Fundamentals of Ecology: Ecosystems and Environmental Factors
Ecological Pyramids: Structure and Representation
The ecological pyramid is a form of representation used to show how various characteristics of trophic levels, such as production or biomass, change when moving from one level to another.
Each trophic level is represented by a rectangle. The rectangle forming the base of the pyramid represents the producers (manufacturers), whose resources are available to other trophic levels. The length of the base of each rectangle is proportional to the measured characteristic value.
Types of Ecological Pyramids
- Production (Energy)
- Biomass
- Numbers
Key Abiotic Factors in Terrestrial Ecosystems
Abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Key abiotic factors related to soil include:
- Soil Texture: Sandy, clay, and mixed soils.
- Water and Air: Essential components needed within the soil structure.
- Chemical Composition: Factors like salinity (salty soil) or pH (neutral soil).
1. Defining Core Ecological Concepts
The Biotope and Biocenosis
A biotope is the place or physical environment occupied by a community (or biocenosis). Each biotope is characterized by well-defined environmental conditions, such as light or moisture.
Population and Community
In a natural area, living organisms of different species exist. A group of individuals of the same species living in a particular area is called a population. For example, in a pond, there are populations of different types of algae, dragonflies, or frogs. The set of populations living in a particular area is known as a community or biocenosis.
Understanding the Ecosystem
It is amazing the variety of species living in a pond, all of which are adapted to survive and reproduce in the special conditions of that particular biotope. What is perhaps most surprising is seeing how these species relate to each other and to the physical environment that surrounds them, and the many different ways they do so.
An ecosystem encompasses the entire community (biocenosis) and the biotope where it lives. It also includes the interactions established between different organisms and with their environment. A pond is a classic example of an ecosystem.
What is Ecology?
Ecology is the science that studies the interactions between living beings and other organisms, as well as the interactions between them and the physical-chemical environment around them.
2. Environmental Factors and Habitat Definition
Defining Habitat
The habitat of an organism or species is the specific type of place where it finds the necessary conditions to live. The environment of that organism includes all the factors or conditions that exist in the place where it lives and affects it at some point in its life.
Types of Environmental Factors
These environmental factors are generally categorized as:
- Biotic Factors: (From bios, meaning “life”). These factors arise as a result of the presence of other living beings, such as competition for food or space, or mutual aid (symbiosis).
- Abiotic Factors: (From a-, meaning “no,” and bios, meaning “life”). These are factors not directly related to living things, although they can modify biological activity. Examples include humidity, light, temperature, the amount of oxygen in water, or soil texture.
Limiting Factors and Tolerance Limits
Species exhibit varying needs; some thrive in high humidity, while others require low humidity. Similarly, some species live in warm places, and others in cold climates.
The Optimum Range and Tolerance
For any given environmental factor, each species has an optimum area in which it grows fastest, produces more offspring, and where those offspring survive better. As the value of this factor moves away from the optimum in either direction, the organism’s ability to leave descendants is limited, though it still survives.
If the factor exceeds a certain threshold—the limit of tolerance—survival of the organisms becomes impossible, and the population may disappear.
Temperature is an abiotic factor that affects the habitat of many organisms.
Defining Limiting Factors
If the value of a particular factor is not optimal, it can restrict the growth, reproduction, and even the survival of a population. Factors that hinder the growth of a population are therefore called limiting factors.
One factor may be limiting for a species, while for the other this same factor can promote growth.
The habitat is the kind of place where an organism lives and, by extension, a species. A habitat must possess the environmental conditions that a species needs to live.