Unit III: Ecosystem Ecology Chapters 3 Part I: Energy Transfer

Chapter Objectives List the basic components of an ecosystem Describe how energy flows through ecosystems. Describe how carbon, nitrogen, and phosphorus cycle within ecosystems Explain how ecosystems respond to natural and anthropogenic disturbances Discuss the values of ecosystems and how humans depend on them

I. Ecosystems Particular location on Earth distinguished by its particular mix of interacting biotic and abiotic components, Components of an ecosystem are interrelated Each ecosystem interacts with surrounding ecosystems through the exchange of energy and matter

Sustain Life on Earth: One-way flow of high-quality energy from the sun, through living things in their feeding interactions, into the environment as low quality (heat) energy and eventually back into space. Cycling of Nutrients (atoms, ions, molecules) through the biosphere. Law of Conservation of Matter governs nutrient cycling process. Gravity: allows planet to hold onto atmosphere and helps movement and cycling of chemicals through air, water, soil, organisms

II. Energy Flows Through Ecosystems Producers (autotrophs) Photosynthesis 6CO2 + 6H2O + light energy C6H12O6 + 6O2 Producers –Make own food from compounds and energy obtained from environment. Most capture sunlight to produce carbs by photosynthesis. on land mostly vascular plants/water phytoplankton Decomposers – mostly bacteria, some fungi, consumers that complete breakdown of and recycling or organic matter. They release these nutrients into soil and water, to be used by producers. Detrivores=live off detritus-extract

Anaerobic Respiration / Fermentation C6H12O6 + 6O2 6CO2 + 6H2O + Energy (38 ATP) Anaerobic Respiration / Fermentation Breakdown of glucose in absence of oxygen. C6H12O6 2C2H5OH (ethanol) + energy C6H12O6 2C3H6O3 (lactic acid) + energy Products are methane (CH4), ethyl alcohol ( C2H6O) and acetic acid (C2H4O2) In aerobic respiration one molecule of glucose can generate 38 molecules of ATP, in anaerobic respiration about 2 molecules of ATP are released per one molecule of glucose

Chemosynthesis: Chemosynthetic microbes grow on and below the seafloor and even within other animals at the vents A process in which certain microbes use chemicals in the vent water to produce energy. They in turn form the base for an entire food chain of animals. Chemosynthesis is the process by which certain microbes create energy by mediating chemical reactions.They make carbs from hydrogen sulfide (H2S) So the animals that live around hydrothermal vents make their living from the chemicals coming out of the seafloor in the vent fluids! Because they are a local food source, hydrothermal vents typically have high biomass, in stark contrast to the very sparse distribution of animals outside of vent areas where animals are dependent on food dropping down from above. Consumers: all other organisms . Omnivore

III. Trophic Levels, Food Chains and Food Webs Consumers: Heterotrophs 1o, 2o, 3o Herbivore Carnivore Omnivore Scavenger Detrivore Acid, Poop, and Barf: Vultures' Secret Weapons Biomes-major eco divisions determined by relationship between altitude and temperature and precipitation/characterized by distinct climate andlife forms that have adapted. Abiotic-sun, temp, precip, wind, latitude, altitude, nutrients ROT-range of abiotic conditions in which an organism (species) can survive.LOT-the existence, abundance, distributino of species whithin an ecosystem determined by whether physical and chemical factors fall within range of tolerance Limiting Factor: A variable that influences that growth, abundance and distribution of a population Example: car manufacturing-if a part is in short supply than cars can only be produced at the rate that part is available, even if there is an abundance of other car parts. In an exosystem is could be sun, temp., water, oxygen,availability of nutrients

Decomposers: break organic compounds down into inorganic substances. Fruit and vegetable Decomposition http://en.wikipedia.org/wiki/Decomposition Bacteria/Fungi Detrivores: Comsume detritus to optain energy. Earthworm, Beetles, Millipedes, Sow Bug Diverstiy: Genetic, Species, Ecological Decomposers: recycle nutrients. Secrete enzymes that digest or degrade dead organisms into simpler INORGANIC compounds Scavangers-Feed of dead organisms killed by others or die naturally nutrients from partly decomposed organic matter.

Food Webs & Energy Flow © Brooks/Cole Publishing Company / ITP

V. Productivity Different Ecosystems use solar energy to produce and use biomass at different rates. To understand how ecosystems function must understand where energy comes from and how it is transferred Gross Primary Productivity-GPP total amount of energy that producers in an ecosystems capture via photosynthesis over a given amount of time GPP: Rate at which producers convert solar energy to chemical energy as biomass. NPP: Producers must use some of the biomass they produce to grow, reproduce and stay alive. What are these processes called? (Respiration) The rate at which producers use photosynthesis to store energy – rate at which they use some for aerobic respiration is the net. It is a measure of how fast producers can supply food to consumers.

Energy captured minus the energy respired by producers is Net Primary Productivity: NPP NPP=GPP-R

Why Productivity is Important The amount of sunlight that reaches a lake determines how much algae can live in the lake Amount of Algae determine the number of zooplankton the lake can support Size of zooplankton population determines size of fish population

Measuring Productivity Rarely does photosynthesis occur w/o respiration. Measure production of CO2 in dark (only produced-no photo means no uptake/loss of CO2) Measure uptake of CO2 in sunlight. (being produced and used) CO2 taken up in photosynthesis = CO2 taken up in sunlight + CO2 produced in dark

Factors Limiting Primary Productivity The planet’s NPP limits the number of consumers-including humans, that can survive on earth. Solar Radiation alone does not determine Primary Productivity Temperature: Relationship between forest net primary productivity and annual temperature. Precipitation Increasing Precipitation increases productivity http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/energyflow/energyflow.html

Energy Transfer Efficiency and Trophic Pyramids The energy in an ecosystem can be measure in terms of biomass (total mass of all living matter) NPP establishes the rate at which biomass is produced over a given amount of time. The amount of biomass present in an ecosystem at a particular time is standing crop Not all energy contained in a trophic level is in a usable form-not digestible

Problem 1% solar energy striking a producer captured by photo 60% of GPP lost to respiration 40% of GPP supports the growth and reproduction of producers A North American Forest has a GPP of 2.5 kg C/m2/year How much is “lost” to respiration? What is the NPP?

An acre of cropland could produce 1,000 kg of soybeans. If that is fed to people, how much biomass is available? Of fed to a cow, how much biomass do we get from the beef? Since 1 kg of soybeans contains 2.5 as many calories as 1kg of beef, 1 acre of land can produce 25 more calories when used for soybeans than beef.