Biotic Factors

Ch 36 Energy in Ecosystems

36.1 Food Chains & Food Webs

34.1 Biotic and Abiotic Factors 



What are biotic and abiotic factors? The biological influences on organisms are called biotic factors. Physical components of an ecosystem are called abiotic factors.

Biotic Factors 

A biotic factor is any living part of the environment with which an organism might interact, including animals, plants, mushrooms and bacteria.



Biotic factors relating to a bullfrog might include algae it eats as a tadpole, the herons that eat bullfrogs, and other species competing for food or space.

Abiotic Factors 

An abiotic factor is any nonliving part of the environment, such as sunlight, heat, precipitation, humidity, wind or water currents, soil type, etc.



For example, a bullfrog could be affected by abiotic factors such as water availability, temperature, and humidity.

Biotic and Abiotic Factors Together 

The difference between abiotic and biotic factors is not always clear. Abiotic factors can be influenced by the activities of organisms and vice versa.



For example, pond muck contains nonliving particles, and also contains mold and decomposing plant material that serve as food for bacteria and fungi.

Biotic and Abiotic Factors Together 

In addition, trees and shrubs affect the amount of sunlight the shoreline receives, the range of temperatures it experiences, the humidity of the air, and even the chemical conditions of the soil.



A dynamic mix of biotic and abiotic factors shapes every environment.

34.1 The Study of Ecology  Ecology: interactions among organisms and their environment  Biotic Factors: Living things found in the environments (bacteria, protists, fungi, animals, plants).

 Abiotic Factors: the nonliving physical and chemical conditions (soil, water, air, sun….).



Organism- Smallest unit of ecological study.

Ex. Blue Sweet lip fish Ecologists might ask, “How do Blue Sweet lip fish adapt to the challenges posed by the environment?”



Population- a group of individual species living in a particular area .

Ex. A group of Blue Sweet lip fish Ecologists might ask, “What factors limit the numbers of sweet lip fish living around this reef?”



Communities- All of the organisms that live in a particular area make up a community.

Ex. Coral reef is home to many living things including fish, coral animals, microscopic algae…. Ecologists might ask, “How might a disease that strikes the coral animals affect the other species in the community?”



Ecosystems- includes the living (biotic factors) and the nonliving (abiotic factors) things in an area.



Reef’s many living species, the temperature of the water, and the amount of sunlight An ecologist might ask, “ How does nitrogen move within the reef ecosystem?”



Biosphere- broadest level of ecological study.



Sum of all Earth’s ecosystems. Envelope of air, water, land that supports and includes all life. Biosphere is a closed system, this means that chemicals in the biosphere’s living and nonliving things mostly come from within the system, not from the outside.



 



An ecologist would study global issues, and the effects of climate change on living things.

Patchiness of the Biosphere 

Biosphere is not uniform, it is unevenly spread out.



Biosphere is like a quilt of many different environments (land,

oceans, lakes, ice) 

You can find an uneven distribution of biomes on a continent.



You can find patches of woods, fresh water, and marshes in a smaller area of wilderness.

 

Patchiness creates a number of different habitats. Habitat: specific environment in which organisms live.



All habitats have different abiotic and biotic factors.

Key Abiotic FactorsHow it affects animals/ plants 1.)Sunlight- provides light and warmth, powers photosynthesis.  

Canopy of forest gets more light than the forest floor. Sea floor gets less light than the surface of the ocean

2.)Water- essential for all life. (we are 70% water)

3.)Temperature- most life exists between a narrow range of temperatures. (0 50 °C)  

Few organisms can maintain an active metabolism below 0 °C Most organisms enzymes are denatured above 50°C

Key Abiotic FactorsHow it affects animals/ plants 4.) Soil- the product of abiotic forces (such as ice, rain, and wind) and the  

actions of the living things (microorganisms, plants and earthworms) on the rocks and minerals of the earth’s crust. Chemical makeup of the soil and rock affect the types of plants that grow there. Dry/ nutrient-poor soil = dominated by little bluestem grasses

5.) Wind- it can affect the distribution and organisms in several ways. It moves clouds and rain over the Earth’s surface.  Stirs up water in ponds, lakes, and streams.  Creates currents that bring up nutrients from the bottom.  Helps to disperse pollen and seeds. 6.) Sever Disturbances- fires, hurricanes, tornadoes, droughts, floods, and volcanic eruptions.  Some are infrequent so organisms have not adapted to these disturbances. 

36.1 Feeding relationships 

Energy flow through ecosystems begins with producers.



Energy flows in 1 direction



Nutrients cycle

Consumers (Heterotrophs) 

Herbivores 



Omnivores 



Eat only plants and fungi Eat both plants/fungi and animals

Carnivores 

Eat only animals

Detrivores/ Decomposers consumers that feed on detritus, the wastes and remains of dead organisms.  Nutrients returned back to the soil 

Producers (Autotrophs) 

Photosynthetic organisms  



Capture energy from sunlight, CO2 and H2O Most producers are photosynthetic

Chemosynthetic or chemoautotrophs organisms 

Capture energy from chemical compounds in the surroundings (DEEP SEA HYDROTHERMAL VENTS)

 Energy is lost in each step up a food chain  Only 10 % of the energy from one level on the food chain is available to the next level (90% lost as heat)

FOOD CHAINS  



The pathway of food transfer from one trophic level to another is called a food chain. In all food chains, producers make up the trophic level that supports all other levels. What’s missing from this food chain?

FOOD WEBS

  

Consumers usually have many food sources. A hawk can eat a small bird, fish, mouse... The pattern made by interconnected and branching food chains is a food web.

Food Webs 



Many consumers and decomposers have more than 1 food source Movement of energy occurs in complex webs rather than in simple chains

A food web shows a complex network of feeding relationships.

A food web shows a complex network of feeding relationships.  

An organism may have multiple feeding relationships in an ecosystem. A food web emphasizes complicated feeding relationships and energy flow in an ecosystem.

Trophic Levels Each of the feeding organisms represents a trophic level in the ecosystem. Both energy and chemicals move from one organism to the next as organisms feed. Producers/Primary Producers 

Autotrophs (Photosynthesizers, Chemosynthetic organisms)

Primary consumers- 1st level  Herbivores and omnivores that eat producers

Secondary consumers- 2nd level  Carnivores and omnivores that eat herbivores-

primary consumer

Tertiary consumers- 3rd level  Carnivore eats another carnivore- secondary consumer

Quaternary Consumers- 4th level

eats another carnivore-

tertiary consumers

Figure 36-2 Each of these food chains includes five trophic levels. The arrows indicate the direction of food transfer between trophic levels.

A Simplified Food Web?

36.1 Objectives p. 788 

Contrast the flow of energy and chemicals in ecosystems



Explain how trophic levels relate to food chains and food webs.

Thumbs Up? Thumbs Down?

36.1 Concept Check p. 791 1.

How are the movement of energy and the movement of chemicals in ecosystems different?

2. In the following food chain, identify the trophic levels: Berriesmouse owl 3.

fig. 36-3 identify a food chain w/ 3 trophic levels