Chapter 23: Global Ecology

global ecology

scientific study of the relationship between biotic systems and environmental processes at a planetary scale

seven main threats to biodiversity

habitat destruction, habitat fragmentation, habitat degradation/pollution, global climate change, overexploitation, invasive species, disease

habitat destruction

the main threat of biodiversity: disappearance of ecosystems and the native organisms that inhabit them

agricultural expansion

biggest cause of habitat loss/destruction (>40% of world's habitable land has been converted to farm land)

main threats to tropical forests

deforestation for agriculture and ranching

edge effects

changes in physical env. within fragments and along forest edges

hotter, drier, higher solar intensity, more wind

decreased diversity

earth's atmosphere

composition: 78% N, 21% O, 1% Ar, 0.03% CO2

highest conc. atmosphere gases in

troposphere

ozone concentrated in

stratosphere

greenhouse effect

warming of the earth's atm and surface as a result of heat trapped near earth's surface by gases in atm.

major greenhouse gases

H2O, CO2, CH4, O3, N2O, CFCs

global warming

describes rise in global temps due to increase in GHGs emissions

climate change

describes all climate characteristics that are changing due to increase in GHG emissions

Keeling's reports

direct atm. CO2 measurements show CO2 levels have been increasing since 1958

several methods indirectly measure changes in CO2 overtime

ice and sediment cones, tree rings, coral reefs, fossils

temperature change is NOT

uniform across the globe (current avg. global temp is 1.28 degrees above 1951-1980)

coral bleaching

temperature increases, coral expel symbiotic algae (zooxanthellae), coral die of starvation, coral bleaching

ocean acidification

increased atmospheric CO2 levels reduce the pH of the ocean

(ex: mussels, clams, corals, can't form shells in low pH and die)

effect of climate change on biodiversity (ocean acidification)

negatively impacts fisheries and food security for humans

effect of climate change on biodiversity (pika)

as temps rise, pikas spend more time in burrows, less time foraging for food and finding mates, decreased chance of surviving

climate change causing mismatches in interacting species

caribou migration is out of sync with emergence of plants they depend on for food

finding solutions to climate change

reduce GHGs emissions, reduce deforestation, establish new conservation areas, identify and protect migration routes