AN EXPERIMENTAL APPROACH: ECTOMYCORRHIZAS IN A NOTHOFAGUS PUMILIO FOREST AFFECTED BY THE PUYEHUE CORDÓN CAULLE´S VOLCANIC ASHES

FERNÁNDEZ NATALIA; PUGA JORGE; FONTENLA SONIA; MOGUILEVSKY DENISE

Valdivia

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

Universidad Austral de Chile (UACh), entre otras

The 2011 Puyehue Cordón Caulle´s eruption affected large areas of Nothofagus pumilio forests where tephra deposition buried all the understory vegetation, and form 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 trees normally have a high proportion 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 was sampled roots from five adults and ten seedlings from each substrate. In all the individuals it was analyzed EM colonization and richness, and seedlings morphometric measures: length and diameter of the stem, epicotyl and root. All the individuals presented EM. The EM colonization and richness were similar between soil seedlings and adults (75% and 70%; 3,8 and 6,0 ectomorfotypes/individual, respectively) and higher than tephra seedlings (50%; 1.3 ectomorfotypes/individual). This difference may be due to the fact seedlings (in pots) and adults were in direct contact with the soil (native inoculum). No differences were found in the morphometric measures between soil and 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 seems 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.