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 7 th 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 Nature Nitrogen 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)