Ecosystems

1. Ecosystems Biological Life Science

2. What is an ecosystem? • System= regularly interacting and interdependent components forming a unified whole • Ecosystem = an ecological system;= a community and its physical environment treated together as a functional system

3. Ecosystem • Unit of biosphere consisting of interacting biotic and abiotic factors. • Biotic Factors: Living physical factors of an environment. • Organisms, parasites, predation, etc. • Abiotic Factors: Non-living physical factors of an environment. • Air, sunlight, water, pressure, etc.

4. Habitat: The physical location in which an organism lives. • Niche: The way of life of an organism (species). • Includes: Habitat, feeding habits, reproductive behavior, etc.

5. Parts of the Biosphere • Species – a group of organisms that can reproduce (Ex – humans). • Population – The number of a species in a given area (Ex – all the humans living in Dresden). • Community – All the species in a given area (Ex – the humans, trees, grasses, bacteria, squirrels, mice….. Living in Dresden.)

6. Parts of the Biosphere • Ecosystem – The community and all the nonliving things in an area (Ex – all the plants, animals, bacteria, fungi and protists, plus the air, water, and climate of Dresden). • Biosphere – The area on the Earth that supports life (includes the bottom of the oceans to the upper atmosphere).

7. Parts of the Ecosystem

8. Competition • Since resources will eventually run out, organisms have to compete for it. • Can be between members of the same species (Ex – Polar Bears have to compete for fish to eat). Intraspecific competition • Can be between members of a different species (Ex – a robin and a woodpecker might compete over a tree to build a nest in.) Interspecific competition

9. Niche • Niche – the role an organism plays in the environment (Ex – The Great White Shark is the top consumer in some marine ecosystems.) • If two organisms occupy the same niche they will compete for resources until one species is forced out.

10. Carrying Capacity • The maximum number of individuals an ecosystem can support is the carrying capacity. • Once the carrying capacity is met, limiting factors (such as space, food, shelter) keeps the population size near this carrying capacity.

11. Carrying Capacity # Of Individuals Time

12. Predator – Prey Relationships Predators Can Control the Prey Population • Predators help control the prey population (Since there are few predators of Deer left in New York State, their population size is out of control). • If there are no natural predators the prey become overpopulated.

13. Predator – Prey Relationships Prey Populations Can Control the Size of Predator Populations • If there are few prey in an area, a small number of predators can survive. • If there are many prey in an area, more predators can survive.

14. Predator-Prey Relationships The Predators and Prey May Have No Relationship • If the predators rely on many sources of food, one disappearing may have little effect (Ex – If cows go extinct we might have to eat more chicken, but humans would still survive.)

15. Predator-Prey Relationship Example Moose Wolves

16. Food Chains Parts of the Food Chain • Producers – (Autotrophs) make their own food from abiotic factors (Ex – Green plants make glucose by photosynthesis.) • Herbivores – Consumers that eat only plants. (Ex – rabbits eat crops and other plants)

17. Food Chains • Carnivores – Eat only other consumers (Ex – lion). • Omnivores – Eat plants and animals (Ex – Humans). • Detrivores – (Decomposers) Feed off of and break down dead organisms. These are usually bacteria and fungi.

18. Energy Pyramid

19. Food Pyramid Relationships Biomass Pyramid • Measures the amount of material at each trophic level. • Like the Energy Pyramid, the larges biomass is at the base (producers) and it decreases as you move up the pyramid.

20. Biomass Pyramid

21. Food Pyramid Relationships Pyramid of Population Size • The third pyramid shows the number of individuals at each trophic level. • Life the other two pyramids, the largest population is at the base (producers) and decreases as you move up the pyramid.

22. Pyramid of Population Size

23. Summary of the Pyramid Relationships Energy Pyramid Shows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat. Pyramid of Numbers Shows the relative number of individual organisms at each trophic level. Biomass Pyramid Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid.

24. Trophic Levels • A trophic level is the position occupied by an organism in a food chain. • Trophic levels can be analyzed on an energy pyramid. • Producers are found at the base of the pyramid and compromise the first trophic level. • Primary consumers make up the second trophic level. • Secondary consumers make up the third trophic level. • Finally tertiary consumers make up the top trophic level.

26. Antarctic Food Web

27. Trophic Levels Found on an Energy Pyramid • The greatest amount of energy is found at the base of the pyramid. • The least amount of energy is found at top of the pyramid.

28. Trophic Structure Reminder • Eltonian pyramids • Number of individuals per species • Is this pyramid stable?

29. Trophic Structure Reminder • What if we transformed each species into biomass instead of absolute numbers?

30. Biomass • Energy is sometimes considered in terms of biomass, the mass of all the organisms and organic material in an area. • There is more biomassat the trophic level of producers and fewer at the trophic level of tertiary consumers. (There are more plants on Earth than there are animals.) • Bio=life Mass=weight • Bio + Mass = Weight of living things within an ecosystem.

31. Trophic Structure Reminder • Express trophic structure as energy transfer • Energy pyramids can never be inverted • Is there room for anyone else • at the top of this food chain?

36. Biological Magnification • If a poison is introduced into an ecosystem, it will affect each level of the food chain more severely. • Each level of the food chain will have more individuals affected.

37. Biological Magnification

39. Accidental Introductions • Zebra Mussel – from Caspian Sea to Great Lakes (1986) from a ship • Now they are everywhere!!! • Problem: clogs water pipes, smothers native clams, consumes plankton, no natural predators • Killer Bees – genetically altered to make more honey • Africanized bees escaped and took over Brazilian honeybees • Problems arose: they are more aggressive, can travel longer distances, swarm, attack people • The real threat? Agriculture

42. More Invasive Species • Asian Carp • Introduced in 1970s • No natural predators • Out compete native fish and mollusks for food • Snakehead Fish • Early 2000s • No natural predators • Eat mostly other fish • Can breathe air • 4 days out of water

43. Nutrient Recycling Water Cycle - Earth’s water supply is constantly recycled throughout the biosphere: • Evaporation – water vapor leaves the oceans and joins the atmosphere. • Transpiration – water vapor evaporates off of plant leaves. • Condensation – water vapor in the atmosphere forms clouds. • Precipitation – water vapor in the atmosphere falls to the ground (rain.)

45. Nutrient Recycling CO2 and O2 Cycle • Photosynthesis and Cellular Respiration work together to recycle carbon dioxide and oxygen in the atmosphere. • Photosynthesis – in plants, uses up CO2 and produces O2 as a waste. • Cellular Respiration – in consumers, uses O2 and produces CO2 as a waste.

46. Nutrient Recycling Nitrogen Cycle • The Nitrogen in the atmosphere is made usable for living things through Nitrogen Fixation. • Plants use this nitrogen in the soil to make protein. This is assimilation. • Once the plants and organisms that eat the plants die, decomposers break down the remains and return the nitrogen to the soil and the atmosphere.

48. Ecological Succession • As organisms live in a given area, they change their environment. • As the environment changes, so do the organisms that can live there.

49. Ecological Succession • Primary Succession – a pioneer organism first grows on a bare rock surface (Ex – Hawaiian Islands) • Secondary Succession – after a disaster (fire, drought) succession begins again at an intermediate stage (Ex – Pine Barrens of Long Island).

50. Human Effects on the Environment Negative Effects: • Urbanization • Industrialization • Agriculture • Exploitation of Wildlife • Deforestation