Exploring Temporal Trends of Plant Invasion in Mediterranean Coastal Dunes

Silvia Cascone,Alicia Teresa Rosario Acosta,Marta Gaia Sperandii,Luigi Cao Pinna,Flavio Marzialetti,Maria Laura Carranza

doi:10.3390/su132413946

Silvia Cascone, Alicia Teresa Rosario Acosta + Show 4 more

Open Access

https://doi.org/10.3390/su132413946

Copy DOI

Abstract

Alien plants represent a significant threat to species diversity and composition in natural habitats. Nevertheless, little is known about the dynamic of the invasion process and how its effects on native species change over time. In this study, we explored vegetation changes that occurred in invaded coastal dune habitats over the last 10–15 years (2005–2020), particularly addressing impacts on alien and diagnostic species. To monitor temporal trends, we used data resulting from a revisitation study. After detecting overall changes in alien species occurrence and cover over time, 127 total plots were grouped into plots experiencing colonization, loss, or persistence of alien species. For these three categories, we compared historical and resurveyed plots to quantify changes in native species composition (using the Jaccard dissimilarity index) and to measure variations in diagnostic species cover. The number of alien species doubled over time (from 6 to 12) and two species, Yucca gloriosa and Agave americana, strongly increased their cover (+5.3% and +11.4%, respectively). Furthermore, plots newly invaded appeared to record the greatest changes in both native and diagnostic species. Our results suggest the need for regular monitoring actions to better understand invasion processes over time and to implement effective management strategies in invaded coastal dune habitats.

Highlights

All the six alien species recorded in the historical plots (Carpobrotus sp., Agave americana, Pittosporum tobira, Oenothera gr biennis, Xanthium orientale subsp. italicum, and Erigeron canadensis) were still present during the resurvey; the number of alien species doubled in the revisited plots
As coastal dunes are highly dynamic systems, revisitation studies allow the detection of significant temporal changes in their plant communities [45,49]
This study revealed an increase in the number of alien species, as well as different impacts on native and diagnostic species, related to diverse temporal trends of invasion

Summary

Introduction

Biological invasion is recognized as an important source of disturbance that threatens biodiversity conservation worldwide [1,2]. The introduction and spread of alien species are strongly connected with the presence of human activities [3,4]. As a matter of fact, the human-related weakening of biogeographic barriers to species dispersal and the acceleration of disturbances have promoted, over the last decades, a considerable expansion of alien species in natural ecosystems (e.g., higher numbers of species covering wider areas) [4,5]. Alien plants that have established self-sustained populations, overcoming abiotic and biotic barriers, can cause severe environmental changes [6,7,8] and impact socio-economic assets with consistent economic losses [9]

Methods

Results

Conclusion