Managing native grasslands – Analysis
The figure below shows boxplots of yield in grams at the second harvest (n=16 for each boxplot).
John and Ian’s main interest was in the growth of the 12 different species of native flowers. There was great variety in the yields of the native flowers at the second harvest. Harvested yields for some species were very low because those species were dormant during the summer. However the mowing and nutrient treatments did influence yield for some species. The effects were different for different species of flowers. The treatments also had varying effects on the yield of the grasses.
Questions to consider
- Examine the boxplots shown above. Broadly, what kinds of analysis would you recommend for the various species?
- Choose a species for which there was variability in the dry weight. Provide a visual display to illustrate the variation in dry weights by treatment.
- Consider the assumptions required for analysing the Latin square design using a standard analysis of variance. For which species are these assumptions met? Produce a visual display to support your conclusions.
- Conduct a statistical analysis of the Latin square design (treatments, rows and columns) for one or more of the grass species. Write a brief summary of the results and include a visual display to illustrate the main findings.
- Investigate the effects of the mowing treatment and the nutrient treatment for native flower species that interests you. Write a brief summary of results and an explanation.
- Investigate the assumptions required for analysing the Latin square for three different species. What kind of strategies are appropriate in cases where the assumptions are not met? What kind of inferences can be made?
- For some species there is little variation in dry weight and only a small number of positive values observed. What kind of descriptive and inferential analyses would you consider for these species?
More about the study
Click on the play button to hear John’s impressions of the effects of nutrients.
Click on the play button to hear John’s impressions of the effects of mowing.