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What is Ecology?
• Ecology is the scientific study of interactions among organisms and between organisms and their environment
Why do we study ecology?
• We live in the natural world and use its resources (water, space,food, etc)
• The natural world effects our lives (weather, fire, economy)
• To protect biodiversity
Levels of Organization
• Ecologists recognize there is a hierarchy of organization in the environment: biosphere, biome ecosystem, community, population, and organisms
What is a Biosphere?
• Part of Earth in which life exists including land, water, and air or atmosphere
What is a Biome?
• A group of ecosystems that have the same climate and similar dominant communities
Temperate Forest Tundra
What is an Ecosystem?
• A collection of all organisms that live in a particular place, which includes the nonliving, or physical, environment
What is a Community and a Population?
• A community is assemblage of different populations that live together in a defined area
• A population is a group individuals that belong to the same species and live in the same area
How Do We Study Ecology?
• Observing• Experimenting• Modeling (Ecological
phenomena that occur over long periods of time)
How Do Organisms Obtain Energy in an Ecosystem?
• Sunlight is the main energy source for life on Earth
• Autotrophs will then use the energy from the sun (or chemicals) to make their own food
• Autotrophs are also known as producers• Examples of autotrophs: plants, algae,
cyanobacteria
How Do Organisms Obtain Energy in an Ecosystem?
• Autotrophs use photosynthesis to convert sunlight, carbon dioxide, and water into oxygen and carbohydrates
How Do Organisms Obtain Energy in an Ecosystem?
• What if there is no light in the ecosystem?
• The autotrophs will use chemosynthesis, which is a process that uses chemical energy to produce carbohydrates (ex: bacteria living in volcanic vents)
How Do Organisms Obtain Energy in an Ecosystem?
• Organisms that rely on other organisms for energy are known as consumers or heterotrophs
Types of Heterotrophs
• Herbivores- consume only plants• Carnivores- consume only meat• Omnivores- consume both plants and animals• Detritivores- consume plant and animal
remains (earthworms, mites, crabs)• Decomposer= breaks down organic matter to
obtain energy (bacteria & fungi)
Feeding Relationships
• Energy in an ecosystem flows in one direction (from sun to the heterotrophs)
• Food chain- a series of steps in which organisms transfer energy by eating and being eaten
Transfer of Energy
• Each step in a food chain or food web is called a trophic level
• Autotrophs make up the first trophic level, consumers make up 2nd, 3rd, 4th or higher levels
• Only about 10% of energy is transferred to organisms at the next trophic level
Transfer of Energy
• If 10% of solar energy is captured by plants then animals who eat the grass gain only 10% of that energy (1%), animals who those animals gain 10% from that (.1%)
• 10% --> 1% --> .1%
What is Biomass?
• Biomass is the total amount of living tissue within a given trophic level
• A biomass pyramid can show you much food is available to each trophic level
Recycling Matter in the Biosphere
• Elements, chemical compounds, and other forms of matter are passed from one organism and from one part of the biosphere to another in biogeochemical cycles
The Water Cycle
• Water moves between the ocean, atmosphere, and land
• Water evaporates from bodies of water into the atmosphere
• Water can also enter the atmosphere through transpiration (process by which water is lost through the leaves of plants)
Nutrient Cycles
• A nutrient is a chemical substance that an organism needs to sustain life
• Important nutrient cycles– Carbon Cycle– Nitrogen Cycle– Phosphorus Cycle
The Carbon Cycle
• Carbon’s Roles– Ingredient in living tissue
– Important component of animal skeletons (CaCO3)
– Important component of the atmosphere (CO2)
The Carbon Cycle
• Carbon enters the atmosphere by:– Respiration– Geochemical processes– Human activities
• Carbon is taken up by:– Photosynthesis– Burial and decomposition of dead organisms
(formation of fossil fuels)
The Nitrogen Cycle
• The roles of nitrogen:– Important component of amino acids
– Major component of fertilizer (NO3-)
– Major component of atmosphere (N2)
The Nitrogen Cycle
• Nitrogen gas (N2) cannot be used by plants so it must be converted into a usable form
• Soil bacteria convert nitrogen gas into ammonia (NH3) in the process of nitrogen fixation
• More soil bacteria convert ammonia into nitrates (NO3
-) and nitrites (NO2-) a usable form
• Other soil bacteria then convert nitrates and nitrites back into nitrogen gas, which is known as denitrification
The Phosphorus Cycle
• Roles of Phosphorus– Important component of DNA and RNA
• Does not enter atmosphere (gas)• Steps
– Phosphorus is found in rocks and sediment which gets moved by water
– Plants absorb phosphorus in the form of phosphate from soil and water
– Heterotrophs consume plants
What is a Limiting Nutrient?
• A nutrient that is scarce of cycles very slowly
• When an aquatic ecosystem receives a large amount of a limiting nutrient it immediately increases the amount of algae, which is known as algal bloom