Fire is an integral and widespread occurrence in Mediterranean ecosystems. Fire risk has increased during the second-half of the 20th century due to climate change (increased temperature, lower precipitation and longer drought periods), as well as to fuel accumulation. Fire causes important changes in soils such as a dramatic reduction of soil water availability and infiltration capacity, and an increase of soil water repellency, thus increasing runoff and erosion. Fire also modifies soil texture, aggregate stability, pH, organic matter and nutrient content and cation exchange capacity, and decreases diversity and abundance of soil biota and vegetation communities. Restoration of fire-affected areas aims at improving soil conditions and recovering the natural vegetation cover. The practice of cyanobacterisation (soil inoculation with cyanobacteria), which has been shown to be effective in increasing soil stability and fertility in natural and agricultural desert lands, could also provide good results in improving soil conditions in burnt soils. Cyanobacteria play multiple roles in the soil by increasing and organic matter and nutrients contents, soil structure and stability, water retention. We conducted an experiment under laboratory conditions consisting of the combined inoculation of two widespread arid soil cyanobacterial strains, Phormidium ambiguum and Scytonema javanicum, on two burnt soils: one from the Madeira Islands (Portugal), the other from Orentano (Tuscany, Italy). The effect of cyanobacteria inoculation on biocrust formation and changes in soil hydrophobicity and stability were monitored during 45 days. Fifteen days after the inoculation the hydrophobicity, determined by the water drop penetration time (WDPT) test, and the repellency index (RI) were decreased by cyanobacteria. The development of a cyanobacteria-induced biocrust was confirmed by the increase in chlorophyll a content and soil resistance on time. These changes were more significant in the soils from Madeira than in those from Orentano. Cyanobacteria inoculation also increased the exopolysaccharide content compared to non-inoculated soils. This study points to the potential of cyanobacterisation on the recovery of post-fire soils and, on the other hand, highlights the importance of the characteristics of the burnt soils in facilitating the improving action of cyanobacteria.
A sustainable approach for restoration of post-fire soils based on inoculation of cyanobacteria / Chamizo S., Adessi, A., Nocentini E., Certini G., De Philippis R.. - ELETTRONICO. - (2019), pp. 0-0. (Intervento presentato al convegno EcoDesert International Symposium: Geoecology and Desertification- from physical to human factors tenutosi a Almeria, Spagna nel 20-22 Febbraio 2019).
A sustainable approach for restoration of post-fire soils based on inoculation of cyanobacteria
Chamizo S.
;Adessi A.;Certini G.;De Philippis R.
2019
Abstract
Fire is an integral and widespread occurrence in Mediterranean ecosystems. Fire risk has increased during the second-half of the 20th century due to climate change (increased temperature, lower precipitation and longer drought periods), as well as to fuel accumulation. Fire causes important changes in soils such as a dramatic reduction of soil water availability and infiltration capacity, and an increase of soil water repellency, thus increasing runoff and erosion. Fire also modifies soil texture, aggregate stability, pH, organic matter and nutrient content and cation exchange capacity, and decreases diversity and abundance of soil biota and vegetation communities. Restoration of fire-affected areas aims at improving soil conditions and recovering the natural vegetation cover. The practice of cyanobacterisation (soil inoculation with cyanobacteria), which has been shown to be effective in increasing soil stability and fertility in natural and agricultural desert lands, could also provide good results in improving soil conditions in burnt soils. Cyanobacteria play multiple roles in the soil by increasing and organic matter and nutrients contents, soil structure and stability, water retention. We conducted an experiment under laboratory conditions consisting of the combined inoculation of two widespread arid soil cyanobacterial strains, Phormidium ambiguum and Scytonema javanicum, on two burnt soils: one from the Madeira Islands (Portugal), the other from Orentano (Tuscany, Italy). The effect of cyanobacteria inoculation on biocrust formation and changes in soil hydrophobicity and stability were monitored during 45 days. Fifteen days after the inoculation the hydrophobicity, determined by the water drop penetration time (WDPT) test, and the repellency index (RI) were decreased by cyanobacteria. The development of a cyanobacteria-induced biocrust was confirmed by the increase in chlorophyll a content and soil resistance on time. These changes were more significant in the soils from Madeira than in those from Orentano. Cyanobacteria inoculation also increased the exopolysaccharide content compared to non-inoculated soils. This study points to the potential of cyanobacterisation on the recovery of post-fire soils and, on the other hand, highlights the importance of the characteristics of the burnt soils in facilitating the improving action of cyanobacteria.
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