Mycorrhizal status of mature red spruce (Picea rubens) in mesic and wetland sites of northwestern New Jersey

During the past 2 decades red spruce (Picea rubens Sarg.) has exhibited growth decline throughout its range. Examination of roots of affected trees in many locations has shown death of fine feeder roots. This study examined the mycorrhizae of red spruce in New Jersey, where it is rare. At two localities just below the Kittatinny Ridge in northwestern New Jersey (elevation 425 m), samples of eight long roots from 40 trees were examined, half from mesic and half from wetland areas. All trees sampled showed >60% ectomycorrhizal tips (average, 89%, sd = 0.17). All mycorrhizae were monopodial. Three morphotypes predominated at both sites. Cenococcum geophilum Fr. colonized over 92% of the sampled trees and accounted for an average of 36% of ectomycorrhizal tips per tree. Ninety percent of trees had plump, pallid mycorrhizae with a smooth mantle, which ranged in color from beige to reddish brown. All wetland trees, but only 40% of the mesic trees, exhibited mycorrhizae with a diffuse network of extramatrical hyphae and a sheathed white tip. Other morphotypes were present in 15-20% of trees. These minor morphotypes were more abundant and more diverse on trees with low levels of colonization by C. geophilum and the white-tip morphotype. There was more variation in level and type of colonization between trees than within individual trees.