Ecosystem all the organisms living in a community, ___ _______________

Energy Flow and Chemical Recycling Energy flows through ecosystems, _______ __________________

Energy Flow Energy: the ability to do work Behavior describe by: 1 st Law of Thermodynamics _______________________________________ _____________________________________________ 2 nd Law of Thermodynamics _______________________________________ _____________________________________________

This means…. With the passage of time, ____________tend to move toward maximum _________, eventually no energy available to do work. But… Living systems, like us, are ____________with a constant input of energy.

Energy, Mass, and Trophic Levels Energy in –from the Sun –captured by _________ = ____________ Energy through –food chain transfer of energy from autotrophs to _____________________ (herbivores to carnivores) heterotrophs = _____________________ –herbivores –carnivores

Figure 42.4 Sun Heat Primary producers Primary consumers Detritus Secondary and tertiary consumers Microorganisms and other detritivores Key Chemical cycling Energy flow

Figure 42.3 Detritivores, or decomposers, are consumers that ________________ ________________ ________________ _______________. Prokaryotes and fungi are important detritivores.

Primary Production The ___________________converted to _____________by an ecosystem’s autotrophs in a given _____________. Sets the budget for the ecosystem. Only ____of the energy striking the earth is converted to chemical energy.

Gross and Net Primary Production – Total primary production is known as gross primary production (GPP). This is the ________________that is converted into ________________in an ecosystem. – The net primary production (NPP) is equal to _________________minus the ___________by the primary producers for _____________(R): NPP = GPP – R a NPP is expressed as – Energy per unit area per unit time (J/m 2  yr), or – Biomass added per unit area per unit time (g/m 2  yr)

Net ecosystem production (NEP) is a measure of the _____________________________during a given period NEP is gross primary production minus the total respiration of all organisms (producers and consumers) in an ecosystem (R T ) NEP = GPP − R T

Figure 42.6 Net primary production (kg carbon/m 2 yr) Where are the most productive areas on Earth? What do you notice about Primary Production in the Oceans?

In aquatic ecosystems, light and nutrients limit primary production Production in Marine ecosystems. –Light is the first variable to control primary production in oceans, since ____________________ ____________________ ____________________ _________(photic zone).

In the open ocean, nitrogen and phosphorous levels are very low in the photic zone, but high in deeper water where light does not penetrate.

Ammonium enriched Phosphate enriched Unenriched control Collection site ABCDEFG Phytoplankton density (millions of cells per mL) Which nutrient limits phytoplankton? Ecologists use the term limiting nutrient to define the nutrient that must be added for production to increase.

Upwelling of nutrient-rich waters in parts of the oceans contributes to regions of high primary production

Production in Freshwater Ecosystems. –________________________________ are closely linked to primary production in freshwater lakes. –During the 1970s, sewage and fertilizer pollution added nutrients to lakes, which shifted many lakes from having phytoplankton communities dominated by cyanobacteria. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

This process is called _______________, and which can lead to loss of most fish species Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Primary Production in Terrestrial Ecosystems In terrestrial ecosystems, _______________ and __________ affect primary production on a large scale Primary production increases with moisture

Figure ,400 1,200 1, Mean annual precipitation (cm) Net annual primary production (above ground, dry g/m 2 yr)

Actual evapotranspiration is the ____________ ____________and evaporated from a landscape It is affected by ____________, _____________, and ____________ energy Actual evapotranspiration can be used as a predictor of net primary production

______________are often the limiting factors in primary production (__________________ ______________) – adaptations help plants access limiting nutrients from soil. ___________________

mycorrhizal fungi – these fungi _____________ __________and other limiting elements Roots have root hairs that increase _______________ Many plants release enzymes that increase _____________ _____________________

Secondary production of an ecosystem is the amount of ____________in food converted to ______________during a given period of time Net secondary production is the energy stored in biomass An organism’s production efficiency is the ________ __________that is not used for _____________.

Energy transfer between trophic levels is typically only _____efficient

Trophic structure Food chains – feeding relationships – food chain usually 4 or 5 links = ________ _____________ – length of food chain limited by _________ ___________________

Why are big, fierce animals rare?

The nitrogen cycle

The phosphorous cycle

The carbon cycle

The water cycle