The MARA (Monitoring Alien species along mountain Roads in the central Apennines) database was developed to monitor the distribution of vascular plant species along mountain roads in the Central Apennines, Italy, focusing on alien (i.e. neophytes) and thermophilous plant species. Data were gathered in 2022 from 118 plots spanning an elevation range from 420 to 2125 meters a.s.l. along 3 main road corridors on three massifs (Gran Sasso, Maiella and Terminillo), following the MIREN road survey protocol. The database comprises 810 taxa (species and subspecies), of which 16 are identified as alien taxa. Major plant families in frequency are Asteraceae, Poaceae, and Fabaceae. MARA captures detailed information on species cover, taxonomy, and ecological traits, such as life forms and Ecological Indicator Values for Europe (EIVE) related to temperature. Notably, 53% of the alien species recorded were thermophilous, thriving in warmer environments, and predominantly concentrated below 1200 meters, though a few species extend to higher elevations. This suggests that rising temperatures due to climate change may facilitate the upward movement of these species, potentially disrupting native vegetation. For such reasons, the MARA database is a valuable resource for long-term ecological monitoring, providing valuable data for both national and international research networks.

Alien taxa, MIREN sampling method, thermophilous taxa, vegetation database

Mountain ecosystems are recognized for their ecological significance and biodiversity richness, characterized by steep environmental gradients that create distinct vegetation zones (Theurillat et al. 2007; Lazarina et al. 2019; Di Biase et al. 2021). The Central Apennines in Italy, including the Gran Sasso and Monti della Laga National Park, Maiella National Park, and Mount Terminillo, are renowned for their unique topography, geological formations (Cosentino et al. 2010), and vascular flora richness (Ciaschetti et al. 2015; Conti and Bartolucci 2016; Piacentini et al. 2017; Conti et al. 2019, 2022). These areas serve as natural laboratories for studying changes in vegetation composition with elevation and the effects of global change on mountain habitats (Barni et al. 2012; Frate et al. 2018; Vitali et al. 2018; Guarino et al. 2021). Nowadays, alien taxa are becoming an emergent threat also in mountain zones around the world, even in high elevation protected areas and in isolated mountain landscapes (McDougall et al. 2011; Alexander et al. 2016; Pauchard et al. 2016; Pathak et al. 2019; Pyšek et al. 2020; Canavan et al. 2021). In this context, mountain roads often facilitate the movement of alien plant species and contribute to habitat fragmentation (Forman and Alexander 1998; Haider et al. 2018; McDougall et al. 2018). Previous research has highlighted the role of roads in altering native species composition and introducing disturbance-adapted taxa, which can lead to shifts in ecosystem dynamics, especially in sensitive high-elevation environments (Alexander et al. 2009; Okimura et al. 2016; Follak et al. 2018; Lázaro-Lobo and Ervin 2019; Corcos et al. 2020; Barros et al. 2022; Dostálek and Frantík 2024; Santoianni et al. 2024).

In the summer of 2022, the first Italian and Mediterranean site of the Mountain Invasion Research Network (MIREN) (Kueffer et al. 2014; Haider et al. 2022) was established in the Central Apennines. MIREN aims to understand the effects of global changes on species distribution and biodiversity in mountainous regions. Its scope is to study mountain species (re)distribution broadly, considering various drivers of global change, including biological invasions, climate change, and land-use change. In this context, monitoring alien (i.e. neophytes) and thermophilous species is particularly important to evaluate future scenarios for alien plant species and the upward shift of thermophilous plants (Dostálek and Frantík 2024). This phenomenon, known as the thermophilization of mountains, could have significant implications for biodiversity and ecological balance in mountain environments that are sensitive to climate change (Gottfried et al. 2012; Sekar et al. 2024). In this context, a database can support biodiversity management and protection entities at both regional and national levels, including national parks, nature reserves, and research centers (Costello et al. 2015; Viciani et al. 2018).

This study aims to establish a database for Monitoring Alien species along mountain Roads in the central Apennines (MARA) to address gaps in knowledge regarding the distribution of alien and thermophilous taxa in the Central Apennines and examines the plant taxa composition, distribution and ecology along mountain roads across an elevation gradient in three mountain sites in Central Italy. The findings may contribute to establishing long-term ecological monitoring of the native and alien plant taxa upshifting and inform conservation strategies for maintaining the integrity of these ecosystems.

The MARA database encompasses a total of 810 plant taxa from 118 plots (60 roadside and 58 inland), comprising 646 species and 164 subspecies, including both native and alien plants. Among these, 16 taxa are classified as alien plant taxa (APT), including 12 species and 4 subspecies. The recorded taxa are distributed across 75 distinct taxonomic families. The most frequent families are Asteraceae (15%), Poaceae (10%), and Fabaceae (10%). Conversely, the families with the highest coverage in the study area are Poaceae (22%), Fagaceae (16%), and Fabaceae (8%) (Fig. 2A). In terms of life form distribution according to Raunkiaer’s classification, the most abundant life forms are Phanerophytes (41%), Hemicryptophytes (36%), and Therophytes (8%) (Fig. 2B). The alien plant taxa are represented across 9 taxonomic families. The most common families of alien plants are Asteraceae (44%) and Poaceae (13%). However, the families with the highest cover are Simaroubaceae (41%), Sapindaceae (29%), and Fabaceae (14%) (Fig. 2C). Regarding alien plants life forms according to Raunkiaer’s classification, the most abundant are Phanerophytes (88%), Therophytes (7%), and Hemicryptophytes (5%) (Fig. 2D).

Considering the taxa’s occurrence across the three mountain sites of the study area (Gran Sasso Massif, Maiella Massif, and Mt. Terminillo) we observed that 23% of taxa are common to all three sites (Suppl. material 1). The most abundant taxa in this category are: Fagus sylvatica, Brachypodium rupestre and Fraxinus ornus. 27% of taxa are common to two sites, with the most abundant species Pteridium aquilinum subsp. aquilinum, Rubus idaeus subsp. idaeus, and Abies alba. 50% of taxa have been only recorded in one site. Among them, Anthemis cretica subsp. columnae is found in Gran Sasso, Pinus mugo subsp. mugo in Maiella, and Patzkea paniculata subsp. paniculata in Terminillo.

The boxplot analysis of taxa richness reveals differences between roadside and inland plots, both below and above 1200 m a.s.l.. Below 1200 m a.s.l. the taxa richness is significantly higher in roadside plots compared to inland plots (p-value < 0.001) (Fig. 3). A similar trend is observed above 1200 m a.s.l, with roadside plots exhibiting higher taxa richness than inland plots (p-value = 0.018). Moreover, roadside plots richness significantly differs between the two elevation ranges (p-value < 0.001).

The analysis of the EIVE Temperature data, associated with each species in the MARA database, reveals that the taxa with EIVE T between EIVE T = 4 and EIVE T = 5.55 are the most common in our dataset (Fig. 4A). This species group is mainly represented by the typical species of deciduous forests, especially of the mountain Fagus forest, such as Fagus sylvatica, Acer pseudoplatanus, Viola reichenbachiana, Cornus sanguinea. Below the 25^th percentile (EIVE T<4), we mainly find taxa occurring in subalpine grasslands, such as Festuca circummediterranea, Leucopoa dimorpha, Juniperus communis, Pilosella officinarum. Above the 75^th percentile (EIVE T>5.55), the thermophilous species group occurs. These taxa are common at low elevations, in Mediterranean grassland and mixed thermophilous woodland, such as Carthamus lanatus, Sesleria nitida, Avena sterilis, Fraxinus ornus and Quercus pubescens.

Regarding the distribution of alien plant taxa along the elevation gradient (Fig. 4B), 88% of plant taxa are concentrated below 1200 m a.s.l. Only a few species, such as Ceratochloa cathartica, Crepis sancta subsp. nemausensis, Erigeron sumatrensis, and Matricaria discoidea subsp. discoidea, reach higher elevations (until 1659 m a.s.l.). Alien taxa EIVE T values show that thermophilous taxa prevail (53%), meaning they exceed EIVE T>5.5. Specifically, Erigeron sumatrensis, with EIVE T=6.54, reaches the maximum altitude of 1610 m a.s.l.

Figure 2. 

The first bar plot shows the percentage of total cover for each taxonomic family in the MARA database. Families contributing less than 4% cover are grouped under ‘Others’ (68 families) (A). The pie chart illustrates the percentage of total cover for each life form according to the Raunkiær classification in the MARA database (P = Phanerophyte, NP = Nanophanerophytes, Ch = Chamaephyte, H = Hemicryptophyte, G = Geophyte, T = Therophyte) (B). The latter bar plot shows the cover percentage of alien plant taxa (APT) for each taxonomic family in the MARA database. Families contributing less than 4% of cover are grouped under ‘Others’ (9 families) (C). The pie chart illustrates the percentage cover of alien plant taxa (APT) for each life form according to the Raunkiær classification in the MARA database (P = Phanerophyte, H = Hemicryptophyte, T = Therophyte) (D).

Figure 3. 

The boxplots show the taxa richness across the two plot types (roadside and inland plots) and elevation ranges (below 1200 m and above 1200 m a.s.l.) Significant differences between box-plots are highlighted using statistical significance markers (*) according to the Student’s t-test (* p < 0.05, ** p < 0.01).

Figure 4. 

Density plot of the EIVE Temperature distribution with highlighted sectors based on percentile thresholds. The graph illustrates temperature density as a percentage, with the 25^th percentile (blue dashed line) and 75^th percentile (red dashed line) demarcating the lower, middle, and upper temperature ranges. The shaded areas represent the proportion of EIVE T falling within these ranges, with colors indicating different density levels: light yellow for EIVE T below the 25^th percentile, orange for EIVE T between the 25^th and 75^th percentiles, and dark orange for EIVE T above the 75^th percentile (A). The point chart shows the distribution of alien plant taxa along the elevation gradient, using EIVE T data for ecological classification. Each colored dot represents the elevation at which the alien plant taxon was recorded, with each color corresponding to a specific EIVE T class (B).

The MARA database was developed through extensive data collection, careful identification of plant specimens, taxonomic revision, and organized digitization and structuring of the data. Its organizational framework allows for scalability and integration into existing vegetation databases. Specifically, MARA represents a national and regional adaptation of data shared within the international MIREN framework (Seipel et al. 2022). The database will be updated by resampling the established plots every five years, with the next global monitoring survey scheduled for 2027.

Additionally, due to the layout (arranged along the elevation gradient) and the standard size of the monitoring plots, they could potentially be integrated into the Italian Long-term Ecosystem Research Network (LTER-IT), as some of the vegetation plots are already located within two LTER Sites: IT01-001-T Central-southern Apennine Majella-Matese, and IT01-003-T central Apennine: Gran Sasso d’Italia (Capotondi et al. 2021) and the Dynamic Ecological Information Management System - Site and Dataset Registry (DEIMS-SDR). DEIMS-SDR provides access to an increasing number of datasets and data products associated with LTER sites. Furthermore, as the plots are permanent, they will be revisited every five years and could be integrated into the ‘ReSurveyEurope’ network (Knollová et al. 2024), an initiative within the European Vegetation Archive (EVA) (Chytrý et al. 2016).

A particularly striking finding is that 53% of alien plant taxa are classified as thermophilous species, meaning they thrive in warmer environments and could potentially disrupt native ecosystems (Carboni et al. 2018). This is significant because, as temperatures rise due to climate change, these taxa might have greater opportunities to expand their range along elevation gradients. The warming climate is giving these thermophilous species a further advantage, allowing them to establish in habitats where they previously could not survive (Di Nuzzo et al. 2021).

In conclusion, our study and the MARA database highlight the importance of monitoring alien taxa in mountain environments and protected areas, especially in the current context of global warming. Understanding these dynamics will help guide future conservation strategies aimed at preserving Mediterranean native biodiversity and mitigating the impact of biological invasions.

MARA database can be obtained by contacting the dataset custodians directly (Angela Stanisci stanisci@unimol.it; Lucia Antonietta Santoianni luciasantoianni@gmail.com).

We acknowledge the Maiella National Park staff and Gran Sasso and Monti della Laga National Park staff for their essential logistic and technical support during the field campaigns. We wish to thank Valter Di Cecco and Francesca Tantalo for their valuable help in fieldwork. We are grateful to the coordinators and members of MIREN Project, especially Sylvia Haider and Meyke Buhaly for their valuable advice.

L. A. Santoianni was funded by PRIN 2022JBP5F8- PREVALIEN. Enhancing Knowledge on Prevention and Early Detection of the Invasive Alien Plants of (European) Union concern in the Italian Protected Areas. CUP Master: J53D2300657-0006.

This work was supported by the Grant of Excellence Departments 2018–2022 and the Grant of Excellence Departments 2023–2026, MIUR Italy. G. La Bella and M. Carboni acknowledge the support of NBFC to the University of Roma Tre, Department of Sciences.

M. Varricchione and A. Stanisci were funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4 - Call for tender No. 3138 of 16 December 2021, rectified by Decree n.3175 of 18 December 2021 of Italian Ministry of University and Research funded by the European Union – NextGenerationEU; Project code CN_00000033, Concession Decree No. 1034 of 17 June 2022 adopted by the Italian Ministry of University and Research, CUP H73C22000300001, Project title “National Biodiversity Future Center - NBFC”.