Root trait variation at the plant community level: Linking
belowground trait diversity to vegetation dynamics and ecosystem
functioning
Ultimately, both inter- and intraspecific variation in root traits
characterize belowground strategies at the community level. In this
Special Issue, root trait patterns within plant communities (Table 1)
reiterate what is observed within and across species, namely, that
plants can display a wide variety of root trait strategies to carry out
their belowground functions. Pierick and collaborators (2022) study the
variation in root traits in tropical montane forests along an
altitudinal gradient in the Andes. In their case, although there were
weak trends towards more conservative root trait syndromes on high
altitudes with deteriorating soil conditions, all tropical forest
communities showed high within-community variance in root traits at each
altitude, confirming the importance of multiple strategies for resource
capture in tropical forests. In addition, Kotowska et al. (2022) present
compelling evidence that expected ecological trends in trait syndromes,
like the dominance of “acquisitive traits” in secondary succession,
were not supported after comparing mature and secondary forests in
Indonesia, despite the large productivity of the secondary forests.
Finally, Erktan and colleagues (2022) provide an in-depth view of root
diameter distributions, where most of the temperate plant communities
(including woody and non-woody species) they studied, showed a
multimodal distribution of root diameter reflecting the distinct
belowground strategies to exploit soil resources that exist within plant
communities.
Such belowground trait diversity may in turn explain vegetation
dynamics. Using a novel deep-learning approach to detect roots and
analyze root growth images from a rhizobox, Alonso-Crespo et al. (2022)
show that the vertical distribution of roots depended on which
functional group was arrived first within a plant community. This may in
turn determine competitive outcomes among plant species, and thus
determine the overall coexistence and exclusion of species within plant
communities. Furthermore, Schuster and co-workers (2022) find evidence
for belowground overyielding (i.e., greater root standing biomass and
root productivity in species’ mixtures compared to monocultures) in
temperate forest communities, especially among angiosperm trees. The
authors argue that such differences in belowground productivity may
occur due to the greater diversity in root systems in angiosperms
compared to gymnosperms, reflecting belowground resource partitioning,
and thereby link diversity in belowground strategies to an important
ecosystem function.