Chapter 3: The Biosphere The Study of Ecology

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

Levels of Organization

What is a Biosphere? Part of Earth in which life exists including land, water, and air or atmosphere

What is a Biome? Temperate Forest Tundra A group of ecosystems that have the same climate and similar dominant communities

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

Food Chain

Food Web

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

Important Biogeochemical Cycles Water cycle Carbon Cycle Nitrogen Cycle Phosphorus Cycle

The Water Cycle

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 Carbon Cycle CO2 in Atmosphere CO2 in Ocean

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 Nitrogen Cycle

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

Algal Bloom What is the result of algal bloom?