Living organisms in a forest fall into three different categories, the forest relies on the services that each of these groups provides.
- Producers
- Consumers
- Decomposers
Consumers in a forest ecosystem are also called heterotrophs because they cannot produce their own “food” as producers do. Instead, they rely on producers and other consumers as a food source.
There are three types of consumers in a forest ecosystem ranked in order of how far away they sit energetically from producers:
Let’s now cover each of the types of consumers more in-depth.
Primary Consumers
A primary consumer is an organism that eats producers for a food source. These organisms are herbivores because they only eat green things. Primary consumers occupy the lowest trophic level of the three types of consumers. If you’d like to learn more about trophic levels, check out the article “Food Chains in a Forest Ecosystem”.
Primary Consumer Example
There are many primary consumers in a forest ecosystem, including:
- Mice
- Butterflies
- Deer
- Squirrels
- Rabbits
- Grasshoppers
For this article, let’s look at a rabbit as a primary consumer. The rabbit is a primary consumer because it eats plants. For example, if the rabbit eats a dandelion, it is ingesting the sugars that the dandelion has produced via photosynthesis, and the rabbit turns these sugars into energy for itself via its metabolic processes.
Secondary Consumers
A secondary consumer is an organism that ingests primary consumers as its main food source. These organisms may also eat producers–they may be omnivorous–but can also be carnivores and only eat other consumers.
Secondary Consumer Example
There are generally fewer secondary consumers in a forest ecosystem than primary consumers because there is fewer resources/energy available to them than the amount of energy available to primary consumers.
Some secondary consumers that the forest relies on are:
- Frogs
- Snakes
- Foxes
- Moles
For this example, let’s look at a snake as a secondary consumer. The snake is a secondary consumer when it eats the rabbit. (Remember, the rabbit is a primary consumer because it ate a dandelion.) The snake digests the rabbit and turns it into energy for itself.
Tertiary Consumers
Tertiary consumers are organisms that eat secondary consumers. These consumers occupy the top spot in the food chain–the highest trophic level–and can also be called the “apex predators” of the forest.
Tertiary Consumer Example
Tertiary consumers are usually any large predator like:
- Birds of Prey
- Grizzly bears
- Wolves
Going back to our snake and rabbit example, let’s look at where a hawk might fit into the equation. A hawk eating a snake is a tertiary consumer because the snake is a secondary consumer. The hawk ingests the snake and turns the energy the snake gained from the rabbit (and indirectly, the dandelion) into energy for itself.
Conclusion
- Consumers are responsible for ingesting other organisms to gain energy.
- The three categories of consumers are primary, secondary, and tertiary and they are organized by how far away they sit from the source of energy (the sun).