The ecosystem concept

The first principle of ecology is that each living organism has an ongoing and continual relationship with every other element that makes up its environment. An ecosystem can be defined as any situation where there is interaction between organisms and their environment.

The ecosystem is composed of two entities, the entirety of life, the biocoenosis, and the medium that life exists in, the biotope. Within the ecosystem, species are connected by food chains or food webs. Energy from the sun, captured by primary producers via photosynthesis, flows upward through the chain to primary consumers (herbivores), and then to secondary and tertiary consumers (carnivores and omnivores), before ultimately being lost to the system as waste heat. In the process, matter is incorporated into living organisms, which return their nutrients to the system via decomposition, forming biogeochemical cycles such as the carbon and nitrogen cycles.

The concept of an ecosystem can apply to units of variable size, such as a pond, a field, or a piece of dead wood. An ecosystem within another ecosystem is called a microecosystem. For example, an ecosystem can be a stone and all the life under it. A meso ecosystem could be a forest, and a macro ecosystem a whole eco region, with its drainage basin.

Unit 13 Energy

1 Introduction

1.1 Read the text title and hypothesize what the text is about. Write down your hypothesis.

1.2 What do you know concerning this issue? List your ideas in the table left column “I know”.

I know that...	I have learnt that...

3. If you know answers to these questions write them down in the space given after each question.

1	How can we define the term “energy”?
2	What are the main energy sources?
3	What are renewable sources of energy?
4	What is the difference between renewable and non-renewable sources of energy?
5	How many types of energy do you know?
6	Which energy sources do we most commonly use?
7	What negative consequences does the extraction of fuel produce?