Ch 55 ecosystems

Ch 55 Ecosystems Jeff Jewett ACS June 2010 Ver 1

Ecosystem

Sum of all organisms in an area AND all the abiotic factors with which they interact

Communities PLUS abiotic factors

Boundaries are rarely clear-cut, may depend on scale of question

Ch 55 Key Topics

Conservation of Energy/Mass

GPP/NPP and limitations

Energy Transfer pyramids of energy/biomass

Biogeochemical Cycles (C, N, H 2 0)

Human impact on biogeo. Cycles

Global warming, eutrophication, biomagnification, acid rain, ozone hole

Energy Flows, Matter Cycles

Energy enters (usually as sunlight)

Converted to biomass (chemical energy) by autotrophs

Passed to heterotrophs (incl. decomposers)

Dissipated as heat

Energy Flows, Matter Cycles (2)

Chemical elements (C, N, P) are cycled between abiotic and biotic parts of ecosystem (Law of Conservation of Mass)

Matter continuously cycles (not created or destroyed)

2 nd law of Thermodynamics:

Energy conversions are never 100% efficient, therefore some is always lost as heat

Ecosystems require constant input of energy

Trophic Levels

Autotrophs = primary producers (redundant)

Photoautotrophs rely on light for energy (by FAR the most common)

Chemoautotrophs oxidize naturally occuring inorganic compounds as fuel (common in hot springs, deep-sea volcanic vents)

All of the ecosystem depends on autotrophs!

Trophic Levels (2)

Heterotrophs

depend directly or indirectly on autotrophs

eat things that are alive or were alive

Consumers & decomposers (detritivores)

Detritivores fungus, bacteria, insects (FBI) eat detritus (non-living organic material such as feces, dead critters, fallen leaves, wood)

Consumers primary, secondary, tertiary, quarternary (higher levels rare)

http://image.tutorvista.com/content/ecosystem/food-web-terrestrial-aquatic-ecosystem.jpeg

55.2 Energy GPP

Gross Primary Production (GPP) = Amount of light energy converted to chemical energy (sugars) per time (rate of photosynthesis)

Some of this energy is used by the plant for life (cellular respiration)

Some is converted into biomass, such as starch storage or structural components (new growth)

NPP a very important ecological statistic!

Net Primary Productivity amount of sugars left over after respiration, per unit time (rate of new biomass production)

NPP = GPP R

Value of NPP gives the size of the base of the food chain (how much total food is there for consumers?)

NPP highest where it is warm/wet

(tropical rainforest)

Global NPP, 2008 NASA Earth Observatory: http://earthobservatory.nasa.gov/IOTD/view.php?id=38889

June NPP http://www.uwsp.edu/geo/faculty/lemke/geog101/images/14c_npp_junemap_nasa.jpg

December NPP http://www.uwsp.edu/geo/faculty/lemke/geog101/images/14e_npp_decmap_nasa.jpg

Human Appropriation of NPP

SKIP THIS SLIDE

http://sedac.ciesin.columbia.edu/es/hanpp.html http://earthobservatory.nasa.gov/Features/HANPP/hanpp.php

Aquatic NPP Limitation

Light -