Description

Prescribed fire and/or thinning may improve oak seedling reproduction in forests and limit competitors such as red maple due to altered light or soil-moisture conditions. Because both leaf and root development may be affected by these disturbances, differences in biomass, mycorrhizal colonization, and leaf anatomy between seedlings of black oak (Quercus velutina, an ectomycorrhizal species) and red maple (Acer rubrum, an endomycorrhizal species) were described and quantified. In spring 2001, four treatments were initiated at Zaleski State Forest, Vinton County, OH: undisturbed control (C); basal area thinned by 29 percent (T); site exposed to prescribed burn (B); or thinned plus burned (T+B). In June and August 2001, four seedlings (two oak, two maple) from six plots per treatment were excavated from three subsites with different moisture levels (two mesic, two intermediate, two xeric; 48 seedlings per species per collection date). Roots were prepared chemically for mycorrhizal analysis; leaf sections were embedded in epoxy resin and examined microscopically. Biomass measurements of all seedling parts were quantified. Endomycorrhizal colonization of maple roots was not affected by treatments. Oak short roots were predominantly ectomycorrhizal; endomycorrhizal structures were observed primarily in June (T+B). In oak leaves, blade thickness and starch grains in chloroplasts (August) were greater in T and T+B than in C or B. Maple leaves, while thinner than oak, had thicker leaf blades in all disturbance treatments compared to C, but less starch in chloroplasts (August). By August, treatments positively affected leaf parameters in oak (leaf area, mass, specific leaf mass) and maple (leaf number, area, mass) probably due to increased light and/or altered soil conditions. Oak seedlings grown on sites with thinning and burning as management tools may gain a competitive advantage by forming both mycorrhizal types early in the season (i.e., additional nutrient uptake) and through increased starch production in leaves late in the season that would improve seedling growth and carbon transfer to roots.