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