Ecological Terms

1. Ecological Terms • Ecology – study of how organisms interact with their living (biotic) environment of other organisms and with their abiotic environment of soil, water, energy, etc. • Population – group of individuals of the same species that live in the same place at the same time • Genetic diversity – slight variation in genetic makeup in a population • Habitat – place where a population or an individual organism normally lives

2. Ecological Terms • Community – all the populations of different species that live in a particular place • Ecosystem – community of different species interacting with one another and with their nonliving environment of soil, water, other forms of matter, and energy • Biosphere – parts of the earth’s air, water, and soil where life is found

3. Levels of organization

4. 4 Major Components of Earth’s Life Support System • Atmosphere – thin spherical envelope of gases surrounding the earth’s surface • Troposphere – 11 mile above sea level at tropics and 4 miles above the earth’s north and south poles – contains majority of air (nitrogen 78%, oxygen 21%) • Greenhouse Gases – trap heat and warm lower atmosphere (1% of gases – water, carbon dioxide, and methane) • Stratosphere – 11-31 miles above earth’s surface • Lower portion – ozone

5. 4 Major Components of Earth’s Life Support System • Hydrosphere – all of the water on or near eath’s surface • Found as liquid water, ice, water vapor • Most in the oceans (covers 71% of globe) • Geosphere • Crust, mantle, core • Biosphere – parts of atmosphere, hydrosphere and geosphere where life exists • Thin layer of earth extends from 6 miles above earth’s surface down to bottom of the ocean. • “no thicker than an apple’s skin”

6. Earth Components

7. 3 Factors Sustain Life on Earth • One Way Flow of High Quality Energy from Sun • No round trips since high quality energy can’t be recycled – 2nd Law of Thermodynamics • Cycling of Matter and Nutrients (Biogeochemical cycles) • Gravity – allow planet to hold onto its atmosphere and helps movement and cycling of chemicals through air, water, soil, and organisms.

8. Ecosystems • Populations have a range of tolerance to variations in its environment • Limiting factors – factors which are important in regulating population growth • Limiting Factor Principle – Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance • Examples: precipitation, soil nutrients such as P, temperature

9. Range of Tolerance

10. Ecosystems • Trophic Level – feeding level • Producers (autotrophs) – make nutrients they need from compounds and energy • Green plants on land and phytoplankton in open water • Photosynthesis – CO2 + water + solar energy yields glucose and oxygen • Chemosynthesis (used by a few) – converts simple inorganic compounds into more complex nutrient compounds without using sunlight • Consumers (heterotrophs) – obtain nutrients by feeding on other organisms (producers, consumers or their remains)

11. Types of Consumers • Primary Consumers (herbivores) – plant eaters such as rabbits, grasshoppers, deer, and zooplankton • Secondary Consumers (carnivores) – meat eaters such as spiders, hyenas, birds, frogs, and fish • Third and Higher Level Consumers – carnivores such as tigers, wolves, mice-eating snakes, hawks, orcas that feed on flesh of carnivores • Omnivores – Feed on both plants and animals such as humans, pigs, foxes, cockroaches • Decomposers – primarily certain types of bacteria and fungi that release nutrients from dead bodies of plants and animals to soil, water and air for reuse by producers • Detritus feeders (detrivores) – feed on wastes or dead bodies of other organisms – mites, earthworms, some insects, catfish, vultures

12. Detrivores and Decomposers

13. Energy Flow • Producers, consumers, and decomposers use chemical energy stored in glucose and other organic compounds as fuel. • Most use aerobic respiration (oxygen) to convert organic compounds to carbon dioxide and water • Some decomposers use anaerobic respiration (fermentation) which is an absence of oxygen • End products are methane, ethyl alcohol, acetic acid and hydrogen sulfide

15. Food Chains • Food Chain – sequence of organisms, each of which serves as a source of food ro energy for the next • Shows how chemical energy and nutrients move from one organism to another through trophic levels through photosynthesis, feeding, and decomposition • Every transfer of energy involves a loss of energy • Food web – a complex network of interconnected food chains in an ecosystem

16. Food Chain

17. Simplified Food Web

18. Energy Flow • Each trophic level in a food chain or web contains an amount of biomass • Biomass – the dry weight of all organic matter contained in its organisms • Energy transfer through the food chain is not very efficient – some ends up as low quality heat • Ecological efficiency - % of usable chemical energy transferred as biomass from one trophic level to the next • Generally about 2% - 40%, 10% is typical • Green plants capturing 10000 units of energy from sun results in only 1000 units of energy to support herbivores and only about 100 units to support carnivores • The more trophic levels there are in a food chain or web, the greater is the loss of usable energy – rarely more than 4-5 trophic levels

19. Productivity • Gross primary productivity (GPP) • Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass • Measured in terms of energy production per unit area over a given time span (kilcalories per square meter per year) • Net primary productivity (NPP) • Rate at which producers use photosynthesis to produce and store chemical energy minus the rate at which they use stored energy through respiration • NPP = GPP - R

20. Productivity • Ocean – highest NPP found in estuaries • High input of nutrients • Open ocean has lowest NPP except where upwelling (water moving up from depths toward the surface) • Still provides the most biomass per year since there is so much of it. • The planet’s NPP ultimately limits the number of consumers that can survive on earth

21. Pyramid of Energy Flow