“…Remarkably, a negative growth rate of the stem diameter was observed in the most declining stands (Cluster 1); this peculiar datum derives from the fact that, during the vegetative season, the new shoots are smaller than the previous ones and the average value decreases in time, as suggested by Engloner [53]. Similar trends were also observed by other authors, who described a decrease in the shoot diameter or height during the vegetative period in declining populations of Phragmites australis [30,[54][55][56][57][58].…”