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| Titel |
Inoculation of soil native cyanobacteria to restore arid degraded soils |
| VerfasserIn |
José Raúl Román Fernández, Beatriz Roncero Ramos, Sonia Chamizo de la Piedra, Emilio Rodríguez Caballero, M. Ángeles Muñoz Martín, Pilar Mateo, Yolanda Cantón Castilla |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138063
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| Publikation (Nr.) |
 EGU/EGU2017-971.pdf |
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| Zusammenfassung |
| Restoration projects in semiarid lands often yield poor results. Water scarcity, low soil
fertility, and poor soil structure strongly limit the survival and growth of planted seedlings in
these areas. Under these conditions, a previous stage that improves edaphic conditions would
turn out to a successful plant restoration. By successfully colonizing arid soils, cyanobacteria
naturally provide suitable edaphic conditions, enhancing water availability, soil fertility and
soil stability. Furthermore, cyanobacteria can be easily isolated and cultured ex-situ to
produce high quantities of biomass, representing a potential tool to restore large areas
efficiently.
The objective of this study was to test the effect of inoculated cyanobacteria on degraded
soils at three different semiarid areas from southeast Spain: Tabernas badlands, a limestone
quarry located in Gádor, and grazed grassland in Las Amoladeras (Cabo de Gata). Soil
native cyanobacteria belonging to three representative N-fixing genera (Nostoc,
Scytonema and Tolypothrix) were isolated from such soils and cultured in BG110
medium. Each strain was inoculated (6 g m−2), separately and mixed (all in the
same proportion), on Petri dishes with 80 g of each soil. Biocrust development was
monitored during 3 months in these soils under laboratory conditions, at a constant
temperature of 25oC. During the experiment, two irrigation treatments were applied
simulating a dry (180 mm) and a wet (360 mm) rainfall year (average recorded in
the study sites). After 3 months, net CO2 flux, spectral response and soil surface
microtopography (1 mm spatial resolution) of inoculated and control soils was measured
under wet conditions, all of them as a surrogate of biocrust development. Samples of the
surface crust were collected in order to determine total soil organic carbon (SOC)
content.
The inoculated soils showed positive values of net CO2 flux, thus indicating a net CO2
uptake, whereas control soils showed CO2 fluxes closed to zero. This higher CO2 fixation in
the inoculated soils was reflected in the higher SOC content found in these soils with respect
to the non-inoculated soils. Soil surface roughness increased with biocrust development in the
inoculated soils as compared to control soils. From the different treatments, soil
inoculation with the mixture of the three strains promoted the highest SOC contents and
absorbance at 680 nm (indicative of higher chlorophyll a content) on the three soil types.
Therefore, using a consortium of cyanobacteria to inoculate degraded soils seems to be a
more promising strategy to restore soils than inoculating individual species. Finally,
differences between irrigation treatments were no significant, suggesting that water
availability was not a key driver for cyanobacteria development under control laboratory
conditions.
Our results underline the viability of cyanobacteria inoculation to form an artificial
developed biocrust that contribute to CO2 uptake and increase soil fertility which could
facilitate further plant cover establishment. However, more studies are necessaries
to test the effectiveness of inoculated crust development under field conditions. |
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