biosphere size
12.5 miles
human impact on exosystems
1/ habitat destruction
2. introduced species
3 overexploitation
4. chemical use
habitat destruction
our destruction and alteration of habitats currently pose the single greaest threat to exosystems and biodiversity *through agriculture, housing, logging, mining, environmental pollution)
ex: we alter habitats dramatically to fit our needs (we aren’t going to stop doing this, but we can be more thoughtful and lessen the effects)
habitat destruction types
- forest –> agriculture (
- agriculture –> housing and development
- wetlands –> housing and development
- fragmentation of habitats
- desertification
forest –> agriculture
basically a forest ecosystem to grassland ecostystem; by changing the species of plan the species of animals also changes rainforest destruction (soil in rainforests is poor humans end to simplify and nature tends to diversity (we tend to plant monocultures, one specie vs polycultures, many species - weeds are one of nature's way of trying to diversify
agriculture –> housing and development
urban sprawl; wetlands filter pollutants out of water as water flows through and help prevent floodin gby sowing down runoff into streams and rivers; important habitat for many species
fragmentation od habitats
habitats get fragmented by logging, farming…
desertification
the conversion of arid or semi-arid regions to desert by drought, overgrazing, over cultivation, deforestation, or poor irrigation practices
introduced species
species that humans have moved from one ecosystem to another; also called exotic species; they are called “invasive species” if they compete with native species
-some can be beneficial (corn, potatoes…)
invasive species
can outcompete the native species and cause them to go extinct often b/c they have no natural predators
ex: intentional - kudzu from japan, honeysuckle from china, european starlings
unintentional
many organisms have been brought in with other goods (woods, food, on boats, on/in people)
ex: zebra mussels, emerald ash borer, asian longhorned beetle
overexploitation
overharvesting a species both on land and sea (harvisting a spcies faster than it can reproduce)
chemical use
we add a lot of chemicals to our environment and some are harmful to exosystems
land - pesticides, herbicides, fertilizers
air - co2, sulfur and nitrogen compounds
water - runoff from agriculture, oil spills
biological magnification
some chemicals including some pesticides, accumulate in the biomass of organisms and increase in concentration as they move up a food chain/web (ex: PCBs in the great lakes) eagles were effect, zebra mussels caused problems
greenhouse effect
solar radiation warms the earth’s surfaces; gases in atmosphere trap som of the heat; natural process that raises earth’s temperature about 50F; a good thing
is the earth getting warmer?
yes, the average temperature rose about 1.1F during the 20th century, and continues to rise
evidence for climate change
- the ten warmest years on record have been since 1998 (benchmark is avg temp b/t about 1951-80 –> 0); 2014 was #1, #2 = 2010
- the ice on the edges of Greenland is melting faster than it is being replenished during the winter
- glaciers are melting on 6 continents
- Phytoplankton in the Atlantic are moving northward into formerly cooler water (phytoplankton near Britain have migrated 10 degrees North in latitude in the last 40 years)
- bleaching of coral reefs (25% of the world’s coral is believed to already be destroyed by global warming and pollution)
- the atlantic ocean huricanes of 2005 (most named storms, most hurricanes, most categroy 5 hurricanes, most hurricanes to make us landfall, wilma strongest hurricane ever recorded) - scientific evidence suggests there is alink between global warming and the power, not frequence, of hurricanes, hurricanes pick up energy from warm water
- polar bears listed as threatened species
- arctic sea ice minimum (september 16)
- arctic gets greeer as climate warms (plant life in thenorthern latitudes look like vegetation 4.3 miles further south in 1983
are we responsible for climagte change
the amount of CO2in the atmosphere has been rising along with
why has CO2 been increasing
because we are adding “new” CO2 by burning fossil fuels; fossil fuels contain carbon that has been out of this cycle for millions of years because it has been buried this entire time;
….
lots of missed flash cards
effects of dams on freshwater fish
dams can disrupt an ecosystem by changing a river ecosystem to a lake ecosystem (flowing and shallow vs still and deep) and block fish that are migrating to spawning grounds
sustainable development
balancing human needs with the needs of the biosphere (realizing we need healthy ecosystems for our survival also; living in ways that are not only good for us but also for the rest of life on the earth) - we do this for ourselves but also for our children and grandchildren, need to think long term
HIPPO
habitat destruction (especially hot spots), invasive species, pollution, population, overharvesting - Wilson says that we need to reverse these activities
biodiversity hotspots
a number of organization are buying up as much land as possible to establish park or preserves in these biological rich areas; saving the habitat; Nature Conservancy and other organizations
