Linear infrastructures, like roads and railways, exist all around the world and spread throughout a great variety of environments. Despite their known negative impacts, these grey infrastructures have the potential to contribute to biodiversity conservation in fragmented landscapes since they can constitute pools of biological diversity and, thus, corridors between ecosystems, increasing habitat connectivity. Native plants, particularly endemic or threatened species, can be promoted by sowing around these infrastructures. Our work is integrated in the LIFE LINES project and aimed at promoting the creation of a demonstrative Green Infrastructure to support conservation, and improving the local biodiversity. To achieve this, we developed two types of seed mixtures using wild native species, one for roads and other for disabled railways (currently used as ecotrails), to enhance plant diversity. The composition of the road mixture took into account road security and prioritize the promotion of native species, contrary to the existing commercial mixtures, which usually add exotic species. The ecotrails mixture favoured species with a more diverse morphology, with aesthetic potential and suitable to enhance fauna’s refuge and food resources. The selection of species to be used in each mixture type comprised several sequential
steps. A preliminary set of species were sort for being native to the Iberian Peninsula, resist to drought and endure the regular mowing of the vegetation. Afterwards, two different assortments of each mixture type were tested in 12 ex-situ plots installed at Herdade da Mitra (Évora, Portugal) in autumn 2016, respecting the following proportions: 30% Fabaceae, 30% Poaceae and 10% Asteraceae. The performance and sustainability of these mixtures were evaluated through the assessment of species frequency, abundance, and biomass production in spring 2017 and 2018, in order to choose the best option for each mixture type. Ultimately, these final assortments were sown in 21 in-situ plots along road verges and ecotrails during autumn 2018. The performance and sustainability of the final seed mixtures were also evaluated through the assessment of species frequency and abundance in spring 2019. The germination of sown species was registered in all the in-situ plots, most of them being endemic and more fragile species. Some species did not germinate in in-situ plots (e.g. Dactylis glomerata), while others only germinated here (e.g. Campanula lusitanica). Also, most of the species were able to produce flowers and seeds, which is a good indicator of sustainability. These preliminary results showed that the local plant diversity increased, suggesting that the final seed mixtures tested are suitable to be used in the south of the Iberian Peninsula. Given the small number of mixtures tested in a Mediterranean context, this study constitutes a basis to improve management standards, that should consider the ideal time for mowing. Nevertheless, further monitoring of the seed mixtures dynamics and evolution will be necessary, since some changes may occur over the next years, and adjustments to species composition or proportions may be required.
Murcia
