B6.1

• how can trends in ecology be spotted?

  by measuring the numbers and species of organisms in an ecosystem and how these change over time
• abundance

  the number of organisms of a particular species in a habitat
• distribution


  the geographical spread of a species
• sample method for animals: pooters

  suck on the mouthpiece to draw insects into the holding chamber. a filter stops organisms from entering the mouth
• sample method for animals: sweep nets


  sweep a large net through the air to catch flying nets or those in long grass
• sample method for animals: kick sampling


  kick a river bed/bank to disturb mud and vegetation. hold a net downstream to capture any organisms released into the flowing water
• sample method for animals: tree beating


  stretch a large white cloth under a tree/bush. shake or beat the tree to dislodge invertebrates which will fall into the cloth
• sample method for animals: pitfall traps?

  dig a hole in the ground, which crawling invertebrates such as beetles, spiders and slugs can fall into. cover the hole with a roof so that the trap doesn't fill with rain water
• types of identification keys for unknown organisms:

  1. branched key (spider key) - by answering yes or no for each question, you can determine an organism's identity
  2. numbered key - the correct answer to a question tells which question you need to answer next. After the series of questions, you will identify the unknown organisms
• how to estimate an animal population?

  capture organisms from a sample area and after marking them, release them back into the community. at a later date, recapture organisms in the original sample area. record the number of marked and unmarked individuals.
• equation for capture-recapture

  first sample size x second sample size

  ----------------------------------

  number of recaptured marked individuals
• random sampling

  when randomly sampling areas of plant populations, individuals are selected by chance. e.g. using a number generator to determine coordinates of where to place quadrat
• why do we need random sampling?

  prevents bias
• what is non random sampling?

  when you need to study how the distribution of organisms varies over a distance - these sample sare taken along line
• samples taken across a line

  transect
• why is biodiversity important?

  species are interconnected, so the removal of one species can affect others. for example, it could lead to a loss of another species food or shelter. biodiversity is essential for maintaining a balanced ecosystem
• deforestation

  the permanent removal of large areas of forest (for wood for buildings and fuel, as well as space for roads, buildings and agriculture)
• how does deforestation reduce biodiversity?

  reduces the number of trees and the number of supported animal species as their food source or home has been lost

  • this in turn can affect predator species
• what is ecotourism?

  ensures that tourism doesn't harm the natural environment or local communities

  • it supports conservation whilst allowing people to observe wildlife
  • tourists are often restricted to certain areas and are asked to keep to footpaths

  this ensures that animal breeding grounds arent disturbed or endangered plants trampled
• what do mayfly lava indicate?

  unpolluted (clean water)
• what do freshwater shrimp indicate?

  low pollution
• what do water louse indicate?

  high pollution
• what do sludgeworm indicate?

  very high pollution