Soil total phosphorus threshold in the Everglades: a Bayesian changepoint analysis for multinomial response data

The Everglades is a historically phosphorus limited freshwater wetland ecosystem. Increasing the supply of phosphorus will lead to changes in the ecosystem. As a cumulative indicator of phosphorus loading to the wetland system, the top 10 cm soil TP concentration is often used to indicate eutrophication. The current study used multivariate species composition data to find the TP threshold, above which species compositional changes are expected. A Bayesian changepoint model was developed in this study. The statistical model can directly use species assemblage data as a measure of structural change. Using diatom species and macroinvertebrate species assemblage data collected from the field as well as from a mesocosm experiment, the soil TP threshold was estimated to be around 400 mg/kg.