Density-dependent regulation of arbuscular mycorrhiza by collembola

In a field microcosm experiment, we tested the hypothesis that adult collembola, depending on their density, may enhance or decrease mycorrhizal development and growth of maize (Zea mays L.) or red fescue (Festuca rubra L.). Collembola decreased mycorrhizal spore number in the soil. A significant decrease in the spore number, compared to the treatment without collembola, was recorded and ranged from 0.2 to 1.6 individuals g−1 soil in both experiments. Highest AM fungi colonization was found at 0.2 and 0.4 collembola g−1 soil density in the maize and red fescue treatments, respectively. This finding may explain why about 0.1 individuals g−1 soil was reported as optimum for plant growth by some authors.