Contrasting patterns of intraspecific trait variability in native and non-native plant species along an elevational gradient on Tenerife, Canary Islands

• Published in: Annals of botany Vol. 127; no. 4; pp. 565 - 576
• Main Authors: Kühn, Paul, Ratier Backes, Amanda, Römermann, Christine, Bruelheide, Helge, Haider, Sylvia
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 24.03.2021
• Subjects: Original; Phenotype; Plant Leaves; Plants - genetics; Spain; Spain; functional diversity; near-infrared spectroscopy; altitudinal gradient; elevation gradient; invasion success; exotic; phenotypic plasticity; forbs; plant functional traits; alien; Intraspecific trait variation
• ISSN: 0305-7364; 1095-8290
• DOI: 10.1093/aob/mcaa067

Non-native plant species are not restricted to lowlands, but increasingly are invading high elevations. While for both native and non-native species we expected variability of plant functional traits due to the changing environmental conditions along elevational gradients, we additionally assumed that non-native species are characterized by a more acquisitive growth strategy, as traits reflecting such a strategy have been found to correlate with invasion success. Furthermore, the typical lowland introduction of non-native species coming from multiple origins should lead to higher trait variability within populations of non-native species specifically at low elevations, and they might therefore occupy a larger total trait space. Along an elevational gradient ranging from 55 to 1925 m a.s.l. on Tenerife, we collected leaves from eight replicate individuals in eight evenly distributed populations of five native and six non-native forb species. In each population, we measured ten eco-morphological and leaf biochemical traits and calculated trait variability within each population and the total trait space occupied by native and non-native species. We found both positive (e.g. leaf dry matter content) and negative (e.g. leaf N) correlations with elevation for native species, but only few responses for non-native species. For non-native species, within-population variability of leaf dry matter content and specific leaf area decreased with elevation, but increased for native species. The total trait space occupied by all non-native species was smaller than and a subset of that of native species. We found little evidence that intraspecific trait variability is associated with the success of non-native species to spread towards higher elevations. Instead, for non-native species, our results indicate that intermediate trait values that meet the requirements of various conditions are favourable across the changing environmental conditions along elevational gradients. As a consequence, this might prevent non-native species from overcoming abruptly changing environmental conditions, such as when crossing the treeline.