Chapter 7: Abiotic Components of Ecosystems

Abiotic and Biotic Components of an Ecosystem

• Abiotic components refer to the physical environment and its variables, including lithosphere, hydrosphere, atmosphere, and radiant solar energy.
• Biotic components comprise the living organisms, including autotrophs (producers) and heterotrophs (consumers).

Ecosystem Definition

• An ecosystem is a biological community of interacting organisms and their physical environment.
• The term "ecosystem" was introduced by Arthur Tansley in 1935.

Food Chain and Food Web

• A food chain is a linear network of links in a food web, starting from producer organisms and ending at apex predator species.
• Food chains were first introduced by Al-Jahiz in the 9th century and later popularized by Charles Elton in 1927.
• A food web is a simplified illustration of the various methods of feeding that links an ecosystem into a unified system of exchange.

Types of Food Chains

• Grazing food chain: starts with primary producers (green plants) and ends at decomposer level.
• Detritus food chain: starts from dead organic matter and ends at decomposer level.
• Parasitic food chain: involves a parasitic relationship between the producer and consumer.

Trophic Levels

• The trophic level of an organism is the position it occupies in a food chain.
• Trophic levels are numbered starting from Level 1 (producers) to Level 5 (apex predators).

Ecosystem Energy Flow

• Energy flows through the ecosystem in the form of food, from producers to consumers.
• Energy is transferred from one trophic level to the next, with a decrease in energy at each level.

Ecological Pyramid

• An ecological pyramid is a graphical model that illustrates the flow of energy through different forms of life in an ecosystem.
• Types of ecological pyramids: number pyramid, biomass pyramid, energy pyramid.

Decomposers and Scavengers

• Decomposers: produce enzymes that digest dead material, providing nutrients for organisms in the soil.
• Scavengers: feed on dead animals, rather than decomposing them.
• Detritivores: feed on detritus, or decomposing organic matter.

Bioenergetics

• Study of energy relationships and energy transformations in living organisms.
• Focuses on energy exchanges between organisms and their environment.

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Ecological Succession

• Primary succession: occurs on a new habitat that has never been colonized before.
• Secondary succession: occurs on a previously colonized, but disturbed or damaged habitat.

Types of Succession

• Mechanisms of succession: nudation, migration, ecesis, reaction, and competition.
• Climax state: a stable stage reached by the ecosystem through the process of ecological succession.

Primary Production

• Primary production: the process of plants making their own food through photosynthesis.
• How plants make their own food: using light from the sun, water, and carbon dioxide to produce glucose and oxygen.

Population

• A population is a collective group of organisms of the same species living in the same place at the same time.
• Measurement of population: census, which is a count of individuals in a population.

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Note: The text is divided into sections, and each section is represented by a subheading. The bullet points are organized under each section, and the key facts are highlighted with context.### Demographics

• The world population is estimated to be 7.4 billion as of August 2016 and is projected to reach 11.2 billion by 2100.
• The highest population growth rates occurred between 1955-1975, peaking at 2.06% between 1965-1970.
• The growth rate has declined to 1.18% between 2010-2015 and is projected to decline to 0.13 by 2100.

Population Density

• Density is the number of individuals per unit of space.
• Two types of density: Crude density (number of biomass per unit total space) and Specific density (number of biomass per unit of habitat).

Population Dynamics

• Population dynamics is the study of the size and age composition of populations as dynamical systems.
• Three dynamic rate functions: Natality (birth rate), Mortality (death rate), and Population growth rate.

Natality

• Natality is the greatest factor that influences population increase.
• Two types of Natality: Maximum Natality (absolute maximum production of new individuals under ideal conditions) and Ecological Natality (population increase under actual environmental conditions).

Mortality

• Mortality is usually expressed as the probability of dying.
• Two types of Mortality: Minimum Mortality (loss of individuals under ideal conditions) and Ecological Mortality (loss of individuals under actual environmental conditions).

Age Distribution

• Age distribution is the distribution of individuals in a population according to their age.
• Three types of Age Pyramids: Broad base (large percentage of young individuals), Bell-shaped polygon (moderate proportion of young to old), and Um-shaped figure (low percentage of young individuals).

Population Growth Rate

• Population growth rate, which measures the growth of individuals in size and length.
• Logistic growth equation: M = r mass N (K - N) / K

Population Dispersal

• Population dispersal is the movement of individuals or propagules into or out of the population or population area.
• Three types of dispersal: Emigration (outward movement), Immigration (inward movement), and Migration (periodic departure or return).

Population Distribution

• Three patterns of population distribution: Clumped (most common), Random, and Uniform.

Life Tables

• Life tables are created to summarize the age-specific pattern of birth and death of a particular population in a particular environment.
• The rate of births and deaths among individuals of different ages can be recorded in a life table.

Energy

• Energy is defined as the ability to produce change or do work.
• Types of energy: Solar, Tidal, Wind, Wave, Fossil fuels (Coal, Oil, and Natural Gas), Biomass, Geothermal, and Hydropower.

Renewable Energy

• Renewable energy sources are replenished in a short time.
• Examples of renewable energy sources: Biomass, Geothermal, Hydropower, Solar, and Wind.

Non-Renewable Energy

• Non-renewable energy sources cannot be replenished in a short period of time.
• Examples of non-renewable energy sources: Coal, Oil, Natural Gas, and Uranium.

Terrestrial Biomes

• Forests occupy approximately one-third of Earth's land area and account for over two-thirds of the leaf area of land plants.

Tropical Rainforest

• Location: Found near the equator, with little variation in temperatures and no distinct seasonal changes.
• Abiotic factors: High biodiversity and biomass, ideal for bacteria and other microorganisms, which quickly decompose matter on the forest floor.
• Threats: Deforestation, pollution, and industrial usage, human stripping of rainforests, clearing for agriculture, timber, and urban development, damage from off-roads vehicles, and pollution of forest streams.

Learn about the abiotic components of ecosystems, including physical environment and interacting variables. Understanding the importance of abiotic factors in biological communities.