Ecosystems exist on a variety of scales. An example of a small scale ecosystem (micro) is a pond. A medium scale ecosystem (messo) could be a forest. The tropical rainforest is an example of a very large ecosystem (biome).
Sunlight is the main source of energy. This allows plants to convert energy by photosynthesis. This provides food for some animals, birds and fish. These are called Herbivores. The other animals eat the animals that have eaten the plants. These are Carnivores. This process is called the FOOD CHAIN.
The World has many different ecosystems. Each one has its own climate, soil, plants and animals. Very few ecosystems are natural today because of human activities. More ecosystems are under threat than ever before and need protecting
The billions of species on our planet, including humans, interact with one another in many ways. These interactions among and between species are what define ecosystems. Ecosystems in turn, provide many "services" from which humans benefit. Ecosystem services are the transformation of a set of natural assets (soil, plants and animals, air and water) into things that we value. For example, when fungi, worms and bacteria transform the raw "ingredients" of sunlight, carbon and nitrogen into fertile soil this transformation is an ecosystem service. However, if we allow natural assets to decline, so do the benefits. Conversely, if we look after and maintain our natural assets, we will benefit from greater returns.