agriculture and biodiversity

• farmers try to maximise the amount of food they can produce from a given area of land - many methods they use reduce biodiversity
• • woodland clearance is done to increase the area of farmland
  • directly reduced the no. of trees and sometimes the no. of different tree species
  • destroys habitats - some species could lose their shelter and their food source
  • means that species will die or be forced to migrate to another suitable area - further reducing biodiversity
• • hedgerow removal is also done to increase the area of farmland by turning lots of small fields into fewer larger fields
  • reduces biodiversity for same reason as woodland clearance
• • pesticides are chemicals that kill organisms (pests) that feed on crops
  • reduces biodiversity by directly killing the pests
  • also any species that feed on the pests will lose a food source - their numbers could decrease too
• • herbicides are chemicals that kill unwanted plants (weeds)
  • reduces plant biodiversity and could reduce no. of organisms that feed on the weeds
• • monoculture is when farmers have fields containing only one type of plant
  • a single type of plant reduced biodiversity directly and will support fewer organisms (e.g. as a habitat or food source) - further reduces biodiversity
• agriculture is one way of producing the resources we need from the environment - we need to produce food and fibres for clothing, as well as some medicines and fuels
• biodiversity helps maintain the environment - provides us with new sources of food and medicines and benefits agriculture e.g. a wide variety of insects help to pollinate crops

  so there needs to be a balance between agriculture and biodiversity - conservationists try to achieve this through conservation schemes
• • giving legal protection to endangered species
  • creating protected areas such as SSSIs (sites of special scientific interest) and AONBs (areas of outstanding natural beauty) - these restrict further development, including agricultural development
  • The Environmental Stewardship Scheme encourages farmers to conserve biodiversity e.g. by replanting hedgerows and leaving margins around fields for wild flowers to grow
• if you need to work out whether there is a correlation between 2 variables/ how strongly 2 variables are correlated - calculate Spearman's rank correlation coefficient
• result of the test is between -1 and +1

  • if the figure is -1 = perfect negative correlation
  • +1 = perfect positive correlation
  • closer the figure is to 0 the weaker the correlation is
• null hypothesis - there is no correlation between the factors
• can reject the null if the calculated value is higher than the critical value
• if calculated value is negative - ignore the minus sign when comparing it to the critical value