently frozen ground), frost-

molded landscapes, extremely low temperatures, little precipitation, inadequate nutrients,
high winds, and short growing seasons. Mostly, lichens, mosses, grasses, sedges, and
low growing shrubs are prominent in this biome. Animals that can be found here are
reindeer, caribou, wolves, arctic hares, arctic foxes, snowy owls, and more.

Taiga (Boreal) Biome represents the largest terrestrial biome occurring south
across the tundra. Trees become more extensive and closer together, giving way to
evergreen forests. This belt of evergreen forest is found in the broad belt of Eurasia and
North America: two-thirds in Siberia with the rest in Scandinavia, Alaska, and Canada. It
has frigid winters and cool summers with moderate to low precipitation, and the growing
season is about 120 days. Mostly, evergreen trees (evergreen conifers with needle-like
leaves, such as pine, fir, and spruce) and a variety of animals in the summer
(woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks,
shrews, and bats).

(Photo Credit: letstalkscience.ca)

The Forest biome is dominated by trees and other woody vegetation and can be
classified according to numerous characteristics, with seasonality being the most widely
used. The most remarkable diversity of species characterizes the tropical Rainforest.
They occur around the equator, where the climate is uniform throughout the year. It is
typically warm and moist. Different species of trees are found with large and
broadleaves, thick vines, and many epiphytes attached to the tree trunks. Also, many
animal species inhabit the rainforest like snakes, lizards, frogs, lemurs, sloths, monkeys,
colorful birds, and insects.

(Photo credit: climatecentral.org/tropical-forest)

 Varying amounts of rainfall characterize temperate Deciduous Forest. It can be
found in Europe and Eastern North America. It has moderate temperature and rain, long
winters, and seasonal animals. Common trees are oak, maple, hickory, chestnut,
shrubs, small trees, herbaceous plants, ferns, lichens, and mosses. Animals include
wolves, gray foxes, bobcat, deer, squirrel, and more.

(Photo Credit: tes.com/lessons/yD4FaAYmLwnBeg/deciduous-forest)

Watch the video entitled “Our Planet: Forest” at the link

https://www.youtube.com/watch?v=JkaxUblCGz0.

Grassland Biome is dominated by grasses rather than large shrubs or trees and
occurs in temperate and tropical climates. This biome is characterized by hot summer
and cold winter, moderate to low precipitation, mostly grasses and small shrubs, and
large mammals or a variety of smaller ones. The world’s grassland includes the
Savanna of South Africa, Steppes of Russia, Pampas of South America, and Prairies of
North America.

(Photo Credit: biomegrasslandinfo.weebly.com)

Desert Biome occurs in hot and dry climate; the soil is sandy and poor. It is
characterized by considerable amount of specialized vegetation, specially cacti, and
dominant animals include species of reptiles (snakes, lizards), insects, scorpion, and
rodents.

(Photo Credit: nationalgeographic.org/encyclopedia/desert-biome)

Aquatic Biomes

INTRODUCTION

Aquatic biomes are characterized ecosystems in the marine environment. Light

Intensity, amount of dissolved gases in water, and the availability of organic and
inorganic nutrients are the factors that affect marine life. In this module, different types
of terrestrial biomes will be presented.

OBJECTIVES
Upon completion of this module, you will be able to:
1. describe the effects of abiotic factors on the composition of plant and animal
communities in aquatic biomes;
2. compare and contrast the characteristics of the ocean zones; and
3. summarize the characteristics of standing water and flowing water freshwater
biomes.

LESSON PROPER
Aquatic Biome is classified into two categories – the marine and freshwater
biomes. The water depth generally distinguishes marine biomes and whether there is a
substrate on which organisms can attach. It has three types – the ocean, coral reefs,
and estuaries.

a. Oceans
Watch the video entitled "Best Ocean Life 2020: Amazing Underwater Marine
Life” at the link https://www.youtube.com/watch?v=vgqRfD5Mco0
 Oceans are huge bodies of water (more than 70%) that dominate the Earth's surface
and are considered the largest of all the ecosystems. Organisms include benthos,
planktons, and nektons. Benthos lives in the ocean floor like clams, starfish, and snails;
Planktons are small organisms floating near the surface and are carried by current like
protozoa, algae, tiny crustaceans; and Nektons are free-swimming organisms like fishes,
squid, turtles, whales.

Oceans are separated into different zones - the intertidal, pelagic, abyssal, and
benthic zones, which have a great diversity of species.

When the ocean meets land, it is the intertidal zone where high, and low tide
occurs. Because of this, communities are constantly changing. Beneath the intertidal
zone is the neritic zone. Neritic Zone extends to depths of about 200 m at the edge of
the continental shelf, where photosynthesis occurs. It is characterized with well-
oxygenated water, contains silt, low in pressure, and has a stable temperature. Mostly,
phytoplankton and floating Sargassum (marine seaweed), zooplankton, protists, small
fishes, and shrimp are found in the neritic zone, the base of the food chain for most of the
world's fisheries.
 The pelagic zone is the open ocean. Within this realm, there is thermal
stratification. The photic zone is a part of the sea, approximately 200 m, where light can
penetrate. A depth greater than 200 m is the aphotic zone where light cannot penetrate.
The flora found in this zone includes surface seaweeds, and the fauna consists of many
fish species and some mammals, such as whales and dolphins.

Beneath the pelagic realm is the benthic zone. It is the deep-water region beyond
the continental shelf, consisting of sand, silt, and dead organisms. The temperature
decreases as depth increases towards the abyssal zone since light cannot penetrate
deeper water. It has a high level of nutrients wherein diverse fungi, sponges, sea
anemones, marine worms, sea stars, fishes, and bacteria exist.

Abyssal zone is the deepest part of the ocean, characterized by very low
temperature, very high pressure, high oxygen content, and low nutrient content. Mid-
ocean ridges, often with hydrothermal vents, are found in the abyssal zones and the
ocean floors. Chemosynthetic bacteria used the hydrogen sulfide and other minerals
emitted from the vents, thus the start of the food web as invertebrates and fishes eat
them.

b. Coral reefs
Coral reefs are one of the most diverse ecosystems globally and widely distributed
in warm shallow waters, tropical seas, and others in the cold, dark depths of the ocean.
Corals are the dominant organisms in coral reefs. Corals consist of both algae
(zooxanthellae) and animal polyps responsible for building reefs.
 Tubbataha Reefs Natural Park, Palawan (Photo credit: tubbatahareefs.org)

Coral reefs are considered as the rainforest of the sea and can be found as barriers
along continents, fringing islands, and atolls.

Watch the video entitled “Explore One of the Most Pristine Coral Reefs in the World
| National Geographic” at the link https://www.youtube.com/watch?v=g-FNhg_K2lc. It
shows the beauty of Tubbataha reefs in Palawan.

The "Coral Triangle" is the most extensive coral reef ecosystem in the world, and
found as part of different countries like the Philippines, Indonesia, Malaysia, Papua New
Guinea, the Solomon Islands, and Timor-Leste.

c. Estuaries
Estuaries are areas where freshwater merge with the ocean with such different salt
concentrations creates a fascinating, diverse, and unique ecosystem. It forms protected
areas for many of the young offspring of crustaceans, mollusks, and fish to begin their
lives. The significant factor that influences this organism to adapt to this kind of
ecosystem is salinity.
 Another aquatic biome is the Freshwater Biomes. Watch the video entitled
“Planet: Freshwater at the link https://www.youtube.com/watch?v=R2DU85qLfJQ.

Freshwater Biome includes standing water (lakes and ponds), flowing water
(rivers and streams), and wetlands. They have a low salt concentration and are generally
distinguished by characteristics such as water depth.

a. Ponds and Lakes

These areas vary in size from just a few square meters to thousands of square
kilometers. Ponds last only for a couple of months, while lakes may exist for hundreds
of years or more. They are divided into three different "zones," which are usually
determined by depth and distance from the shoreline.

Kayangan Lake, Coron, Palawan Pinatubo Crater Lake, Botolan, Zambales

(Photo Credit: Haundreis of flickr.com) (Photo Credit:Darren A. of flickr.com)

The topmost zone near the shore of a lake or pond is called the littoral zone. It is
the warmest since it is shallow and can absorb more of the Sun's heat. It sustains a
relatively diverse community of algae species, rooted and floating aquatic plants, snails,
clams, insects, crustaceans, fishes, and amphibians. These vegetation and animals are
the base food for other organisms, such as turtles, snakes, and ducks.

The limnetic zone is near-surface open water, well-lighted, and is dominated

by planktons. The profundal zone is the cold, deep-water part of the lake/pond. It is where
plankton falls into when they die.
 b. Streams and Rivers
Rivers and streams are bodies of continuously flowing water that carry large amounts of
water from the source (headwater). The source water is characterized as cold, low in
nutrients, and transparent. From the source water, the river or stream flows away
where the width of the channel gradually widens and the current slows, and travels
through the opening. The water becomes warmer and murky from all the sediments that
it has picked upstream as it is near the mouth (opening).

Panguil River, Laguna Hinatuan Enchanted River, Surigao Del Sur

(Image credit: jojo nicdao of flickr.com) (Image credit: 2il org of flickr.com)

c. Wetlands
Wetlands are characterized with areas in which the soil is either permanently or
periodically saturated with water. It is composed of shallow bodies of water like marshes,
swamps, and bogs. The vegetation consists of plants rooted in the soil but has portions
of leaves, stems, and flowers extending above the water's surface.

Candaba Swamp, Pampanga Agusan Marsh, Agusan del Sur

(Photo Credit: allanbarredo of of flickr.com) (Photo Credit by Rhea Arjona)