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).