Woodiness and succulence of the Canary Islands flora

Occurrence data: We used occurrence data from the Banco de Datos de Biodiversidad de Canarias, an open-access database, for single-island endemic (SIE; n = 325), archipelago endemic (AE; n = 234) and definitely non-endemic native (NEN; n = 149) extant seed plant species (excluding subspecies), in a raster of 500 m x 500 m grid cells covering the Canary Islands (https://www.biodiversidadcanarias.es/biota/) [accessed 14/03/2022]. The database includes all species listed in the checklist of the Banco de Datos de Biodiversidad de Canarias, across 31,628 grid cell assemblages. Species range in occurrence from 1 to 4,466 cells. We only retrieved occurrences for which a species has been certainly observed or collected (precision level 1 of four levels). The Banco de Datos de Biodiversidad de Canarias provides presence-only information that is spatially biased by sampling effort (Hortal et al., 2007). However, the sampling bias of SIEs, AEs, and NENs is less than for species overall because studies incorporated into the database involved focus on, and extensive sampling of, endemic and non-endemic native species (https://www.biodiversidadcanarias.es/biota/documentos). We considered a species (pseudo-)absent if it was not recorded at a site, although we recognise that there is debate as to whether this truly represents absences. Functional strategies: We collected data on insular woodiness and succulence, which are relevant for species’ responses to changing climatic conditions. As insular woodiness can be challenging to distinguish from non-insular woodiness (ancestral and derived woodiness) and herbaceousness, we mostly referred to literature sources from extensive studies on the woodiness of Canary Island plants (Hooft van Huysduynen et al., 2021; Lens, Davin, et al., 2013; Zizka et al., 2022). We defined plants as succulent if they displayed thickened leaves or fleshy stems. The thickness or fleshiness of plant organs indicates their ability to store water in their tissue (including moderately succulent species such as Rumex lunaria). We retrieved information on succulence from Muer et al. (2016) and taxonomic monographs, which have been shown to be reliable sources for trait data (Cutts et al., 2021).