Ch 5 Energy Flow through Ecosystems

• Food Chains• Food Webs• Trophic levels• Energy loss as it’s passed from trophic levels• Bioaccumulation/biomagnification

Food Chains are direct transfers of energy through an ecosystem

Where do I label decomposers?

• You don’t!

Food Webs – interconnections between all food chains.

AUTOTROPHSOrganisms that produce their own food

Aka PRODUCERS

HETEROTROPHSOrganisms that consume their food.

Aka - CONSUMERS

Types of consumers• Herbivore : eats only producers• Carnivore: eats other consumers.• Detrivore: eats dead consumers• Omnivore: eats both producers and consumers• Decomposer: breaks down nutrients and recycles them

10% is the magic number!

• Only 10% of the energy is the trophic level is passed up.

• Most food webs rarely have more than 6 steps/trophic levels in the ecosystem due to the loss of energy.

Energy is lost from each species

BIOMASS

• The term "biomass" refers to organic matter that has stored energy through the process of photosynthesis. It exists in one form as plants and may be transferred through the food chain to animals' bodies and their wastes, all of which can be converted for everyday human use through processes such as combustion, which releases the carbon dioxide stored in the plant material.

How much energy is lost to respiration?

Wait? So I just by 10 as I go up?

Energy decreases by 10% each level!!!

Food Webs

Bioaccumulation

• Is a process resulting in the concentration of substances in living tissues.

• Used to reference chemical contaminants that may do harm to organims like pesticides or heavy metals.

Biological Magnification(On page 312)

• “the increasing concentration of a pollutant in organisms at higher trophic levels in a food web”

• Pollutants become concentrated in the bodies of consumers the higher up the chain it goes SINCE THEY EAT MORE!

• Therefore intake of a few organism can affect the whole food web.

Bioaccumulation vs. Biomagnification

• Bioaccumulation is increasing the concentration of a substance in one organism whereas biomagnification is increasing the level as you go up in a food chain.

• Bioaccumulation occurs within a tropic level and biomagnification occurs between tropic levels.

FUN VIDEO CLIP

• https://www.youtube.com/watch?feature=endscreen&NR=1&v=E5P-UoKLxlA

Humans and DDT

• Now complete the Humans and DDT ws.

• http://www.youtube.com/watch?v=ldZjaT4WXrA

5.2 Cycling of materials

• Carbon• Nitrogen• Phosphorus

• Just as water is Recycled, so are the elements in food chains!

Carbon Cycle

• “process by which carbon is cycled between the atmosphere, land, water, and organisms.”

Wait? How would a plant get Carbon?

• From carbon in our CO2 that is absorbed for photosynthesis?

How would that carbon get out of a plant to help others?

• Eat the plant!!! or• Plants dies and the

Carbon is returned to the ground or water , and then recycled.

Crash Course – Carbon Cycle

• https://www.youtube.com/watch?v=2D7hZpIYlCA

• Start at 5:10

Carbon Cycle• Early earth = 95% CO2

• Now is only .04% thanks to photosynthesis

• Present in 3 main sources: (aka: CARBON SINKS)• 1. living things

2. oceans = CO2 dissolves in water easily3. fossil fuels

Short Term VS. Long Term SINKs

Short TermCycles through a lifetime

through the food web

Long Term Millions of years

Ex – fossil fuels

Problems with sinks…• Humans are using these

sinks and releasing the Carbon back into the ecosystems – upsetting its balance

• Ex – burning FF

• 6 billion metric tons of carbon are released into the atmosphere each year!

• Some remains in the atmosphere, some dissolves into oceans, some absorbed by plants

Crash Course – Nitrogen and Phosphorus

• https://www.youtube.com/watch?v=leHy-Y_8nRs

Nitrogen Cycle - All organisms need nitrogen to build PROTEINS.- 78% percent of atmosphere- But must be FIXED before it can be used - Nitrogen- fixing bacteria to the rescue!!!

Nitrogen Fixing Bacteria

• Plays a CRUCIAL part of the nitrogen cycle

• Live in nodules on the roots of plants called LEGUMES – beans, peas, clover

• They produce nitrogen-containing compounds called nitrates that and put excess back into the soil.

• When an organisms eats the plant they get the converted nitrogen.

This keeps the nitrogen cycling between the

atmosphere and living things.

Decomposers and Nitrogen

• Decomposers return Nitrogen in living things to the soil.

• Some will be converted to gases released back to the atmosphere, but most of the Nitrogen will be cycled between soil and living things and

Phosphorus Cycle• “movement of phosphorus from the

environment to organisms and then back to the environment.

• Not typically in the atmosphere.• Enters from dissolved rocks which enters soil

and water.• Excretions from animals, dead/decomposed

animals

Two Sources of P

Natural Sources

• Enters from dissolved rocks which enters soil and water.

• Excretions from animals, dead animals

Phosphorus Cycle

Effects of additional Nitrogen &Phosphorus

• Fertilizers: Runoff enters aquatic and terrestrial ecosystems.

• Causes ALGAL BLOOMS

Effects of additional Nitrogen &Phosphorus

• https://www.youtube.com/watch?v=2v-9R1JrVqI

Effects of additional Nitrogen &Phosphorus

Acid Precipitation- Affects the N cycle when we burn fuel since it releases Nitric Oxide into atmosphere.

5.3 SUCCESSION

• Ecological succession is the observed process of change in the species structure of an ecological community over time

TWO TYPES:

PRIMARYSUCCESSION THAT BEGINS

WHERE NO LIFE PREVIOUSLY EXISTED

Ex – bare rocks

SECONDARYSUCCESSION THAT BEGINS WHERE LIFE PREVIOUSLY

EXISTED

Ex - soil

Fun Video Claymation

• https://www.youtube.com/watch?v=dhYArqKVF9Q

Primary Succession(#1) = “Starting from square #1”

• This means the ecosystem has had no previous life.

• Nothing, nope, nada.• Nothing here but barren rocks.• Ex – volcano forms a new island, glaciers

slowly moves and leaves behind rocks.

How does it begin succession?

• Rock is colonized by pioneer species• Pioneer species = Lichens and Mosses

• These will break down the rock and turn it into SOIL! Yay!

• Now smaller plants will begin to grow which adds to the soil content & nutrients so bigger plants can grow, etc.

PRIMARY SUCCESSION

• no soil initially exists• (such as caused by a lava flow following

volcanic eruption or severe landslide that covered the land).

• The primary succession is important in pioneering the area to create conditions favorable for the growth of other forms of plants and animals.

Secondary Succession = “begins with SOIL!”

• If an ecosystem is disturbed, it will leave behind not much but SOIL.

• This soil will serve as a basis for small pioneer plants to grow, then bigger plants, and so on as in Primary succession.

• Ex – forest fires, man building structures, tsunamis, etc.

SECONDARY SUCCESSION

• This process of regrowth that an ecosystem undergoes after a destructive event such as a fire, avalanche, agricultural clearing, deforestation, or disease

• one thing is important to keep in mind: for secondary succession to occur, there must already be, you guessed it, dirt!

Secondary Succession

Both types of Succesion are attempting to reach…

• A MATURE ecosystem is known as the climax community for that area.

(most complex community it can have)

• Ex - large hardwood trees.

• Most ecosystems do not mature to this ideal community, because disaster strikes again too soon, leading to more succession…

Another Fun Succession Clip

• https://www.youtube.com/watch?v=AWwe0udewD8

Old Field SuccessionThe form of ecological succession which occurs on abandoned farmland is referred to as old field succession. When a plowed field is abandoned, it represents a new habitat for plant and animal species to colonize, but because it is basically bare soil, it is a stressful habitat for many plants.

VIDEO CLIP

• http://www.mrphome.net/mrp/succession.swf