Community Ecology, Ecosystem Dynamics, and Biogeochemical Cycles Vocabulary

Vocabulary flashcards covering key terms and concepts in community ecology, ecosystem structure, energy flow, trophic interactions, and biogeochemical cycles based on the lecture transcripts.

Community

An assemblage of plant, animal, fungal, and microbe populations living and interacting within a particular habitat.

Emergent Properties of a Community

System-level traits created by interacting populations, including spatial structure, temporal structure, species richness, species diversity, trophic structure, and succession.

Spatial Structure

The arrangement and distribution of species relative to one another within a habitat, often creating physical frameworks that support other organisms.

Community Stratification

The vertical layering of species within a habitat, such as rainforest foliage divided into herb, immature, understory, canopy, and emergent layers.

Temporal Structure

The timing of appearance, germination, or activity of species within a community across days or seasons.

Species Richness

The total number of distinct species present in a sampled biological community.

Species Diversity

A community metric combining species richness with the relative abundance (evenness) of each species present.

Shannon-Wiener Index

A mathematical diversity index calculated as $H' = -\frac{\text{S}}{\text{i}} p_i \text{Ln}(p_i)$, quantifying species richness and relative abundance.

Ecological Succession

The sequential process of species colonization, recovery, and replacement in a community following a physical disturbance.

Disturbance

An event—such as a flood, fire, drought, or human action—that alters a community by eliminating individuals, reducing populations, and changing resource availability.

Primary Succession

Succession initiated in a sterile, novel environment lacking pre-existing soil or living organisms, requiring external colonization.

Secondary Succession

Succession following a disturbance that clears dominant species but leaves soil and surviving organism populations behind.

Facilitation

A successional mechanism where early colonizing species modify the environment in ways that allow subsequent species to establish.

Inhibition

A successional mechanism where early establishing species restrict or slow the arrival and growth of later species through priority effects.

Climax Community

A relatively stable, late successional stage dominated by species highly adapted to long-term resource competition.

Trophic Structure

The hierarchical organization of feeding relationships and energy flow within an ecological community.

Food Web

A comprehensive diagram depicting all interconnected feeding paths and energy exchanges across a community.

Food Chain

A single linear pathway through a food web tracing energy flow from a primary producer to successive consumer levels.

Fundamental Niche

The full range of physical and climatic conditions under which a species can survive and reproduce in the absence of negative biological interactions.

Realized Niche

The restricted environmental conditions and resources a species actually utilizes in the presence of competitors and predators.

Keystone Species

A species that plays a disproportionately large role in maintaining community structure and diversity relative to its physical abundance.

Anthromes

Anthropogenic biomes where community ecological processes and land cover are primarily driven by sustained human activity.

Interspecific Competition

Resource competition occurring between individuals belonging to different species.

Intraspecific Competition

Resource competition occurring between individuals belonging to the same species.

Exploitation Competition

Indirect competition where individuals consume and deplete a shared limiting resource, reducing its availability to other organisms.

Interference Competition

Direct competition where individuals use aggressive, territorial, or behavioral mechanisms to block others from accessing resources.

Competitive Exclusion Principle

The ecological rule stating that two species competing for the exact same limiting resource cannot stably coexist.

Gause's Paramecium Experiment

A laboratory demonstration showing Paramecium aurelia outcompeting and excluding Paramecium caudatum when grown together in mixed culture.

Resource Partitioning

An evolutionary adjustment where competing species differentiate their resource or habitat usage to minimize direct competition.

Commensalism

An interspecific relationship where one species gains ecological benefits while the other species is unharmed and unaffected.

Inquiline

An organism that lives commensally inside the nest, colony, or shelter of another species, such as a termitophilic rove beetle.

Mutualism

An interspecific interaction that increases the survival, growth, or reproductive success of both participating species.

Mutualistic Symbiosis

A mutualism involving intimate physical contact or living inside the body or tissue of a partner organism.

Facultative Mutualism

A beneficial interaction between two species that is helpful but not strictly necessary for the survival of either.

Obligate Mutualism

A mutualistic interaction essential for the survival and reproduction of one or both participating organisms.

Parasitoid

An organism that hunts host prey like a predator but lays eggs inside its body, where larvae feed internally and eventually kill the host.

Social Parasitism

A form of parasitism where one species exploits the worker labor or parental care of another species, such as Bombus hyperboreus enslaving arctic bumblebees.

Introduced Species

A non-native organism intentionally or unintentionally transported into a new geographical region by human action.

Invasive Species

An introduced organism that establishes self-sustaining populations and inflicts ecological harm, species extinctions, or economic damage.

Lumbricus friendi

An introduced European earthworm species that alters forest floor communities by breaking up detritus layers and drying the soil.

Ecosystem

A biological unit composed of living organisms interacting with one another and with the non-living abiotic components of their environment.

Biosphere

The largest, most encompassing global ecosystem containing all living organisms and environments on Earth.

Producers

Autotrophic organisms that capture light or chemical energy to synthesize organic biomass from non-living materials.

Energy Flow vs. Matter Cycling

The fundamental principle that energy arrives from the sun and leaves as heat, whereas matter continuously cycles within Earth's closed system.

Biomass

The total weight of living organic matter, typically measured in dry weight per unit area.

Pyramid of Biomass

A diagram quantifying the relative amount of dry living organic mass present at each successive trophic tier.

Assimilation Efficiency

The percentage of ingested food energy absorbed across the gut and made available for metabolic work or biomass growth.

Apex Predator

A top-level carnivore at the peak of a food web that faces no natural predators.

Detritivores

Organisms that feed directly on non-living organic matter, such as leaf litter and animal carcasses.

Decomposers

Microscopic heterotrophs, such as bacteria and fungi, that break down organic waste into inorganic chemical elements.

Primary Productivity

The rate at which biomass is generated by producers through photosynthesis per unit area and time.

Gross Primary Productivity (GPP)

The total amount of chemical energy fixed by autotrophs through photosynthesis per unit area and time.

Net Primary Productivity (NPP)

The rate of producer biomass production remaining after accounting for respiration losses: $\text{NPP} = \text{GPP} - R$.

Ecological Reservoir

An abiotic storage pool in the physical environment containing a biologically meaningful element in a form not easily accessible to organisms.

Phosphorus Cycle

A sedimentary biogeochemical cycle driven by rock weathering, runoff, plant absorption, and decomposition, lacking a major atmospheric gaseous phase.

Carbon Fixation

The biochemical capture of inorganic atmospheric carbon dioxide ($\text{CO}_2$) and its conversion into organic carbohydrates by photosynthetic plants.

Greenhouse Effect

The thermal warming mechanism where atmospheric gases absorb outgoing infrared heat radiation emitted by Earth's surface.

Radiative Forcing

The thermal imbalance in Earth's energy budget caused by altered atmospheric greenhouse gas concentrations, driving climate warming or cooling.

Nitrogen Fixation

The process converting biologically inert atmospheric dinitrogen gas ($\text{N}_2$) into bioavailable compounds such as ammonia ($\text{NH}_3$) or ammonium ($\text{NH}_4^+$).

Rhizobium

A genus of symbiotic bacteria that inhabit root nodules of legume plants and fix atmospheric nitrogen.

Nostoc

A genus of filamentous cyanobacteria capable of fixing atmospheric nitrogen within specialized heterocyst cells.

Denitrification

The bacterial process converting soil nitrites ($\text{NO}_2^-$) and nitrates ($\text{NO}_3^-$) back into gaseous dinitrogen ($\text{N}_2$) and nitrous oxide ($\text{N}_2\text{O}$).

Haber-Bosch Process

An industrial chemical method synthesizing ammonium fertilizer by combining atmospheric nitrogen and hydrogen gas over a catalyst.

Planetary Boundaries

A framework quantifying nine critical Earth system thresholds within which humanity can safely operate without causing abrupt global environmental change.

Montreal Protocol

A 1989 international treaty regulating chlorofluorocarbon (CFC) emissions to protect stratospheric ozone from catalytic degradation.