2 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 gatheringAgriculture – 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 rapidlyUrban development – spread of suburban communities to new landsAll of this activity by humans has affected ecosystems
3 Renewable and Non-renewable Resources Renewable – can regenerate and are replaceable, but not necessarily unlimitedNon-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.
4 Renewable Resources There are several renewable resources available: LandForestOceanAirWater
5 Renewable Resources (continued) Land Resources – soil – should be renewable if managed properly – plowing leads to increased rate of soil erosion – leads to desertification
6 Renewable Resources (continued) Forest Resources – lumber – should be renewable – selective cutting vs. clear cutting – deforestation = erosion
7 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
8 Renewable Resources (continued) Air Resources – air pollution – smog – asthma – acid rain, ozone depletion, global warming – all affect air as a renewable resource
9 Renewable Resources (continued) Water Resources – industrial pollution, domestic pollution, groundwater contaminationNeed to protect water supply to keep it as a renewable resource
10 Biodiversity* Biodiversity is the sum total of the genetically based variety of all organisms in the biosphereThree divisions of biodiversityEcosystem diversitySpecies diversityGenetic diversity
12 Species DiversitySpecies Diversity – number of different species in biosphereInsects54.4%ProtistsOther Animals4.2%19.7%Plants18%BacteriaFungi0.3%3.4%
13 Genetic DiversityGenetic Diversity – sum total of all the different forms of genetic information carried by all organisms
14 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/ecosystemsDevelopment of land = habitat fragmentation (split ecosystem into pieces) – less species can live herePollution - DDT – biological magnification – concentrations of a harmful substance increases in organisms at higher trophic levels – can destroy food webs/ecosystemsIntroduced species – invasive species – transported/not native – crowd out native species, often killing native species
16 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.
17 Charting a Course for the Future 2 major concerns: Thinning/Depletion of Ozone and Global WarmingOzone Depletion – Ozone absorbs UV radiation – “hole” in ozone layer = damaging UV radiation. Must limit CFCs which destroy ozoneGlobal 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