Abiotic Factors and Ecosystems

Abiotic Factors

• Non-living physical factors affecting organisms and ecosystems.
• Examples: temperature, sunlight, pH, salinity, precipitation.

Albedo

• Proportion of solar radiation reflected by a surface or body.

Biochemical Oxygen Demand (BOD)

• Measure of dissolved oxygen needed to break down organic matter in water.
• Measured through aerobic biological activity.

Biodegradable

• Capable of decomposition by natural biological processes.
• Example: decomposer organisms.

Biodiversity

• Amount of biological variety per unit area.
• Includes species diversity, habitat diversity, and genetic diversity.

Biomass

• Mass of organic material in organisms or ecosystems.
• Often measured per unit area.
• Sometimes "dry weight biomass" is used, measuring mass after removing water.

Biome

• Collection of ecosystems with similar climate conditions.
• Examples: tundra, tropical rainforest, desert.

Biosphere

• Part of Earth inhabited by organisms.
• Thin zone (a few km thick) where life exists, from upper atmosphere to deep crust.

Biotic Factors

• Living, biological factors influencing organisms and ecosystems.
• Examples: predation, parasitism, disease, competition.

Carrying Capacity

• Maximum sustainable population size an environment can support.

Climax Community

• Relatively stable community in equilibrium with environmental conditions.
• End point of ecological succession.

Community

• Group of interacting populations in a common habitat.

Competition

• Demand for limited resources (food, water, light, space, mates, nesting sites) by multiple organisms.
• Can be intraspecific (within a species) or interspecific (between species).

Correlation

• Measure of association between two variables.
• Positive correlation: variables move in the same direction.
• Negative correlation: variables move in opposite directions.

Crude Birth Rate

• Births per 1000 individuals per year in a population.

Crude Death Rate

• Deaths per 1000 individuals per year in a population.

Demographic Transition

• Model describing changing fertility and mortality in human populations over time.
• Often associated with industrialization and urbanization.

Diversity

• General term for heterogeneity.
• Meaning depends on context (species, habitat, or genetic).

Genetic Diversity

• Variety of genetic material in a gene pool or population.

Habitat Diversity

• Range of habitats or ecological niches per unit area.
• Conserving habitat diversity often conserves species and genetic diversity.

Diversity Index

• Numerical measure of species diversity.
• Based on number and relative abundance of species.

Species Diversity

• Variety of species in a given area.
• Includes species number and relative abundance.

Doubling Time

• Years for a population to double in size at its current growth rate.
• 70 / natural increase rate = doubling time (approximately)

Ecological Footprint

• Area of land and water needed to sustainably provide resources consumed by a population.

Ecosystem

• Community of interdependent organisms and their physical environment.

Entropy

• Measure of disorder, chaos, or randomness in a system.
• Higher disorder = higher entropy.

Environmental Impact Assessment (EIA)

• Detailed survey before major development.
• Usually independent and paid for by the developer.
• Includes baseline study (environmental conditions before).
• Report is called an Environmental Impact Statement (EIS).

Equilibrium

• Balanced state among system components.

Eutrophication

• Natural or artificial enrichment of water (nitrates and phosphates).
• Can lead to oxygen depletion.
• Accelerated by human activities (detergents, sewage, fertilizers).

Evolution

• Gradual change in genetic characteristics over generations.
• Results in new species from common ancestors.

Feedback

• Part of system output returned as input, affecting future outputs.

Negative Feedback

• Dampens deviation from equilibrium, promotes stability.

Positive Feedback

• Amplifies change, leads to exponential deviation from equilibrium.

Fertility

• Potential for reproduction in a population.
• Measured by fertility rate (births per 1000 women of child-bearing age) or total fertility (average children per woman's lifetime).

Gaia

• Earth compared to a living organism with feedback mechanisms maintaining equilibrium.

Global Warming

• Increase in average Earth temperature.

Gross National Product (GNP)

• Current value of all goods and services produced annually in a country.

Greenhouse Gases

• Atmospheric gases absorbing infrared radiation, causing warming.
• Examples: water vapor, CO2, methane, nitrous oxide.
• Human activities increasing CO2, methane, nitrous oxide levels.

Habitat

• Environment a species normally lives in.

Halogenated Organic Gases (Halocarbons)

• Potent greenhouse gases, e.g., chlorofluorocarbons (CFCs).
• Initially identified as ozone layer depleters.

Isolation

• Process separating populations geographically, behaviorally, genetically, or reproductively.
• Prevents gene flow, leading to new species.

K-strategist

• Species investing in fewer offspring, increasing survival rate, adapting to climax communities.

Latitude

• Angular distance from the equator, measured in degrees.

LEDC (Less Economically Developed Country)

• Low to moderate industrialization and GNP per capita.

MEDC (More Economically Developed Country)

• Highly industrialized with high GNP per capita.

Model

• Simplified representation of an object, system, or concept.

Mutualism

• Relationship where all species benefit.

Natural Capital

• Natural resources providing goods and services.

Non-renewable Natural Capital

• Resources not replenished within human timescales (e.g., fossil fuels).

Renewable Natural Capital

• Resources with sustainable yields (e.g., food crops, timber).

Replenishable Natural Capital

• Non-living resources replenished by solar energy (e.g., groundwater).

Natural Increase Rate

• Human population growth rate, ignoring migration.

Niche

• Species' role in its habitat, including where it lives and what it does.

Parasitism

• Relationship where one species (parasite) lives on or in another (host), obtaining food.

Plate Tectonics

• Movement of Earth's lithosphere plates on the asthenosphere.

Pollution

• Addition of harmful substances (heat) at a rate exceeding environmental cleanup.

Non-point Source Pollution

• Pollutants from numerous dispersed sources (e.g., vehicle exhausts).

Point Source Pollution

• Pollutants from a single, identifiable source (e.g., factory).

Population

• Group of same species organisms in the same area, capable of interbreeding.

Gross Productivity (GP)

• Total energy or biomass gain per unit area per unit time.

Gross Primary Productivity (GPP)

• Energy or biomass gain per unit area per unit time in photosynthesis by producers.

Gross Secondary Productivity (GSP)

• Energy or biomass gain by consumers through absorption.

Net Productivity (NP)

• Energy or biomass gain remaining after respiratory losses.

Net Primary Productivity (NPP)

• Producer energy or biomass gain after respiratory losses.

Net Secondary Productivity (NSP)

• Consumer energy or biomass gain after respiratory losses.

Primary Productivity

• Producer energy or biomass gain per unit area per unit time (gross or net).

Secondary Productivity

• Biomass gained by heterotrophic organisms through feeding & absorption (mass/energy/area/time).

R-strategist

• Species spreading reproduction over many offspring, colonizing new habitats, exploiting short-lived resources.

Sere

• Set of communities succeeding one another during ecological succession.

Smog

• Hazy atmosphere caused by air pollutants.
• Photochemical smog: UV light effects on internal combustion engine products (ozone).

Society

• Arbitrary group of individuals sharing a common characteristic.

Soil

• Mixture of mineral particles and organic material, supporting terrestrial plants.

Soil Profile

• Vertical section of soil layers (horizons) to parent material.

Speciation

• Process of new species formation.

Species

• Interbreeding organisms producing fertile offspring.

Stable Equilibrium

• Tendency to return to previous equilibrium after disturbance.

Standing Crop

• See biomass.

Steady-State Equilibrium

• Open system without long-term change, with short-term oscillations.
• Constant matter/energy inputs/outputs.

Succession

• Orderly community change over time.
• Environmental changes by community shifts allow new communities to establish via competition.

Sustainability

• Resource use at a rate allowing natural regeneration and minimal environmental damage.

System

• Set of interrelated parts forming a complex whole.

Closed System

• Energy, but not matter, exchanged with surroundings.

Isolated System

• Exchanges neither matter nor energy with surroundings.

Open System

• Matter and energy exchange with surroundings (e.g., natural ecosystems).

Transfer

• Energy/matter flow changing location but not state.

Transformation

• Energy/matter flow changing state (chemical/physical/energy).

Tipping Point

• Critical threshold where small changes cause large effects.

Trophic Level

• Organism's position in a food chain or group occupying the same position.

Zonation

• Arrangement of plant communities/ecosystems in parallel bands.
• Response to environmental factor changes over distance.