Forest Food Chain Trophic Levels

Forest Food Chain Trophic Levels Explained

Forest food chain trophic levels are; Level 1 (Producers), Level 2 (Primary Consumers), Level 3 (Secondary Consumers), Level 4 (Tertiary Consumers), Level 5 (Quaternary Consumers).

This article discusses the trophic levels of a forest food chain, as follows;







1). Level 1: Producers (as part of the Forest Food Chain)

Producers in a food chain generally refer to all organisms that are capable of manufacturing or producing their own food through biochemical and photochemical processes.

These organisms are also called autotrophs, and are responsible for introducing bioenergy into the forest ecosystem [3].

Bioenergy itself comes ultimately from the Sun, as the producers are usually equipped with chlorophyll pigmentation that enables them capture and convert solar energy to chemical energy through the process of photosynthesis.

Examples of producers in a forest are mosses, lichens, liverworts, and vascular plants like shrubs, and trees [2]. Among these, trees are the most dominant, and play a key role in determining the sustainability, organic species, soil and climatic conditions, as well as structure, of forests.

Some forest trees are; lodgepole pine, sandalwood, kheiri, douglas-fir, cast redwood, teak, oak, giant sequoia, and spruce. The particular trees that occur in a given forest, and their species-richness, depend on the geographic, climatic, and biological conditions of the area in question.

However, many terrestrial primary consumers depend on smaller plants like shrubs, for food.






2). Level 2: Primary Consumers

Trophic level two (2) is the first trophic level that is occupied by organisms which are incapable of producing their own food.

These organisms are generally called consumers, and they are heterotrophic, depending either directly or indirectly on the autotrophic producers for their food and energy.

Consumers range from primary and secondary to tertiary and quaternary (although most food chains and energy pyramids stop at tertiary consumers.

The difference between primary, secondary, tertiary and quaternary consumers in a forest ecosystem, lies in their range of food options; where the primary consumers have the narrowest range of options and the tertiary (and quaternary) consumers have the broadest range.

Primary consumers in a forest food chain are organisms that depend solely and directly on plants (producers) for food.

These organisms are described as herbivorous (or called herbivores) because their range of food options are all plant-based, and may include seeds, roots, leaves, and berries.

Examples of primary producers in a forest are; herbivorous rodents like squirrels, deer, beetles, locusts, caterpillars, and some birds.

Forest Food Chain Trophic Levels: Primary Consumers (Credit: Raul654 2005 .CC BY-SA 3.0.)
Forest Food Chain Trophic Levels: Primary Consumers (Credit: Raul654 2005 .CC BY-SA 3.0.)






3). Level 3: Secondary Consumers (as part of the Forest Food Chain)

Secondary consumers occupy trophic level three (3), which is directly above the herbivorous primary consumers of trophic level two.

These organisms are carnivorous, and their diet consists mainly of primary consumers, so that they derive bioenergy from plants through indirect energy transfer; with primary consumers as the mediators in the transfer sequence.

Secondary consumers are generally smaller in size and nutritional demand, than tertiary and quaternary consumers.

Examples of secondary consumers in toads, lizards, insectivorous birds, hawks and owls [1].

In temperate forests, secondary consumers may include racoons and skunks.






4). Level 4: Tertiary Consumers

In a forest ecosystem, the tertiary consumers include large carnivorous (and omnivorous) animals that feed on primary and secondary consumers.

This is the same for other ecosystems like tundras, deserts and grasslands.

In most ecological models, tertiary consumers occupy the highest trophic level; meaning that they are not prey to any other category of animals in the ecosystem.

Classifications like Apex Predators, Decomposers and Quaternary Consumers, are of found where there is high species diversity and complexity, so that the ecosystem contains multiple feeding relationships that cannot be summarized into four levels.

It must also be noted that the organisms classified as secondary, tertiary or quaternary consumers in any food chain model, depends on the range of organisms present in the ecosystem, and their dynamic relationships with each other.

This means that an organism classified as secondary consumer in one food chain could be classified (correctly) as a tertiary consumer in another food chain, provided there are other organisms beneath it that can be considered secondary consumers, relative to the organism in question.

Examples of some tertiary consumers in a forest are; leopard, jaguar, eagle, lynx, cougar and coyote. It must be noted that these examples range across tropical and temperate forest zones.

The tertiary consumers usually have a small population size compared to other trophic levels of a forest food chain. This can be explained by the fact that up to 90% total bioenergy is lost in each level, so that only about 10% is available to be transferred to the next, overlying level.

Their relative-small population size allows tertiary consumers to survive on other organisms which are more abundant, and ensures that the ecosystem is sustained.

Forest Food Chain: Jaguar as a Tertiary Consumer in Tropical Forest (Credit: USFWS 2004)
Forest Food Chain: Jaguar as a Tertiary Consumer in Tropical Forest (Credit: USFWS 2004)





5). Level 5: Quaternary Consumers (as part of the Forest Food Chain)

Quaternary consumers are organisms that can prey on tertiary consumers, as well as on organisms from all other trophic levels of the food chain aside producers. They may also be called Apex Predators.

In a forest, the quaternary consumers are determined based on available species, distribution, and ecological dynamics.

For example, leopards may be classified as quaternary consumers if the tertiary consumers are canines like jackals.

In forests with less ecologic diversity and complexity, quaternary consumers are not necessarily identified as a trophic of the food chain.







A forest food chain comprises of four to five trophic levels which are;

1. Level 1: Producers

2. Level 2: Primary Consumers

3. Level 3: Secondary Consumers

4. Level 4: Tertiary Consumers

5. Level 5: Quaternary Consumers







1). Beacom, B. (2018). "Food Chains in the Deciduous Forest." Available at: (Accessed 26 March 2023).

2). Dynesius, M.; Zinko, U. (2006). "Species richness correlations among primary producers in boreal forest." Diversity and Distributions 12(6):703 - 713. Available at: (Accessed 27 March 2023).

3). Wirtz, K. W.; Kerimoglu, O. (2916). "Autotrophic Stoichiometry Emerging from Optimality and Variable Co-limitation." Frontiers in Ecology and Evolution 4. Available at: (Accessed 27 March 2023).

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