Predicting the need for tending of conifer seedling stands in southern Finland

Assessing the need for and timing of tending in seedling stands is based on the stem numbers and heights of crop trees and competing broadleaves, as well as the expected forthcoming development of stand. The assessment is partly an outcome of field worker’s opinion and experience. The tending need of Norway spruce- and Scots pine-dominated seedling stands was modeled using the National Forest Inventory (NFI) data from southern Finland. The models predict the probabilities that the NFI field team leader’s proposal falls in the following four categories: tending is late, during the first or second 5-year period or no need for tending. The predictors such as stem numbers, tree heights, site fertility, regeneration method and accomplished tending logically explained the tending need. The overall accuracy of the models was only fair: 54% (kappa 0.27) for spruce and 55% (kappa 0.33) for pine. However, about 95% of the stands needing immediate tending were classified as stands needing immediate or first 5-year period tending. The surveyor-specific random effects were statistically significant, and the surveyors were likely to propose tending similarly in spruce and pine stands. The models can be utilized in forest planning systems and practical forest inventory.