Revista Chilena de Historia Natural 85 (1): 61-71, 2012
RESEARCH ARTICLE
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
