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Revista Chilena de Historia Natural 85 (1): 61-71, 2012
The ectomycorrhizal community in a chronosequence of Pinus radiata (Pinophyta: Pinaceae) of the transitional Mediterranean-temperate climatic zone of central Chile
In natural forest ecosystems and plantations, most trees live in mutualistic association with mycorrhizal fungi. Studies of this association in South America are still scarce, especially when referring to the causes of temporal dynamics of this symbiotic community, despite its importance in countries with a thriving forestry industry like Chile. This study evaluates the dynamics of the ectomycorrhizal community of Pinus radiata stands of 3, 10 and 20 years of age, identifying and quantifying the most common fungal colonizers of fi ne roots in each age class. The results confirm that the mycobiont community changes with host tree age but that age classes differ in dominance patterns rather than in species richness, with the three- and ten-year-old tree cohorts forming a group separate from the 20-year-old trees. A total of eleven ectomycorrhizal root morphotypes could be distinguished. Four of them which were identified as Hebeloma crustuliniforme, Inocybe sp., Russula sardonia and Pinirhiza spinulosa, were the most abundant (77, 29, 78 and 8 % respectively) and were found in more than one root sample whereas the remaining morphotypes accounted for less than 100 (< 7 %) root tips and showed a patchy distribution. Inocybe sp. was only found on root tips of three-year-old trees, characterizing as an early-stage mycobiont. H. crustuliniforme appeared as a multi-stage colonizer in all three age classes but was clearly dominant on roots of three- and ten-year-old trees, whereas R. sardonia was mainly found on roots of 20-year- old trees, classifying as a late-stage species together with the unidentified morphotype Pinirhiza spinulosa which is reported for the fi rst time from Chile. Our results suggest that the observed changes in the ectomycorrhizal community are not induced by the site per se, but are rather an effect of the interaction between the trees and their environment.
Key words:
fungal diversity, succession, ectomycorrhizal morphotypes, forest plantations

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