Ecosystems and Restoration

Concept 55.2: Energy and Limiting Factors

• Primary production: Autotrophs convert light energy into chemical energy.

• Gross Primary Production (GPP): The total amount of primary production.

• Net Primary Production (NPP): GPP minus the energy primary producers use for their respiration.

• NPP = GPP - Respiration

• Net Ecosystem Production (NEP): GPP minus the total respiration of all organisms in the ecosystem.

• Primary production is limited by light and nutrients.

• A limiting nutrient is the element that must be added to increase production.

Primary Production in Terrestrial Ecosystems

• Temperature and moisture influence primary production.

• More moisture leads to increased primary production.

• Evapotranspiration (water loss from plants and evaporation) is related to net primary production.

• Nitrogen and phosphorus are common limiting nutrients in land-based ecosystems.

Concept 55.3: Energy Transfer Between Trophic Levels

• Secondary production: Chemical energy in food converted into new biomass.

• Production efficiency: The percentage of energy stored in food that isn't used for respiration.

• Production_Efficiency = \frac{Net\ Secondary\ Production}{Assimilation\ of\ Primary\ Production} \times 100\%

• Trophic efficiency: The percentage of production transferred from one trophic level to the next (usually around 10%).

Concept 55.4: Nutrient Cycles

• Nutrient cycles include biotic and abiotic components (biogeochemical cycles).

• Key factors in studying nutrient cycles:

  • Biological importance of each chemical.

  • Forms available to organisms.

  • Major reservoirs where nutrients are stored.

  • Key processes driving nutrient movement.

Decomposition and Nutrient Cycling Rates

• Decomposers (detritivores) are crucial in chemical cycling.

• Decomposition rate depends on temperature, moisture, and nutrient availability.

• Fast decomposition leads to low nutrient levels in the soil.

Concept 55.5: Restoration Ecology

• Restoration ecology aims to speed up the recovery of damaged ecosystems.

• Two main strategies:

  • Bioremediation: Using organisms to clean up ecosystems.

  • Biological Aug