Browsing by Subject "Kaistalehakkuu"

The goal of this study was to estimate the success of natural regeneration of Scots pine, on unscarified strip cut areas on forestry-drained dwarf shrub peatland sites, as to find the explanatory factors affecting regeneration. The sites were in Southern Finland and the seedling inventory was conducted 3–4 growing seasons after the cutting. On two sites the seedling densities were satisfactory (3000–6300 ha-1) but the spatial distribution was uneven, as the share of empty plots was 41–57 %. On the remaining two sites the regeneration had either failed or was unsatisfactory, with seedling densi-ties 600–1000 ha-1. The most important variables explaining seedling density were the soil scarification-effect of the logging trails and the water table level. The seedling density on the logging trails was 3–21 fold, depending on the site, compared to surfaces outside the trails. The small spots of bare peat were remarkably well-stocked. The explanatory value of variables for the water table level were weakened by the limited number of dipwells. However, it seems the development of seedlings on a clear-cut strip would require an average water table level deeper than 30 cm from the ground level, during growing sea-son. Of the vegetation groups, dwarf shrubs clearly had a negative impact on seedling density. In relation to the cover per-centage of the forest floor, bog mosses hosted more seedlings than upland mosses. The abundance of cotton grass raised seedling density and the longest seedlings grew in the vicinity of cotton grass. The reason was assumed to be the early colonization of the logging trails by both species. A thicker humus layer lowered the seedling density. Among other variables growing season temperature seemed to explain seedling emergence better than seed years. In addition to Scots pine seedlings, regression models are also presented for seedlings of broad leaves and conifer germinants. Common denominators for the occurrence of different groups of seedlings were the positive effect of log-ging trails and bare peat and the negative effect of dwarf shrub cover. According to the results some level of soil prepa-ration seems necessary to achieve a satisfactory level of natural regeneration. The thesis also proposes a forecast model for the occurrence of Scots pine seedlings, which is derived from the rela-tionship between the features of the uncut stand and the seedling densities of the clear-cut strips. According to the forecast model of the average water table level, the water table level preceding a strip cut should be at least -42 cm and preferably deeper, as a prerequisite for strip cutting. The sphagnum moss model states that sphagnum mosses should not cover far more than 5 percent of the forest floor. A higher water table level or a wider sphagnum cover on uncut strips, predicts a water table level too high for the development of Scots pine seedlings on clear-cut strips.