Functional traits of alien plants across contrasting climatic and land‐use regimes: do aliens join the locals or try harder than them?

Abstract

Summary1. Two main views have been put forward to explain whether coexisting alien and resident plant species should show converging or diverging functional attributes. According to the 'try-harder' hypothesis, successful aliens should differ from resident species with traits that allow them to deal better with the local conditions than resident species. On the other hand, the 'join-the-locals' hypothesis stresses the importance of filtering by environmental factors and predicts strong functional trait similarities between alien and native species, especially among the dominants. 2. On the basis of a functional trait comparison between native and alien species of central-western Argentina across five contrasting ecosystems and four land-use regimes, we tested these hypotheses over a broad range of habitats. We built a data set with common measurement methods and biogeographical factors but strongly varying environmental conditions, ranging from mesic to extremely dry, and from nearly pristine to heavily disturbed. 3. When considering all species together, the main trend of variation in trait syndromes was between acquisitive (tender, large leaves, with high specific area) and conservative (tough, small leaves, with low specific area and low nutrient content). Although both native and alien species appeared to be well spread across the whole range of trait variation, woody alien species showed a significantly more acquisitive set of attributes (higher specific leaf area, larger and thinner leaves, lower wood density) than native species. No significant difference was detected between herbaceous alien and native species. These general trends were maintained under contrasting climatic and landuse conditions. 4. Synthesis. The patterns detected for herbaceous species were in line with the 'join-the-locals' hypothesis. In contrast, those found for woody species, with woody alien species showing more acquisitive attributes than native species in more resource-rich habitats, provide partial support for the 'try-harder' hypothesis. Overall, our findings reinforce the idea that a universal suit of attributes is unlikely to explain alien plant distribution. They also stress the need for caution when mixing major life-forms in comparative plant trait analysis.

Environmental tolerances of rare and common mangroves along light and salinity gradients

“…Rhizophora mangle was introduced to Hawaii in 1902, where it is now well established and vigorously expanding its local distribution (Krauss and Allen 2003;Chimner et al 2006), as is R. stylosa, which was introduced to two of the Society Islands of French Polynesia in about 1946 (Taylor 1979;Smith 1996). Several broadly comparative analyses have detected little or no difference between traits of invasive exotic species and common native species, including carbon capture strategy (Leishman et al 2010;Tecco et al 2010), growth response to nutrients, and survival in a competitive environment (Dawson et al 2012).…”

Interactions between seedlings of the invasive treeAilanthus altissimaand the native treeRobinia pseudoacaciaunder low nutrient conditions

“…Some researchers suggest that the superior competitive ability of invasive species over native species is closely related to more efficient resource acquisition or resource conservation (Tecco et al 2010;Gioria & Osborne 2014). A variety of invasive species have higher resource-use efficiency than native species, especially in low-resource environments (Funk & Vitousek 2007).…”

Plant traits across different habitats of the Italian Alps: a comparative analysis between native and alien species

“…While it is well known that the success of alien plants in new environments greatly depends on their functional attributes, and is often associated with traits related to physiology, biomass allocation, growth rate, size, and fitness (van Kleunen et al 2010;Ordonez et al 2010), to date only a few other studies have tested whether coexisting alien and native species show converging or diverging functional attributes (Tecco et al 2010). Two main hypotheses have been put forward in this respect.…”