Functional traits indicate faster resource acquisition for alien herbs than native shrubs in an urban Mediterranean shrubland

• Published in: Biological invasions 2020-09, Vol.22 (9), p.2699-2712
• Main Authors: Díaz de León Guerrero, Samantha D., González-Rebeles Guerrero, Georgina, Ibarra-Montes, Teresa M., Rodríguez Bastarrachea, Anaid, Santos Cobos, Ramiro, Bullock, Stephen H., Sack, Lawren, Méndez-Alonzo, Rodrigo
• Format: Article
• Language: English
• Subjects: Assimilation; Bark; Biomedical and Life Sciences; Carbon; Carbon dioxide; Conductance; Developmental Biology; Ecology; Ecosystems; Flowers & plants; Freshwater & Marine Ecology; Indigenous species; Introduced species; Invasive plants; Leaves; Life Sciences; Mesophyll; Native species; Nonnative species; Original Paper; Physiology; Plant Sciences; Population density; Resistance; Shrublands; Shrubs; Stems; Stomata; Stomatal conductance; Transpiration; Urban environments; Vessels; Water potential; Xylem
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-020-02290-w

In urban Mediterranean ecosystems, invasive alien plants should have characteristics that enable faster resource acquisition and utilization than native species. We tested this hypothesis by comparing stem and leaf functional traits from five abundant native woody shrubs and five of the most abundant alien species within an urban coastal scrub community in Ensenada, Baja California, México. Twelve anatomical and ecophysiological traits were studied: light-saturated CO 2 assimilation rate, stomatal conductance, stem and leaf water potentials during transpiration, % stem allocation to bark, xylem and pith, stem xylem vessel diameter and density, leaf size, and % allocation to spongy and palisade mesophyll. Alien species varied more in these traits, and their trait combinations reflected less investment in long-lived tissues; they had higher CO 2 assimilation and stomatal conductance rates, higher values of leaf and stem water potential, and higher allocation to pith, larger stem xylem vessels, and larger leaf areas. In contrast, native woody shrub species were relatively convergent in leaf and stem traits reflecting more conservative resource use. Within disturbed urban environments, alien species may outcompete the native stress-tolerant species through rapid resource acquisition, enhanced by a broader set of functional trait combinations across species.