HUMANS IN THE BIOSPHERE

A Changing Landscape  Growing populations depend on the limited natural resources of earth for survival.  Humans rely on ecological life support systems to provide us with; clean air, water, and fertile soil.  Humans must be aware that our activities on earth have an impact on and can change our environment.

Human Activities that Impact Natural Resources  Hunting & Gathering:  Human hunting and gathering causes mass extinction of animals  Agriculture:  Farming destroyed many forests to make farm land. (decrease in oxygen, increase in carbon dioxide).  Fertilizers & pesticides contaminate water supplies  Irrigation strains water supply  Food supply demand puts strain on environment( soil nutrients).  Industrial Growth & Urban Development:  Makes life easier and more productive  Causes pollution (Acid rain).

Renewable & Nonrenewable Resources  Renewable Resource: Resource that can regenerate or be replenished quickly by the earth.  Not unlimited  Example; Water  Nonrenewable Resource: Cannot be replenished by the earth.  Example; Fossil fuels  Sustainable Development: Using natural resources without depleting them and still providing for human need as well as, without causing environmental harm.  Example: Using lady bugs to eat insects that eat crops instead of using insecticides/pesticides.

Human Impact on Renewable Resources  Land Resources: Space for construction, over farming/over grazing.  Soil Erosion- wearing away of surface soil by air & water.  Desertification-turning farmlands into deserts.  Forest Resources: Wood supplies for building and heat, oxygen, habitats, food.  Deforestation-loss of forest that can’t re-grow.  Fishery Resources: Food supply, over fishing.  Aquaculture- Raise aquatic animals for human consumption.  Air Resources: Air quality, pollution, burning of fossil fuels, smog, acid rain.  Freshwater Resources: Only 3 % of water on earth is freshwater, very limited resources.

The Value of Biodiversity  Biodiversity- The sum total of the variety of organisms in the biosphere.  Ecosystem Diversity- Variety of habitats, living communities, and ecological processes in the living world.  Species Diversity- Number and variations of different species in the biosphere.  Genetic Diversity- Sum total of all the different forms of genetic information carried by all organisms living on earth today.  The diversity of life and the diversity of the environments that they live in are good indicators of the heath of a species or ecosystem.  Increased diversity is critical to maintaining balance in ecosystems and the biosphere as a whole.  Biodiversity is very important and provided us with many things like food, medicine, etc.

Threats to Biodiversity  Extinction- The disappearance of a species from existence in all parts of its geological range.  Endangered Species- A species whose population size is rapidly declining and will become extinct if the trend continues.  Maintaining biodiversity is key to maintaining a stable environment.  A variety of human activities has and will continue to push species to become endangered and even to the brink of extinction.  As endangered species populations decrease so does genetic diversity.

Habitat Alteration  Habitat Fragmentation- The splitting of an ecosystem into smaller sections of fragments of the original ecosystem. Can lead to the destruction of ecosystems and the extinction of species.  Natural habitats destroyed  Species vanish  Ecosystems split (biological islands): a patch of one habitat surrounded by another very different habitat.

Pollution  Biological Magnification- The increase in the concentration of a harmful substance in organisms at higher trophic levels in a food chain or food web.  Impacts the entire food web or food chain but has the most significant impact on the highest level carnivores. (increase in toxin levels as consumers consume food it multiplies the concentration levels of the toxins as the energy flows through the ecosystem).  Affects food wed Example DDT

Introduced Species  Invasive Species- Plants or animals that have migrated or been moved from their native environment to a habitat that they are not native to.  Reproduce rapidly (lack of natural predator).  Causes major ecological damage to the habitat they invaded and harm native species.  Can be devastating to an ecosystem and require significant changes to prevent the destruction of the ecosystem or the extinction of specific species.

Conserving Biodiversity  Conservation- The management of natural resources, including the preservation of habitats and wildlife.  Captive Breeding Programs- The raising of animals in captive but protected environments until they can be reintroduced and released into their natural wild habitat.

Charting a Course for the Future  Ozone Depletion:  Ozone Layer: high concentration of ozone gas in the earths atmosphere. Absorbs UV radiation (sunscreen for the earth).  Ozone Depletion: the breakdown of the ozone layer. Caused by CFC’s (chloroflurocarbons). CFC’s mostly banned today. Scientists predict that damage done to the ozone by CFC’s should be repaired within 50yrs.  Global Warming: Increase in the average temperature of the biosphere.  Caused by humans; Burning of fossil fuels, deforestation, landfills, fertilizers.