Document: IAN-3-58-5

Chestnut oak (Quercus prinus L.) and red maple (Acer rubrum L.) stump sprouts, ectomycorrhiza, and red oak (Quercus rubra L.) seedlings.

DICKIE, I.A.*, K.C.STEINER and R.T.KOIDE

The Pennsylvania State University, University Park, PA 16802 USA 1

Abstract:
We examined the influence of existing vegetation on mycorrhizal infection, nutrition and growth of red oak (Quercus rubra L.) seedlings in a site that had burned and was logged 8 years previously. Vegetation on the site consisted of stump sprouts of oak (ectomycorrhizal) and red maple (VA mycorrhizal) in a matrix of VA mycorrhizal grasses and forbs, and ericoid mycorrhizal shrubs. For two years, we grew red oak seedlings near resprouted stumps of 1) chestnut oak (Q. prinus L.) or 2) red maple (Acer rubrum L.). In the second year we also grew red oak seedlings near oak stumps that had not resprouted. In years 1 and 2, seedlings germinated near resprouted chestnut oak stumps had 478% and 185% more ectomycorrhizal root tips cm-1, 303% and 59% higher shoot N concentration, and 292% and 49% higher shoot P concentration than seedlings planted near resprouted red maple stumps (all P < 0.05). Seedlings germinated near resprouted chestnut oak stumps were also infected by a different community of mycorrhizal fungi than in the other treatments. Seedlings germinated near resprouted chestnut oaks in the first year grew 80% taller than seedlings near resprouted red maple (P < 0.05). Seedlings germinated in the second year did not show significant differences in growth, perhaps due to severe drought conditions. Seedlings germinated near unsprouted oak stumps had ectomycorrhizal infection, and shoot N and P concentrations similar to seedlings germinated near maples. There were no differences between treatments in soil pH, or available P, NH4+ or NO3-. These results show that living root systems of existing ectomycorrhizal vegetation can provide an important source of mycorrhizal symbionts for red oak seedlings, influencing the quantity and quality of colonization. Ultimately, this can result in increased seedling growth and may play a role in forest successional dynamics.

Keywords: Mycorrhiza, forest regeneration, overstory-seedling interactions

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This abstract is being presented at: 11:00 AM in session:
Oral Session #8: Mycorrhizal Fungi.