Assembling a global dataset of liana functional traits and
climbing strategies
We built a dataset from peer-reviewed studies and published databases,
searching for studies that measure functional traits considered
important to explain plant form and function along a continuum of fast
acquisitive to slow, conservative species (Reich, 2014; Diaz et al.,
2015) in liana species. We restricted our analyses to traits having the
most information available at the species level:
individual leaf area (LA),
specific leaf area (SLA), maximum leaf photosynthetic capacity per area
(Amax), nitrogen foliar content per mass
(Nmass), wood density -(WD) and seed mass -(SM). We
focused on angiosperm woody species (lianas) as the traits analyzed may
vary significantly between woody and herbaceous species. Palm climbers
and monocot species, such as from the genera Smilax spp., were
not included in the analyses given that monocots have a different
ecophysiological behavior. In our study we adopted the liana definition
as proposed by Gerwing et al. (2006): “climbing plants that produce
true wood (xylem tissues derived from a vascular cambium) and that
germinate on the ground but lose their ability to support themselves as
they grow, so they have to rely on external physical support to ascend
to the canopy”. Therefore, we did not include species with a
classification of “hemiepiphyte”. However, we noticed that the
criterion of woodiness would exclude some genera of dicotyledons, such
as Passiflora , Ipomea and many Cucurbitaceae, which have
perennial fibrous stems but are abundant and important in many liana
inventories (Gentry, 1991; Gerwing et al., 2006). Thus, we have also
included those genera and respective families in our analyses. Species
present in more than one study and showing different classifications for
their climbing strategies were excluded to avoid uncertainties about
their true climbing mechanisms. If the liana climbing mechanism was not
informed in the original studies, we searched this information through a
thorough literature survey in the literature. We checked online sources
and databases (e.g., virtual herbaria, online floras) to ascribe the
climbing mechanism to all liana species we used in the analyses
(Appendix S1). We classified liana climbing mechanisms according to the
classification proposed by Sperotto et al. (2020) and we focused on the
comparison between the active and passive climbing mechanisms used by
lianas (see Box 1 for a complete explanation, Fig. 1 and Appendix S1 in
Support Information). We only included species identified at the
binomial level, to facilitate the name standardization of the species
among different datasets. Species names were matched against accepted
names in The Plant List using the “taxonstand” R package (Cayuela et
al., 2012). We also limited our search to studies reporting the traits
of adult plants growing in natural conditions and, therefore, we did not
include assembled data for seedlings and saplings, in addition to plants
growing in experimental conditions. In total, we assembled data from 42
studies encompassing 755 species of lianas, with information for at
least one of the above traits for each species (Appendix S1).