Exploring species attributes and site characteristics to assess plant invasions in Spain

Abstract

Aim Biological invasions are a major component of global change with increasing effects on natural ecosystems and human societies. Here, we aim to assess the relationship between plant invader species attributes and the extent of their distribution range size, at the same time that we assess the association between environmental factors and plant invader species richness. Location Spain, Mediterranean region. Methods From the species perspective, we calculated the distribution range size of the 106 vascular plant invaders listed in a recently published atlas of alien plant species in Spain. Range size was used as an estimation of the degree of invasion success of the species. To model variation in range size between species as a function of a set of species attributes, we adopted the framework of the generalized linear mixed models because they allow the incorporation of taxonomic categories as nested random factors to control for phylogenetic relationships. From the invaded site perspective, we determined invader plant species richness as the number of species for each 10 × 10 km Universal Transverse Mercator (UTM) grid. For each grid cell, we estimated variables concerning landscape, topography, climate and human settlement. Then, we performed a generalized linear mixed model incorporating a defined spatial correlation structure to assess the relationship between plant invader richness and the environmental predictors. Results From the species perspective, wind dispersal and minimum residence time appeared to favour invasion success. From the invaded site perspective, we identified high anthropogenic disturbance, low altitude, short distance to the coastline and dry, hot weather as the main correlates to UTM grid cell invader richness. Main conclusions According to these results, an increasing importance of man‐modified ecosystems and global warming in the Mediterranean region should facilitate the expansion of plant invaders, especially wind‐dispersed species, leading to the accumulation of invasive species in some sites (i.e. invasion hot spots).

Alien plant species and factors of invasiveness of anthropogenic vegetation in the Northwestern Balkans — a phytosociological approach

“…However, this fact is strongly influenced by the scale of sampling units (vegetation plot, city, state) [6,14] and by the latitudinal and altitudinal gradient [12]. Many studies dealing with alien flora have mainly used grid data [41][42][43][44][45] and results are not comparable to the results of studies in which flora was sampled in habitat plots [6,14,16].…”

“…Gasso et al [44] designate these areas as hot spots of invasive plant richness. Our data of man-made habitats are from such areas and therefore show a similar level of invasion to those of the more temperate inland regions.…”

Spreading to a limit: the time required for a neophyte to reach its maximum range

“…They found times of 151, 177, 145 and 141 years for Ireland, Britain, Germany and the Czech Republic, respectively. It should perhaps be noted that this process can be modelled in various ways and that different models are needed for different species (Williamson et al, 2009b).Here we note that applying the same logit transformation used in Williamson et al (2009a) to the range sizes in Gassó et al (2009) gives a graph (Fig. 1) which shows unambiguously that neophytes in Spain, on average, reach a maximum range size at 143 years (the peak point in the loess line in Fig.…”

Plant invasions are context‐dependent: multiscale effects of climate, human activity and habitat

“…Presence of non-natives in coastal areas could also be enhanced by the increased propagule pressure associated with higher human influence in these regions (Gassó et al, 2009;González-Moreno et al, 2013b). Still, we already accounted by human activity by adding the land-cover variables and considered distance to the coast as a good proxy for low seasonality.…”

“…Human activity can also clearly affect patterns of invasion (Ibáñez et al, 2009a;Vilà & Ibáñez, 2011;González-Moreno et al, 2013b). For example, human land-covers types such as built-up areas or crops are highly associated with plant invasions due to the increased propagule pressure and disturbance that benefit non-natives establishment (Ohlemüller et al, 2006;Gassó et al, 2009;Gavier-Pizarro et al, 2010). In addition, the level of plant invasion has also been shown to vary among habitat types at a local scale (Vilà et al, 2007;Ibáñez et al, 2009a) with anthropogenic, mesic, and nutrient rich habitats being more invaded than natural, dry, and nutrient poor habitats (Chytrý et al, 2008b).…”