Francisco Rocha

Introduction: Mediterranean coastal wetlands are biodiversity hotspots increasingly threatened by climate change, particularly by salinization, which strongly constrains plant recruitment during early life stages. Native soil microbiota may provide nature‐based solutions (NbS) to enhance plant establishment under saline conditions. Objectives: We evaluated microbial seed biopriming with native biocrust‐derived microorganisms to improve germination and early seedling development of three Mediterranean wetland species differing in salinity tolerance, that is, Arthrocaulon meridionale , Juncus acutus , and Mentha aquatica . Methods: Four microbial strains were isolated and selected based on salinity tolerance and plant growth‐promoting traits: Nodosilinea ramsarensis (cyanobacteria), Bacillus licheniformis , Fredinandcohnia salidurans , and Rossellomorea aquimaris (bacteria). Their effects were assessed on bioprimed seeds, exposed to increasing NaCl concentrations (0, 0.3, 0.5, and 0.7 M) under controlled conditions. Results: Salinity primarily defined germination limits, producing threshold‐like and species‐specific responses and delayed germination with increasing concentrations. Microbial treatments accelerated germination only where salinity did not fully constrain the process. Cyanobacterial biopriming enhanced germination and enabled germination at the highest salinity levels in A. meridionale and J. acutus , whereas M. aquatica did not germinate under saline conditions. Cyanobacteria also consistently promoted longer roots across species under non‐saline and moderately saline conditions. Conclusions: Salinity defines the recruitment niche of Mediterranean wetland plants, while native microbial inoculation, particularly cyanobacteria, acts as a secondary modulator enhancing establishment within these limits. Microbial biopriming thus represents a context‐dependent NbS for ecological restoration under increasing salinization.

Post‐fire environmental conditions can heavily influence the natural regeneration of pine species in Mediterranean forests. Therefore, enhancing post‐fire recovery of pine species is fundamental for effective ecological restoration of Mediterranean forests. In this study, the effects of a post‐fire restoration treatment on the seedling emergence and survival of Spanish black pine (Pinus nigra Arn. ssp. salzmannii) were investigated under a treatment consisting of manual cut of burnt tree canopies placed on the soil surface with their tree branches, following contour lines (contour‐felled log debris, CFD) in comparison with a control site at plot scale. Both CFD and control plots were tested on three slope gradients and two experimental conditions, that is, protected vs. non‐protected seeds. The initial seedling recruitment of Spanish black pine was improved by CFD treatment and seed protection, specifically through increased survival of emergent seedlings by about 10 and 15 times, respectively, compared to control. Seedling emergence was not significantly different between the treatments or controls; however, the highest seedling emergence in the study (18.9 ± 14.9%) was recorded under the least severe drought conditions. The study demonstrates that post‐fire CFD and seed protection treatments can be favorable for supporting ecological restoration of these pine forests. However, the environmental conditions are important drivers for the success of these strategies. Since droughts are expected to be more frequent in the upcoming years, post‐fire management strategies that include treatments like CFD and seed protection can be useful in the ecological restoration of Mediterranean pine forests.

Soil salinization poses an important threat to terrestrial ecosystems and is expected to increase as a consequence of climate change and anthropogenic pressures. Conventional methods such as salt-leaching or application of soil amendments, or nature-based solutions (NBSs) such as phytoremediation, have been widely adopted with contrasting results. The use of cyanobacteria for improving soil conditions has emerged as a novel biotechnological tool for ecosystem restoration due to the unique features of these organisms, e.g., ability to fix carbon and nitrogen and promote soil stabilisation. Cyanobacteria distribute over a wide range of salt concentrations and several species can adapt to fluctuating salinity conditions. Their application in agricultural saline soil remediation has been demonstrated, mostly in laboratory studies, but there is a lack of research regarding their use in natural ecosystems restoration. In this article, we provide an overview of the current knowledge on cyanobacteria in the context of ecosystem restoration. Examples of the application of cyanobacteria in alleviating salt-stress in plants and soils are presented. Furthermore, we acknowledge gaps regarding the extensive application of cyanobacteria in salt-affected soils remediation and discuss the challenges of NBSs in salt-affected soils restoration.