Energy Flow In Ecology

How does energy flow within ecosystems? From Trophic Level  Trophic Level Trophic Level-each of levels in an ecosystem, made up of organisms that share the same step in the food chain The levels of a food pyramid/chain Means that energy flows up a food chain or through a food web

Trophic Levels

Trophic Levels Primary Producers: The autotrophs that capture energy to make food (Plants) Primary Consumers: heterotrophs that eat autotrophs (herbivores) Secondary Consumers: heterotrophs that eat other heterotrophs (carnivores) Higher Level Consumers: carnivores that eat other carnivores Decomposers: consumers of dead organic material ( Bacteria, Fungi)

ENERGY FLOW Food chains: One specific energy pathway in an ecosystem Food webs: complex energy interactions found in an ecosystem. Many food chains interacting Energy pyramids: representation of the total energy available to a trophic level.

https://www.youtube.com/watch?v=-oVavgmveyY

How do I read a food web? Where to start? Always start with plants Producers are the bottom of the energy pyramid and energy begins with them

FOREST FOOD WEB

Arctic Marine Food Web

Lets Practice…

What happens at each level? At the producer level plants take energy from the sun and change it to produce chemical (Food) energy PHOTOSYNTHESIS!!!!!! The plant then stores SOME of that energy and uses some of that energy to live The energy that is used is released as heat OR is broken down and recycled after death The animal that eats the plant gets the plants stored energy Then that animal stores some energy and uses some energy…..and so on up the food chain

So that energy… At each level the amount of energy DECREASES Why? At the previous level a lot of the energy is lost as heat Only 10% of the energy is transferred up each level of the food chain

What is a biomass pyramid? Shows you how many organisms are at each level of the food pyramid As you move up the amount of organisms DECREASES Why?

Why? As you move up a food chain the energy DECREASES Less energy to support larger animals Less animals at each level

Biomass Pyramid

Energy Pyramid

https://www.youtube.com/watch?v=-YwW-iWxLr4

Growth of Populations Don’t write this… The goal of populations is to grow and get bigger. This growth however can be different depending on the circumstances

Growth of Populations Exponential Growth : the maximum possible growth rate of a population

Do most populations achieve exponential growth? NO!!!! What stops them? (HINT: YOU ALREADY KNOW THE ANSWER!) Limiting Factors

Limiting Factors : those environmental factors that keep a population at the carrying capacity, like food, predators, amount of water how much land there is

What is carrying capacity? Carrying Capacity of the Environment: The maximum population that a particular environment can support

Different Growth When a population is approaching carrying capacity and growth slows down it is referred to as LOGISTIC GROWTH

Population Growth over Time

Exponential growth can lead to massive die-off In 1944, 20 reindeer were brought to St. Matthew Island. Initially there were abundant food sources, and the reindeer population increased dramatically. There were no predators to cull the population. However, about 20 years later, the reindeer had overshot the food carrying  capacity of the island, and there was a sudden, massive die-off.  About 99% of the reindeer died of starvation. Exponential growth can lead to massive die-off

Why did the reindeer die off? Starvation The environment can only support so many deer There is only enough food to support a certain number of deer The amount of food is the limiting factor Then the deer die off!

Carrying capacity of the Environment

Break it down… The population begins by growing exponentially When it reaches carrying capacity it will go over it at the beginning Then die off will begin to happen because of limiting factors The population will shrink back below carrying capacity Then it will grow to slightly above carrying capacity…die off…grow…and so on

Let’s visualize how this looks… Deer of the kaibob

https://www.youtube.com/watch?v=8FPMP41LYJ8

Project 2 Create your own- Using clip art/magazines/drawings create one food chain. Then incorporate that food chain into a food web. On the back identify each organism in your web and label them as Producer Primary Consumer Secondary Consumer Decomposer Remember! Each Food Web/Chain MUST have at least one of EACH producer, consumer and decomposer