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Biodiversity of endomycorrhizae in forests with distinct patterns of Araucaria angustifolia regeneration in southern Brazil.
ZANDAVALLI, ROBERTA1, DILLENBURG, LUCIA1, STURMER, SIDNEY2, 1 2
ABSTRACT- Araucaria angustifolia is a tree of great ecological and economic value in southern Brazil. Timber exploration in the past has dramatically reduced the area covered by araucarian forests. Ecological factors affecting the species regeneration are poorly understood. One of these relates to mycorrhizal associations. This study aims to characterize the relationship between spore diversity of endomycorrhizal fungi and the regeneration of A. angustifolia. Three forest sites were selected: a Pinus plantation (PP), with colonization of Araucaria, an Araucaria plantation (AP), with regeneration of the species, and a native araucarian forests (NF), with no regeneration. Population structure of A. angustifolia and seasonal variation in spore abundance and richness in all sites were characterized. Six compound soil samples in each forest were collected at four different times in a one-year period. Spores were isolated by wet sieving and centrifugation, counted and identified at the species level. Spore density was much greater in the AP site than in the others, except for the winter. Seasonal variation in spore density was also much more pronounced in this site, showing a peak of 68.7 spores per gram in the fall. Species number displayed great seasonal and site variation, with maximum number of 12, 8, and 5 for the AP, PP and NF sites, respectively. Species of Acaulospora and Glomus were present in all sites and AP displayed the greatest and NF the smallest number of genera (5 and 2, respectively). Differences in spore biodiversity does not seem to account for differences in Araucaria regeneration.
KEY WORDS: Araucaria angustifolia, mycorrhizae, regeneration, biodiversity