Drivers of Plant Invasion at Broad and Fine Scale in Short Temperate Streams

Abstract

Riparian ecosystems have been described as highly prone to alien plant invasions; thus, disentangling the contributing factors of the invasion process is of utmost importance to conserving and managing these valuable ecosystems. In this study we examined the drivers of riparian plant invasion in 16 Cantabrian river basins (northern Spain) ranging from 100 to ca. 1050 km2. A complete flora was determined for five randomly selected sites within those basins. One hundred and thirty alien plant species were found across the 80 sampling sites, representing 21% of the recorded total flora. At site scale, the level of plant invasion, measured as alien richness (AR) and relative alien richness (RAR), was assessed in relation to a set of explanatory variables by means of Generalised Linear Mixed Models. This level of invasion was influenced by environmental variables such as the thermicity index, the average riverbed width and the number of plant communities and by human‐related variables such as the distance to the nearest town and the proportion of surrounding urban land. At basin scale, industrialised river basins were more heavily invaded than non‐industrialised basins, and they both differed in their alien plant composition. Given that some of the alien species occurring in Cantabrian streams are specially abundant (Crocosmia x crocosmiiflora) and/or form very dense stands (Fallopia japonica, Paspalum distichum), future research should focus on the drivers that influence the presence and distribution of these species of special concern. Copyright © 2016 John Wiley & Sons, Ltd.

Alien plant invasions in European woodlands

“…Europe (e.g., Liendo, García-Mijangos, Campos, López-Muniain, & Biurrun, 2016;Schnitzer, Hale, & Alsum, 2007) and regions outside of Europe (Kalusová, Chytrý, Peet, & Wentworth, 2015;Parks et al, 2005). Although an increasing number of studies documented differences in the levels of invasion across habitats, the relative importance of individual mechanisms underlying the observed patterns, such as intrinsic vulnerability (invasibility) and human activities (e.g., proximity to gardens, habitat fragmentation, management practices), is not well understood (but see Conedera, Wohlgemuth, Tanadini & Pezzatti 2017;Chytrý, Jarošik et al, 2008).…”

“…The high percentage of alien therophytes in this habitat type (33%) supports the importance of transient competition-free bare places, that is empty niches for alien plant establishment. In addition, extrinsic factors such as human disturbance could also explain the high levels of invasion in riparian woodlands (Liendo et al, 2016). Riparian habitats are highly degraded worldwide due to damming, canalization, drainage, dredging and straightening (Naiman, Decamps, & McClain, 2010) and were exposed to a high total emission of nitrogen and phosphorous in the last century (ICPDR, 2005).…”

Diversity and environmental variability of riparian tall herb fringe communities of the order Convolvuletalia sepium in Polish river valleys

“…Agricultural intensification and urbanization are among the most important land-use drivers affecting the incidence of alien invasive species [199]. A higher invasion level at sites subjected to a high level of anthropogenic pressure was also reported by Lambdon et al [200], Liendo et al [194,201], and Myśliwy [202].…”

“…In addition, valleys of large rivers are often anthropogenically transformed and deforested, hence they receive a higher supply of diaspores of alien species. The riverbed width, directly related to the size of the river, also emerged as an important predictor of the level of plant invasion in the study of Liendo et al [194]. The distribution patterns of alien plants shown by Planty-Tabacchi et al [195] and confirmed by studies of Truscott et al [196], point to a longitudinal trend along the river, whereby the number of aliens, relatively low in headwaters, increases consistently down river.…”

Nuevas aportaciones a la flora alóctona y nativa en hábitats riparios de la Cuenca Cantábrica (Norte de España)

“…Additionally, summer low water period is shorterandlessintenseinCantabrianstreams as a result of a higher summer rainfall. Riparian and adjacent habitats of the Cantabrianwatershedhavebeenintenselydisturbedinthelastdecadesas aresultofhuman population increase and related anthropogenicactivities,suchasagriculture,industrial development, urbanisation, and the developmentofanincreasinglydensetransportnetworkwhich,coupledwiththebenign climate, has resulted in many different alien plant species establishing in these habitats (Campos,2010;Liendo& al.,2016).…”