Chapter 3 – The Biosphere

3.1 Ecologists study environments at different

levels of organization.Ecology is the study of the interactions among living things, and between living things and their surroundings.

Organism

Population

Community

Ecosystem

Biotic and Abiotic Factors

Biotic factors are any living part of an environment.

plants animals fungi bacteria

Abiotic factors are any nonliving part of the environment.

Sunlight Temperature Precipitation Humidity Wind

Biotic and Abiotic Factors Together

Physical factors can be strongly influenced by the activities of organisms.

Also, a change in physical factors can strongly affect the survival of the living organisms.

3.2 Energy in Ecosystems Living organisms need energy for growth,

reproduction, and their metabolic processes.

Producers provide all of the available energy in an ecosystem

Primary Productivity Producers are also called autotrophs

because they make their own food. Most producers uses sunlight as an energy

source.

Heterotrophs acquire energy from other organisms.

Also called consumers

Consumers are not all alike. Herbivores eat plants. Carnivores eat other animals. Omnivores eat both plants and animals. Detritivores eat dead organic matter

(detritus). Decomposers break down organic matter

into simpler compounds.

carnivoredecomposer

3.3 Energy Flow in Ecosystems

A food chain links species by their feeding relationships.

A food chain follows the connection between one producer and a single chain of consumers within an ecosystem.

The ultimate source of energy for all producers and consumers is the sun.

Trophic Levels

First Level – Producers Determine the available energy in the ecosystem

Second Level – First Level Consumers AKA – primary consumers Herbivores

Third Level – Second Level Consumers AKA – secondary consumers Omnivores and carnivores

Fourth Level Third level consumers

(carnivores that eat other carnivores)

AKA - top carnivores or tertiary consumers

Decomposers – obtain energy from dead and decaying matter at all trophic levels.

produce detritus Ex: bacteria and fungi

decomposer

Energy Flow

An energy pyramid shows the distribution of energy among trophic levels. Only 10 percent of the

energy at each tier is transferred from one trophic level to the next.

90 percent of the energy is lost into the atmosphere as heat.

energy transferredenergy

lost

100%

10%

1%

0.1%

Food Webs

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.

Pyramid of Biomass

Biomass is usually measured in grams of organic matter per unit area.

Why does the amount of biomass decrease moving up the trophic levels?

tertiaryconsumers

secondaryconsumers

primaryconsumers

producers

75 g/m2

150g/m2

675g/m2

2000g/m2producers 2000g/m2

3.4 Cycles of Matter

Elements essential for life cycle through ecosystems.

A biogeochemical cycle is the movement of a particular chemical through the living and non-living parts of an ecosystem.

Matter is recycled within and between ecosystems.

Biogeochemical Cycles

Water Cycle

Carb

on C

ycl

e

Nitrogen Cycle