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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. [ABSTRACT FROM AUTHOR]

We studied the effects of different cutting intensities (0%, 5–10%, 15%, and 20% basal area removal) on stand growth, structure, and net carbon storage in spruce–fir (Picea jezoensis(Sieb. et Zucc.) Carr.–Abies nephrolepis(Trautv.) Maxim.) and broadleaf mixed forests on Changbai Mountain (Northeast China) over 19 years. At this site, inventory-based low-intensity selection cutting was used to maintain a continuous forest canopy. After two cutting events, results showed significant differences in growth, structure, and carbon storage among cutting intensities. When increasing cutting intensity, the growth rate of average diameter, basal area, and volume significantly increased, with the highest increment rates found in the plots with 20% basal area removal. Tree diameters for all plots showed a roughly inverse J-shaped distribution before cutting and a left-skewed unimodal distribution after two cuttings. Volume ratio (the relative amount of volume contained in different diameter classes) for small (6–14 cm), medium (14–26 cm), large (26–36 cm), and very large (>38 cm) diameters remained unchanged in the plots with 5 and 10% basal area removal, but the volume ratio of large and very large diameters increased in the plots with 15 and 20% basal area removal, reaching approximately a 1:2:3:4 ratio in the plots with 20% basal area removal after two selection cuttings. Net carbon storage increased when increasing cutting intensity, reaching maximum storage in the plots with 20% basal area removal (cutting intensity and net C storage increase: 0%, 7.21 Mg C ha−1, 5–10%: 11.68 Mg C ha−1, 15%: 21.41 Mg C ha−1, 20%: 26.47 Mg C ha−1). Therefore, our results show the potential of low-intensity selection cutting to meet demands of both timber production and maintenance of forest cover for biodiversity values. [ABSTRACT FROM AUTHOR]

Damage to 0.5-2.5 m saplings in selection cuttings in uneven-aged Norway spruce stands was studied in three stands in Finland. Harvest removals were 96-122 m3ha-1 or 32-41% of initial basal area. Harvesting was carried out with one-grip harvester and forwarder in March-April 2007. The strip road network had been established in previous cuttings. Before harvesting, trees higher than 2.5 m were measured and mapped with coordinates. Saplings 0.5-2.5 m were measured on circular sample plots of 10 m2 on a square grid, where line and plot intervals were 7.07 m. Trees to remove were selected with a computerized tree selection procedure and marked before cutting. Factors affecting the probability and severity of injury to an individual sapling were studied with logistic regression models. Percentage of injured saplings was 17.6, 29.8, and 61.0%, depending on study stand. Stem breakage was the most common type of injury. Distance of the sapling from the nearest strip road, sapling height, harvested basal area within 25 m of the sapling, and the distance to the nearest remaining tree were statistically significant factors in the model of the probability of injury. In the model for the severity of injury, only the distance from the nearest strip road and the sapling height were significant. Saplings near strip roads were vulnerable during both cutting and forwarding, and they often ended up under slash or logs. Development in working methods and machinery are potentially effective in reducing sapling damage in selection cuttings. [ABSTRACT FROM AUTHOR]

Previous studies have indicated that the effect of overstorey density on height increment and mortality of seedlings and saplings is affected by the vertical structure of the overstorey. To test this, 28 plots, including four control plots, were studied at two sites, in northern and central Sweden. Norway spruce dominated all plots. The overstorey was thinned from "above", i.e. harvesting mainly large-diameter trees and maintaining a multilayered structure, or from "below", i.e. harvesting mainly smaller trees and creating a shelterwood. Three different densities were created for each structure, in the range 20-140 m[sup 3] ha[sup -1] at the northern site, and 40-200 m[sup 3] ha[sup -1] at the southern site. Seven years after treatment, seedling (0.1 m5 heightB 0.5 m) and sapling (0.5 m5 heightB 2.0 m) height increment tended to decrease with increasing overstorey density at both sites for plots thinned from below, but the effect was not statistically significant. Cutting regime had a significant effect on seedling height increment year 5 after treatment at the northern site, and cutting regimen and overstorey density combined had a significant effect on saplings in years 5 and 6 after treatment at the southern site. Annual mortality rates were 2-7% for seedlings and 0-4% for saplings. Ingrowth past 10 cm in height during the 7 yrs after treatment was less than 20 seedlings per hectare and year at the northern site, and less than three at the southern site. [ABSTRACT FROM AUTHOR]