Moreover, soil compaction also exerts some effects on root
anatomy. For instance, soil compaction was negatively related to
the proportion of xylem CSA dedicated to vessels and this was positively
related to xylem vessels diameter (Fig. 5, model 3). These
effects can be explained as a response to a water deficit situation
(Holste et al., 2006). These changes in root anatomy has
consequences on plant growth as the xylem vessel diameter was
positively correlated with total plant area and the latter with the
plant biomass (Fig. 5, model 3). According to Wahl and Ryser (2000)
and Hummel et al. (2007), xylem vessel diameter is closely related
to plant height (a proxy of plant biomass) in a wide spectrum of
herbaceous species, which can be associated with an important
aspect of the trade-offs between anatomical structures, and plant
growth.