Transcript Human Impact on Resources, Biodiversity, and Ecosystems

Human Impact on Resources,
Biodiversity, and Ecosystems
Types of Resources
• natural resources – goods and
services provided for by nature
• renewable resources – replaced
naturally in a reasonable amount of
time
• non-renewable resources
• commons – resources owned by
everyone
tragedy of the commons
• renewable common resources which
tend to be over-exploited
• Why?
• “if I don’t use them then someone
else will so it might as well be me”
exploitation of resources
• carrying capacity – the maximum size of a
population that can be supported over the
long term
• maximum sustainable yield (MSY) – the
greatest “use” of a renewable resource
Human Impact on Biodiversity
• species biodiversity – the total number of
different kinds of species
• genetic biodiversity – the total gene pool
for a given species
• biosphere biodiversity – the total number
of species in existence
- known species: 2 million
- unknown species: 3 – 50 million
Value of Biodiversity
Why should we care about protecting other species?
• Food
agriculture and meat production has led to
a decline in species biodiversity as well as
genetic biodiversity
• Medicine
many modern medicines come from plant
extracts
* biopiracy
Value of Biodiversity cont.
• ecosystem sustainability
the greater the biodiversity, the greater the
stability
* keystone species
• commercial value
- ecotourism
- recreation; hunting, fishing, wildlife watching
- timber
• intrinsic value
preservationist philosophy – existence of other
species has value aside from any use we make
of it
HIPPO
Human Causes of Biodiversity Decline
• habitat destruction
deforestation, wetlands destruction,
development
• introduction of exotic species
most introduced species do not survive
their new habitat – those that do, often
out-compete native species (and are
termed invasive)
human causes continued …
• overuse (hunting, fishing)
* poaching
• pollution
* climate change
Reduced Ranges
Indian Tiger
Range 100 years ago
Range today
(about 2,300 left)
Fig. 9-8a, p. 191
Reduced Ranges
Black Rhino
Range in 1700
Range today
(about 2,400 left)
Fig. 9-8b, p. 191
Deliberately Introduced Species
Purple looselife
European starling
Marine toad
Water hyacinth
African honeybee
(“Killer bee”)
Japanese beetle
Nutria
Hydrilla
Salt cedar
(Tamarisk)
European wild boar
(Feral pig)
Fig. 9-11a, p. 193
Accidentally Introduced Species
Sea lamprey
(attached to lake trout)
Formosan termite
Argentina fire ant
Zebra mussel
Brown tree snake
Asian long-horned
beetle
Eurasian muffle
Common pigeon
(Rock dove)
Asian tiger mosquito
Gypsy moth larvae
Fig. 9-11b, p. 193
Kudzu
Fig. 9-12, p. 194
Fire Ant Invasion
1918
2000
Fig. 9-13, p. 195
Extinction Threats from Poaching
• Profits of poaching
• Causes of poaching: food, fur, pets,
traditional medicines, trophies, eliminating
pests, etc.
• Bushmeat
• Illegal pets and decorative plants
Bushmeat
Fig. 9-15, p. 196
Confiscated Products From
Endangered Species
Fig. 9-18, p. 199
Extinction Threats from Climate
Change and Pollution
• Global Warming
• Pesticide threats
• DDT biomagnification
(bioaccumulation)
Biomagnification of DDT
DDT in fish-eating
birds (ospreys)
25 ppm
DDT in large
fish (needle fish)
2 ppm
DDT in small
fish (minnows)
0.5 ppm
DDT in
zooplankton
0.04 ppm
DDT in water
0.000003 ppm,
or 3 ppt
Fig. 9-16, p. 197
Litter Kills Seals
Fig. 9-19, p. 200
Extinction
• background extinction rate
- naturally occurring extinctions
- 99 % of all species are now extinct
• local extinction
extinction of a population but not an entire
species
• species extinction
- disappearance of an entire species
- criteria for claiming this?
• mass extinction
5 major episodes of extinction in Earth’s past
Extinction Crisis Question
• the species-area relationship
lose 50% of a habitat, lose 15% of the
biodiversity found there
• fragmentation and edge effect
carving up a habitat into several smaller
pieces increases edge habitat, decreases
interior habitat and results in a loss of
biodiversity
• interior species, edge species
Fragmentation
Cleared plots
for grazing
Highway
Cleared plots
for agriculture
Fig. 8-10b, p. 161
Case Study: Amazonia
• satellite images are used to measure
species loss – How?
• deforestation rate is slower than originally
thought
• however, the pattern of deforestation
(fragmentation) may be causing a faster
loss of species
• primary (old growth) vs. secondary forests
(less biodiversity)
Strategies for Protecting Biodiversity
• laws and treaties
- CITES Convention on International
Trade of Endangered Species
- MMPA Marine Mammal Protection Act
- ESA Endangered Species Act
endangered, threatened, special
concern
• captive breeding, zoos, game parks,
cloning
Protecting Marine Biodiversity
• why do we use preservation techniques
with some species (whales) and
conservation techniques with other
species (fish)?
• part of protecting biodiversity involves
measuring populations and migratory
patterns – how is that done with
whales?
Case Study: Whale Preservation
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conservation vs. preservation
commercial whaling
IWC 1986 commercial whaling ban
scientific whaling
subsistence whaling
Study of Whales
• fluke prints
• satellite tags
• captivity