Canadian Forest Service Publications
Confidence regions for foliar nutrient analysis. Bernier-Cardou, M.; Thiffault, É., Morris, D.M. 2016. For. Sci. 62: 260-267.
Issued by: Laurentian Forestry Centre
Catalog ID: 36618
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The interpretation of foliar nutrient composition data through vector nutrient analysis to assess treatment effects such as those of fertilization has expanded in the forest sciences and related fields of research over the last few years. However, it rarely includes measures of variability that would allow formal statistical assessment of the true effect of treatments. We propose a mixed linear multilevel model for the analysis of unit leaf mass and nutrient concentrations from which all treatment effects on nutrient concentration and content can be estimated and assessed. It accounts for the correlation between leaf concentration and content of all nutrients. Confidence regions are developed from the model and drawn around the tips of the vectors to facilitate the interpretation of statistical tests of the treatment effects or vector positions. Adjustments for multiplicity are also considered. The procedure is illustrated with a case study from an experiment designed to investigate foliar nutrient response to two harvesting methods.
Plain Language Summary
In this study, the researchers suggest a statistical analysis method for foliage weight and foliage nutrient concentrations. The method makes it possible to compare treatments and evaluate their effects. It is illustrated by means of an example that evaluates the effect of two forest tree harvesting methods on the nitrogen and potassium levels in shoot foliage.
The analysis of nutrient concentration (e.g., nitrogen, phosphorus, potassium) in plant foliage is an important part of numerous research initiatives in every field relating to the study of plant growth.