56-ecosystems Flashcards
Ecosystem
All of the organisms living in a given area, and the physical and chemical environment
-influenced by both biotic and abiotic conditions
Energy flows…
- energy is constantly added as sunlight photosynthesis) or as inorganic compounds (chemosynthesis)
- energy is constantly lost (in the form or metabolic heat)
Nutrients cycle…
- nutrients are locked in ecosystems, and cycle through the biotic and abiotic components
- each nutrient cycle is different
Net primary production (NPP)
The amount of biomass incorporated into the tissues of primary producers after respiration
- varies with latitude and ocean/terrestrial
- NPP = GPP - respiration
- NPP—> The amount of carbon remaining in plants after respiration
- GPP—> gross primary production (the total amount of carbon fixed by primary producers)
Terrestrial primary production
-accounts for 52%
-controlled largely by temperature and precipitation
-NPP increases as average rainfall increases, to a certain point (flooding)
Then declines
-NPP increases as temperatures increase (NPP higher closer to equator)
-also affected by nutrient availability & atmospheric CO2 concentrations
Aquatic primary production
- 48% (even though larger)
- controlled largely by Light & nutrients
- NPP is higher with more light penetrance & nutrient availability (coastal zones and surface waters) - NPP is limited by iron, phosphorus, and nitrogen
Eutrophication
- Process initiated by an increase in nutrients which are consumed by phytoplankton and Cyanobacteria which causes a algal blooms
- algae and bacteria die releasing CO2 and causing an oxygen deficiency (hypoxia)
Net secondary production
The amount of biomass obtained from the consumption of other organisms
-depends on 3 things
Consumption efficiency
How much plant tissue is consumed
Assimilation efficiency
How much of the food is actually digested versus releases as feces or urine
Production efficiency
How much of the digested food is used in metabolic activities and released as CO2 through respiration versus stored in biomass
- % of energy stored in assimilated food that is used to produce new biomass
- endotherms have lower production efficiencies than ectotherms because of their need to regulate high body temperatures
Trophic efficiency
Amount of energy in one trophic level, divided by the amount of energy in the trophic level immediately below it
- pyramid diagrams
- terrestrial ecosystems support less biomass at higher trophic levels than at lower ones (avg. 13% biomass consumed by primary consumers)
- trophic efficiencies are higher in aquatic systems (avg. 35% biomass consumed by primary consumers)
Bottom-up forces (food webs)
- when energy in a system is controlled by the NPP entering that system
- comes from bottom (primary producer level) of food web
Top-down forces (food webs)
-comes from higher trophic levels, who regulate the amount of NPP by feeding on Lowe trophic levels
Decomposition
When detritus (dead organisms and their waste products) are broken down by bacteria and fungi into nutrients and energy
