The Earth’s Ecosystems

Land Ecosystems – The Earth’s Biomes

A biome is a geographic area characterized by certain types of plant and animal communities which are determined by the abiotic, or nonliving factors in the area. A biome contains a number of smaller but related ecosystems. For example, a tropical rainforest is a biome that contains river ecosystems, treetop ecosystems, forest-floor ecosystems, and many others.

A biome is NOT a specific place. For example, a desert biome does not refer to a particular desert. A desert biome refers to any and all desert ecosystems on the Earth.

ForestsForest biomes develop where there is enough rain and where the temperature is not too hot in the summer or too cold in the winter. There are 3 main types

of forest biomes. The type of forest that develops depends on the area’s temperature and rainfall.

Temperate Deciduous Forests contain several different species of trees and support a variety of animals, such as bears and woodpeckers. Trees that are deciduous, which comes from a Latin word meaning “to fall off”, lose their leaves in the fall which allows them to conserve water in the winter.

Average Temperature: Summer: 28C (82.4 F) Winter: 6C (42.8 F)Average Yearly Rainfall: 75 – 125 cm (29.5 – 49 in.)

ForestsConiferous Forests do not change very much from summer to

winter. They are found in areas with long cold winters and consist mainly of evergreen trees which are trees that don’t lose their leaves and stay green all year. Most of these trees are conifers: trees that produce seeds in cones. A coniferous forest is home to many insects, birds, moose, deer, fox, and lynxes.Average Temperature: Summer: 14C (57.2 F) Winter: -10C (14 F)

Average Yearly Rainfall: 35 – 75 cm (14 – 29.5 in.)

ForestsTropical Rain Forests have more biological diversity than

any other biome on the planet = it contains more species than any other biome. A huge variety of animals live in the canopy, or treetops of the forest. Most of the nutrients in a tropical rain forest biome are in the vegetation.

Average Temperature: Daytime: 34C (93 F) Nighttime: 20C (68 F)Average Yearly Rainfall: Up to 400 cm (157.5 in.)

GrasslandsGrasslands are regions where grasses are the major type of vegetation. Names for these regions are: plains, steppes, savannas, prairies, pampas. Gasslands are found between

forests and deserts. They exist on every continent. Most grasslands are flat or have gently rolling hills.

Temperate Grassland vegetation is mainly grasses mixed with a variety of flowering plants. Fires prevent the growth of most slow-growing plants like trees. Temperate grasslands support small, seed-eating mammals, such as prairie dogs and mice, and large herbivores, such bison.Average Temperatures: Summer: 30C (86 F) Winter: 0C (32 F)

Average Yearly Rainfall: 25-27 cm (10-29.5 in.)

GrasslandsThe Savanna is a tropical grassland with scattered clumps of trees. During

the dry season, the grasses die back but the roots survive. During the wet season, the savanna may receive as much as 150 cm of rain. The savannas of Africa are home to the most abundant and diverse groups of large herbivores in the world: elephants, giraffes, zebras, gazelles, and wildebeats.

Average Temperatures: Dry Season: 34C (93 F) Wet Season: 16C (61 F)Average Yearly Rainfall: 150 cm (59 in.)

DesertsDeserts are hot, dry regions

where most of the water that falls to the ground evaporates.

A variety of plants and animals that have adapted to limited water supply live in deserts. For example, some plants have shallow widespread roots to absorb water quickly during a storm, and most animals are active only at night when temperatures are cooler. Jack rabbits’ huge ears help them get rid of body heat. Kangaroo rats recycle water from the foods they eat.

Average Temperatures:Summer: 38C (100 F)

Winter: 7C (45 F)Average Yearly Rainfall:Less than 25 cm (10 in.)

TundraIn the far north, and on the tops of high mountains where the climate is so cold that no trees can grow is where we find a

biome called the tundra.Only the surface of the soil thaws during the short growing season of

the Arctic Tundra. The soil below the surface, the permafrost stays frozen all the time. This is the major feature of the arctic tundra. There is little rain, but the permafrost keeps the rainwater from draining; surface soil stays wet. Lakes and ponds are common.

Grasses, sedges, rushes, small woody shrubs, mosses, and lichens are common. Tundra animals include: caribou, musk oxen, wolves, lemmings, shrews, hares, and migratory birds in the summer.

TundraAverage Temperatures: Summer 12C (53.6 F) Winter: -26C (-

14 F)Average Yearly Rainfall: 30 – 50 cm (12 – 20 in.)

Alpine Tundra is found above the tree line of very high mountains. Alpine tundra receives a lot of sunlight and precipitation, mostly in the form of snow.

Marine Abiotic Ecosystems Factors RuleA marine ecosystem is one

that is based on salty water: oceans & seas

They cover almost ¾ of the earth’s surface and contain almost 97% of Earth’s water supply.

Marine ecosystems support a broad diversity of life, from some of the largest animals on earth, like the humpback whale, to microscopic creatures like phytoplankton.

Biodiversity in our oceans.

Like terrestrial biomes, marine biomes are shaped by abiotic factors.

Temperature, the amount of sunlight penetrating the water, the distance from land, and the depth of the water, are used to define certain areas of the ocean.

Water absorbs light, so sunlight can only penetrate about 200 m below the ocean’s surface.

Most producers use sunlight for photosynthesis, so most producers are found only where light penetrates. The most abundant producers in the ocean, called phytoplankton, are microscopic, photosynthetic organisms that float near the surface of the water.

Zooplankton are consumers that feed on phytoplankton. These small animals, along with phytoplankton, form the base of the ocean’s trophic relationships.

Major Ocean Areas(“Watery Biomes”)

The Intertidal Zone is the area where the ocean meets the land. This area is above water when the tide is out. Mud flats, rocky shores, and sandy beaches are all in the intertidal area.

Sea grasses, periwinkle snails, herons, sea stars, anemones, crabs, clams, and conchs are common in intertidal areas.

The next zone outward from shore is the Neritic Zone. The water becomes gradually deeper towards the edge of the continental shelf, but is generally less than 200 m deep and receives a lot of sunlight.

Producers in this area include phytoplankton and seaweed. Sea turtles, dolphins, corals, sponges, and colorful fish live here.

In the Oceanic Zone, past the continental shelf, the sea floor drops sharply. This is the deep water of the open ocean. Very little to no light penetrates, so most organisms obtain their energy by consuming organic material that falls from the surface.

Animals adapted for darkness and high pressures live here, like whales, squids, and fish that glow.

The Benthic Zone is the sea floor. It extends from the upper edge of the intertidal zone to the bottom of the deepest ocean waters. Organisms here obtain food mostly by consuming material that filters from above.

Some bacteria are chemosynthetic, which means they use chemicals in the water near thermal vents, a place on the ocean floor where heat escapes through a crack in the Earth’s crust, to make food.

A Closer Look…

Marine environments provide most of the water for Earth’s rainfall through evaporation and precipitation. Ocean temperatures and currents have major effects on world climates and wind patterns (El Nino & La Nina). Humans harvest enormous amounts of food from the oceans and dump enormous amounts of waste into them…..

El Nino - Ocean Current and Temperature - NOAA

Special Ocean EnvironmentsCoral reefs: Corals live in a close relationship with single-celled algae. The

algae produce organic nutrients through photosynthesis that provides food for the coral. The coral provide a place in the sun for the algae to live. Coral reefs are home to many marine species.

Sargasso Sea: In the middle of the Atlantic Ocean is a large ecosystem with no land boundaries – the Sargasso Sea. Sargassum is a type of algae, usually found attached to rocks, but it forms huge floating rafts in the Sargasso Sea. Many animals adapt to this environment and live among the algae.

Polar ice: The Arctic Ocean and the open waters surrounding Antarctica make up a marine biome that includes ice. The icy waters are rich in nutrients from the surrounding landmasses. These nutrients support large populations of plankton which support a great diversity of fish, birds and mammals.

Estuaries: Areas where fresh water from streams and rivers spills into the ocean are called estuaries. The fresh water is rich in nutrients. It supports large numbers of plankton, which provide food for many larger animals.

Intertidal Areas: mudflats, sandy beaches, rocky shores. Organisms that live here include: worms, crabs, shorebirds, clams, plankton, and sea stars among others.

Fresh Water EcosystemsLike other ecosystems, freshwater ecosystems are

characterized by abiotic factors, primarily the speed at which the water is moving.

Water on the MoveBrooks, streams, and rivers are ecosystems

based on moving water.Water begins flowing from melting ice or snow,

or it may come form a spring where water flows up to the surface of the earth. Each trickle or stream of water that joins a larger trickle or stream is called a tributary.

Fast moving water: As more tributaries join a stream, the stream becomes larger and wider, forming a river.

Aquatic plants line the edge of the river. Fish live in the open waters. Burrowers, such as clams and mussels make their home in the muddy bottom.

Organisms that live in moving water require special adaptations to avoid being swept away with the current. Some cling to rocks, live under rocks and some have suction disks to hold them to the rocks.

Slower water: As a river grows wider, it may meander back and forth across the landscape depositing organic material and sediment on the bottom building deltas. Dragonflies, water striders, and other invertebrates live in and on slow-moving water.

Still WatersPonds and lakes have different ecosystems than

streams and rivers. Lake Superior, the largest lake in the world, has more in common with a small beaver pond than with a river. Lakes are divided into three zones:

Littoral Zone: This is the zone closest to the edge of the land. Plants that grow here include: cattails, rushes, water lilies, and pond weeds. These plants provide a home for small animals such as: snails, small arthropods, and insect larvae. Clams, worms, frogs, salamanders, water turtles, fish and water snakes also live in this area.

Open-water Zone: This zone extends from the edge of the littoral zone across the top of the water and only goes as deep as light can reach. Bass, blue gills, lake trout, and other fish live here. Phytoplankton are the most abundant producers in the open-water zone.

Deep-water Zone: This zone is below the open-water zone, where no light reaches. Catfish, carp, worms, insect larvae, crustaceans, fungi, and bacteria live here. These organisms feed on dead organic material that falls from above.

WetlandsA wetland is an area of land where the water level is near or above the surface of the ground for most of the year. They

support a variety of plant and animal life and play an important role in flood control and replenishing underground

water supplies.

MarshesA marsh is a treeless wetland

ecosystem.Freshwater marshes are

found in shallow waters along shores of lakes, ponds, rivers , and streams.

Grasses, reeds, bulrushes, and wild rice are common marsh plants

Muskrats, turtles, frogs, and red-winged blackbirds are animals commonly found in marshes.

SwampsA swamp is a wetland ecosystem

where trees and vines grow.

Swamps are found in low-lying areas and beside slow moving rivers.

Most swamps are flooded only part of the year.

Trees include: willows, cypresses, oaks, and elms. Vines, such as poison ivy grow up the trees and Spanish moss hangs from the branches.

Swamps provide a home for a variety of fish, snakes and birds.