Ecosystems And Conservation Biology Flashcards
Ecosystem
Sun of all the organisms living in a given area and the abiotic factors that interact w/ biotic and abiotic components, defined by integration, and can vary greatly in spatial extent; two emergent processes: energy flows through ecosystems and chemicals cycle within ecosystems
Primary production
Amount of light energy converted to chemical energy by autotrophs (per unit time); in a few ecosystems, chemoautotrophs are the primary producers
Gross primary production (GPP)
Total primary production
Net primary production (NPP)
Gross primary production minus energy used by autotrophs for cellular respiration (R); NPP=GPP-R
What limits primary production?
In aquatic ecosystems: light and nutrients control primary production
In terrestrial ecosystems: moisture, temp., and nutrients control primary production
You have 5 kg of eggs, 10 kg of flour, 10 kg of butter, and 10 kg of sugar. How many cakes can you make (when the recipe is 1 kg eggs, 10 kg flour, 1 kg butter, 1kg sugar)? What is the limiting ingredient?
Eggs
Flour
Butter
Sugar
Flour
Trophic levels
Position an organism occupies in a good chain
Autotroph
An organism that obtains organic food molecules w/o eating other organisms or substances derived from other organisms. Autotrophs use energy from the sun or from oxidation of inorganic substances to make organic molecules (i.e., primary producers)
Heterotroph
An organism that obtains organic food molecules by eating other organisms or substances derived from them
Decomposer
An organism that absorbs nutrients from no living organic material such as corpses, fallen plant material, and wastes, and converts them to inorganic forms (i.e., detritivores)
Green food chain
Live maple leaves -> cricket -> robin -> Cooper’s hawk
Brown food chain
Dead maple leaves -> bacteria, archaea -> earthworm -> robin -> Cooper’s hawk
How much energy is transferred to each trophic level?
Only 10%
What is cycle of energy across trophic levels?
Energy enters most ecosystems as sunlight, is converted to chemical energy by autotrophs, passed to heterotrophs as food, and dissipated as heat
Top down control
A situation in which the abundance of organisms at each trophic level is controlled by the abundance of consumers at higher trophic levels; thus, predators limit herbivores, and herbivores limit plants
Bottom up control
A situation in which the abundance of organisms at each trophic level is limited by nutrient supply or the availability of food at lower trophic levels; thus, the supply of nutrients controls plant numbers, which control herbivore numbers, which in turn control predator numbers
Trophic cascade
Indirect interactions that can control entire ecosystems. Trophic cascades occur when predators limit the density and/or behavior their prey and thereby enhance survival of the next lower trophic level
Biogeochemical cycles
Describe the flux of atoms and molecules between biotic and abiotic reservoirs
Reservoir
Place where a type of atoms or molecules accumulate are held for a kind period of time
Flux
Rate of movement between reservoirs
What are the two characteristics that define the main reservoirs of elements?
-Whether they consist of organic or inorganic materials
-Whether these materials are available for direct use by organisms or unavailable
What are the four major factors to consider in the cycling of water, carbon, nitrogen, and phosphorus?
- Each chemical’s biological importance
- Forms available to life
- Reservoirs
- Key processes driving movement of each chemical through its cycle
Water cycle
-liquid water is the primary physical phase in which water is used
-reservoirs: oceans (97%), glaciers and polar ice caps (2%), and lakes, rivers, groundwater’s (1%)
-water moves by the processes of evaporation, transpiration, condensation, precipitation, and movement through surface and groundwater
Carbon cycle
-photosynthetic organisms convert CO2 to organic molecules that are consumed by heterotrophs
-reservoirs: fossil fuels, soils and sediments, biomass, atmosphere, and sedimentary rocks
-CO2 is taken up and released through photosynthesis and respiration; additionally, volcanoes and the burning of fossil fuels contribute CO2 to the amosphere
Nitrogen cycle
-N is a component of amino acids, proteins, and nucleus acids
-main reservoir: atmosphere (N2)
-atmospheric N2 must be converted to NH4+ or NO3- for uptake by planted via nitrogen fixation by bacteria
Phosphorus cycle
-phosphorus is a major constituent of nuclei acids, phospholipids, and ATP
-phosphate is the most important inorganic form of phosphorus
-reservoirs: sedimentary rocks of marine origin, soil, oceans and organisms
-weathering of rocks releases phosphate into the soil, and it reaches aquatic systems through leaching
For which biogeochemical cycle is photosynthesis important?
Carbon
Nitrogen
Phosphorus
Carbon
What is the rate of decomposition controlled by?
Temperature, moisture, oxygen, and nutrient availability
Cellular respiration (R)
The catabolic play heats of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP
