Ecology Ch 3 The Biosphere 3 1 What

Ecology Ch. 3 – The Biosphere

3. 1 - What is Ecology? • It is the scientific study of interaction among organisms and between organisms and their environment

What is the Biosphere? • The biosphere is the combined portions of the entire planet where life exists.

Levels of Organization • To understand relationships within the biosphere ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere

Levels (con’t. ) • Species: a group of organisms so similar to one another that they can breed and produce fertile offspring. • Populations: a group of individuals that belong to the same species and live in the same area. • Communities: different populations that live together in a defined area.

Levels (con’t. ) • Ecosystems: all the organisms that live in a particular place, together with their nonliving or physical environment. • Biomes: a group of ecosystems that have the same climate and dominant communities.

Levels of Organization

Biotic and Abiotic Factors • Biotic Factors – Any living part of the environment with which an organism might interact – Ex. – animals, plants, mushrooms & bacteria • Abiotic Factors – Any nonliving part of the environment – Ex. – sunlight, heat, water, soil, etc.

Biotic and Abiotic Factors Together • The differences between biotic and abiotic factors are not always clear and simple • Many physical factors can be strongly influenced by the activities of organisms – Ex. – pond “muck” is a combination of soil (abiotic) and leaf mold & decomposing plant material (biotic)

Biotic and Abiotic Factors

Ecological Methods Scientists use three basic approaches to conduct ecological research. They are: • Observing • Experimenting • Modeling

3 -2 Energy, Producers, and Consumers • What happens if your car runs out of gas? • What do you need before you can play in a soccer game or run for 5 miles? • Living systems need a constant input of Energy.

Primary Producers • Autotrophs – Organisms that use energy from the environment to make complex organic compounds – Also known as producers. Why? – Two types • Photosynthesis - Energy from the Sun • Chemosynthesis - Life without Light

Primary Producers • Primary Producers – The first producers of energy-rich compounds that are later used by other organisms • Energy from the Sun – Capturing light energy and using it to convert CO 2 & H 2 O into O 2 & Carbohydrates • Energy without Light – Using chemical energy to make Carbohydrates

Sources of Energy

Consumers • Heterotrophs – Rely on other organisms for their energy and food supply. – Also known as consumers • Why?

Consumers • Types of Consumers – Herbivores • Obtain energy and nutrients by eating plant materials – Carnivores – • Kill and eat other animals – Omnivores • Eat both plants and animals – Scavengers • Consume the carcasses of dead animals – Detritivores • Feed on dead and decaying plant and animal remains – Decomposers • Chemically break down matter

Beyond Consumer Categories • These simple categories often don’t express the real complexities of nature. • Examples: – Hyenas (carnivores) will scavenge if they get a chance – Aquatic animals will eat a mixture of algae, bits of animal carcasses, and detritus

3. 3 Energy Flow in Ecosystems • Energy flows through the ecosystem in one direction.

Energy Flow in Ecosystems

Food Chain • A series of steps in which organisms transfer energy by eating and being eaten.

Food Web • A network of many feeding interactions

Food Web

Food Webs and Disturbance • Relationships in Food Webs are not simple. • Disturbances do happen and their effects can be dramatic. • Example - Marine Food Web / Krill

Antarctic Food Web

Trophic Levels and Ecological Pyramids • Each level in a food chain or food web is a trophic level. • Each trophic level depends on the level below it for energy.

What is a Trophic Level?

Ecological Pyramids • Can be used to represent energy, matter or number of individuals at each trophic level

Energy Pyramid • Only 10% of the energy available at one trophic level makes it to the next level • When one organism eats another, energy is lost. Where does this energy go?

Energy Pyramid

Biomass Pyramid • Represents all the living tissue (food) at each trophic level.

Biomass Pyramid

Pyramid of Numbers • The number of individual organisms at each trophic level usually decreases as you go up the pyramid of numbers.

Pyramid of Numbers

3 -4 Cycles of Matter • Unlike the one-way flow of energy, matter is recycled in the biosphere. • Where does your body get the materials, such as Carbon, it needs to function? _____ • Elements , chemical compounds and other forms of matter are passed from one organism to another through biogeochemical cycles. Bio - ______ Geo - ______ Chemical - ______

Water Cycle

Other Biogeochemical Cycles • Carbon Cycle - carbon is especially important because it is the key ingredient in all living organisms. • Carbon is found in oceans, the air, and certain types of rock.

Carbon Cycle

• Nitrogen Cycle - All organisms require nitrogen to make amino acids which are used to build proteins.

Nitrogen Cycle

• Phosphorus Cycle - Unlike carbon nitrogen and oxygen, phosphorous does not enter the air, it remains mostly in rock, soil minerals, and ocean sediments. – Phosphorous is of great biological importance for molecules like DNA and RNA.

Phosphorous Cycle

Nutrient Limitation • Primary Productivity: the rate at which organic matter is created by a producer. - Controlled by the availability of nutrients in the environment • How can a nutrient be a limiting factor for an ecosystem? - If even a single essential nutrient is in short supply, primary productivity will be limited

Nutrient Limitation • Limiting Nutrient – the nutrient whose supply limits productivity – Ex. - If ample sunlight and water are available, the primary productivity of an ecosystem may be limited by the availability of nutrients.

Nutrient Limitation • In Soil – Growth of crop plants is limited by one or more nutrients that must be taken up by plants through their roots – That’s why farmers use fertilizers! • In Aquatic Ecosystems – Sometimes receive large amounts of a limiting nutrient (runoff from fertilized fields) – The result can be an Algal Bloom which can cover the water’s surface and disrupt the ecosystem