Yearly precipitation varied between treatments and growing seasons, and was incorporated into the models to determine their significance and effect size. We graphed precipitation in relation to growing seasons because treatments occurred during two years, and precipitation after treatment may have influenced outcomes. Untreated controls were randomly assigned one of the two treatment years, and are included in the growing seasons since treatment groups. Gray boxes indicate whether measurements were taken pre-treatment (0) or a number of growing seasons after treatment (1 to 11). Bold lines are the medians, and the boxes represent 50 % of the data. Outliers are dots and are the maximum value if present. When there are no outliers, the whiskers’ ends depict minimum and maximum values.