UNIT 10 – ECOLOGYEcology: The scientific study of interactions among organisms and between organisms and their environment.Levels of organization: SpeciesPopulationCommunityEcosystemBiomeBiosphereThe Biosphere is HUGE, which is why we usually study smaller divisions like biomes and ecosystems. Biomes can be sub-divided into smaller divisions called ecosystems.Biomes: Biomes are environments that have characteristic “climax communities” (don’t change over time). Some people think that there are over 30 different types of biomes in the world.Aquatic Biome: Characteristics: Rivers, streams, lakes, estuaries

Area’s Found: Intertidal, neritic (low tide zone), open-sea, deep-sea

Terrestrial Biome: Characteristics: Land areas, plant life Areas: Tundra, taiga, temperate deciduous forests, grasslands,

tropical rain forest, desertEcological Methods: Regardless of the tools used, scientists conduct modern ecological research using three basic approaches:

Observing, Experimenting, and ModelingEcosystems

An ecosystem is the combination of an area’s abiotic and biotic factors. Abiotic: Air, Water, Rainfall, Temperature, Soil, Rocks, Elevation,

and Humidity Biotic: anything living!

Abiotic + Biotic factors = Ecosystem.

Energy Flow: All of the energy that comes to earth, comes from the sun. Which means the process has to start with some kind of plant, doing photosynthesis. From there, herbivores eat plants and carnivores eat the herbivores. Its a simple interaction that passes energy up the food chain.

6CO2 + 6H2O C6H12O6 + 6O2In the absence of light, organisms can use chemical energy to produce carbohydrates, which is called chemosynthesis. This happens in deep ocean trenches and hot springs. Often in the absence of light.Trophic Levels: how energy flows from one organisms to another:

1˚= primary, 2˚= secondary, or 3˚= tertiary consumer.Biomass:Energy Flow:Producers:Consumers;

Decomposition:Biodegradation:Decomposers:Autotrophs:Herbivores:Carnivores:Omnivores:Detriovores:Decomposers:Feeding Relationships: Four Types: Food chain, Food Web, Trophic Levels, Ecological PyramidsFood Chain: Shows one interaction that passes energy from one organism to the next in an ecosystem. Is a food chain an accurate representation of what REALLY happens in an ecosystem? A food chain is a very simple way to show what is happening in an ecosystem. In reality, organisms eat more than one thing in an ecosystem.

Food Web: A food web links all of the food chains in an ecosystem together, shows a more holistic view of energy transfer in the ecosystem. Combinations of many food chains.Always starts with producers and ends with consumers. Food chains and food webs do not show how many organisms live in the ecosystem at each level. They only show energy flow.

Trophic Levels: Each step in a food chain or food web is a trophic level. As you increase trophic level, the amount of energy decreases.Ecological Pyramids: Pyramids can come in the energy form as the last one we’ve seen (trophic levels), or they can come in the form of a Biomass Pyramid, or a Pyramid of Numbers.

Biomass Pyramid: As we move up a food chain, there are less and less numbers of organisms at each level.

Energy Pyramid: Shows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat.

Ecosystem ChangeAny change in an ecosystem can be referred to as Ecological Succession, there are 2 types.Primary Succession: Occurs on land surfaces where no soil exists.Lava covered! Gradual growth of an ecosystem over a long time.Secondary Succession: When a disturbance changes a community without removing soil. Caused by an event that reduces the existing population in the ecosystem.Sometimes ecosystems change dramatically into others, but for the most part the changes are so small we barely see them over time!Climax Community: last stage of succession, when an ecosystem has reached equilibrium. Mature plant life and animal populations.

Cycles of MatterMatter is recycled within the ecosystem and its done through Biogeological Cycles. This is the way that water, carbon, nitrogen, and phosphorus cycle through the atmosphere.Water Cycle: All living things depend on water. It is through the process of condensation, evaporation, and precipitation that water cycles through the atmosphere. It takes on water molecule 4,000 years to make it all the way through the entire cycle!

Carbon Cycle: All living things are made of carbon, which makes it very important! In the carbon cycle, there are 4 major processes: Photosynthesis, respiration, decomposition, erosion, and volcanic activity. Burial and decomposition of dead organisms and their conversion into coal and petroleum. Human activities such as mining, cutting and burning forests, and burning fossil fuels, releasing carbon into the atmosphere as carbon dioxide.

Nitrogen Cycle: In the nitrogen cycle there are two processes which help gaseous nitrogen come into our soil.

Nitrogen Fixation: bacteria which turn gas into ammonia. This ammonia is then converted to nitrates/nitrites by other bacteria.

Denitrification: process where bacteria convert nitrates into nitrogen gas.

Prosperous Cycle: Phosphorous helps form DNA and RNA. Phosphorous does NOT enter the atmosphere (like water, carbon, oxygen, and nitrogen). Phosphorous exits as phosphate and is found in rocks, soil, and ocean sediments (sand). Phosphate is used by producers and then moves up the food chain.

Limiting Nutrients: When nutrients are needed in an ecosystem, but not in large amounts, they are called “limiting nutrients”.That is because they are released slowly through the cycles, instead of all at once. When you get an influx of nutrients into an ecosystem it can result in the killing of organisms because they absorb too much, or it can make algal blooms. This is an increase in algae because they are a primary producer which absorbs the nutrients.Climate: There are a few things which contribute to climate, which refers to the average, year after year conditions of temperature and precipitation. Ex: Latitude, Elevation, Ocean currents.Greenhouse Effect: Carbon dioxide, water vapor, methane gas, and other atmospheric gases contribute to the greenhouse effect. This is how the earth is naturally heated.Latitude: The earth can be divided into zones depending on how much sun exposure they receive.

Polar zones, Temperate zones, and Tropical zonesHeat Transport: occurs though the earth in a few different ways. One of which is ocean currents, another is wind. Remember the way which heat is always transported, it moves from hot to cold!

Population GrowthIf you have two dogs, and those two dogs have six puppies a year; how many dogs would you have in 5 years?Population is controlled by density-dependent limiting factors like: Competition, Predation, Parasitism, Migration & Immigration.The density-dependent limiting factors are all related to each other and can exacerbate each other (make worse). Ex: Crowding makes it easier for parasites to infect more hosts, which causes more stress to parasitized animals, which can make them more vulnerable to predation and less able to complete with other animals for resources.Density Independent: Populations can also be affected by density-independent factors such as: Flood, Tsunami, Drought, Fire.

Types of Growth: Populations can have two different types of growth: Exponential and Logistic.

Exponential: With unlimited resources a population will grow exponentially to huge numbers!

Logistic: As resources and population play a game of balance, the population growth stops when it reaches “carrying capacity”.

If population exceeds the carrying capacity, then death occurs. If it drops below carrying capacity, then growth occurs.

Lets take a look at human population growth over the past 2,000 years! What’s happening? Have we reached our carrying capacity (K)?

K