Unit 4 Ecology (PCB 3043) - Dr. David Lewis Lecture Objectives

Comprehensive vocabulary flashcards covering Unit 4 Ecology learning objectives, including production, nutrient cycling, succession, landscape ecology, and global ecology.

Photoautotrophs

Organisms that generate energy by starting the food web using sunlight as their energy source.

Chemoautotrophs

Organisms that generate energy by starting the food web using energy-providing reduced minerals.

Trophic levels

The hierarchical levels in an ecosystem, comprising producers, primary consumers (herbivores), secondary consumers (predators), and subsequent levels.

Detritus branch

The component of the food web that deals with the consumption of nonliving organic matter, eventually ending in heat loss.

Primary producer

An autotroph, such as a plant or algae, that produces organic compounds from carbon dioxide through photosynthesis or chemosynthesis.

Heterotroph

An organism that cannot produce its own food and must consume other organisms; also known as a consumer.

Secondary producer

A consumer that converts the energy or organic matter it eats into its own biomass.

Detritivore

An organism, also known as a scavenger or decomposer, that consumes decaying organic matter.

Gross Primary Productivity (GPP)

The total amount of energy captured or organic matter created by primary producers in an ecosystem.

Plant/Primary Producer Respiration ($R_p$)

The percentage of $GPP$ that is consumed by the producers themselves for their own metabolic maintenance.

Net Primary Productivity (NPP)

The amount of energy left over after accounting for $R_p$ ($NPP = GPP - R_p$) that is available for growth and consumption by higher trophic levels.

Limiting nutrient

The specific chemical element (often nitrogen or phosphorus) whose limited availability restricts the rate of primary production in an ecosystem.

Compensatory growth

The phenomenon where moderate grazing stimulates plant productivity, resulting in faster growth than if no grazing occurred.

Ecological efficiency

The efficiency with which energy is transferred from one trophic level to the next, which is typically low, ranging from approximately $5-20\%$.Ratio

Top-down effects

The regulation of lower trophic levels (like primary producers) by the activities of higher trophic levels (like predators or grazers).

Bottom-up effects

The regulation of higher trophic levels (like secondary producers) by the availability of resources or primary production at the base of the food web.

Decomposition

The process by which organic matter is broken down into simpler forms, influenced by climate (temperature and water) and tissue properties.

Mineralization

The transformation of organic carbon, nitrogen, and phosphorus into inorganic mineral chemical compounds.

Nutrient spiraling

A concept used in stream ecosystems to describe the downstream transport of nutrients as they cycle between inorganic and organic forms.

Nutrient spiraling length

The distance a nutrient atom travels downstream to complete one full cycle of uptake and release.

Body stoichiometry

The balance of chemical elements in an organism's body tissue, such as the $N:P$ ratio, which determines how it retains or recycles nutrients.

Primary succession

Ecological succession that begins on newly exposed geological surfaces where no soil or life previously existed.

Secondary succession

Ecological succession that occurs following a disturbance that destroys a community but leaves the soil intact.

Chronosequence

A research approach used to study long-term succession (e.g., $1,500$ years in Glacier Bay) by examining sites of different ages that represent different stages of development.

Facilitation

A successional mechanism where early-arriving species modify the environment to make it more suitable for later-arriving species.

Inhibition

A successional mechanism where early-arriving species modify the environment in ways that hinder the establishment of later species.

Steady state phase

A late phase in ecosystem development where the amount of stored biomass remains large but is no longer increasing.

Landscape structure

The specific arrangement and components of a landscape, including patch types, shapes, sizes, and their connectivity.

Patch edge

The outer portion or boundary of a habitat patch that interacts with the surrounding environment differently than the interior.

Patch core

The interior area of a habitat patch that is unaffected by edge effects; its size is maximized by compact shapes and large total areas.

Alluvium

Soil or sediment, such as silt or sand, that is deposited by running water, influencing plant communities in landforms like bajadas.

Ecosystem engineer

An organism, like a beaver, that significantly modifies the physical structure of a landscape and influences nutrient retention.

Insular habitats

Isolated 'island-like' environments, such as mountaintops, ponds, or forest fragments, that exhibit diversity patterns based on size and isolation.

Equilibrium model of island biogeography

A model predicting the species richness ($S$) of an island based on the balance between colonization rates and local extinction rates.

Species turnover

The process where the specific identity of species in a community changes over time, even if the total species richness remains constant.

Latitudinal gradient in diversity

The observed pattern where species diversity generally increases from the poles toward the equator.

El Niño

A climatic event in the equatorial Pacific involving changes in atmospheric pressure and wind that lead to warm water temperatures and reduced upwelling.

Upwelling

The movement of deep, cold, nutrient-rich water to the surface, which is often suppressed during El Niño, affecting primary and fisheries production.

Endemic species

Species that are native to and found only within a specific, limited geographic location.

Biodiversity hotspot

A region with high levels of endemic species that is experiencing significant habitat loss.

Plate tectonics

The geological process involving the movement of Earth's lithospheric plates, which influences species dispersal, speciation, and biogeographic regions.

Nitrogen fixation

The process of converting inert $N_2$ gas from the atmosphere into biologically reactive forms of nitrogen.

Nitrogen deposition

The transfer of already-fixed nitrogen from the atmosphere to ecosystems via dust particles or rain.

Reactive nitrogen

Forms of nitrogen that are biologically available; human activities account for $40-80\%$ of the emissions of three specific nitrogen gases.