Transcript Chapter 4 - Cloudfront.net

Chapter 6
Humans in the Biosphere
A Changing Landscape
“Earth is an Island”
 All organisms- including humans -that live on Earth share
limited resources & depend of them for their survival.
 Natural ecological processes sustain these resources (water,
carbon, nitrogen cycles)
 To protect these resources – we must understand how humans
interact with the Earth
Humans and the Biosphere
 We as humans depend on chemical cycles (H20, C, N) to provide:
a. breathable air
b. drinkable water
c. fertile soil
d. storage & recycling of nutrients
 We must understand how human activity affects these cycles
Human Activities that Affect the
Biosphere
 Hunting & gathering
 Agriculture
 Industry
 Urban development
 Human activity has become the most important source of
environmental change on the planet.
 We do not fully understand how these activities affect our
ecosystems
Human
Activities
that have changed the biosphere include
Hunting and
gathering
may have once caused
Industrial
growth
Agriculture
often relies on the methods of the
Extinctions of
large animals
Green
revolution
Food supply
Pesticide use
have resulted in
High standard
of living
which increased
Monoculture
use
Urban
development
Increased
pollution
Renewable Resources
 Can regenerate or can be replenished
 Not always unlimited
 Example:
- Water can become limited by drought or overuse
 Human activity can affect the quality of renewable resources
such as:
- land, forests, fisheries, air & freshwater
Nonrenewable Resource
 Cannot be replenished by natural processes
 When they are depleted –
they are gone forever
 Example:
- coal
- oil
- natural gas (fossil fuels)
Sustainable Development
 Way of using natural resources without depleting them
 Provides humans with what they need without causing long
term environmental harm
 This can have a positive impact on the environment we create
for ourselves & future generations
Biodiversity
 The sum of the genetically based variety of all organisms in the biosphere
 Basically, how all living things are so different!!!
 Greatest natural resource
 The many different species provides us with:
1. food
2. industrial products
3. medicines (painkillers, antibiotics, heart, antidepressants &
anticancer drugs)
 When biodiversity is lost, potential sources of material with significant
value to Earth & mankind may be lost with it
Types of Diversity
 Ecosystem Diversity:
 Variety of habitats, communities, and ecological processes in the living
world
 Examples:
habitats
1. deserts
2. mountains
3. rain forests
4. oceans
ecological processes
1. water cycle
2. carbon cycle
3. nitrogen cycle
4. phosphorus cycle
Types of Diversity
 Species Diversity
 Refers to the # of different species in the biosphere
 Scientists have identified & named about 1.5 million species
 They estimate millions will still be discovered
 Genetic Diversity
 Refers to the total of all the different forms of genetic
information carried by all organisms living on Earth today
(DNA)
Threats to Biodiversity
 Altering habitats
 Hunting to extinction
 Introducing toxic compounds into food webs
 Introducing foreign species to new environments