Transcript A Changing Landscape--How humans have impacted ecosystems

A Changing Landscape--How
humans have impacted
ecosystems
 How have we changed the landscape?
 What are the consequences of these
changes?
What was the Green
Revolution?
 1950s--> Increase food production
 HOW?
 1) New, highly productive varieties of crops
(High yield wheat & corn)
 2) Monoculture--Growing the same crop
 3) Chemical pesticides & fertilizers
 4) Heavy equipment
Industrial and Agricultural
Chemicals
 High concentrations can cause serious problems for
wildlife and humans. Widespread DDT use in the
1950s threatened fish-eating birds like pelicans,
osprey, falcons, and bald eagles. It caused females
to lay eggs with thin, fragile shells, reducing hatching
rates and causing a drop in birth populations. Since
DDT was banned in the 1970s, bird populations are
recovering.
 Still a concern is mercury, which accumulates in the
bodies of certain marine fish such as tuna and
swordfish.
In the highest trophic levels, pollutant
concentrations may reach 10 million times
their original concentration in the
environment.
Biological Magnification
Eutrophication
 excessive nutrients
in a lake or other
body of water,
usually caused by
runoff of nutrients
(animal waste,
fertilizers, sewage)
from the land ...
Stages of Lake Succession
Ozone Layer Thinning
The Ozone Hole
Biodiversity--Types
 Species Diversity--The variety of species
within a community
 Genetic Diversity-- the genetic variability
within a species.
 Ecosystem Diversity-- the organization of
species in an area into distinctive plant and
animal communities.
THREATS TO BIODIVERSITY
Services of an Ecosystem
(What an Ecosystem does for us)
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Solar Energy
Production of oxygen
Storage & Recycling nutrients
Regulation of climate
Purification--H2O & Air
Storage of fresh H2O
Food Production
Nursery habitats for wildlife
Detox. waste
Natural Pest & Disease control
HEAVY METALS
Why are they harmful?
 Lead (Pb)
 Mercury (Hg)
 Cadmium (Cd)
 All interfere with normal nervous
system function(s)
 Note--Some heavy metals are important
in our diet--Fe (iron) Ca (calcium)
BIODIVERSITY HOT SPOTS
CONSERVING BIODIVERSITY
 Identify & Protect habitat
 HOW?
 National Parks & wildlife refuges
 Captive breeding programs