Ecosystem Basics: Trophic Levels, Food Webs, and Cycles
Trophic Nutrition and Food Chains
What is Trophic Nutrition?
Trophic nutrition refers to the feeding process or alimentation.
What is a Food Chain?
A food chain describes the feeding relationships between different species.
Why Are Food Chains Not Linear?
Food chains are not linear because some species are consumed by multiple others, connecting with other networks and forming what is called a trophic web (or trophic mesh).
Understanding Trophic Levels
Trophic levels group species based on common food sources, operating on a basic food source in a similar manner.
Main Trophic Levels:
- Producers
- Primary Consumers
- Secondary Consumers
- Higher Consumers (Tertiary/Quaternary)
- Decomposers
Who are the Producers?
Producers are organisms, primarily green plants, that create their own food.
Who are the Primary Consumers?
Primary consumers are herbivores, feeding directly on producers.
Who are the Secondary Consumers?
Secondary consumers include carnivores, certain insects, and parasites that feed on primary consumers.
Who are the Top Consumers?
Top consumers (or tertiary/quaternary consumers) include predators, certain insects, and hyperparasites.
Who are the Decomposers?
Decomposers are organisms like bacteria, fungi, microorganisms, certain insects, and protozoa that break down dead organic matter.
Ecosystems and Environmental Factors
What is the Fundamental Unit of the Biosphere?
The fundamental unit of the biosphere is the ecosystem.
Defining Biotic and Abiotic Factors
Sunlight as an Abiotic Factor:
Sunlight is the main source of energy, directly and indirectly, that sustains the ecosystem.
Water as an Abiotic Factor:
Water permits the classification of the environment into two main habitats: aquatic and terrestrial.
Substrate as an Abiotic Factor:
The substrate is the surface upon which living beings exist, and which can be modified by them.
Autotrophs and Heterotrophs
What are Autotrophs?
Autotrophs are organisms that produce their own food. Example: Plants
What are Heterotrophic Organisms?
Heterotrophic organisms feed on external sources, utilizing and decomposing complex materials. Example: Consumers
Climate and Ecosystem Dynamics
What is Climate?
Climate is a set of abiotic factors that determine the thermal characteristics and influence ecosystem dynamics.
Disintegrating Elements (Decomposers Revisited)
Disintegrating elements, such as bacteria, fungi, and protozoa, simplify and then absorb compounds from dead organic matter.
Ecosystem Equilibrium
An ecosystem is considered to be in equilibrium when all living things within it have the opportunity to feed, socialize, and reproduce uninterruptedly.
Ecological Relationships
There are two main kinds of relationships between living things: intraspecific and interspecific.
Intraspecific Relationships
Intraspecific relationships occur between members of the same species.
Interspecific Relationships
Interspecific relationships occur between two or more different species.
Example of Intraspecific Relationship:
A pride of lions demonstrates an intraspecific relationship.
Example of Interspecific Relationship:
The relationship between bees and flowering plants is an example of an interspecific relationship.
Types of Interspecific Relationships
Predation:
Predation is a feeding relationship where one organism (the predator) hunts, captures, and devours another organism (the prey). Example: Wolf and Hare
Mutualism:
Mutualism is a compulsory, dependent association between two organisms of different species in which both benefit. Example: Leguminous plants and bacteria
Parasitism:
Parasitism is an association between different species where one benefits (the parasite) and the other is harmed (the host). Example: Fleas on dogs
Herbivory:
Herbivory is the consumption of plants by animals, comparable to predation.
Amensalism (or Antibiosis):
Amensalism is a non-dependent relationship between organisms of different species where one organism (the amensal) is harmed, while the other (the host) is neither benefited nor harmed.
Competition:
Competition is the struggle for survival between organisms of the same species (intraspecific) or different species (interspecific).
Neutralism:
Neutralism is an interspecific relationship in which organisms of one species occupy a niche without significantly affecting another, even if resource appeal is limited.
Commensalism:
Commensalism is a non-dependent association between organisms of different species where one organism (the commensal) benefits, and the other (the host) is neither benefited nor harmed.
Biogeochemical Cycles
What is a Biogeochemical Cycle?
A biogeochemical cycle represents the trajectories, movements, and more or less recurrent conversion of chemical elements, energy, and matter through biochemical activity between organisms. These cycles occur on a global scale, profoundly affecting our planet’s current environment.
Examples of Biogeochemical Cycles:
Here are six examples of biogeochemical cycles:
- Water Cycle (Hydrologic Cycle)
- Nitrogen Cycle
- Carbon Cycle
- Sulfur Cycle
- Phosphorus Cycle
- Silicon Cycle