Ecosystem ecology
-processes and interactions between species are important
- range from a micro to a large area
-ecologists
-Energy flow through ecosystem
-matter cycles within ecosystem
-abide by laws of physics
Ecologists
study the transformations of energy and matter within ecosystems
Ecosystem
community plus all the abiotic interactions associated with that community
Conservation of energy
- first and second law of thermodynamics
- energy enters ecosystem as solar radiation and is lost from organisms as heat
- energy conversions are not always efficient
first law of thermodynamics
Energy cannot be created or destroyed, only transformed
second law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe.
Conservation of mass
- matter cannot be created or destroyed
-chemical elements are continually recycled within ecosystems
- in a forest, most nutrients enter as dust and carried out by water
-ecosystems are open, they absorb energy/mass and release heat/waste
Energy, mass and trophic levels
-autotrophs
-heterotrophs
-energy/nutrients pass from primary producers through many levels of consumers
Energy Budget
- primary production
- rate of primary production
Primary Production
fixation of energy by autotrophs in an ecosystem
and converts inorganic energy into organic energy
-aquatic ecosystems
-terrestrial ecosystems
Rate of Primary Production
amount of energy fixed over a given period of time
- gross and net
Gross
total amount of energy fixed by autotrophs
Net
Amount of energy leftover after needs are met
Aquatic Ecosystems
- light and nutrients control primary production
- depth of light penetration affects primary production in the photic zone of and ocean/lake
-nitrogen and phosphorus
-upwelling of nutrient rich waters
-large amounts of nutrients
Nitrogen and Phosphorous
nutrients that limit marine production
Upwelling of nutrient rich waters
high primary production
Large amounts of nutrients
- result in sewage runoff
- limits cyanobacterias growth
- reduce eutrophication
Terrestrial Ecosystems
- temp and moisture affect primary production
-primary production increase with moisture
-soil nutrients= limiting factor
-nitrogen and phosphorous= most common limiting nutrient
Energy
- transfer
-flow in temperate deciduous forest (Gosz)
Transfer
- 10% effecient between trophic levels
- apron. 0.1% of chemical energy fixed by photosynthesis reaches a tertiary consumer
Gosz's study of energy flow
- 99% of solar energy unavailable for use by second trophic level
-as energy losses between trophic levels, eventually there is insufficient energy to transport a population at a higher trophic level
- most food chains have 3-4 trophic levels with a maxim
Cycles
- biogeochemical
- water
- carbon
- phosphorus
-nitrogen
Biogeochemical
-Nutrient cycle
-gaseous carbon, oxygen, sulfur, and nitrogen occur in atmosphere and cycle globally
-less mobile elements
Nutrient Cycle
- that involves biotic and abiotic components
- transformation, movement and reuse of nutrients in ecosystems
Less mobile elements
phosphorous, potassium and calcium
- these cycle locally in terrestrial systems and broadly in aquatic
Water
- essential to all organisms
- liquid is primary physical phase water is used
- oceans contain 97% of biosphere water, 2% glaciers, 1% lakes/rivers
-moves by processes of evaporation, transpiration, condensation, precipitation and movement through groundw
Carbon
- important in all organic molecules and in atmosphere as carbon dioxide and methane
- moves in-between organisms and atmosphere as due to phototsythesis and respiration
-reservoirs
Reservoirs
fossil fuels, soils/sediments, solutes in ocean, plant/animal biomass, atmosphere, sedimentary rocks
CO2 is taken up and released through
photosynthesis and respiration
- volcanoes and burning fossil fuels contribute to CO2 in atmophere
Nitrogen
- can be released by fungi and bacteria during organism decomposition
- released as ammonium
Phosphorous
- important in ATP, RNA, DNA and cell membrane
- phosphate is most important inorganic form
- global phosphorous cycle does not include substantial atmospheric pool
Decomposition and nutrient cycling rates
next 6 questions
Decomposers play a key role in..
general pattern of chemical cycling
Rates that nutrients cycle vary greatly, mostly because of
decomposition
Rate of decomposition is controlled by
temperature, moisture, and nutrient availability
Rapid decomposition results in
relatively low levels of nutrients in the soil
Cold and wet ecosystems store large amounts of
undecomposed organic matter as decomposition rates are low
Cycling rates may be altered greatly by
human activities
Restoration Ecology
goal: return degraded ecosystems to a more natural state
- with time, bio communities can recover from many types of disturbances
- seeks to initiate of speed up the recovery of degraded ecosystems
Two key strategies in restoration
bioremediation and biological augmentation
Bioremediation
Use of living organisms such as prokaryotes, fungi, or plants to detoxify polluted ecosystems.
- can take up and metabolize toxic molecules
Augmentation
uses organisms to add essential materials to a degraded ecosystem
-long term objective of restoration
Long term objective of restoration
return ecosystem as much as possible to its predisturbance state