Unraveling the clonal trait space: Beyond aboveground and fine-root traits

Plant trait variation is constrained by mechanical and energetic tradeoffs
as attested by the global spectrum of plant form and function and the
fine-root economics space for above- and belowground traits. However,
traits that are key for fitness maintenance in some plant groups, such as
clonal and bud bank traits, have not yet been integrated within the
frameworks provided by the aboveground and the fine-root economics space.
By using an extensive dataset encompassing aboveground, fine-root, clonal,
and bud bank traits of 2000 species of Central European herbs, we asked
whether clonal and bud bank traits correspond to the placement of species
in the aboveground or fine-root trait spaces. Perennial clonal and
non-clonal herbs show indistinct positioning within the aboveground and
fine-root trait spaces. This extends and reinforces previous fragmentary
evidence of weak correlations between clonal and bud bank traits and
aboveground trait dimensions. Additionally, we identify for the first time
a limited correlation between clonal and fine-root traits as well. This
disconnection suggests that clonal traits operate independently from other
trait spectra. For this reason, we introduce the concept of a “clonal
trait space” for clonal herbs. The first dimension of this space is
defined by bud bank size and the persistence of clonal connection,
reflecting a gradient of species specialisation for on-spot persistence
and tolerance to disturbance (persistence dimension). The second
dimension, defined by multiplication rate and lateral spread, reflects a
specialisation axis for clonal multiplication and horizontal size
dimension (clonal multiplication dimension). Clonal trait dimensions add
non-redundant information to the aboveground or fine-roots trait space.
Synthesis: We champion the integration of the persistence and clonal
multiplication dimensions from the “clonal trait space” into the
frameworks provided by the aboveground trait and the fine-root economics
spaces, thereby enhancing our comprehension of the multifaceted trait
strategies exhibited by plants.