Site-specific growth and nutrition of planted Piceamariana in the Ontario Clay Belt.: I. Early performance

Piceamariana (Mill.) B.S.P. (black spruce) seedlings were outplanted in three black spruce dominated ecosystems (operational groups of the regional Forest Ecosystem Classification system) of the Clay Belt and also planted in pots of intact forest humus substrates from these sites to investigate response to site nutrient condition, to diagnose limiting nutrients, and to test the effectiveness of a bioassay relative to field results. Over two seasons, growth was consistently superior on upland Feathermoss substrates, intermediate on Alnus–Herb poor substrates, and poorest on Ledum substrates, in both field and pot experiments. The inferior performance of seedlings on lowland sites was related by plant analysis to low N uptake on sphagnum-dominated substrates. Vector analysis of shoot nutrient concentration, content, and dry mass allowed simultaneous comparison of the nutrient status of seedlings outplanted on the three sites. Lower total N and higher C:N ratio in forest humus substrates on the Alnus and Ledum sites suggested that N availability may be low. The pot experiment demonstrated close correspondence with field results in the first season, indicating that a bioassay may be most useful for assessing short-term response and diagnosing nutritional factors affecting early performance.