Seedling damage caused by wood harvesting and soil scarification in rotation and continuous cover forestry in Scots-pine-dominated boreal forests

Continuous cover forestry (CCF) is gaining popularity as an alternative to rotation forest management (RFM), especially in forests with multiple uses. The success of CCF depends on the amount and quality of remaining seedlings, but the effect of harvesting on their status is not well known. In the present study, the proportion and number of undamaged seedlings after harvesting (and soil scarification) in Scots-pine-dominated stands in Northern Finland were modelled by applying logistic binomial mixed-effects and negative binomial count data models. The treatments included both CCF (gap cutting and selection cutting) and RFM (clearcutting and seed tree cutting) harvesting methods. The clearcut areas and most seed tree areas were treated with disc trenching. In the clearcutting and seed tree cutting areas, 25-34% of the inventoried seedlings were damaged. In the gap cutting and selection cuttings, c. 7% and 12% of the seedlings were damaged respectively. Harvesting machinery traffic and soil scarification were the most important causal agents of seedling damage. An increase in slash coverage also significantly increased seedling damage. The average number of undamaged seedlings in the selection cutting areas was ca. 1500 pcs ha-1, indicating at least satisfactory regeneration potential in the experimental stands.

Automated summary

The present study investigated the impact of different harvesting methods, including continuous cover forestry (CCF) and rotation forest management (RFM), on the proportion and number of undamaged seedlings in Scots-pine-dominated stands in Northern Finland. It was found that harvesting machinery traffic and soil scarification were the main causative factors for seedling damage. Increase in slash coverage also significantly increased seedling damage. The selection cutting areas showed satisfactory regeneration potential with an average of around 1500 undamaged seedlings per hectare.