Environmental Systems and Societies Review: Systems, Ecology, and Sustainability

A comprehensive set of vocabulary flashcards covering environmental systems, sustainability models, ecological sampling techniques, population dynamics, biomes, and successional processes based on lecture notes.

Systems thinking

A approach that allows seeing connections between components such as inputs, outputs, stores, flows, and feedbacks to understand complex environments.

Open systems

Systems that exchange both energy and matter with their surroundings, meaning changes in one part can affect others.

Closed system

A system that exchanges energy only, not matter, with its surroundings; Earth is considered approximately closed as matter is recycled internally.

Negative feedback

A regulatory mechanism that stabilises systems by counteracting change and returning the system to equilibrium, such as temperature regulation.

Positive feedback

A mechanism that amplifies change and destabilises a system, potentially leading to tipping points (e.g., ice melt reducing albedo).

Tipping point

A threshold where small changes cause large, often irreversible shifts to a new system state due to positive feedback.

Storages

Components in a system diagram, represented by rectangles, where energy or matter is held temporarily.

Flows

The movement of energy or matter between stores, represented by arrows; these can be transfers (movement only) or transformations (change in nature).

Sustainability

The practice of maintaining environmental balance over the long-term without harming future generations.

Environmental justice

The fair distribution of environmental benefits and harms across different populations and scales.

Ecological footprint

A measure of resource demand and waste absorption required per population compared to the Earth's productivity.

Biocapacity

The measure of the Earth’s ability to regenerate the resources consumed by a population.

Planetary boundaries model

A framework that defines Earth system limits, such as climate change and biodiversity loss, that must not be exceeded to maintain Holocene-like conditions.

Doughnut economics model

A model combining a social foundation of minimum human needs with an ecological ceiling of planetary boundaries.

Circular economy

An economic system aimed at eliminating waste and the continual use of resources through recycling, reuse, and remanufacturing.

Random sampling

A sampling method where points are chosen without bias, often using a random number generator, typically used when a habitat is uniform.

Systematic sampling

A method where samples are taken at regular intervals, often along a transect, to study environmental gradients.

Quadrat

A square frame (e.g., $0.25$–$1\,m^2$) used to sample non-mobile organisms to estimate population density, percentage cover, or percentage frequency.

Population density formula

Calculated as: $\text{Total number of organisms} \div (\text{quadrat area} \times \text{number of quadrats})$.

Lincoln Index

A formula used in capture-mark-release-recapture to estimate population size: $\frac{M \times N}{R}$, where $M$ is the first capture marked, $N$ is the second capture total, and $R$ is the marked animals in the second capture.

Carrying capacity

The maximum population size an environment can sustainably support, controlled by factors like food, water, space, and predation.

Density-dependent factors

Limiting factors that increase with population size, such as competition, disease, and predation, acting as negative feedback.

S-shaped (sigmoid) curve

A population growth curve featuring a lag phase, exponential phase, transitional phase, and a stationary phase at carrying capacity.

J-shaped growth curve

A curve showing exponential growth with no clear limiting factors, often followed by an eventual population crash.

Community

All the populations of different species living and interacting within a specific ecosystem.

Ecosystem

A set of interacting biotic (living) and abiotic (non-living) components forming an open system with energy and matter exchange.

Keystone species

A species that has a disproportionately large effect on ecosystem stability, such as the agouti's role in dispersing Brazil nut seeds.

Biodiversity Intactness Index (BII)

A measure where $90\%$ indicates a stable ecosystem, and $\leq 30\%$ indicates a high risk of ecosystem collapse.

Photosynthesis

The process of converting light energy into chemical energy: $CO_2 + H_2O \rightarrow \text{glucose} + O_2$ (light + chlorophyll).

Cellular respiration

The process by which all organisms release energy from glucose: $\text{glucose} + O_2 \rightarrow CO_2 + H_2O + \text{energy (ATP + heat)}$.

Trophic levels

The hierarchical levels in an ecosystem, starting with producers (first level), followed by primary, secondary, and tertiary consumers.

10% rule

The principle that typically only about $10\%$ of energy is transferred from one trophic level to the next, with the rest lost mostly as heat.

Net productivity (NP)

The energy remaining after respiratory losses ($NP = GP - R$), representing energy available for growth and the next trophic level.

Bioaccumulation

The accumulation of non-biodegradable pollutants, such as $DDT$ or mercury, within an individual organism over time.

Biomagnification

The process where the concentration of pollutants increases at higher trophic levels because predators eat many contaminated organisms.

Carbon sequestration

The capture and long-term storage of atmospheric $CO_2$ in biomass, oceans, soil, or underground via technologies.

Ocean acidification

The lowering of seawater $pH$ as $CO_2$ dissolves to form carbonic acid, damaging coral reefs and marine food webs.

Biome

A large group of ecosystems sharing similar climate conditions (temperature, precipitation, and insolation) regardless of location.

Whittaker’s climograph

A model that maps biomes based on their average temperature ($x$-axis) and annual precipitation ($y$-axis).

Tricellular model

A model explaining global biome distribution through three atmospheric circulation cells: Hadley ($0$–$30^∘$), Ferrel ($30$–$60^∘$), and Polar ($60$–$90^∘$).

Zonation

The spatial change in communities along an environmental gradient, such as the distinct bands of species on a rocky shore.

Succession

The directional change in ecosystem structure and species composition over time as organisms modify abiotic conditions.

Pioneer community

The first hardy colonisers, such as lichens and mosses, that begin the process of succession by creating soil.

Climax community

The stable, self-maintaining final stage of succession that exists in a steady-state equilibrium.

Primary succession

Succession that begins on bare substrate with no pre-existing soil, such as lava flows or glacial rock.

Secondary succession

Succession that occurs in areas where soil already exists after a disturbance, like a forest fire or abandoned farmland.

Ecosystem resilience

The ability of an ecosystem to resist change and recover from a disturbance, which is increased by high biodiversity and large nutrient stores.