All the revision notes you need to know for Ess topic 2.5. Well organised and has practice exam questions. Combined class notes with notes from a revision guide. Used for IB ESS exams.
MEASURING CHNAGES DUE TO A SPECIFIC HUMAN ACTIVITY
Human activities can change abiotic and biotic components of an ecosystem. Human impacts
include toxins from mining activity, landfills, eutrophication, effluent, oil spills and
overexploitation.
Techniques outlined in this section can be used to investigate ecosystems and to see how
human activities are affecting them.
CASE STUDY
Deforestation in the amazon:
Scientists are measuring the effects of human activity on the Amazon rainforest.
Logging is causing large areas of forest to be lost.
Deforestation is being carried out to provide timber, and to clear land for
agriculture and housing.
Remaining areas can become fragmented, forming islands of habitat.
Satellite photos can be used to monitor the amount of deforestation taking place:
This method is very reliable, can cover a large area, and monitors change over
time.
The visual impact of the photos is useful for motivating action against logging.
Abiotic and biotic factors can be measured:
These must be taken in both undisturbed and disturbed habitats so that
comparisons can be made.
Habitat islands of different sizes will have different environmental conditions,
and so a variety of different- sized patches must be measured.
Samples must be repeated so that data are reliable.
Abiotic factors can include the species of plants and animals present, and the
population sizes of selected indicator species.
Where environmental gradients are present, factors must be measured along
the full extent of the gradient so that valid comparisons can be made.
Factors must be measured over a long period of time to take into account daily
and seasonal variations.
Measurements should be represented to increase reliability of data. The number of
repetitions required depends on the factor being measured.
QUICK CHECK QUESTIONS
-Outline how human activities can change the abiotic and biotic components of an
ecosystems.
-Describe and evaluate methods for measuring changes in abiotic and biotic components of
an ecosystem due to a named specific human activity.
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