Key Concepts in Ecology, Biogeography, and Population Dynamics

Fundamental Concepts in Ecology and Biogeography

Ecosystem Structure and Energy Flow

Tidal Amplitude

The difference between the levels of high tide and low tide. This measurement varies based on depth, the volume of the water basin, and coastal morphology.

Gross Primary Production (GPP)

The total amount of energy fixed by autotrophic organisms (or organic matter produced) per unit of time.

Net Primary Production (NPP)

The quantity of energy or organic matter stored per unit of time, representing the remaining biomass after respiration.

Secondary Production

The amount of energy (or organic matter) fixed or assimilated by animals and other heterotrophic organisms.

Gross Secondary Production (GSP)

The total amount of energy absorbed by an animal per unit time.

Net Secondary Production (NSP)

The amount of energy accumulated in the animal organism per unit time (representing biomass increase).

Productivity

In an ecosystem, productivity is the relationship between net production and the initial biomass over a unit of time. It is typically expressed as:

(Net Production / Biomass) x Unit of Time

Global and Regional Biological Systems

Biosphere

The part of Earth where life exists.

Biome

A large-scale ecosystem that has reached a maximum state of development and balance, primarily conditioned by climatic factors.

The biosphere is composed of two main interacting components:

• The biocoenosis (or community): All living things.
• The biotope (or habitat): The physical living space where the community develops.

This forms a biological system where living things are interrelated and connected to their surrounding physical environment, a system known as the ecosystem.

Geographical Features and Hydrology

Deltas

Accumulations of mud and sediment at the mouth of a river. Conditions favoring delta formation include:

• Low wave energy (absence of heavy swell).
• Minimal tidal currents.
• Shallow river beds.
• Rivers carrying significant sediment loads.

Rivers

Stable watercourses characterized by constant, non-seasonal flow channels. They have variable lengths and slopes depending on the section of the course:

• Upper Course: Erosion predominates.
• Lower Course: Sedimentation predominates.

Population Ecology and Life Strategies

r-Strategy (r-Selection)

A survival strategy characterized by ensuring survival through high reproductive rates. Typically found in small, short-lived organisms.

K-Strategy (K-Selection)

A survival strategy characterized by living in stable environments, slow individual development, and lower mortality rates.

Ecological Valence (Tolerance)

The margin of an environmental factor (e.g., temperature, salinity) that a species is capable of tolerating or surviving within.

Population Dynamics Terminology

Natality (Birth Rate)

The number of individuals born per unit time. This includes realized natality (actual births) and potential natality (maximum possible births).

Immigration

The number of individuals joining a population from other populations.

Mortality (Death Rate)

The number of individuals who die in a population. This includes potential mortality (theoretical maximum death rate).

Emigration

The number of individuals leaving the population to move to other ecosystems.