Transcript ATMOS 397G Presentation

ATMOS 397G Presentation
Long Cao April 19th, 2100
The Vulnerability of Biotic
Diversity
William H. Schlesinger
How global climate change may
cause biotic impoverishment

Nitrogen deposition from fossil fuel
combustion

Increase in atmospheric carbon dioxide

Increased exposure to UV light due to
decrease in stratospheric ozone
Beautiful Wildlife
Introduction
Preservation of the biosphere is essential for
the preservation of the conditions in which
human evolved and flourished.
 Human dilemma: Keep usurping the
resources on earth or allow a biotic diversity
to persist?
 General loss of biotic diversity : from local
pollution to global industrial activity

Decline in the density of birds in
New Hampshire
Do Species Matter?
The disruption and simplification of the
natural biosphere could alter the
environmental conditions and even lead to
the demise of human species.
 The presence or absence of a single species
can cause a dramatic change in ecosystems
 Disproportionate influence on ecosystems.
Food Webs.

Food Webs
Ecosystem Function

Ecosystem function is the ability of a unit of
the earth’s surface to sustain life over a long
period time.
Indices of ecosystem function
Relatively high net primary production
 Stable levels of soil organic matter
 Biogeochemical mass balance(inputs of
nutrients to an ecosystem are greater than or
equal to losses)
 Internal nutrient cycling(more nutrients are
made available by decomposition than from
new inputs to the system)

NPP

Most human industrial activities seem to
lower the species diversity and NPP of
natural ecosystems

In most instances, the NPP of
agroecosystems is lower than that of
adjacent natural ecosystems
Potential Causes of Biotic
impoverishment
Nitrogen Deposition
Through industrial activities, humans have
roughly doubled the supply of fixed
nitrogen on land
 Fertilization of natural ecosystems is likely
to result in a loss of species diversity
 Any addition of a resource to a community
will lead to the dominance of the species
than can use the resource most efficiently

Atmospheric Carbon Dioxide
Increased rates of photosynthesis and
greater water-use efficiency
 C3 plants are much more responsive to high
concentrations of atmospheric CO2, which
increases their water-use efficiency and
competitive ability in dry climates
 Climate change will cause changes in the
distribution of earth vegetation


An onset of global warming may stimulate
decomposition in cold, northern
ecosystems,releasing CO2 from soils that
will further contribute to the greenhouse
effect
Change in Ultraviolet(UV-B)
Light

Decline in the ozone content of the polar
stratosphere leads to ozone depletion and
greater flux of UV-B to the earth surface

Little is known about the effect of UV-B
radiation on organisms other than human
Current depletion of stratospheric ozone
suggests an alarming potential for a
reduction in the diversity and activity of the
biosphere
 Depletion of stratospheric ozone should
lead to a greater period of exposure of the
plants and animals of high-latitude
ecosystems to UV-B radiation


Conclusions
Global industrialization is likely to cause a
loss of species from the planet
 Those species that survive are likely to be a
group of hardy generalists that are superior
competitors in disturbed environments-in
short, weeds
 It’s time to stop usurping the biotic
productivity
