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Armillaria rhizomorphs consist of differentiated hyphae with a melanized outer cortex. Melanin is known to prevent lysis of fungal structures by hydrolytic enzymes and may protect against antagonistic microorganisms. Our studies indicate that melanized rhizomorphs also adsorb high concentrations of cations from the surrounding soil environment. Rhizomorphs of four Armillaria species (A. ostoyae (Romagn.) Herink, A. calvescens Bérubé & Dessureault, A. gemina Bérubé & Dessureault, and A. sinapina Bérubé & Dessureault) collected from Minnesota, New Hampshire, and Oregon had substantially elevated levels of metal ions compared with the soil from which they were collected. With some elements, ions were 50–100 times more concentrated on rhizomorphs than in soil. Concentrations of Al, Zn, Fe, Cu, and Pb on rhizomorphs ranged up to 3440, 1930, 1890, 15, and 680 μg/g, respectively. Energy dispersive X-ray microanalysis showed that metal ions were located only on the outer portions of the rhizomorphs and not concentrated in the interior. A coating of metal ions may play a key role in the longevity and survival of rhizomorphs in soil. Key words: Armillaria, rhizomorphs, metals, fungal antagonism.

Crown dieback and mortality of red spruce and balsam fir in the subalpine zone of the northern Appalachian Mountains have been attributed to wind-induced crown and root damage. Vertical root movements, damage to roots and crowns, and growth rate were measured on wind-exposed spruce and fir trees near canopy gaps at Kancamagus Pass (875 m elevation) and Wildcat Mountain (1160 m) in the White Mountain National Forest, New Hampshire. Root movements were significantly correlated with windspeed, crown exposure, and depth of soil to rock. Woody roots that had made movements in excess of 10 mm had fewer small (1–3 mm diameter) roots, more abrasion wounds, and a greater amount of nonconducting (dry or discolored) xylem than roots that had made smaller movements. Hydraulic conductivity was significantly reduced in roots with greater than 40% xylem cross-sectional area that was nonconducting. Spruce and fir trees at gap margins grew slower and had more root and crown damage than trees sheltered within the canopy. Decreases in growth rate of spruce and fir trees at both sites during the past 20 years were significantly correlated with wind exposure and some of the root and crown damage variables.