1. Ecology – Part 2 The Cycling of Matter and Energy in Ecosystems General Biology Name__________________

2. There is a flow of materials and energy throughout every ecosystem

3. There is a constant flow of materials and energy between the living (biotic) and nonliving (abiotic) parts of every ecosystem.
Materials (atoms, molecules) must be recycled but energy is NOT!
So, a constant supply of energy must enter every ecosystem. On earth, this is supplied by the SUN!

4. Remember, organisms must be able to:
produce or obtain nutrients
convert the nutrients into usable forms of chemical energy (cellular respiration – producing ATP!!)
use these forms of energy to power their life processes.

5. 2 Categories based on how living things produce/obtain nutrients….
Heterotrophs
Autotrophs
Obtains food by consuming other living things
CONSUMER
Ex: Animals, fungi, some microorganisms (bacteria)
Categories:
Herbivores,
Omnivores
Decomposers
Capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds
PRODUCER or Primary Producer
Ex: All Plants, some microorganisms (bacteria)

6. Don’t forget – Different types of Autotrophy

7. Types of Heterotrophy
Carnivores kill and eat other animals. Ex: snakes, dogs
Herbivores eat plant leaves, roots, seeds or fruits. Ex: birds, insects
Scavengers consume the carcasses of dead animals. Ex: vulture
Omnivores eat both plants and animals. Ex: humans, bears
Detritivores chew or grind dead/waste matter into smaller pieces. Ex: snails, crabs
Decomposers “feed” by chemically breaking down organic matter and recycle the materials for producers to use. Ex: bacteria and fungi

8. Food Chains
Series of steps in an ecosystem in which organisms transfer energy and materials by eating and being eaten.
Arrow points to the “eater”.
Vary in Length but usually 4-5 steps max.
Example – how many steps (trophic levels) in the food chain below?
Must always start with a producer; then goes to one or more consumers.
Although not always shown, the final link is decomposers.

9. Examples of Food Chains

10. Food Webs Diagram showing interconnected food chains
Shows networks of feeding interactions
Many animals eat more than 1 type of food
Each step in a food chain/web is called a trophic level
Changes at any level can cause drastic changes in other level(s).

11. What would happen if…..
-Algae was killed off?
-Alligators were killed off?

12. Decomposers & Detritivores in Food Webs
Convert dead/waste material into detritus
Eaten by detritivores
Ex: Grass Shrimp, Crayfish, Worms
Decomposers releases nutrient that can be used by primary producers
Nature’s Recyclers
Without them – nutrients would remain locked in dead organisms
Examples: Bacteria & Fungi

13. Ecological Pyramids
These are used to show the relative amounts of energy, biomass, or numbers of organisms in each trophic level of a given food chain or web.
Three types:
Pyramid of Energy
Pyramid of Biomass
Pyramid of Numbers

14. Energy Flow in the Community
Energy initially comes from SUN.
As energy passes through each member of chain, some energy is lost as HEAT.
WHY? Each organism performs cellular respiration and uses part of the energy for its own needs. Also some is lost to waste products.
Energy Pyramid – wider at bottom (more organisms can exist b/c more energy at this level.
ENERGY PYRAMID

15. Pyramids of ENERGY
Pyramids of Energy show the relative amount of energy available at each trophic level of a food chain/food web
What happens to the amount of energy available at each trophic level?
It DECREASES!!
Only 10% of available energy gets passed to the next level
Where does the other 90% go??
Most released as heat, from C/R
Some lost in waste products
Organisms expend much of the energy they acquire on LIFE PROCESSES – respiration, growth, reproduction etc
Most of the remaining energy is released into the envionment as heat – byproduct of these activities

16. Energy Pyramid

17. Pyramids of BIOMASS What’s Biomass??? Pyramid of biomass
Total amount of living tissue within a given trophic level
Pyramid of biomass
The amount of biomass a given trophic level can support is determined by the amount of available energy.
Relative amount of living organic matter
Greatest biomass is at base – see image

18. Pyramids of NUMBERS
Shows the relative number of individual organisms at each trophic level in an ecosystem.
In most ecosystems, the shape of the pyramid of numbers is similar to the shape of the pyramid of biomass for the same ecosystem, with the numbers of individuals on each level decreasing from the level before it.
This is the only pyramid that can be inverted!!
Pyramids will be upside down or inverted if there are a lot of small animals feeding on a large plant. They are also inverted where an animal has a large number of small parasites feeding on it. One human, for example, can have a large number of head lice.

19. Matter is recycled, energy is not…

20. Nitrogen Cycle
Nitrates – chemical in soil that contain nitrogen. Needed by plants to make proteins.
NITROGEN CYCLE (repeating steps)
Bacteria on roots change N in air into nitrates in soil.
Nitrogen in dead organisms changes to nitrates in soil.
Nitrates can be used by plants/animals to make proteins.
Bacteria change some nitrates in soil back into nitrogen in air.

21. Soil Soil comes from rocks that have broken down.
Place for plants to anchor roots
Home for worms, insects, rodents
Loosened, aerated by organisms
Many bacteria live there
Holds water, nutrients, gases
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22. Water Cycle All cells need water to live!!
Rain/snow – water falls to earth
Water runs into rivers, ponds, oceans
Water soaks into soil
Plants & animals use water; the rest flows into underground lakes/rivers
Plants/animals lose excess water (plants – transpiration; animals – evaporation) to the air
Evaporation from lakes, rivers, oceans
NOTE: repeating cycle; steps not necessarily in order!

23. Oxygen-CO2 Cycle OXYGEN Given off by producers during photosynthesis
Used by all living things during respiration
CARBON DIOXIDE
Given off during respiration
Used by producers during photosynthesis
This cycle goes on in both land and water ecosystems.

24. What did we learn so far?
The sun is the ultimate source of energy for most ecosystems. As a result, organisms exhibit different strategies to obtain this energy.
Energy relationships can be represented in a graphical depiction called a pyramid.
Elements cycle in various molecular forms through the bioshere. The carbon, oxygen, nitrogen and water cycles are examples essential to life.
Matter cycles through food chains but energy must be continually supplied.
There are varying levels of biodiversity found in the different biomes.