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Evolution of mycorrhizal propagules in a burnt soil after fertilization and revegetation treatments

POSTER
CONTRIBUTED SESSION: 3 Mycorrhizae in Stressed Ecosystems
CASTELAO, ANA1, MARIA J. SAINZ1 & ANTON VILARIÑO2
1Departamento de Ingeniería Agroforestal y Producción Vegetal, Universidad de Santiago de Compostela, E-27002 Lugo, Spain
2Instituto de Investigaciones Agrobiológicas de Galicia (C.S.I.C.), Apdo. 122, E-15080 Santiago de Compostela, Spain
ICOM1 Abstract
The surface of a hill soil covered by shrubs was burnt for about one hour. Representative samples of the burnt soil were taken at 2-5 cm depth to evaluate mycorrhizal propagules left in soil and be compared with the corresponding samples in the unburnt soil. After the fire, a revegetation experiment was designed to control soil erosion, using two seed mixtures with the following species: i) Lolium perenne, Dactylis glomerata , Trifolium repens and Trifolium pratense, ii) Lolium multiflorum , D. glomerata , T. repens and T. pratense. Each mixture was sown in autumn under two fertilization treatments: a) an unfertilized control, b) liming and addition of a NPK (8:24:16) fertilizer. There were four replicates of 12 m2 per treatment. In every replicate, samples of soil were taken in July and November to study the evolution of mycorrhizal propagules; samples of roots were also taken to determine the mycorrhizal colonization of the dominant plant species established. The introduced plant species failed to compete with the indigenous flora (mainly Pteridium aquilinum and Arrenatherum sp. with high percentages of root mycorrhization), which covered most of the soil surface in all treatments. Only a small proportion of Lolium multiflorum and Dactylis glomerata , both also extensively mycorrhized, could grow in the fertilized treatments. The number of propagules was strongly reduced after the fire, remaining low both in the fertilized and unfertilized treatments for about six months. This fact might help to partly explain the failure of the introduced plant species to get established in the burnt soil.