Lecture 2. Energy and Ecosystems. Lecture 2

Transcription

1 Lecture 2 Energy and Ecosystems Lecture 2 1. Ecology The Ecological Hierarchy 2. Energy Laws of Thermodynamics Photosynthesis and Cellular Respiration 3. Flow of Energy Through Ecosystems Producers, Consumers and Decomposers Path of Energy Flow: Who Eats Whom Ecological Pyramids Ecosystem Productivity 1

2 Ecology Ecology A branch of the Biological Sciences logy study of, eco house Study of one s house 1. The study of interactions among and between organisms in their abiotic environment, or 2. Study of the structure and function of nature 2

3 Ecology Popular vs. Scientific Ecology Ecologists are interested in the levels of life above that of organism Autecology study of the organism, physiology, natural history, genetics, etc. 3

4 Ecology Biotic - living environment Includes all organisms (plants, animals, etc.) Abiotic - non living or physical environment Includes living space, sunlight, soil, precipitation, etc. Ecology Ecological Hierarchy 4

5 Ecology Definitions Species - A group of similar organisms whose members freely interbreed to produce fertile offspring Currently 1.2 million Estimates 8.7 million Ecology Organisms interact with biotic components, but also effect many physical and chemical processes Physical walking on soil, digging burrows, gnawing trees, etc. Chemical CO 2, O 2, wastes 5

6 Ecology Hierarchy Population - A group of organisms of the same species that live in the same area at the same time 6

7 Ecology Hierarchy Community - All the populations of different species that live and interact in the same area at the same time Ecology Hierarchy Community - All the populations of different species that live and interact in the same area at the same time 7

8 Ecology Hierarchy Ecosystem - A community (biotic) and its physical (abiotic) environment Ecology Hierarchy Landscape - Several interacting ecosystems (ex: bear hunting for salmon in a river, living in adjacent forest) 8

9 Ecology Hierarchy Biosphere all the areas of the earth that contain living organisms; the global sum of all ecosystems. Ecology Hierarchy Part of Earth that contains living organisms Community and physical environment All populations of species in an area Group of same species Individuals 9

10 Ecology Biosphere contains earth s ecosystems and includes, but these organisms interact with the three main abiotic realms: Atmosphere- gaseous envelope surrounding earth Hydrosphere- earth s supply of water Lithosphere- soil and rock of the earth s crust Ecology Lithosphere Atmosphere Hydrosphere 10

11 Energy Energy of Life The ability or capacity to do work Chemical, Thermal, Mechanical, Nuclear, Electrical, and Radiant/Solar (below) 11

12 Energy Basics Energy exists as: Potential energy (stored energy) Kinetic energy (energy of motion) Potential energy is converted to kinetic energy as arrow is released from bow Thermodynamics Study of energy and its transformations (potential energy to kinetic energy, etc.) System- the object being studied Closed System- Does not exchange energy with surroundings (rare in nature) Open System- exchanges energy with surroundings 12

13 Laws of Thermodynamics First Law of Thermodynamics Energy cannot be created or destroyed; it can change from one form to another Conservation of Energy Laws of Thermodynamics Second Law of Thermodynamics When energy is converted form one form to another, some of it is lost as heat Engine converts the chemical energy of gasoline into mechanical energy inefficiently 13

14 Energy Basics Solar radiation is the primary source of energy on planet Powers ALL life on the planet (99%) Plants turn solar radiation into food All energy on this planet Mr. Sun 14

15 Photosynthesis A biological process - energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules (potential energy) 6 CO H 2 O + radiant energy Chlorophyll in plants C 6 H 12 O H 2 O + 6 O 2 Potential Energy Cellular Respiration The process where the chemical energy captured in photosynthesis (PE) is released (KE) within cells of plants and animals C 6 H 12 O O H 2 O 6 CO H 2 O + energy (kinetic energy) This energy is then used for biological work 15

16 Photosynthesis and Cellular Respiration Represent an Open System Life without Sun 1970s discovered hydrothermal vents in deep ocean (200 o C or 392 o F) Rich ecosystem supported without light Bacteria perform chemosynthesis Similar to photosynthesis, but use chemical (H 2 S) not sunlight 16

17 Energy Flow Through Ecosystems Food Chain a hierarchical sequence of organisms through which matter and energy pass as one organism eats another. 17

18 Food Chains The Path of Energy Flow Energy from food passes from one organism to another based on their Trophic Level Trophic Level - An organism s position in a food chain, which is determined by its feeding relationships Energy Flows Through Ecosystems Passage of energy through an ecosystem 18

19 Food Chains The Path of Energy Flow First Trophic Level- Producers (plants) Food Chains The Path of Energy Flow Second Trophic Level- Primary Consumers 19

20 Food Chains The Path of Energy Flow Third Trophic Level- Secondary Consumers Food Chains The Path of Energy Flow Fourth Trophic Level- Tertiary Consumers 20

21 Food Chains The Path of Energy Flow Decomposers are present at all trophic levels Food Chains Autotrophs = Producers (First Trophic Level) Auto self and tropho nourishment Produce own food from inorganic material Ex: plants via photosynthesis and hydrothermal vent bacteria via chemosynthesis 21

22 Food Chains Heterotrophs = Consumers heter different and tropho nourishment Uses bodies of other organisms as food Omnivores eat both plants and animals Carnivores eat other animals Herbivores eat plants Food Chains Consumers of detritus (detritivores) Eat dead material such as leaves, carcasses, feces Ex: crabs, worms, millipedes, snails 22

23 Food Chains Decomposers or saprotrophs sapro rotten and tropho nourishment Breakdown dead organic material Release inorganic molecules (CO 2 and nutrients) that producers can use Food Web Food Web - feeding relationships within a community More complex than food chain Still simplified compared to nature 23

24 Ecological Pyramids Graphically represent the relative energy value of each trophic level Important feature - large amount of energy is lost as heat between trophic levels Three main types Pyramid of numbers Pyramid of biomass Pyramid of energy Pyramid of Numbers Illustrates the number of organisms at each trophic level Fewer organisms occupy each successive level 24

25 Pyramid of Biomass Illustrates the total biomass at each successive trophic level Biomass: measure of the total amount of living material ~90% 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 Lost as heat and energy to maintain each level Explains why there are so few trophic levels 25