INTRODUCING BIOGEOGRAPHY

“Ecology” oikos : home; that which is held in

common

Study of the interrelationship of living plants and animals with their non-living environment.

Energy/heat is common to both.

Ecosystem

Combination of living organisms (biotic) with the non-living (abiotic) surroundings.

Biotic Componentsorganized in communities

• Community: group of interlocking populations of plants and animals in a habitat.

• Habitat: place in which an organism is suited to live.

• Niche: functional “role” of organism in ecosystem.

Habitats of Canadian boreal forest

Community in upland habitat: red squirrels, pine and spruce trees, mushrooms, lichens, wolves, etc.

Niche of red squirrel:

Spreads seeds in the forest

Abiotic componentscycle through the earth-atmosphere

• Nutrient cycles– Oxygen, nitrogen, carbon cycles, etc.

• Water cycle

• Energy : solar converted into other forms

Recall solar radiation budget…

69% insolation absorbed . converted to other forms of energy follows one of two pathways:

1.HEAT PATH (>99%)

2.ORGANIC PATH (< 1% )

HEAT PATHconverted to heat by

atmosphere,oceans, land surfaces.hydrologic system, nutrient cycles, atmospheric

circulation

ORGANIC PATHconverted to organic compounds in

plants.the energy that drives ALL LIFE ON

EARTH!

HOW does energy flow through ecosystems??????

FOOD CHAIN

Sequence in which energy flows through trophic levels (successive consumer stages).

Fourth-order consumer

Primary Producergreen plants;photosyntheticbacteria and algae

Primary consumer

Secondary consumer

Tertiary consumer

hete

rotro

ph

sauto

trop

hs

AUTOTROPHS : manufacture living (organic) tissue from non-living (inorganic) chemicals

HETEROTROPHS rely on autotrophs

• Grazing Chain (above ground)

• Detritus Chain : the decomposers who consume dead organic matter (detritus)

Underground food web (detritus food chain)

On average, 10 times as much energy flows through the detritus chain as through the grazing chain.

ENERGY PYRAMID

Energy passed from one trophic level to the next

Only 10% of energy from each level gets passed along to the next level.

Log scale

Where does the “wasted” energy go???

It is used in respiration.

Energy transfer

Green plants contain CHLOROPHYLL– reflects green; absorbs all other colors

• absorption of light = absorption of energy

PHOTOSYNTHESIS:CO2 + H2O + energy C6H12O6 + Oxygen

(sun) Glucose: carbohydrate

Only autotrophs can do this!

RESPIRATION– Plants and animals derive energyC6H12O6 +Oxygen CO2 + H2O +

energy

Heterotrophs do this.

Animals, roots, microorganisms in soil

Primary productivity• Gross primary productivity: rate at which

energy is stored in organic chemicals by primary producers in photosynthesis.

• In respiration, carbohydrates are broken down and energy is released; remaining carbohydrates can become plant tissue.

• Net primary productivity: rate at which energy is stored in plant tissue.

• Gross P.P. = Respiration + Net P.P.