BIOL 314 Chapter 20-23 Flashcards

Gross and Net Primary Production

• Gross primary production (GPP) refers to total energy captured by autotrophs through photosynthesis and chemosynthesis over time.
• Net primary production (NPP) is the energy left after autotrophs use some for cellular respiration, measuring the energy available for consumers.

NPP Variability

• NPP is highest in tropical regions and decreases towards the poles.
• Yearly variations in NPP can indicate ecosystem health, indicating potential impacts from environmental stresses like drought or acid rain.
• NPP is connected to the global carbon cycle.

Secondary Production and Heterotrophs

• Secondary production is the energy obtained from consuming organic compounds produced by other organisms (heterotrophs).
• Heterotrophs are categorized based on their food sources.

Ecosystem Input Types

• Allochthonous inputs are external energy sources, such as plant material in aquatic ecosystems.
• Autochthonous inputs are energy produced within the ecosystem by autotrophs, like green plants and algae.
• Example: Bear Brook relies heavily on allochthonous inputs, while Mirror Lake capitalizes on autochthonous energy.

Trophic Pyramid and Efficiency

• A trophic pyramid illustrates energy or biomass levels across trophic layers, reflecting energy flow in ecosystems.
• Trophic efficiency is energy at one level divided by the energy at the level below, accounting for consumption and assimilation rates.

Inverted Biomass Pyramids

• In many aquatic ecosystems, primary producers (phytoplankton) may have shorter life spans, resulting in inverted biomass pyramids where heterotrophs outweigh autotrophs by biomass, though autotrophs produce more energy.

Trophic Cascade Controls

• Bottom-up control is influenced by NPP and resource availability, dictating energy flow upward through trophic levels.
• Top-down control focuses on consumption by predators affecting lower trophic levels' biomass and composition, leading to simultaneous operation of both control types in ecosystems.

Trophic Levels Influences

• Trophic levels depend on energy input through primary production.
• Disturbances, including diseases, influence population sustainability of higher predators.
• Ecosystem size affects biodiversity; larger areas may support more trophic levels due to larger populations.

Net Interaction Strength

• Describes the impact of one species on another’s population, capturing direct and indirect effects within food webs.
• Understanding interaction strengths aids in research and conservation efforts by clarifying key ecological links.

Food Web Complexity and Stability

• Complexity in food webs can enhance community stability, providing resilience against disturbances through interconnected species interactions.

Nutrification Processes

• Nitrification converts ammonia and ammonium to nitrate via nitrifying bacteria in aerobic conditions.
• Denitrification transforms nitrate back into nitrogen gas, facilitating nitrogen cycle completion under hypoxic conditions.

Nutrient Cycle Definition

• Nutrient cycles represent the exchange and movement of organic and inorganic matter, regulated by food webs and influenced by climate conditions.
• Nutrients vital for primary productivity cycle faster than those that are not limiting.

Nutrient Spiral in Aquatic Ecosystems

• Describes the upstream-downstream cycling of nutrients, characterized by repeated nutrient absorption and release along water flow.

Conservation Biology's Value Basis

• Conservation biology reflects human values and operates within societal contexts, requiring transparency about the values inherent in conservation practices.

Background Extinction Rate

• Refers to the natural rate of extinction over geological time, with current extinction rates greatly elevated compared to historical background levels.

Taxonomic Homogenization

• Describes the global decline in biodiversity from the spread of non-native species, leading to reduced native specialists and increased presence of generalists.