Post on 18-Dec-2015
A Changing Landscape
• * Human activities change the flow of energy in an ecosystem and can reduce the ability of ecosystems to recycle nutrients. Some activities that have transformed the biosphere:– Hunting and gathering– Agriculture – domestication of animals, modernization of
practices – Green Revolution (farming practices that increased yields of rice, wheat, and other crops)
– Industry – machines and factories during 1800s – cities grow rapidly
– Urban development – spread of suburban communities to new lands
• All of this activity by humans has affected ecosystems
Renewable and Non-renewable Resources
• Renewable – can regenerate and are replaceable, but not necessarily unlimited
• Non-renewable – cannot be replenished by natural means (fossil fuels – coal, oil, gas, uranium)
• Sustainable Use – using natural resources at a rate that does not deplete them
• * Human activities affect the supply and quality of renewable resources, including resources such as land, forests, ocean resources, air, and water.
Renewable Resources
• There are several renewable resources available:– Land – Forest – Ocean– Air– Water
Renewable Resources (continued)
• Land Resources – soil – should be renewable if managed properly – plowing leads to increased rate of soil erosion – leads to desertification
Renewable Resources (continued)
• Forest Resources – lumber – should be renewable – selective cutting vs. clear cutting – deforestation = erosion
Renewable Resources (continued)
• Ocean Resources – commercial fishing – should be renewable – overfishing leads to stock collapse – Aquaculture (farming of aquatic ecosystems) an option or limiting fishing amounts
Renewable Resources (continued)
• Air Resources – air pollution – smog – asthma – acid rain, ozone depletion, global warming – all affect air as a renewable resource
Renewable Resources (continued)
• Water Resources – industrial pollution, domestic pollution, groundwater contamination– Need to protect water supply to keep it as a
renewable resource
Biodiversity
• * Biodiversity is the sum total of the genetically based variety of all organisms in the biosphere
• Three divisions of biodiversity– Ecosystem diversity– Species diversity– Genetic diversity
Species Diversity
• Species Diversity – number of different species in biosphere
Insects
BacteriaFungi
Plants
Protists Other Animals
54.4%
4.2%
18%
3.4%0.3%
19.7%
Genetic Diversity
• Genetic Diversity – sum total of all the different forms of genetic information carried by all organisms
Biodiversity (continued)
• *****Biodiversity is one of Earth’s greatest natural resources. Biodiversity provides us with foods, industrial products, and medicines.*****
• * Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments.– Extinction and endangered species (possibly due to over-
hunting) – can destroy food webs/ecosystems– Development of land = habitat fragmentation (split ecosystem
into pieces) – less species can live here– Pollution - DDT – biological magnification – concentrations of a
harmful substance increases in organisms at higher trophic levels – can destroy food webs/ecosystems
– Introduced species – invasive species – transported/not native – crowd out native species, often killing native species
PollutionFish-Eating Birds
Magnification ofDDT Concentration
10,000,000
100,000
10,000
1,000,000
1
1000
LargeFish
Small Fish
Zooplankton
Producers
Water
Biodiversity (continued)
• Conservation efforts focus on protection of entire ecosystems as well as single species. This will ensure that the natural habitats and the interactions are preserved.
Charting a Course for the Future
• 2 major concerns: Thinning/Depletion of Ozone and Global Warming– Ozone Depletion – Ozone absorbs UV radiation –
“hole” in ozone layer = damaging UV radiation. Must limit CFCs which destroy ozone
– Global Warming – human activities vs. natural variations in climate (not sure which is the cause…must study more with models)
• Value of a Healthy Biosphere- recycle, energy conservation – will help maintain a healthy biosphere