Ecosystem Dynamics, Biomes, Matter Cycles, and Trophic Energetics

Vocabulary flashcards covering ecological organization, aquatic and terrestrial biomes, open vs. closed systems, laws of thermodynamics, productivity equations (GPP and NPP), nutrient cycling, and trophic interactions.

Ecosystem

A dynamic system where plants, animals, and microorganisms interact with each other and their abiotic environment as a functional unit.

Ecology

The branch of biology focused on the levels of organization spanning from individual organisms, populations, and communities up to ecosystems, biomes, and the biosphere.

Niche

The specific functional role or ecological job that an organism plays within its community.

Oceanic Zone

The relatively shallow aquatic marine zone of the open ocean that lies directly over the continental shelf.

Profundal Zone

The deep-water or bottom aquatic zone where sunlight does not penetrate.

Benthic Zone

The bottom substrate layer of an aquatic ecosystem, consisting of the sediment surface and underlying sub-surface layers.

Lentic Ecosystem

A freshwater ecosystem consisting of slow-moving or standing water, such as pools, ponds, and lakes.

Lotic Ecosystem

A freshwater ecosystem consisting of rapidly moving water, such as streams and rivers.

Wetlands

Freshwater areas where the soil is saturated or inundated with water for at least part of the time.

Anadromous Fish

Fish species (such as salmon and trout) that hatch and reproduce in freshwater but migrate to spend most of their adult lives in the sea.

Dead Zone

A region in an aquatic ecosystem that is unable to support life due to severely depleted oxygen levels (hypoxia).

Fringing Reef

A coral reef that is attached directly to a mainland or island shore, or borders it with an intervening shallow channel or lagoon.

Barrier Reef

A coral reef separated from a mainland or island shore by a deep lagoon.

Atoll Reef

A circular or continuous reef extending all the way around a central lagoon without a central landmass or island.

Taiga

A high-latitude northern biome situated between tundra and temperate forest (mostly from $52^\top N$ to $66^\top N$) that makes up $27\%$ of the world's forest cover.

Closed System

A physical system where matter is contained entirely within the system boundaries and cannot enter or exit, while energy freely enters and leaves.

Open System

A physical system in which both matter and energy freely cross and interact with the system boundaries.

Law of Conservation of Matter

A physical law stating that matter cannot be created or destroyed; it only changes form, remaining conserved within a closed system.

First Law of Thermodynamics

The law of conservation of energy, which states that total energy input into a system must equal total energy output ($\text{Energy}_{\text{in}} = \text{Energy}_{\text{out}}$).

Second Law of Thermodynamics

The principle stating that when energy is transformed, the quantity of energy available to do work decreases, with the dissipated energy lost predominantly as heat.

Source / Sink

A reservoir in a biogeochemical cycle where matter remains secured and resides for periods of time until a biological, geological, or chemical process transfers it.

Equal Earth Projection

A map projection designed to accurately preserve the relative size and surface area of continents, demonstrating that Africa is $14$ times larger than Greenland.

Photosynthesis

The metabolic process carried out by plants, algae, and some bacteria that converts light energy into chemical energy stored in glucose: $\text{Solar energy} + 6\,H_2O + 6\,CO_2 \rightarrow C_6H_{12}O_6 + 6\,O_2$.

Cellular Respiration

The metabolic process carried out by all living organisms that consumes chemically stored glucose to release usable energy: $C_6H_{12}O_6 + 6\,O_2 \rightarrow \text{Energy} + 6\,H_2O + 6\,CO_2$.

Gross Primary Productivity (GPP)

The total rate at which solar energy is captured by autotrophic producers through photosynthesis over time, accounting for roughly $1\%$ of solar energy striking them.

Net Primary Productivity (NPP)

The amount of energy captured by producers that remains after accounting for respiratory energy losses ($\text{NPP} = \text{GPP} - R$), representing approximately $40\%$ of GPP used for producer growth and reproduction.

10% Rule

The ecological guideline stating that approximately $10\%$ of the chemical energy stored as biomass at one trophic level is incorporated into the next level, while the remaining $90\%$ is lost as heat or metabolic waste.

Scavenger

A carnivore or omnivore that consumes already dead animals and carcasses (e.g., vultures, gray foxes).

Detritivore

An organism that feeds on and breaks down dead tissues and waste products into smaller pieces (e.g., dung-rolling beetles, earthworms).

Decomposer

Microscopic organisms, including bacteria and fungi, that break down dead organic matter and recycle essential inorganic nutrients back to producers.

Nitrogen Fixation

The first transformation in the nitrogen cycle wherein atmospheric nitrogen ($N_2$) is converted by specialized bacteria into bioavailable ammonium ($NH_4^+$) or ammonia ($NH_3$).

Phosphorus Cycle

A biogeochemical cycle that lacks an atmospheric phase, cycling primarily between terrestrial rock reservoirs, soil, and aquatic sinks to provide an essential building block for DNA, RNA, and ATP.

Indirect Ecological Effect

A trophic feedback where the relationship between two species is mediated by a third species, such as fish consuming dragonfly larvae, which lowers adult dragonflies and leads to increased pollinator visits to riparian plants.