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Cantelmo, AJ; Ehrenfeld, JG. 1999. Effects of microtopography on mycorrhizal infection in Atlantic white cedar (Chamaecyparis thyoides (L.) Mills.). Mycorrhiza. 8(4):175-180. Address: JG Ehrenfeld; Rutgers State Univ; New Brunswick; NJ; USA; 08903
The presence and intensity of mycorrhizal infection in wetland trees has received relatively little attention. We report here a study of mycorrhizal infection in Atlantic white cedar (Chamaecyparis thyoides), a member of the Cupressaceae, which forms monospecific stands in swamps throughout the Atlantic Coastal Plain of North America. The trees grow on the tops of elevated hummocks, but the fine roots extend along the sides of the hummocks to the flooded hollows. Roots from all microtopographic positions on the hummocks are colonized by vesicular-arbuscular mycorrhizae (VAM). In addition to arbuscules and vesicles, occasional hyphal coils are observed within the cortex cells. However, frequencies of occurrence of vesicles and arbuscles are significantly higher on the tops and sides than at the bottoms of the hummocks. These differences correspond to higher concentrations of acetylglucosamine in the roots at these positions. Frequencies of all mycorrhizal structures (arbuscles, vesicles and hyphae) in roots at the base of the hummocks are very low. These results suggest that mycorrhizal colonization in wetland trees is greater in aerobic microsites, a finding in accord with results from studies of both herbaceous wetland plants and other wetland trees.
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