atmos 397g presentation long cao april 19th, 2100
TRANSCRIPT
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
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
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.
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
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