Download Chapter 6 – Humans in the Biosphere

Chapter 6 – Humans in the
Biosphere
6-1 A Changing Landscape
Earth as an island – we need to need to see
how models can be used to make
predictions about complex systems…
Hawaii pg 139
Among human activities that affect the
biosphere are
- hunting and gathering – decreases natural
species in certain areas; has caused major
mass extinctions
- agriculture – created dependable food
source… villages settled… habitat
destruction, introduced species, pest
control, irrigation
- industry – machines and factories use fossil
fuels (coal, oil, natural gas)
- urban development – discarded wastes…
pollution, movement to suburbs… habitat
destruction
American artist Chris Jordan recreated
Seurat’s masterpiece with digital images of
106,000 aluminum cans - the number
used in the US every thirty seconds!
6-2 Renewable and nonrenewable
resources
Tragedy of the commons – idea that any
resource that is free and accessible may
eventually be destroyed.
Renewable resource – can regenerate or be
replenished by a chemical cycle; trees,
water
Nonrenewable resources – cannot be
replenished by natural processes; fossil
fuels burn and energy is given off
*** a population of trees may be
nonrenewable if ecosystem changes
Sustainable development – use ecological
studies to see how we are impacting the
environment in order to save resources
Land resources – soil can be permanently
damaged
- soil erosion and desertification occur
when humans change environment…
contour plowing and leaving in roots can
help
Forest resources – used for materials,
oxygen, habitats, and food
- deforestation can lead to erosion and
loss of habitats
Fishery resources – oceans and lakes
provide a lot of food – aquaculture
- overfishing is an example of the tragedy
of the commons
Air resources – cities produce smog, a
pollutant from the burning of fossil fuels
that can cause health problems
-acid rain – nitric and sulfuric acids with a
high pH which can kill plants and animals
Formation of Acid Rain
Emissions to Atmosphere
Nitrogen oxides
Sulfur dioxide
Chemical Transformation
Nitric acid
Sulfuric acid
Condensation
Dry Fallout
particulates, gases
Industry
Transportation
Ore smelting
Power generation
Precipitation
Acid rain, fog,
snow, and mist
Freshwater resources – pollution threatens
water supplies; improperly discarded
chemicals, domestic sewage
6-3 Biodiversity
Biodiversity = the sum total of the genetically
based variety of all organisms in the
biosphere
- one of Earth’s greatest natural resources.
Species of many kinds have provided us
with foods, industrial products, and
medicines – including painkillers,
antibiotics, heart drugs, antidepressants,
and anticancer drugs.
Human activity can reduce biodiversity by
altering habitats, hunting species to
extinction, introducing toxic compounds
into food webs, and introducing foreign
species to new environments.
Species Diversity
Pollution – DDT, a pesticide, became more
concentrated as it moved up the food
web… biological magnification
Biological Magnification of DDT
Magnification of
DDT Concentration
Fish-Eating Birds
10,000,000
Large
Fish
Small Fish
Zooplankton
Producers
Water
1,000,000
100,000
10,000
1000
1
Introduced species – humans transport
plants and animals around the world that
take over a new habitat
Conserving Biodiversity
- managing endangered species,
protecting habitats, fishing regulations
Sustainable Agriculture
Cover Crops
Legumes, grasses, and other
cover crops recycle soil nutrients,
reduce fertilizer need, and
prevent weed growth.
Controlled Grazing
By managing graze periods and herd
densities, farmers can improve nutrient
cycling, increase the effectiveness of
precipitation, and increase the carrying
capacity of pastures.
A
Contour Plowing
Contour plowing reduces
soil erosion from land runoff.
On hilly areas, plowing is done
across the hill rather than
straight up and down.
Biological Pest Control
The use of predators and parasites
to control destructive insects
minimizes pesticide use as well as
crop damage
B
C
Yr. 1
corn
Yr. 2
corn
Crop Rotation
Different crops use and
replenish different nutrients.
By rotating crops, the loss
alfalfa
(plowed in) of important plant nutrients
is decreased.
oats alfalfa
alfalfa
Yr. 3
oats alfalfa
corn
6-4 Charting a Course for the
Future
Ozone depletion – ozone layer absorbs harmful
ultraviolet radiation; evidence exists that
chlorofluorocarbons, CFCs, could damage the
ozone layer; use of most CFCs are banned in
US
Global Climate Change – increase in the average
temperature of the Biosphere; some scientists
attribute this to human activities and the burning
of fossil fuels… CO2
Ecosystem Services
Solar energy
Production of oxygen
Storage and recycling of
nutrients
Regulation of climate
Purification of water and air
Storage and distribution of
fresh water
Food production
Nursery habits for wildlife
Detoxification of human and
industrial waste
Natural pest and disease
control
Management of soil erosion
and runoff
How does everything fit?