Ecosystems

1. Ecosystems Biology/Env S 204 Spring 2009

2. Scale of relationships Molecules smallest Genes Cells Organisms (individuals) Populations Species Communities Ecosystems Biomes Biosphere largest

3. Ecological Principles • Everything is connected to everything else. • Everything has to go somewhere. • There is no free lunch in nature. (Or, you don’t get something for nothing.)

4. Communities Community: all of the organisms in a given area (habitat) and their interactions.

5. Ecosystems Ecosystem = biotic community + abiotic environment Energy from the sun Precipitation, etc. e.g., flower + pollinator Nutrients such as carbon, etc.

6. Ecosystems The scale can be… very small (a leaf) to very large (global)

7. Ecosystems Energy flow is one-way through ecosystems. Materials (nutrients) are cycled through ecosystems.

8. Ecosystems—1) Energy processes Photosynthesis Respiration

9. Ecosystems—1) Energy processes Photosynthesis transforms radiant (solar) energy into chemical energy (stored as chemical bonds in sugars and carbohydrates. O2 CO2 plant sun sugars, starches in cells

10. Ecosystems—1) Energy processes Respiration is a step-by-step process that allows organisms to use the energy stored the chemical bonds manufactured during photosynthesis. O2 energy for cellular work + heat sugars, starches

11. Ecosystems—2) energy users • There are three main categories of organisms • according to the ecological roles they play: • Producers (primary producers, autotrophs) • Consumers (heterotrophs) • 3) Decomposers (a special type of consumer)

12. Ecosystems—2) energy users Producers capture the sun’s energy and transform it into chemical energy through photosynthesis. plants + algae + blue-green algae

13. Ecosystems—2) energy users Consumers are organisms that eat other organisms. Herbivores eat producers directly, carnivores eat other consumers. Examples: panda eating bamboo, bird eating nectar or flowers snail grazing on algae Herbivores (grazers, primary consumers)

14. Ecosystems—2) energy users Consumers are organisms that eat other organisms. Herbivores eat producers directly, carnivores eat other consumers. Examples: limpkin eating apple snails American alligator amoeba Carnivores (secondary or tertiary consumers)

15. Ecosystems—2) energy users Decomposers (detritivores) are a type of consumer that feed on dead organic matter—they can obtain this from any of the other trophic levels. fungi and many bacteria but also scavengers such as vultures

16. Ecosystems—3) Energy flow Energy flow is one-way through ecosystems. WHY?

17. Ecosystems—3) Energy flow In any energy transformation (e.g., from one trophic level* to another) there is a net loss of usable energy. *Trophic level: feeding relationships, who is eating whom.

18. Ecosystems—3) Energy flow Lost as heat decomposer decomposer decomposer cow jaguar sun plant Lost as heat

19. Ecosystems—3) Energy flow Lost as heat decomposer decomposer decomposer 90% 90% 90% 10% 10% 10% 10% 10% 1-5% sun cow plant jaguar captured 90% 90% Lost as heat

20. Ecosystems—3) Energy flow Carnivores, especially secondary or tertiary ones, are rare. carnivores herbivores producers

21. Ecosystems—Materials Water and elements (e.g., carbon, nitrogen) and other materials are cycled through ecosystems. They move between organic and inorganic phases by both biotic and abiotic processes. The diversity of microorganisms (especially bacteria) controls key steps in various cycles (see textbook examples of the nitrogen cycle, the carbon cycle, etc.)

22. Ecosystem Services • Services provided by biodiversity that keep ecosystems functioning. • Often thought of in terms of human wellbeing. • Indirect-use value of biodiversity (these services are not factored into the marketplace).

23. Ecosystem Services—examples • Photosynthesis • Nutrient cycling • Decomposition