Introduction to Ecology: The Biosphere. A. Interactions and Interdependence 1. Ecology: the...

Introduction to Ecology: The Biosphere

A. Interactions and Interdependence

1. Ecology: the scientific study of interactions among organisms and between organisms and their environment

2. Biosphere: portions of the Earth in which all of life exists, includes land, water and aira) Ranges from surface to 8 km above and 11 km

below

Biosphere

Ecosystem

Community

Population

The part of Earththat contains allecosystems

Community and its nonliving surroundings

Populations thatlive together in a defined area

Group of organisms of onetype that live in the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

Levels of Organization

Organism

Groups ofCells

Cells

Molecules

Individual livingthing

Tissues, organs,and organ systems

Smallest functionalunit of life

Groups of atoms;smallest unit of most chemicalcompounds

Bison

Nervous tissue Nervous systemBrain

Nerve cell

Water DNA

Section 3-1

Producers

1. The Sun is the main energy source for life on Earth.– Less than 1% of all sunlight is used by living

things.

2. Some organisms rely on the energy stored in inorganic chemical compounds (chemosynthesis)

3. Autotrophs can capture energy from sunlight or chemicals to produce food (plants, some algae and bacteria).

a) Energy is used to combine simple inorganic compounds into complex organic molecules

a) Resulting organic molecules combine and recombine to make living tissue.

b) Photosynthesis: light energy used to power chemical reactions that convert CO2 and H2O into O2 and carbohydrates (such as sugar and starch)

1) Photosynthesis is responsible for adding oxygen and removing CO2 from the atmosphere.

2) Performed by plants, algae and some bacteria (ex:cyanobacteria)

c) Chemosynthesis uses energy within chemical bonds of inorganic molecules to produce carbohydrates

1) performed by several types of bacteria

Consumers1. Heterotrophs rely on other organisms for

their energy needsa) herbivores consume plantsb) carnivores consume animalsc) omnivores consume plants and animalsd) detritivores consume organic remains and dead mattere) decomposers break down organic matter

1. Energy flows in one direction through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food).

Your body gets the energy and materials it needs for growth and repair from the foods you eat.

Feeding Relationships

2. Food Chain: a series of steps in which organisms transfer energy through feeding

Food Chains

3. Food Web: demonstrates the complex interactions between the organisms in food chains in an ecosystem.

• The base of a food web is occupied mostly by vegetation (producers) and fine organic debris (decomposers).

• Herbivores (primary consumers) and carnivores (secondary consumers) occupy the higher levels.

• Omnivores occupy an intermediate level in the food web.

4. Trophic level: each step in a food chain or food web.

D. Ecological Pyramids

Shows the relative amounts of energy or matter contained within each trophic level.

1. Energy Pyramida) Only ~ 10% of the energy in a trophic level can

be transferred to the next level (can range from 0.05 to 20%

b) The more levels that exist between a producer and a top-level consumer the less energy remains from the original amount.

2. Biomass Pyramid

a) Biomass: the total amount of living tissue within a trophic level.

b) represents the amount of potential food available for each trophic level

3. Pyramid of Numbers

a) Based on the actual numbers of organisms at each trophic level.

Pyramid of NumbersShows the relativenumber of individualorganisms at eachtrophic level.

Biomass PyramidRepresents the amount ofliving organic matter at each trophic level. Typically, thegreatest biomass is at the base of the pyramid.

Energy PyramidShows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat.

Energy Pyramids

III. Cycles of Matter

A. Recycling in Biosphere1. Matter is recycled within and between

ecosystems.a) Biogeochemical cycles: connect biologic,

geologic and chemical portions of the biosphere through the conversion of elements, chemical compounds and other matter between organisms and their environment.

b) Matter can cycle because biologic systems do not use up matter – they transfer it into living tissue or pass it as waste products

B. The Water Cycle1. The process by which water is moved through

the biosphere

a) Evaporation: water changes to gaseous form by absorbing energy

b) Transpiration: loss of water through leaves due to evaporation

c) Condensation: changing of water from gas to liquid by releasing energy

d) Precipitation: movement of water from atmosphere to surface as rain, snow, hail or sleet.

• It is estimated that a single drop of water can take 4000 years to complete the water cycle.

Condensation

Seepage

Runoff

Precipitation

TranspirationEvaporation

RootUptake

Water Cycle

C. Nutrient Cycles

1. Nutrient: chemical substances required for life functions and growth

a) nutrients are passed between organisms and the environment through biogeochemical cycles

1) Prevents dangerous levels of nutrients (too high to too low)

2. Carbon Cycle

Important because carbon is the key ingredient in all living organisms

a) Less than 1% of all C on Earth circulates in the biosphere

1) ~ 71% in oceans as CO3 and Ca(CO3)2, 22% in fossilized carbon

b) 4 main processes for carbon cycling

1) Biological processes (e.g.: photosynthesis, respiration, decomposition)

2) Geological processes (e.g.: volcanic outgassing, absorption in ocean/precipitation)

3) Mixed biogeochemical processes (e.g.: creation of fossil fuels, limestone)

4) Human activity (e.g.: mining, burning of fossil fuels and forests)

CO2 inAtmosphere

CO2 in Ocean

Carbon Cycle

Global Warming• Global warming is an observed increase in the

average temperature of the Earth's atmosphere and oceans.

• Part of this increase may be due to natural processes, and would have occurred independently of human activity.

• The remainder is due to a human-induced intensification of the greenhouse effect. – The increased volumes of carbon dioxide and other

greenhouse gases released by the burning of fossil fuels, land clearing and agriculture, and other human activities, are the primary sources of human-induced warming

Greenhouse Effect

• Greenhouse gases (GHG) are gaseous components of the atmosphere that contribute to the greenhouse effect.

• The major natural greenhouse gases are water vapor (36-70% of the greenhouse effect); carbon dioxide (9-26%); and ozone (3-7%)

3. Nitrogen Cycle

Important because N is used to make amino acids which are used to build proteins.

a) Occurs in many forms, 78% as nitrogen gas (N2)

1) Ammonia (NH3), nitrate ions (NO3-) and

nitrite ions (NO2-) from dead and decaying

matter.

b) Nitrogen fixation: conversion of N2 (gas) into NH3 by bacteria in soil or on legumes (roots of certain plants)

1) Decomposers further converted NO3- and

NO2- ions which can be used by producers

to make proteins.

• C) decomposers return nitrates to soil as ammonia to be used again

• D) soil bacteria convert nitrates into N2 (denitrification)

N2 in Atmosphere

NH3

NO3-

and NO2-

Nitrogen Cycle

4. Phosphorus Cycle

Important because used in DNA and RNA

a) Not very common, found in rock and soil minerals and ocean sediments

1) Note that it is not found in the atmosphere

b) As rocks and sediments erode, phosphate is released and may be dissolved in water

1) Used by marine organisms in the oceans

2) Some phosphate remains on land and cycles between organisms and the soil

i) Plants absorb phosphate and bind it into organic compounds

ii) Organic compounds move through the food web

5. Nutrient Limitation

a) Primary productivity: rate at which organic matter is created by producers.

1) Depends on recycling of available nutrients – if any are in short supply it will limit an organisms growth.

b) Limiting nutrient: a nutrient that is scare or cycles very slowly and limits growth in an ecosystem.

1) Fertilizer used to compensate for limiting nutrients (N,P and K)

c) Oceans are (by their nature) nutrient-poor compared to the land.

1) Algal bloom: an increase in the amount of algae and other producers due to an increase of limiting nutrient(s).

i) If there are not enough consumers, an algal bloom can upset the health of an ecosystem by oxygen depletion from bacteria during decomposition of dead algae.