Biology - Ecology

• introduced species


  any organism that was brought to an ecosystem as the result of human actions-threaten the stability of ecosystems; are better competitors or are predators of native species-cause tremendous damage to the environmentex. fire ants, kudzu, zebra mussels, purple loosestrife, burmese pythons
• habitat fragmentation


  when a barrier prevents an organism from accessing its entire home range
• habitat destruction


  loss of habitat eliminates species
• threats to biodiversity

  -loss of habitat and pollution affect animal and plant populations-loss of biodiversity can reduce an ecosystem's stability and make it more difficult for the ecosystem to handle future change-biodiversity is highest in rainforests in the world, which are being deforested
• biomagnification


  -causes accumulation of toxins in an individuals' bodies in the food chain-process in which pollutants move up the food chain as predators eat prey, accumulating in higher concentration in the bodies of predators, with the most serious effect in the bodies of the top predators
• indicator species/bioindicators


  typically the first organisms in an ecosystem to be affected by pollution
• eutrophication


  process resulting from pollution of water from runoff, especially from fertilizers, that causes algae blooms, fish kills, and finally the filling of the body of water with debris and sediment
• water pollution


  affects ecosystems eutrophication
• greenhouse gases

  CO2, H2O, CH4 - absorb heat energy in the atmosphere
• greenhouse effect


  occurs when carbon dioxide, water, and methane molecules trap energy in the Earth's atmosphere, which allows for a stable temperature so life can exist
• air pollution


  -earth's atmosphere has naturally occurring cycles of high and low levels of carbon dioxide-high levels of CO2 correspond with high atmospheric temperatures; low levels with lower temperature
• acid rain


  precipitation produced when pollutants in the water cycle cause rain pH to drop below normal levels-pollutants released from factories, cars, power plants, etc.-pH of 5.6 or lower affects organisms in lakes and streams by decreasing pH of the water-causes a decline in growth rates of organisms likes trees, and leaves trees vulnerable to disease and harsh weather-destroys rock by increasing weathering
• smog and ozone


  fossil fuels produce the most common pollutants in our air
• pollution


  any undesirable factor, or pollutant, that is added to the air, water, or soil; especially synthetic chemicals and materials added to the earth that cannot be integrated into normal ecosystem functions
• footprint size depends on

  amount and efficiency of resource useamount and toxicity of waste produced
• ecological footprint


  the amount of land necessary to produce and maintain enough food and water, shelter, energy and waste for the population. the larger the footprint, the more negative the impact is on the ecosystem
• renewable resources


  a resource that can be replace at the same rate it is usedex. wind, solar, water
• nonrenewable resources


  a resource that is used faster than it can be reformedex. oil, coal, natural gas
• secondary succession


  re-establishment of a damaged ecosystem in an area where the soil is exposed

  
• pioneer species

  typically lichens and some mosses; first organisms that live in an uninhabited area on bare rock
• primary succession


  establishment and development of an ecosystem in an area that was previously uninhabited

  
• succession


  sequence of biotic changes in a community
• limiting factor


  the characteristic or resource that has the greatest effect in limiting the size of a populationex. competition, predation, parasitism, disease, unusual weather, natural disasters, human activities
• population crash


  dramatic decline in the size of a population over a short period of time
• carrying capacity


  maximum number of individuals of a particular species that the environment can normally and consistently support
• logistic growth


  s-curve; occurs when a population begins with slow growth, followed by a period of rapid growth, before leveling off at a stable size
• exponential growth


  J-curve; occurs when a population size increases dramatically over a period of time-may occur when a species is introduced into an uninhabited area-typical of bacteria and small animals
• factors affecting population size

  immigration - individuals coming into a populationbirths - individuals being born into a populationemigration - individuals going out of a populationdeaths - individuals being removed from the population through death
• population growth patterns

  population size changes, increasing, decreasing, or staying fairly constant
• random population dispersion


  individuals are spread randomly

  
• uniform population dispersion

  individuals live specific distances from each other; results from territoriality and competition

  
• clumped population dispersion

  individuals live close together in groups; facilitates mating, protection, and access to food and other resources

  
• population dispersion


  the way in which individuals of a population are spread in an area
• population density


  -number of individuals that live in a defined area-important measure of the health of a species in an area-fluctuations indicate that changes need to be made to keep the population healthy
• natural disruptions of the nitrogen cycle

  volcanic eruptions that release carbon dioxide and nitrogen gases that overload normal cycle
• human disruption of the nitrogen cycle

  -poor farming practices-planting too many legume crops that carry nitrogen fixing bacteria on their root nodules
• denitrification


  converting nitrates into nitrogen gas
• nitrification


  converting ammonia into nitrates
• ammonification


  produced by bacteria during decomposition or decay processes
• decomposition


  break down of organisms and return the nitrogen to the soil so plants can take it up again