Chapter 3

Ecology, ecosystems and food webs

Ecology

Groupings Organism – single living thing Species – several of same type of organism Population – several of same species

interacting Community – several populations interacting in

a certain area Ecosystem – community interacting with each

other and the environment

Fig. 4.2, p. 72

BiosphereBiosphere

Ecosystems

Communities

Populations

Organisms

Parts of the planet

Planet as a solid – inner/outer core, mantle, crust

Lithosphere is the crust and asthenosphere Hydrosphere is the water regions Atmosphere is the 5 layers of air

– Troposphere (11 miles) 78% N2, 21% O2, 1% Ar

– Stratosphere (11 – 30 mi) O3, blocks UV

Fig. 4.6, p. 74

Atmosphere

Vegetation and animals

Soil

Rock

Biosphere

Crust

core

MantleLithosphere

Crust

Lithosphere(crust, top of upper mantle)

Hydrosphere(water)

Atmosphere(air)

Biosphere(Living and dead

organisms)

Crust(soil and rock)

Incoming solar energy

34% reflected by clouds 42% heats earth and atmosphere 23% evaporates water 1% creates wind <1% photosynthesis

Fig. 4.8, p. 75

Solarradiation

Energy in = Energy out

Reflected byatmosphere (34%)

UV radiation

Absorbedby ozone

Absorbedby the earth

Visiblelight

Lower Stratosphere(ozone layer)

Troposphere

Heat

Greenhouseeffect

Radiated byatmosphere

as heat (66%)

Earth

Heat radiatedby the earth

Greenhouse effect

Solar energy (light) that reaches the earth is converted into short wave radiation (heat) infrared.

This infrared radiation has a hard time passing through the gasses in our atmosphere thereby trapping heat and keep the planet about 30 degrees (Celsius) warmer

Important gasses – H2O, CO2, CH4, N2O, O3

Biomes

Large regions characterized by a distinct climate and adapted vegetation

Remember climate is weather patterns over a long period of time, usually several decades

Because certain plants are adapted to a particular biome, so too are certain animals which depend on those plants for food

Biomes

There are not distinct boundaries between biomes, rather there are ecotones.

An ecotone is a blending of biomes and generally carries a greater quantity and variety of species

Components of Ecosystems

Abiotic – nonliving– Sunlight– Temperature– Precipitation– Wind– Latitude– Soil – Salinity (aquatic)

Fig. 4.13, p. 79

Terrestrial Ecosystems Aquatic Life Zones

• Sunlight

• Temperature

• Precipitation

• Wind

• Latitude (distance from equator)

• Altitude (distance above sea level)

• Fire frequency

• Soil

• Light penetration

• Water currents

• Dissolved nutrient concentrations (especially N and P)

• Suspended solids

Components of Ecosystems

Range of tolerance – how much of an abiotic factor can an organism withstand

Limiting factor – the one factor that is holding back a population from reaching its biotic potential (max growth)

Important limiting factors in aquatic systems– Dissolved oxygen, salinity, temperature, light,

nutrients, etc.

Fig. 4.14, p. 79

Po

pu

lati

on

siz

e

Low High Temperature

Zone ofintolerance

Zone ofphysiological stress

Optimum range Zone ofphysiological stress

Zone ofintolerance

Noorganisms

Feworganisms

Lower limitof tolerance

Abundance of organismsFew

organismsNo

organisms

Upper limitof tolerance

Food webs (chains)

Producers (autotrophs) plants– Using chemosynthesis (some bacteria)– Using photosynthesis (plants)

6 CO2 + 6 H2O + sun (yields) C6H12O6 + 6 O2

Plants convert only about 1-5% of the light they absorb into chemical energy, and absorb only about half the light that strikes them

Herbivores

Primary consumers – eat producers (oh the humanity)– Teeth designed for grinding

Carnivores

Secondary consumers – meat eaters only Feed on primary consumers (herbivores)

Teeth designed for tearing (large canines and sharp molars) cats for example

Omnivore

Tertiary consumer – eat anything, feeding on other carnivores makes them tertiary

We are omnivores, just look at our teeth, – but we really should eat more veggies and less

meat (in my opinion)

The other consumers

Scavengers – feed on dead organism they did not kill, but found dead

Detritivores – feed on parts of dead organisms

Decomposers – bacteria and fungi, break down small detritus into raw nutrients

Biodegradable means can be broken down by decomposers

Aerobic respiration

Normal cellular process for most organisms

Convert sugar and oxygen into energy leaving water and carbon dioxide as products

C6H12O6 + 6O2 yields 6 CO2 + 6 H2O + energy

Anaerobic Respiration

Also called fermentation The breakdown of glucose without oxygen

present

Produces: methane, ethyl alcohol, acetic acid, and hydrogen sulfide

Food chains

Trophic level – feeding level First trophic level – plants Second trophic level – primary consumers Third trophic level – secondary consumers Fourth trophic level – tertiary consumers

Remember heat is lost in every transfer between trophic levels

Pyramid of energy flow

Only about 10% of the usable energy transfers between trophic levels (5-20%)

For this reason we must rely on the transfer of solar energy from producers to consumers

This is why it is so important to care for the plants of this planet

Biomass

Organic matter produced by producers (photosynthesis)

Total dry weight of organic matter in plants and animals in an ecosystem

Biomass Productivity

Highest net biomass productivity per square meter is in wetlands, estuaries, and rain forests

Highest gross (but lowest per sq. meter) is the open ocean. Because of its size it has a lot of algae that add up to high productivity

Nutrient cycles

Atmospheric – Carbon and Nitrogen Sedimentary – Phosphorus and Sulfur

Hydrologic cycle – water cycle helps to transport many nutrients

Hydrologic cycle

Evaporation/transpiration Condensation Precipitation Infiltration Percolation Runoff

Powered by the Sun and gravity

Carbon cycle

Atmosphere

Photosynthesis/respiration

Fossil fuels Limestone Dissolved in the ocean

Nitrogen cycle (very important)

Nitrogen in the air Nitrogen fixation by bacteria to ammonia Nitrification by bacteria to nitrite NO2

-

Nitrification by bacteria to nitrate NO3- Assimilation by plants Ammonification of dead organic material by

bacteria and fungi Denitrification of nitrate by bacteria back to

atmosphere

Phosphorus cycle

Very slow Limited amount found in the soil Limiting factor for plant growth Excess causes prolific plant growth (algal

blooms in water)

We add phosphates to detergents/fertilizers

Sulfur cycle

Passed as sulfates (salts) mostly Hydrogen sulfide (swamps/volcanoes) Sulfur dioxide (volcanoes) Ammonium sulfate (sea spray)

Reacts in atmosphere to create hydrogen sulfate (H2SO4) sulfuric acid (acid rain)

Ecosystem services

Waste removal pest control Soil formation biodiversity Water purification matter resources Air purification aesthetic pleasure Climate control Recycling vital chemicals Renewable energy

Achieve sustainability

Use renewable energy (especially solar)

Recycle chemical matter

REALIZE WE LIVE IN A CLOSED SYSTEM!

The END!!!