2.1 Energy Flow in Ecosystems Biomass is the total mass of all living things (ie. plants, animals, fungi, bacteria) in a given area. –Biomass can also refer to the mass of organic materials (ie. plant crops, manure) used to produce biofuels such as biogas. –Biomass is generally measured in g/m 2 or kg/m 2.

2.1 Energy Flow in Ecosystems Within an organism’s niche, the organism interacts with the ecosystem by: 1.Obtaining food from the ecosystem 2.Contributing energy to the ecosystem Energy flow is the flow of energy…  from ecosystem to organism  from one organism to another organism

2.1 Energy Flow in Ecosystems Plants are called producers because they produce carbohydrates via photosynthesis from… –carbon dioxide –water –and the sun’s energy

2.1 Energy Flow in Ecosystems Consumers get their energy by feeding on producers or other consumers. Decomposition is the break-down of wastes and dead organisms into usable nutrients, by organisms called decomposers, through the process of biodegradation.

Energy Flow and Energy Loss in Ecosystems: Food Chains Scientists use different methods to represent feeding relationships & energy moving through ecosystems. –Food chains –Food webs –Food pyramids

Energy Flow and Energy Loss in Ecosystems: Food Chains Food chains show the flow of energy in an ecosystem Each step is a trophic level, showing feeding & niche relationships –Primary producers = 1st trophic level –Primary consumers = 2nd trophic level –Secondary consumers = 3rd trophic level –Tertiary consumers = 4th trophic level Examples of terrestrial and aquatic food chains

Energy Flow and Energy Loss in Ecosystems: Food Chains Consumers in a food chain can be classified in the following ways, depending on their diets or behaviours.

Energy Flow and Energy Loss in Ecosystems: Food Chains 1.Detrivores - consumers that obtain energy and nutrients from dead organisms and waste matter –include small insects, earthworms, bacteria and fungi –feed at every trophic level –have their own, separate food chains, and are numerous

Energy Flow and Energy Loss in Ecosystems: Food Chains 2.Herbivores - primary consumers –herbivores eat only plants (producers)

Energy Flow and Energy Loss in Ecosystems: Food Chains 3. Carnivores - secondary or tertiary consumers Secondary consumers eat primary consumers (ie. herbivores) Tertiary consumers eat secondary consumers Tertiary consumers are also known as:  top consumers  top carnivores  top predators

Energy Flow and Energy Loss in Ecosystems: Food Chains 4.Omnivores - consumers that eat both plants and animals –Examples include... humans and bears

Energy Flow and Energy Loss in Ecosystems: Food Webs Most organisms are part of many food chains. To represent interconnected food chains, scientists create a food web. –Food webs are models of the feeding relationship in an ecosystem. –Arrows in a food web represent the flow of energy and nutrients. –The arrows lead to the top carnivore(s).

Energy Flow and Energy Loss in Ecosystems: Food Webs This food web represents a terrestrial ecosystem that could be found in British Columbia.

Energy Flow and Energy Loss in Ecosystems: Food Pyramids Food pyramids are models that show the loss of energy from one trophic level to another. Energy enters at the first trophic level (producers), where there is a large amount of biomass, and therefore much energy It takes many organisms in one trophic level to meet the energy needs of the next trophic level. –Each level loses large amounts of the energy it gathers through basic processes of living. –80% - 90% of energy taken in by consumers is used in chemical reactions in the body, and is lost as heat energy. –There is very little energy left over for growth, or increase in biomass.

Energy Flow and Energy Loss in Ecosystems: Food Pyramids Food pyramids are also known as ecological pyramids. The amount of life an ecosystem can support is determined by the amount of energy captured by producers (found at the bottom level of the ecological pyramid).

Energy Flow and Energy Loss in Ecosystems: Food Pyramids Ecological pyramids may show… 1.biomass 2.numbers 3.energy

Pyramid of Numbers

Pyramid of Biomass

Pyramid of Energy

Energy Flow and Energy Loss in Ecosystems: Food Pyramids There is a 90% decrease of energy from one trophic level of the pyramid to the next. Lower trophic levels have much larger populations than upper levels. This shows the importance of maintaining large, biodiverse populations at the lowest levels of the food pyramid.

Section 1.2 Quiz