Different growth strategies to invade undisturbed plant communities by Acacia dealbata Link Jonatan Rodríguez a,⇑,1 , Paula Lorenzo b,1 , Luís González a a Plant Ecophysiology Group, Department of Plant Biology and Soil Science, University of Vigo, 36310 Vigo, Spain b Centre for Functional Ecology (CFE), Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal article info Article history: Received 13 February 2017 Accepted 6 May 2017 Keywords: Invasive plants Shrublands Pine forests Soil nutrients Photosynthetically active radiation Acacia dealbata abstract The leguminous Acacia dealbata is one of the most aggressive invasive tree species worldwide. The inva- sion process of A. dealbata is mainly favoured by environmental disturbances. However, this species is currently invading unaltered plant communities and environmental factors influencing its spread in these ecosystems remain unclear. In this study, we evaluated the A. dealbata growth related to environ- mental factors in non-altered shrublands and pine forests in North-Western of the Iberian Peninsula. Permanent sampling plots were placed along the invasion edge in each plant community and height and stem diameter increments were recorded on labelled A. dealbata individuals throughout two years. The number of new A. dealbata saplings was recorded at the end of the study. Environmental factors such as physicochemical soil properties, native vegetation cover and plot features were evaluated in each sam- pling plot in order to determinate their effect on the A. dealbata growth. Our results showed a different growth pattern of A. dealbata depending on the studied plant community. Pine forests had A. dealbata individuals with significantly higher height and diameter increments and higher number of new A. deal- bata individuals than shrublands. Additionally, results also showed a clear seasonality effect on A. deal- bata growth that was stimulated in spring in pine forests, while it did not variate along the year in shrublands. Regarding environmental parameters influencing the growth of A. dealbata, we found a neg- ative effect by the photosynthetically active radiation and plot orientation, but also a positive effect by soil potassium content and plot elevation. However, our results indicated that other environmental fac- tors not evaluated here might be also influencing. We conclude that A. dealbata can invade unaltered areas and the intensity of the invasion depends on the ecosystem. The natural shrubland could be an effective barrier to slow down the rapid invasion of A. dealbata. These results contribute to new knowl- edge of A. dealbata colonization without help of environmental disturbances in the field, which may help to define hot-priority areas and stablish new control strategies. Thus, we suggest that the management of A. dealbata in pine forests should receive preferential treatment on South-Western Europe. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction Invasive alien species are one of the most important direct threats to biodiversity (Butchart et al., 2010; Vilà et al., 2011). The continuing increase of human mobility around the world acts as a key factor in the processes of biological invasions, facilitating migration and colonization of species (van Kleunen et al., 2015). Considered globally, invasions by exotic trees are a pervasive com- ponent of the global change that severely impact on ecosystems they invade and are able to spread quickly worldwide (Richardson et al., 2013; Richardson and Rejmánek, 2011; Simberloff et al., 2013). Ecosystem transformations and homogene- ity caused by invasive species result in loss of native species and altered ecosystem processes and services fundamental to resident organisms including humans (Hierro et al., 2005; Pejchar and Mooney, 2009; Wardle et al., 2011). One of the most problematic exotic group worldwide consists of woody Australian acacias belonging to subgenus Phyllodineae (Lorenzo et al., 2010a; Lorenzo and Rodríguez-Echeverría, 2015; Richardson and Rejmánek, 2011). In fact, increasing literature reporting above and belowground impacts of these invaders has been released during the last years (e.g. Fuentes-Ramírez et al., 2011; Lorenzo et al., 2012; Rodríguez-Echeverría et al., 2013; Lazzaro et al., 2014; Aguilera et al., 2015a,b; Marchante et al., 2015; Guisande-Collazo et al., 2016). Among the invasive Australian acacias, Acacia dealbata Link is the third most widespread species of http://dx.doi.org/10.1016/j.foreco.2017.05.007 0378-1127/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: jonatan@uvigo.es (J. Rodríguez). 1 Both authors contributed equally to this study. Forest Ecology and Management 399 (2017) 47–53 Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco