Optimum habitat for natural regeneration of Fraxinus mandshurica under canopy of Pinus koraiensis plantations

The result showed that Manchurian ash regenerated well under the canopy of Korean pine plantations. Seedlings from 1 to 5 years old were the main parts in the regenerated colony, and they grew vigorously. Seedling sprouts grew varying, but the average increments of their height and basal diameter were evidently better than those of seedlings. Light deficiency was the key factor influencing the age structure of seedlings and seedling sprouts, and caused the seedlings and seedling sprouts to remain much young. The optimum site factors for natural regenerated Machurian ash seedlings and seedling sprouts were as follows: canopy density 0.4-0.6, litter thickness 3.0-5.2 cm, down part of sunny slope less than 5°, the cover density of grass and bush 20%-40%, soil water content 30%-50%. The importance sequence of the main factors decreased in turn.