Ecosystem Components: Biotope & Biocoenosis Explained

Biotope: The Foundation of Ecosystems

The biotope refers to the main components that determine the presence of living organisms: the medium and environmental (physical and chemical) factors.

The Medium

The medium is the place where living organisms reside and interact within an ecosystem, maintaining constant exchanges of matter and energy. Broadly speaking, we can distinguish two primary types of media:

• Terrestrial Medium: Located on the surface of continents, characterized by direct contact with the atmosphere.
• Aquatic Medium: Consists of water and is characteristic of aquatic ecosystems.

Abiotic Environmental Factors

Abiotic environmental factors encompass all physical and chemical conditions of the biotope. This set of external conditions significantly affects the lives and development of living beings. Some key factors include:

• Light: Influences the proliferation of photosynthetic organisms.
• Water: Essential for most living things, though adaptations exist for arid environments.
• Temperature: The average temperature and its fluctuations.
• Salinity: Particularly important in aquatic environments, such as ocean waters.
• pH: Depends on the composition of elements that form the soil.

Habitat

The habitat of a species is the specific physical place it occupies within an ecosystem that satisfies the conditions necessary for its survival.

Biocoenosis: Interacting Life in Ecosystems

The biocoenosis of an ecosystem is composed of different populations of various species that interact with one another. All individuals of the same species inhabiting a particular place are collectively called a population.

Ecological Niche

The ecological niche is the specific role a species plays within an ecosystem. It encompasses different dimensions, such as physical space and food resources. To understand the role of a species within an ecosystem, we need to examine its way of life: its food sources, its reproductive cycle, and its interactions.

The potential niche is the role a species would occupy without considering interactions with other species in the community. The realized niche is the actual role a species occupies, as interactions with other organisms often lead to overlapping areas that reduce the potential niche.

Organisms that can adapt to very different ways of life and tolerate varied environmental conditions are called generalists (e.g., rats, pigeons, gulls). Conversely, species whose ecological niche is very narrow and are limited to a very specific habitat are called specialists.

Population Dynamics

The growth rate value of a given population determines whether it experiences expansion, stability, or decline. Key characteristics used to describe population dynamics include:

• Population Size: The total number of individuals.
• Ecological Density: The number of individuals per unit area or volume.
• Birth Rate: The number of births per unit time.
• Death Rate: The number of deaths per unit time.
• Immigration Rate: The rate at which individuals enter the population from elsewhere.
• Emigration Rate: The rate at which individuals leave the population to go elsewhere.

The evolution of populations can be represented by pyramids, where each level is proportional to the number of individuals included in a particular age range.