CH48: Human Impacts on the Biosphere

The Anthropocene

the current geologic interval, in which human activities are leaving a global impact on the earth

mass extinction

increased rate of extinction over a short period of time

How many major extinction events occurred in the past?

five

greatest mass extinction

occurred in the Permian, about 90% of species went extinct

endangered species

currently at a high risk of extinction in the wild

threatened species

likely to become endangered in the future

niche

specific habitat of a species

endemic species

only live in a single area; more likely to become extinct than a widely distributed species

desertification

conversion of grasslands or woodlands to desert conditions

deforestation

encourages flooding and raises landslide risk. reduces soil fertility, affects local weather

pollutants

can be natural or man-made substances released into soil, air, or water in greater than natural amounts

acid rain

low pH rain formed when sulfur dioxide and nitrogen oxides mix with water vapor in the atmosphere

bioaccumulation

an organism accumulates increasing amounts of a chemical pollutant in its tissues over the course of its lifetime

where do pollutant accumulate in animals?

in the fatty tissues

biological magnification

concentration of a chemical increases as the pollutant as it moves to higher trophic levels/up the food chain

ozone layer

region of high ozone concentration in the upper atmosphere between 10.5-17 mi above sea level. benefits living organisms by absorbing most UV radiation

ozone hole

a very pronounced thinning of the ozone layer over Antarctica

near-ground ozone pollution

ozone is naturally found very little near the ground so it is considered a pollutant. irritates eyes and respiratory tracts, effects plant growth

biodiversity

measured in three levels: genetically within a species, species diversity, and ecosystem diversity

conservation biology

field of applied biology that surveys the range of biodiversity and finds ways to maintain and use it to benefit human populations

biodiversity hot spot

threatened region with great biodiversity that is considered high priority for conservation efforts

ecological restoration

work designed to renew or recreate a natural ecosystem that has been degraded or destroyed, fully or in part