Naturally regenerated birch and planted Norway spruce : comparison with soil moisture maps

Sammanfattning: Nowadays, when Lidar technologies are developing so fast, it is a lot easier and efficient to use information in forest management processes. Such technologies allow forest owners to make more rational and clever decisions in forest management taking into account different factors which in the past where not possible to use. Firstly, soil moisture maps from Södra were obtained and used to define stands where groundwater level is high and could affect regeneration and soil preparation. Then 30 clear-felled stands, larger than 2 ha, were selected which have been harvested in 2012 and regenerated with Norway spruce, so that seedlings would have overgrown ground vegetation and effects of high groundwater could be seen. After that a systematic grid with 25 m spacing was created in ArcGIS program. For stands larger than 5 ha, 50 m spacing between sample plots was used. In each selected stand sample plots were created according to the grid, with radius of 1,78 m (10 m2). Due to systematic grid, sample plots will represent both, areas in the stand where groundwater level is acceptable and areas where groundwater level is estimated to be high. In each sample plot all seedlings were counted and for each group average height was measured. Seedlings were divided by species and their origin, although, only Norway spruce occurred as planted species. In total, 791 sample plots were measured. All plots were grouped by their mean soil moisture values representing wet/mesic (value 0 – 0,9) and mesic (value 0,91 – 1), thus observed scarification was also taken into account. Results show that birch natural regeneration is very strong and had highest seedling mean density and height in wet/moist plots where soil scarification was not observed. For planted Norway spruce highest density and mean height was observed in mesic plots where soil scarification was carried out.