Ecosystem Fundamentals: Biocenosis, Trophic Levels and Succession
Ecosystem Fundamentals
An ecosystem is the set formed by the populations of different species living in a particular place, interconnected with their physicochemical characteristics.
Biotope
The biotope is the physical environment where organisms live, defined by its physicochemical conditions. Key elements include:
- Energy
- Minerals
- Substrate
- Environment and environmental conditions
Biocenosis (Community)
Biocenosis, or a community, consists of populations of different species that live together and establish biotic relationships among themselves.
Ecological Niche and Habitat
- Ecological Niche: The set of strategies developed by a species to obtain food and the ranges of tolerance to various environmental factors. It represents the species' functional role, where competition may occur.
- Habitat: The set of sites where a species inhabits or would inhabit. It is equivalent to the physical location.
Trophic Levels
A trophic level refers to the group of organisms in a community that are nourished in the same way, occupying the same position in a food chain. They are classified as:
- Producers
- Primary consumers
- Secondary consumers
- Tertiary consumers
- Decomposers
Biomass and Production
- Biomass: The mass of living organisms per unit area (land) or volume (water), expressed in g/cm² or g/cm³.
- Production: The increase in biomass per unit time (e.g., mg/cm³/day or kg/ha). It represents the organic matter provided by one trophic level to the next. It can be primary or secondary, and net or gross.
- Productivity: The relationship between biomass and production. Smaller organisms with shorter lifespans and rapid reproduction are generally more productive.
Food Pyramid
The food pyramid is a graphical representation of the trophic levels of an ecosystem. Each level is represented by a rectangle, with the size corresponding to biomass, production, or the number of individuals.
Ecological Succession
Ecological succession refers to the gradual changes in the species composition of a community over time in response to environmental changes. The climax stage is reached when the community remains stable over a long period.
Types of Succession
- Primary: Occurs in places where no life has existed before. It begins with pioneer species, followed by shrubs, and finally trees.
- Secondary: Occurs in places where previous communities existed but have been partially or completely altered.