Effects of soil nutrient availability and ozone on container-grown Japanese larch seedlings and role of soil microbes

The interactive effects of ozone, soil nutrient availability and root microorganisms on physiological, growth, and productivity traits were studied for the first time for Japanese larch ( Larix kaempferi ) seedlings grown in containers over a growing season, using a free air ozone-concentration enrichment exposure system. High nutrient availability altered leaf and root nutrient dynamics and enhanced plant growth; however, it also enhanced seedling susceptibility to damping-off disease compared to low nutrient availability. Negative effects of elevated ozone, as compared with ambient ozone, on leaf gas exchange and plant stem form were neither offset nor exacerbated by soil nutrient availability and root colonizers. Such negative effects suggest that elevated ozone may have implications for ecological health even when plant vigor is limited by factors other than ozone. Inoculation of roots with ectomycorrhizae had negligible influence on the effects of either soil nutrient availability or ozone. However, this lack of effect may be upon impeded formation of complete mycorrhizal root tips due to factors other than the manipulated variables. B and Na appeared to have an important role in stress responses, so further studies to examine their link with physiological mechanisms as a function of time. This study provides an important perspective for designing forestry practices to enhance seedling health.