1. Biological Production and Ecosystem Energy Flow
AP Environmental Chapter 9
Unit 2

2. Energy Flow
Movement of energy through an ecosystem from the environment, through organisms, and then back to the environment
Inputs:
Energy fixed by organisms
Energy transferred as heat through the air, water or land currents

3. Energy Flow
Kinetic energy in the environment can be visible as heat in living organisms
The infrared picture on
the right shows clover
leaves with and without
ozone exposure

4. 1st Law of Thermodynamics
“Conservation of Energy”
States that in any change energy is neither created or destroyed

5. 2nd Law of Thermodynamics
Whenever work is done some energy is always lost to heat and cannot be efficiently recovered
This decrease in order (disorganization of energy) is called entropy

6. 2nd Law of Thermodynamics
For an ecosystem to function energy must continuously be added to replace energy lost by metabolic processes

7. Energy Efficiency
As energy flows through a food web, it is degraded, and less and less is useable.
Energy efficiency- the ratio of output to input
The amount of useful work obtained from some amount of available energy

8. Energy Efficiency
Trophic-level efficiency- the ratio of production of one trophic level to the production of the next trophic level.
Never very high
1-3% in natural ecosystems
10% may be maximum
90% of all energy lost as heat

9. Biological Productivity
The goal of ecological communities is to efficiently use energy for the production of biomass (biological material)
Energy is the ultimate
limiting factor for the
growth of a species or
population

10. Biological Productivity
Biomass- the total amount of organic matter on Earth or in any ecosystem or area.
Usually measured as the amount per unit surface area
Biological production- the capture of usable energy from the environment to produce organic compounds in which that energy is stored.

11. Biological Productivity
Change in biomass over a given time is called net production.
Three measures used for biological production
Biomass
Energy stored
Carbon stored

12. Types of Production Autotrophs
Make their own organic matter from energy source and inorganic compounds
Primary production
Most photosynthesize, some chemoautotrophs
Heterotrophs
Cannot make their own organic compounds and must feed on other living things
Secondary production

13. Biological Productivity
Primary production generates the most biomass
Secondary production stores or uses biological energy through processes like tissue growth or respiration to create smaller amounts of biomass
In a food chain decomposers carry out decomposition of biomass into abiotic nutrients

14. Biological Productivity
Use of energy from organic matter by both heterotrophic and autotrophic organisms is done by respiration.
Organic matter (glucose) combines with oxygen
Releases energy stored in chemical bonds along with carbon dioxide and water
Respiration- the use of biomass to release energy that can be used to do work.

15. Gross and Net Production
Production of biomass for use as energy
1. An organism produces organic matter in its body. (gross production)
2. It uses some of this new organic matter as a fuel for respiration.
3. It stores some of the newly produced organic matter for future use. (net production)

16. Gross and Net Production
Gross Primary Production(GPP) is the total amount of CO2 that is fixed by the plant in photosynthesis.
Net Primary Production (NPP) = GPP – Respiration
Net Ecosystem Production (NEP) =
GPP – Respiration from all sources in the ecosystem

17. Primary Production
There are 2 ways to measure the primary production of a biological community
Rate of photosynthesis (measurement of CO2 depletion or O2 production)
Rate of increase in plant biomass (weight of organic tissue)
What are the sources of errors in both methods for a natural environment?

18. Biological Productivity
Depending on the situation involved there are different ways to measure productivity of a system
Standing crop: measure of the biomass of a system at a single point in time (Ex: the amount of corn growing in a corn field)
Energy output (Ex: machinery)

19. Biological Productivity
Biomass can be gained through ingestion of chemical energy created by primary production
Biomass is lost through excretion (decomposition or respiration)
Assimilation is the amount of biomass created overall
Assimilation = ingestion-excretion

20. Biological Productivity
Different ecosystems reach different levels of productivity based on environmental factors

21. Biological Productivity
Worldwide production based on the area covered by the ecosystem globally

22. Ecological Succession
Ecosystems are dynamic systems that are constantly changing and requiring change
If systems are disturbed then the recovery process is called ecological succession

23. Ecological Succession
Succession is represented by gradual changes in the species within a community over time
Two types:
Primary succession: the establishment of an ecosystem where one did not exist before
Secondary succession: the re-establishment of an ecosystem after a disturbance where remnants of a biological community have been left behind

24. Primary Succession
Begins in a place that has no soil and no living species
The first species that move into an area are called pioneer species
Lichen is an example of a pioneer species that is able to break solid rock down into soil through chemical weathering processes

25. Primary Succession
Lichens:  a symbiotic relationship between algal or cyanobacterial cells that are photosynthetic and a fungus.
The fungi provides support, water and minerals and are able to decompose organic material.
The algae or bacteria provide sugars through photosynthesis.

26. Primary Succession
As lichens die they break down into organic material that enters the newly made soil
Once nutrient rich soil has been created other small plant species are able to enter the ecosystem and find the nutrients necessary to survive

27. Primary Succession
As small plants continue to add organic matter to the soil larger organisms are then able to be supported by the ecosystem

28. Secondary Succession
With soil and some biologic activity in the environment secondary succession takes less time to develop nutrients to support larger organisms

29. Climax community
A climax community is the goal of succession in an environment because it marks a period of stability after a disturbance and is characterized by mature organisms that are able to reach sustainability in the ecosystem

30. Succession patterns in NC
The types of intermediate and climax plants that arise during succession depend on the surrounding environment
Succession in most North Carolina environments result in pine species during the intermediate phases that then give way to hardwood species like oak and hickory trees

31. Succession patterns in NC
During the intermediate stages pine tree development occurs relatively quickly and creates a forest canopy that blocks sunlight from reaching shrubs and underbrush
Without sunlight, the forest floor clears and creates a bed of leaf litter that chokes out new pine seedlings leaving room for the hardwood saplings to take root and thrive
As hardwoods flourish they choke out the pine trees to reduce competition for nutrients

32. Succession Patterns in NC