Statistical Analyses
Whole plot average plant biomass, foliar P concentration and N:P ratio
were calculated using a weighting factor for each species, which was
estimated by determining the average basal diameter of each species from
2013 to 2019. Foliar N concentrations were originally presented in Lie
et al., (2021). Plant P uptake was estimated by the weighted sum of P
accumulated by the four species (data from Wu et al., 2020). Plant P
resorption efficiency was calculated as (1 –
Pl/Pf × MLCF) × 100%, where
Pl is litter P concentrations and Pf is
the weighted foliar P concentrations of the four species; MLCF is the
mass loss correction factor, which is 0.78 for evergreen broad-leaved
forest tree species (Vergutz et al., 2012).
Differences in P status in plant, soil and leachate, as well as soil
phosphatase activity and soil Fe
minerals under treatment were analyzed using linear mixed-effects model.
Warming treatment and experimental time were treated as fixed factors,
while plot was treated as a random factor. Pairwise comparisons of means
were tested by Least Significant Difference test. Data were transformed
to meet the assumptions of normality and homogeneity of variances when
necessary. Statistical significance was defined
as P < 0.05. Linear mixed models were performed
by “lmer” function in “lme4” package (Bates et al., 2015) using R
version 3.6.1.