Abstract

Effects of different sized and different aged canopy gaps on the ectomycorrhizae of yellow birch and vesicular-arbuscular mycorrhizae of sugar maples collected from two deciduous forests in central Quebec were examined. The colonization of maple roots by arbuscules, vesicles, and coils were quantified. Colonization by ectomycorrhizal fungi was quantified and characterized using morphotyping and molecular techniques. In the 1-yr old 1000 m 2 cuts, colonization increased in the maple roots as the season progressed. In October, there were more arbuscules in the seedlings from the gaps vs those from the uncut areas. No differences in ECM colonization between uncut and 1-year old gaps were noted in the yellow birch seedlings and high levels of colonization occurred throughout the season. In the 5- and 10-yr old gaps, colonization in both species increased as the season progressed, and higher colonization levels were present in the large (V100 m 2 ) vs small naturally occurring gaps (0-2 m 2 ). Based on morphotypes, species richness on yellow birch was unaffected by gap size and age, but diversity was slightly greater in the older gaps. Sixteen different ECM morphotypes were found, 10 of which were characterized using molecular methods, yielding 17 different restriction patterns. These results emphasize the importance of using molecular methods to back up morphological assays of ectomycorrhizal species richness.