In order to explore the potential for reducing weeding frequency in replanted Larix kaempferi plantations, we investigated the survival and growth of L. kaempferi seedlings for five growing seasons and the status of their competition with competing vegetation, in Iwate prefecture, northern Japan. Height and root collar diameter of L. kaempferi seedlings after five growing seasons decreased with reduced weeding frequency. L. kaempferi seedlings that had been covered by competing vegetation at the end of the last growing season showed significantly decreased annual height growth compared to the seedlings that have more than half of their canopies exposed. In one of the measurement periods, height growth of L. kaempferi seedlings was decreased even when the tops of their canopies had been free from competing vegetation. Survival of L. kaempferi seedlings had no consistent relationship with weeding frequency; local differences in the species composition of competing vegetation may have altered their survival process. These results suggest that L. kaempferi seedlings are very likely to experience a substantial decrease in growth under a biannual weeding treatment.

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