This document summarizes key concepts about ecosystems, including: 1) Ecology studies interactions between living things and their environment at different levels of organization, from organisms to ecosystems. Biotic factors are living parts of the environment like plants and animals, while abiotic factors are non-living like sunlight, temperature, and wind. 2) Energy enters ecosystems through producers, mostly plants that use photosynthesis, and flows through food chains of consumers like herbivores, carnivores, and decomposers. Only about 10% of energy is transferred at each trophic level with 90% lost as heat. 3) Matter cycles through ecosystems in biogeochemical cycles like the water, carbon, and nitrogen cycles which move

1. Chapter 3 – The Biosphere

2. 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.

3. Organism
Population
Community
Ecosystem

4. Biotic and Abiotic Factors
 Biotic factors are any living part of an environment.
 plants
 animals
 fungi
 bacteria

5.  Abiotic factors are any nonliving part of the
environment.
 Sunlight
 Temperature
 Precipitation
 Humidity
 Wind

6. 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.

7. 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.

9.  Heterotrophs acquire energy from other organisms.
 Also called consumers

10.  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.
carnivore
decomposer

11. 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.

12. 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

13.  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

14. 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 transferred
energy
lost
100%
10%
1%
0.1%

15. 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.

17. 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?
tertiary
consumers
secondary
consumers
primary
consumers
producers
75 g/m2
150g/m2
675g/m2
2000g/m2producers 2000g/m2

18. 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

19. Water Cycle

20. CarbonCycle

21. Nitrogen Cycle