ECOSYSTEMS AND CYCLES

EVERYTHING IS CONNECTED

• Ecology is the study of the interactions between living things and their environment– Living things are

known as biotic– Non living things are

abiotic

The environment is organized into 5 layers

• Organism– Single living thing

• Population– All the same kind of organism in one

place at one time

• Community– All the different populations living in

the same place at the same time

• Ecosystem– The community AND the abiotic parts

of the environment

• Biosphere– All of the ecosystems throughout the

Earth

LIVING THINGS NEED ENERGY

• The sun is the ultimate source of energy in almost all ecosystems

• Energy is passed from organism to organism

• A balanced ecosystem has organisms in all of the following roles– Producers– Consumers– Decompsers

Producers

• Most producers use sunlight, carbon dioxide and water to make food for other organisms through the process of photosynthesis.

• Plants and algae are main producers

• A few producers use “chemosynthesis” where chemicals in the environment are used to make food without light

Consumers• Consumers are organisms that

eat (consume) other organisms– Herbivores eat plants (primary

consumers)– Carnivores eat other consumers

(secondary consumers)– Omnivores eat both plants and

animals (are both primary and secondary consumers)

– Scavengers feed on the bodies of already dead animals (secondary consumers)

Decomposers

• Breakdown the remains of dead organisms into simple nutrients (water, CO2, etc.) and return them to the soil or atmosphere

• Bacteria and Fungi are decomposers

Food chains and food webs

• Both are models that show how energy moves, in the form of food molecules, from one organism to the next– Food chains are simple and show ONE route

for the energy to move– Food webs are complex and show multiple

(and possibly ALL) paths for the energy to move like overlapping food chains.

Energy pyramids• Model that shows

HOW MUCH energy is at each level of the ecosystem

• Producers are at the bottom showing that the number of organisms and the amount of energy are the greatest there

ENERGY PYRAMIDS – 2• The herbivores are next

because they get the energy directly from producers

• Then carnivores• Then scavengers• At each level the number

of organisms decreases since there is less energy available to them to sustain life

Wolves…stay or go?

• One hundred years ago wolves were eliminated from Yellowstone National Park

• Why would people do this intentionally?

• What would be some advantages or disadvantages of taking them out?

DISCUSS

Wolves and the energy pyramid(When reintroduced into Yellowstone)

• Wolves are top carnivores in the ecosystem

• Reduced the number of large unhealthy, weak, old herbivores

• Increased number of smaller herbivores

• Improved balance of ecosystem

Types of interactions• Interactions in the environment

– Limiting factors • those resources that prevents the population from

getting too large such as food, space, water, and for plants sunlight.

• Any single resource can be a limiting factor to population size

– Carrying capacity• Is the largest a population can be in an

environment.• Limiting factors determine what the carrying

capacity is.

Types of interactions-continued

• Competition – Occurs when two or more species try to

use the same limited resource• Food• Space• sunlight

– Can occur between populations of different organisms or within the same population

Types of interactions-continued• Predators and prey

– Predators are carnivores that have developed adaptations to help them catch other animals to eat them

• Vision• Speed• Camouflage• Others?

– Prey are animals that are adapted to survive so that even though their species is being killed by predators enough of them survive for their population lives on

• Vision• Speed• Camouflage• Others?

Types of interactions-continued

• Symbiosis –long term association between two or more species– Mutualism – both types of organism benefit– Commensialism – one organism benefits and the

other organism is unaffected– Parasitism – one organism benefits and the other is

harmed or killed

• Coevolution – is a long term change that has occurred because of the close relationship between two species.

CYCLES OF MATTER

• Matter is anything that has mass and occupies space

• Certain types of matter is constantly reused and recycled in nature

• Examples studied in 7th grade:– Water– Carbon – Nitrogen

Cycles in Nature• Water cycle

– Precipitation – liquid water falls to earth in four forms rain, sleet, snow, hail

– Evaporation – liquid water becomes water vapor

– Ground water – liquid water seeps into the earth and is stored under the ground

Cycles in Nature• Other processes

– Run-off – water flows along the ground and collects in streams, rivers, lakes, and oceans

– Transpiration –water vapor is released from plants

– Condensation – water vapor cools, becomes liquid water

Carbon cycle - part of all living things.• move carbon from the atmosphere into the organisms and back to

the atmosphere. – Photosynthesis – plants use carbon dioxide and water to make sugar

( food) – Respiration – organisms use the food and it is broken down to produce

energy for the organism carbon dioxide and water are released

Carbon Cycle• Other processes that

put carbon back into the atmosphere– Combustion – coal,

oil and natural gas contains high amounts of carbon. When burned carbon is released

– Decomposition – breakdown of dead organisms releases the carbon stored in their bodies back into the environment.

Cycles in Nature• Nitrogen Cycle –

nitrogen is essential to life because it is the main ingredient in proteins, which build muscles and is in DNA.

• The nitrogen cycle has two processes:– Fixation

– decomposition

Cycles in NatureNitrogen cycle – continued

• Fixation – the atmosphere is 78% nitrogen but it is not in a form organisms can use. – Nitrogen must be “fixed” so

it can be absorbed by plants and then passed onto animals.

– Nitrogen is fixed by bacteria and lightning

• Decomposition – when organisms die nitrogen stored in their bodies is released into the environment to be used again

Succession

• Succession is a series of slow gradual, predictable steps in the development of a community. There are two types.– Primary – occurs in an area where there is no soil or

life of any kind. Soil must be formed first so it takes a VERY long time (hundreds or thousands of years)

– Secondary – occurs in an area where the existing life had been destroyed by a natural disaster such as a flood or a forest fire. Soil is already present so it takes place over a shorter period of time (100 years)