Leaf litter traits of invasive species slow down decomposition compared to Spanish natives: a broad phylogenetic comparison

Abstract

Leaf traits related to the performance of invasive alien species can inXuence nutrient cycling through litter decomposition. However, there is no consensus yet about whether there are consistent diVerences in functional leaf traits between invasive and native species that also manifest themselves through their “after life” eVects on litter decomposition. When addressing this question it is important to avoid confounding eVects of other plant traits related to early phylogenetic divergences and to understand the mechanism underlying the observed results to predict which invasive species will exert larger eVects on nutrient cycling. We compared initial leaf litter traits, and their eVect on decomposability as tested in standardized incubations, in 19 invasive-native pairs of co-familial species from Spain. They included 12 woody and seven herbaceous alien species representative of the Spanish invasive Xora. The predictive power of leaf litter decomposition rates followed the order: growth form > family > status (invasive vs. native) > leaf type. Within species pairs litter decomposition tended to be slower and more dependent on N and P in invaders than in natives. This diVerence was likely driven by the higher lignin content of invader leaves. Although our study has the limitation of not representing the natural conditions from each invaded community, it suggests a potential slowing down of the nutrient cycle at ecosystem scale upon invasion.