An experimental approach: ectomycorrhizas in a Nothofagus pumilio forest affected by the Puyehue Cordón Caulle´s volcanic ashes

PUGA JORGE; FERNÁNDEZ NATALIA; MOGUILEVSKY DENISE; FONTENLA SONIA

Valdivia

Workshop; International Workshop: Mycorrhizal Symbiosis in the Southern Cone of South America; 2017

Universidad Austral de Chile, Universidad de La Frontera, Universidad de Concepción, Centro de Estudios Avanzados en Fruticultura, EarthShape Project (DFG)

The 2011 Puyehue Cordón Caulle´s eruption affected large areas of Nothofaguspumilio forests where tephra deposition buried all the understory vegetation, forming a brand-new substrate for plants and microorganisms. After this disturb, there are natural regeneration of N.pumilio seedlings growing in the tephra. N.pumilio normally have a high proportion of colonization of ectomycorrhizas (EM) (adults ≥70%). The aim was to study how tephra deposition influences N.pumlio´s EM colonization and seedling development. In a forest with high tephra deposition (>40cm), ten pots were placed in the tephra and filled with their forest soil, obtained under the tephra. It was selected N.pumilio seedlings growing in the tephra, two were transplanted into each pot (soil seedlings) and ten remained growing in the tephra. After one year, it wassampled roots from five adults and ten seedlings from each substrate. In all theindividuals, it was analyzed EM colonization and richness, and seedlingsmorphometric measures: length and diameter of the stem, epicotyl and root. All the individuals presented EM. The EM colonization and richness were not statistically different between soil seedlings and adults (75% and 70%; 3,8 and 6,0 ectomorfotypes/individual, respectively) and were higher than tephra seedlings (50%; 1.3). This difference may be due to the fact that soil seedlings and adults were in direct contact with the soil (native inoculum). No differences were found in the morphometric measures between soil/tephra seedlings, suggesting that, in the short term, seedling growth was not influenced by the different substrates. The tephra not only allowed the germination and survival of seedlings, but also possessed EM infective capacity, although it appeared to be lower than soil. After a high impact disturbance, the re-establishment of the native inoculum in the tephra and the mycorrhizal capacity of N.pumilio seedlings seems to be an important process for the forest regeneration.