Lesson 1 of 11 · 5 min

Ecosystem: meaning and types

NCERT §12 (introduction)

A new term starts, and Ma'am Deshpande tells the survey group they will look at the same lake again, but this time as one working machine rather than a list of species.

The story this chapter follows: Rohan's lake as one machine

Rohan, the Class 12 student from Pune who spent last term counting populations at a lake near school, goes back with the same survey group. This time Ma'am Deshpande wants them to see the lake, a forest reserve, a compost heap and the school canteen as working ecosystems, with energy coming in and matter going round. Each visit is one part of this chapter.

The lesson in notes

In short

An ecosystem is a functional unit of nature in which living organisms interact with each other and with their physical surroundings.

An ecosystem can be as small as a pond or as large as a whole forest or sea.

Many ecologists treat the whole biosphere as one global ecosystem, made up of all the local ecosystems on Earth.

Since the biosphere is too large and complex to study at once, it is divided into two basic kinds: terrestrial and aquatic.

Terrestrial examples: forest, grassland, desert. Aquatic examples: pond, lake, wetland, river, estuary.

Crop fields and an aquarium count as man-made ecosystems.

The chapter follows the input (productivity), the transfer of energy (food chains and webs) and the output (degradation and loss of energy).