Humans in the Biosphere

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: –L–Land –F–Forest –O–Ocean –A–Air –W–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 –Genetic diversity –Species diversity –Ecosystem diversity

Genetic Diversity Genetic Diversity – sum total of all the different forms of genetic information carried by all organisms The genetic diversity within populations of a species is the raw material that makes microevolution and adaptation to the environment possible. Genetic resources for that species are lost if local populations are lost and/or the number of individuals in a species declines.

Species Diversity Species Diversity – number of different species in biosphere Ecologists believe that we are pushing species toward extinction at an alarming rate. Insects Bacteria Fungi Plants Protists Other Animals 54.4% 4.2% 18% 3.4% 0.3% 19.7%

Ecosystem Diversity Ecosystem Diversity – variety of habitats, communities, ecological processes –The local extinction of one species can have a negative effect on the entire ecosystem. –The disappearance of natural ecosystems results in the loss of ecosystem services, functions performed by an ecosystem that directly or indirectly benefit people, including air and water purification, climate regulation, and erosion control

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, introducing foreign species to new environments, hunting species to extinction, and introducing toxic compounds into food webs –Development of land/Habitat Destruction = habitat fragmentation (split ecosystem into pieces) – less species can live here –Introduced species – invasive species – transported/not native – crowd out native species, often killing native species –Extinction and endangered species (possibly due to over- hunting/overexploitation) – can destroy food webs/ecosystems –Pollution - DDT – biological magnification – concentrations of a harmful substance increases in organisms at higher trophic levels – can destroy food webs/ecosystems

Pollution Fish-Eating Birds Magnification of DDT Concentration 10,000, ,000 10,000 1,000, Large Fish Small Fish Zooplankton Producers Water

Charting a Course for the Future Concerns: Global Warming, Thinning/Depletion of Ozone, and Carbon Footprint –Global Warming – human activities vs. natural variations in climate (not sure which is the cause…must study more with models) –Ozone Depletion – Ozone absorbs UV radiation – “hole” in ozone layer = damaging UV radiation. Must limit CFCs which destroy ozone –Carbon Footprint - The amount of greenhouse gas emitted as the result of the actions of a single person We can reduce our carbon footprints by –Reducing our use of electricity, –driving less, and –recycling.

Charting a Course for the Future Value of a Healthy Biosphere - recycle, energy conservation – will help maintain a healthy biosphere 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.