Chapter 3 Ecosystem Ecology

Reversing the Deforestation of Haiti Life prior to 2010 earthquake  hard People use forest (wood) for fuel Effects of relying on charcoal Deforestation rate very high and not sustainable Deforestation - disrupts ecosystem services U.S. Agency for International Development – has funded planting of 60 million trees More successful: planting mango trees Looking to find/develop alternative fuel sources Why talk about this? All ecosystems can be influenced by human decisions

Ecosystem Ecology Examines Interactions Between the Living and Non-Living World Components of ecosystem are highly dependent on climate

Ecosystem Boundaries Ecosystem boundaries may or may not be defined In most ecosystems it is difficult to determine where one ecosystems stops and the next begins Boundaries are _________________________________

Large vs. Small Ecosystems:

Ecosystem Processes Important to remember: Even though it is helpful to distinguish between two different ecosystems, ecosystems interact with other ecosystems.

Energy Flows through Ecosystems Most energy on Earth comes from _____________________ Major Players: Producers (autotrophs) Consumers (heterotrophs) Herbivores Carnivores Remember 2nd Law of Thermodynamics

Photosynthesis and Respiration Photosynthesis – producers use solar energy to convert carbon dioxide and water to glucose and oxygen Cellular respiration – process by which other organisms gain energy from eating the tissues of producers. Overall, producers photosynthesize more than they respire Plants are carbon “_________________________”

Remember these formulas!

Trophic Levels, Food Chains, and Food Webs Consumers (heterotrophs)- Primary Consumers (herbivores)- Secondary Consumers (carnivores)- Tertiary Consumers (carnivores)- Rarer

Food Chain

Trophic Levels, Food Chains, and Food Webs Food Chain- the sequence of consumption from producers through tertiary consumers Food Web- a more realistic type of food chain that takes into account the complexity of nature

Food Web

Trophic Levels, Food Chains, and Food Webs Some other important key players in food webs: Omnivores – eats both plant and animal materials Scavengers – consume dead animals Detritivores – break down dead tissues and waste products into smaller particles Decomposers – organisms that complete the breakdown process; These are all very important!

Ecosystem Productivity Life in an ecosystem is dependent on the amount of energy available Gross primary productivity (GPP) - total amount of solar energy that the producers in an ecosystem capture via photosynthesis over a given amount of time Net primary productivity (NPP)- ** NPP = GPP – respiration**

Ecosystem Productivity Cannot just measure actual value – instead we determine the rate of photosynthesis and the rate of respiration to calculate this Look in your textbook for more details! NPP of ecosystems range from 25-50% of GPP This is equivalent to about 0.25% of solar energy striking planet

NPP Varies Among Ecosystems

Energy Transfer Efficiency and Trophic Pyramids Biomass – Standing crop - amount of biomass present in an ecosystem at a particular time Ecological efficiency - Some energy lost Fairly low numbers  5-20% range; average 10%

Energy Transfer Efficiency and Trophic Pyramids THIS IS NOT IN YOUR TEXTBOOK: Trophic pyramids - Graphically represent the relative energy value of each trophic level Important feature is that large amount of energy are lost between trophic levels to heat Three main types Pyramid of numbers Pyramid of biomass – only one Chapter 3 covers Pyramid of energy

Pyramid of Numbers Illustrates the number of organisms at each trophic level Usually, organisms at the base of the pyramid are more numerous Fewer organisms occupy each successive level 10 % rule Do not indicate the biomass of the organisms at each level or the amount of energy transferred between levels

Pyramid of Biomass Illustrates the total biomass at each successive trophic level Biomass: measure of the total amt of living material Biomass indicates the amount of fixed energy at a given time 10% rule Illustrates a progressive reduction in biomass through trophic levels

Pyramid of Energy Illustrates how much energy is present at each trophic level and how much is transferred to the next level Most energy dissipates between trophic levels Explains why there are so few trophic levels Energy levels get too low to support life

Matter cycles through the biosphere Biogeochemical cycles - The movement of matter within and between ecosystems involving biological, geologic and chemical processes Involves biological, geological and chemical processes Pools Flows Important chemical elements to life on Earth?

The Hydrologic Cycle

The Carbon Cycle

The Nitrogen Cycle

The Phosphorus Cycle

Homework: Check out page 73 Calcium, Magnesium, Potassium, and Sulfur:

Ecosystems respond to disturbance How do these disturbances affect the flow of matter and energy through ecosystems?

Chandeleur Islands in LA Almost completely submerged by Hurricane Katrina (2005)

Watershed Studies Watershed- All of the land in a given landscape that drains into a particular stream, river, lake or wetland. Common place for scientists to conduct ecosystem studies

Watershed Studies One of most thorough examples: Hubbard Brook ecosystem of NH (since 1962) Monitoring of the hydrological and biogeochemical cycles of 6 watershed at Hubbard Brook Investigating effects of clear cutting and subsequent suppression of plant regrowth Control area – Experimental area –

Resistance versus Resilience Not all disturbances = disasters Resistance- A measure of how much a disturbance can affect its flows of energy and matter. Resilience- The rate at which an ecosystem returns to its original state after a disturbance. High resilient Less resilient Restoration ecology-

The Intermediate Disturbance Hypothesis The intermediate disturbance hypothesis - states that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels.

Ecosystems Provide Valuable Services Instrumental value – when a species has worth as an instrument or tool that can be used to accomplish a goal See next slide Intrinsic value – People who believe an ecosystem to be inherently valuable may argue we have a moral obligation to protect

Instrumental Values of Ecosystems Estimated that ecosystem services are worth over $30 trillion per year Provisions- Goods that humans can use directly Regulating services- The service provided by natural systems that helps regulate environmental conditions Support systems- The support services that natural ecosystems provide such as pollination, natural filters and pest control Resilience- Resilience of an ecosystem ensures that it will continue to provide benefits to humans. This greatly depends on species diversity. Cultural services- Ecosystems provide cultural or aesthetic benefits to many people.