Road Disturbance Shapes the Functional Composition of Native Plant Species but Not That of Non‐Natives in the Arid Andes

Abstract

Aims: Species assemblages in mountains are affected by variation in environmental conditions linked to elevation and anthropogenicdisturbance. How species respond to these factors may vary based on the species origin. We examined the functionalresponse of non-nativeand native assemblages and the relative contribution of intraspecific variation to road disturbance andelevation.Location: Cordón del Plata Provincial Park, Andes, Argentina.Methods: We used the functional ecology approach. We calculated community-weightedmeans (CWM) and functional divergenceof leaf area, SLA, LDMC, and plant height of natives and non-nativesin transects along elevation, at roadsides and 52 maway from the road. We used linear models to assess changes with elevation and disturbance and estimated the contribution ofintraspecific variability using variance partitioning.Results: Non-nativesshowed more acquisitive traits than natives. Non-nativesresponded only to elevation by lower stature andLDMC and higher SLA. For native species, road proximity was related to more acquisitive foliar traits, while community leafarea, SLA, and plant height varied with elevation. Species turnover explained most of the variability observed in the CWMs inboth species' origin. The contribution of intraspecific variability was greater in non-nativespecies.Conclusions: Human disturbance affects the functional composition of native species. In contrast, the community traits of non-nativesdid not differ between road edges and the interior plots, suggesting that they are not affected by disturbance. Therefore,it is critical to reduce propagule pressure because of the potential of roadside species to invade undisturbed sites.