Humans and the Biosphere/Populations Humans and the biosphere Can result in species extinction Can result in · Biodiversity = The sum total of all endangered species organisms in the biosphere. The splitting of ecosystems by developing Habitat fragmentation lands Threats to biodiversity Biological Over hunting magnification = Human activities concentrations of a harmful substance increase at higher trophic levels in a food chain or Pollution Example: DDT food web. Invasive species A pesticide Resulted in a A foreign species, without sever drop in the Reproduces rapidly any natural predators, bald eagle population introduce into an and negatively affects the environment. ecosystem. Humans and the Biosphere/Populations 1 Humans and the Biosphere/Populations Renewable resources= Humans and can be replenished (ex. the biosphere trees, grass, water) Sustainable development = A way of using natural resources without depleting them and of providing for human needs Non-renewable resources= without causing long term cannot be replenished (oil, coal environmental harm. natural gas) Topsoil=the nutrient rich upper Land resource layer of soil Resources threats Erosion=the wearing away of the surface soil by water Forest resource and wind threats Fishery resource Desertification=Land turns into Due to farming, threats Deforestation=loss of the forest barren desert overgrazing, drought Overfishing=harvesting Leads to erosion fish faster than they are able to reproduce Humans and the Biosphere/Populations 2 Humans and the Biosphere/Populations Pollutant = harmful material that can enter Humans and the biosphere through the land, air or water. the biosphere Air resource Smog = mixture of pollutants that occur threats as a gray-brown haze in the atmosphere. Acid rain=Nitrogen and Sulfur combine with Freshwater water vapor to form nitric resource threats and sulfuric acid Pollution The fish and shellfish Sewage and fertilizer die runoff increase the nitrogen and phosphorus in lakes, river and oceans All of the oxygen is used up by the bacteria Can lead to Eutrophication The algae die Promotes the overgrowth and aerobic bacteria of algae decompose the algae Humans and the Biosphere/Populations 3 Humans and the Biosphere/Populations Humans and The burning of the biosphere Global warming-An increase fossil fuels and the in the average temperature cutting down and burning of the biosphere of forests has led to an increase in carbon dioxide in the atmosphere Ozone layer The increase in carbon dioxide has resulted in more heat being trapped Ozone gas in the High levels of UV upper atmosphere in the atmosphere due radiation can damage to the greenhouse effect protects life from life on earth ultraviolet radiation As a result Chlorofluorocarbons (CFCs) CFCs were used as a the global temperature damage the ozone layer. propellant in aerosol cans and has increased as a refrigerant in refrigerators High levels of CFCs has led to a hole in the ozone layer · Melting polar ice above the arctic · Sea levels may rise and flood coastal areas. · More droughts during the summer. · Organisms may not be able to survive Today most uses of CFCs are the climate change. banned Humans and the Biosphere/Populations 4 Humans and the Biosphere/Populations · Geographic distribution = Populations Characteristics of Area inhabited by a population. · Population density = number Birth a population of individuals per unit area. · Growth rate Deaths Factors that number of affect population individuals Logistic growth=Growth of a growth Growth patterns population slows or stops Immigration = the movement of individuals into an area. · Birthrate decreases Emigration=the Exponential growth=individuals · Death rate increases movement of in a population reproduce at a Follows a period of · Birth rate and death rate equal each individuals constant rate exponential growth other out of an area · Rate of immigration decreases · Rate of emigration increases Carrying capacity=The largest number of individuals that an environment can support Humans and the Biosphere/Populations 5 Humans and the Biosphere/Populations Competition for Populations resources Factors which Density-dependent become limiting limiting factors when the population density Predator-prey reaches a certain level relationships Limits to population growth Parasites and disease Density-independent Unusual weather limiting factors Factors which affect the Human population population regardless growth of the population size natural disasters Human activities Demography=the scientific study of human populations People begin to have Advances in nutrition, fewer children. This is medicine and sanitation called the demographic lowers the death rate transition The birth rate falls The population increases and population growth slows rapidly at this time Humans and the Biosphere/Populations 6.