ENVS 1308 Lecture 3: Biological Communities, Disturbance, and Succession

Flashcards covering key vocabulary, community properties, spatial patterns, resilience mechanisms, disturbance types, succession, and post-disturbance trajectories from ENVS 1308 Lecture 3.

Diversity (Community Property)

The variety of species and ecological roles present in a community, which changes the number of potential ecological roles.

Abundance (Community Property)

The number of individuals present in a community, which changes which species dominate community processes.

Spatial Structure

The distribution pattern of organisms (random, uniform, clustered, layered, patchy), which changes exposure to edges, predators, competitors, microclimate, and disturbance.

Complexity (Community Property)

How species are connected through trophic levels, interactions, redundancy, and pathways, which can create alternative pathways when one species or interaction is disrupted.

Species Richness

The total number of species contained within an ecological community.

Species Evenness

The degree to which individuals are distributed equally or unequally among the species in a community.

Random Distribution

A spatial pattern resulting from chance events combined with broadly available resources.

Uniform Distribution

A spatial pattern driven by competition, territoriality, or inhibitory effects between individuals.

Clustered Distribution

A spatial pattern driven by localized resources, reproduction, social behavior, or shelter.

Vertical Stratification

Layering of vegetation at different heights in a community, creating varied light, temperature, food, and microclimate conditions.

Core Habitat

Interior habitat unaffected by edge conditions; two preserves of equal total area (e.g., 50 ha) can have different amounts of core area depending on shape.

Asynchrony

The phenomenon in high-diversity communities where not all species decline at the same time in response to environmental conditions, allowing aggregate community function to vary less.

Functional Insurance

The role of species diversity in stabilizing ecosystem function by offering alternative responses and pathways when conditions change or interactions are disrupted.

Disturbance

A process that alters existing patterns of abundance, community structure, or ecological relationships, rather than simply causing 'damage'.

Succession

Community change through time along multiple possible trajectories rather than following a single fixed or predetermined climax endpoint.

Biological Legacies

Surviving seeds, roots, or living organisms left behind after a disturbance that help drive ecological recovery toward prior community structure.

Reorganization

A post-disturbance pathway in which different species combinations restore certain functions without recreating the original community state.

Regime Shift

An ecological transition where altered conditions or feedbacks maintain a persistent, different community state.

Yellowstone 1988 Fires

A large-scale natural disturbance that burned ~1.4 million acres, leading to a recovery characterized by a more varied vegetation mosaic of savannas and mixed forest types.

Periodic Fire Effects

Ecological functions of recurring fire, including suppressing dominant competitors, opening habitat gaps, releasing/stimulating seeds, rapidly recycling nutrients, and creating landscape heterogeneity.