UNIT 3 NATURAL SCIENCE: ECOSYSTEMS

WHAT IS AN ECOSYSTEM?

An ecosystem consists of all the organisms living in one place, as well as the physical environment they live in. Organisms in an ecosystem interrelate with each other. For example, a dessert is an ecosystem that consists of all the living things that live there (camels, lizards, snakes, cactuses,...), the physical environment (sand, rocks and air), and the interrelationships among the living things and the environment.

Ecosystems come in all shapes and sizes. They can be as small as a terrarium in your room or as big as an ocean.

ECOSYSTEM = PHYSICAL ENVIROMENT + LIVING THINGS (fauna and flora)

PHYSICAL ENVIRONMENT

The physical environment is made up of the non-living components in an ecosystem. It includes:

• Non-living things, such as rocks, water and air.
• Factors that affect living things, such as temperature, humidity and light.

In our planet we can find two types of physical environments:

• Terrestrial environments: these are found on land and are surrounded by air.
• Aquatic environments: these can be freshwater environments, such as rivers and lakes, or saltwater environments, such as seas and oceans.

LIVING THINGS

The living things in an ecosystem are all the animals, plants and other living things, such as algae, fungi and bacteria.

Every ecosystem has a particular fauna and flora:

• FAUNA: all animals in a ecosystem.
• FLORA: all plants in a ecosystem.

All living things are grouped into species. All organisms of one species in an ecosystem make up a population. All the populations in an ecosystem make up a community.

TERRESTRIAL ECOSYSTEMS

Terrestrial ecosystems are located on land and are surrounded by air. There are different types of terrestrial ecosystems:

• FORESTS: are ecosystems with many trees and various animals like birds, owls, foxes, squirrels... There are different types of forests depending on the climate:
• ATLANTIC FORESTS: these grow in regions with a humid climate and cool summers.
• MEDITERRANEAN FORESTS: these grow in regions with a dry climate and warm summers.
• MOUNTAIN GRASSLAND: are herbaceous. They grow in humid regions with cold winters and are home to animals like butterflies, grasshoppers, ladybirds and deers.
• DESERTS AND STEPPES: deserts and steppes are found in very dry regions with extreme temperatures. Living things in these ecosystems have adapted to several conditions. Typical plants include herbaceous plants and cactucses. About animals, we can find lizards, scorpions, mice,...

AQUATIC ECOSYSTEMS

Aquatic ecosystems are located in water enviroments. Depending on salinity we can find 2 types of aquatic ecosystems:

• Marine ecosystems or saltwater ecosystems: they have high salinity. Water in these ecosystems is in constant movement due to waves and currents. Some saltwater ecosystems are:
• Sandy beaches
• Rocky shores
• Open sea
• Freshwater ecosystems: has very low salinity. For example:
• Rivers
• Lagoons