Potential of nitrogen-fixing symbiotic systems for revegetation strategies of calcareous quarries in Mediterranean conditions
Anthropogenic degradation activities (overgrazing, deforestation, quarry exploitation...) together with a long dry and hot summer, with erratic but torrential rainfalls, are major threats to Mediterranean ecosystem sustainability. Quarry exploitation, in particular, removes native plants and natural soils, and generates an anthropogeomorphic soil material. Revegetation of such degraded ecosystems requires selection of suitable plants adapted to unfavorable soil and climatic conditions. Nitrogen-fixing legumes are key components of plant successions because rhizobial symbioses constitute the major nitrogen input into impoverished ecosystems. Several Mediterranean native legumes were selected from different areas in the South of France: some of them, Coronilla glauca and Medicago arborea, belonged to the shrub community whereas others like Astragalus monspessulanus, Dorycnium hirsutum and Coronilla varia were herbaceous species. Seeds were collected for plant multiplication. Rhizobial partners were isolated, characterized and the most efficient N2-fixing ones were selected for inoculum's preparation. Seedlings were transferred into plastic containers in an experimental nursery according to usual forestry practices, then were inoculated with the appropriate inoculum and grown for 6-9 months before transplantation to the vegetation site. Symbiotic plants were transferred into a rock-spolic soil material of a calcareous quarry and experimental variables including survival rates, plant growth, endomycorrhizae, soil organic matter and total N accumulation were recorded after three years. The highest plant growth rates were measured for C. glauca, M. arborea and D. hirsutum. A thin (0-5 mm) and discontinuous O horizon was formed with a high and heterogeneous accumulation of organic carbon (11.9% + 13) under plants of C. glauca, M. arborea and D. hirsutum. Total nitrogen (0.03-0.1%) was slightly incorporated into top vegetalised spolic material (0-5 cm) in comparison with non-vegetalised material. Thus, C. glauca, M. arborea and D. hirsutum was the most suitable legume species for reclamation and rehabilitation of spolic soil material. (Texte intégral)
Main Authors: | , , , , , |
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Format: | conference_item biblioteca |
Language: | eng |
Published: |
s.n.
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Subjects: | F61 - Physiologie végétale - Nutrition, |
Online Access: | http://agritrop.cirad.fr/537038/ |
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Summary: | Anthropogenic degradation activities (overgrazing, deforestation, quarry exploitation...) together with a long dry and hot summer, with erratic but torrential rainfalls, are major threats to Mediterranean ecosystem sustainability. Quarry exploitation, in particular, removes native plants and natural soils, and generates an anthropogeomorphic soil material. Revegetation of such degraded ecosystems requires selection of suitable plants adapted to unfavorable soil and climatic conditions. Nitrogen-fixing legumes are key components of plant successions because rhizobial symbioses constitute the major nitrogen input into impoverished ecosystems. Several Mediterranean native legumes were selected from different areas in the South of France: some of them, Coronilla glauca and Medicago arborea, belonged to the shrub community whereas others like Astragalus monspessulanus, Dorycnium hirsutum and Coronilla varia were herbaceous species. Seeds were collected for plant multiplication. Rhizobial partners were isolated, characterized and the most efficient N2-fixing ones were selected for inoculum's preparation. Seedlings were transferred into plastic containers in an experimental nursery according to usual forestry practices, then were inoculated with the appropriate inoculum and grown for 6-9 months before transplantation to the vegetation site. Symbiotic plants were transferred into a rock-spolic soil material of a calcareous quarry and experimental variables including survival rates, plant growth, endomycorrhizae, soil organic matter and total N accumulation were recorded after three years. The highest plant growth rates were measured for C. glauca, M. arborea and D. hirsutum. A thin (0-5 mm) and discontinuous O horizon was formed with a high and heterogeneous accumulation of organic carbon (11.9% + 13) under plants of C. glauca, M. arborea and D. hirsutum. Total nitrogen (0.03-0.1%) was slightly incorporated into top vegetalised spolic material (0-5 cm) in comparison with non-vegetalised material. Thus, C. glauca, M. arborea and D. hirsutum was the most suitable legume species for reclamation and rehabilitation of spolic soil material. (Texte intégral) |
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