Analysis

• What is the aim of the investigation described?

  To investigate changes in sand dune characteristics
• What is Hypothesis 1 regarding soil pH?

  Soil pH decreases with distance from the shoreline
• What does the graph description indicate about the relationship between soil pH and distance?

  There is a negative relationship
• What was the soil pH at site 2, the youngest dunes?

  8.9
• What was the soil pH at site 12, the oldest dunes?

  6.7
• What anomaly was observed at site 5 regarding soil pH?

  pH value of 7.6 was higher than expected
• Why does soil pH decrease with increasing distance from the shoreline?

  Due to decreased seashells and increased humic acid
• What effect do seashells have on soil pH near the shoreline?

  They make the soils more alkaline
• How does the decomposition of DOM affect soil pH inland?

  It increases acidity due to humic acid
• What could explain the anomaly at site 5 regarding vegetation?

  Lower species number led to less litter
• What statistical method was used in the investigation?

  Spearman's rank correlation coefficient
• Why is statistical analysis important in fieldwork investigations?

  It helps prove or disprove the hypothesis
• What does a strong negative relationship indicate in this investigation?

  Soil pH decreases with distance from the shoreline
• What was the Spearman's rank correlation coefficient value found?

  -0.97
• What does the -0.97 value indicate about the hypothesis?

  It proves the hypothesis at the 99% significance level
• What is the critical value at the 99% significance level with 10 degrees of freedom?

  0.77
• What does the statistical significance indicate about the relationship between soil pH and distance?

  There is a strong negative relationship
• What are the key factors affecting soil pH as distance from the shoreline increases?

  • Decrease in seashells and CaCO3
  • Increase in humic acid from DOM decomposition
  • Variability in vegetation affecting litter and decay
• What are the steps involved in conducting a Spearman's rank correlation test?

  1. Rank the data sets for both variables
  2. Calculate the difference in ranks
  3. Square the differences
  4. Sum the squared differences
  5. Apply the Spearman's formula
  6. Determine significance level
• What conclusions can be drawn from the statistical analysis of the investigation?

  • Soil pH decreases with distance from the shoreline
  • Hypothesis is accepted at the 99% significance level
  • Anomaly at site 5 does not invalidate overall trend