*2.5. Data Analysis*

The datasets of meristematic and non-meristematic transplanted fragments were processed separately, accounting for the irregular shape of meristematic lobes and possible dimensional differences with non-meristematic ones. The non-parametric rank-sum Wilcoxon–Mann–Whitney test was used to test the significance of the differences in the pairwise comparisons between samples transplanted respectively in the logged and in the unlogged stand. A Principal Component Analysis (PCA) was used as an explorative unsupervised multivariate analysis to study the relationships among variables. Multiple linear regression models were applied to fit the relationship between the above-mentioned predictors (delta Chl, delta FV/FM and forest management) and the response variable 'growth rate'. Two models were performed accounting separately for meristematic and non-meristematic thallus fragments. Regarding each model, *R*2, adj*R*<sup>2</sup> and F statistics were considered.

The following variables were considered for data processing:

• Growth rate = (area TF − area T0) area T0 <sup>−</sup>1, where:

area TF: area of the transplanted thallus fragment at the end of the exposure. area T0: area of the transplanted thallus fragment at the beginning of the experiment.

• Delta fluo <sup>=</sup> [(FV/FM)TF <sup>−</sup> (FV/FM)T0)] (FV/FM)T0<sup>−</sup>1, where:

(FV/FM) TF: FV/FM of the transplanted thallus fragment at the end the exposure. (FV/FM) T0: FV/FM of the transplanted thallus fragment at the beginning of the experiment.

• Delta Chl <sup>=</sup> (ChlTF <sup>−</sup> ChlT0) Chl T0<sup>−</sup>1, where:

Chl TF: chlorophyll content of the transplanted thallus fragment at the final time of the exposure. Chl T0: chlorophyll content of the transplanted thallus fragment at the beginning of the experiment.

The R package *Stats* was used for all the analyses [61].
