Browsing by Author "Karjalainen, Johanna"

The purpose of this study was to find out the effect of different seed tree densities on natural regeneration and height development of pine (Pinus sylvestris) in Finnish Lapland. There was no soil preparation done in the stands. An additional aim was to find out the effects of understory vegetation on pine seedling establishment. The purpose of preparatory cutting is to prepare the stand for natural regeneration by enhancing the conditions for good seedling establishment and improve the seed production of the mature trees before the actual regeneration cutting. It also decreases the costs of regeneration in the low-productive and slow-growing forests in Finnish Lapland. The study was established in year 2004 on four different areas in Lapland. The replications were conducted for every area in the years 2005 and 2006.The period of measurement in every replication was 8 years. The examined seed tree densities were 50, 150, 250 stems per hectare and a non-thinned control that demonstrated the initial state of the stands. The data consisted of four hierarchical levels, which were area, replicate, treatment (seed tree densities) and experimental plot. The density model was a generalized mixed model and the height model a general linear model. The best result in seedling establishment was achieved in seed tree density of 50 and 150 stems per hectare, where the requirements for the density of the forest law (1200 seedlings ha-1) was reached in 4‒5 years after the preparation cutting. The amount of the seedlings at the end of the measurement period, did not on an average reach the recommended seedling densities (4000‒5000 seedlings ha-1). The seed tree density of 250 stems per hectare, did not reach either of these requirements for density. In the control plot, the average seedling density was 1500 seedlings per hectare at the end of the measurement period. The variables affecting seedling establishment were interactions between the see tree densities and time, thickness of the moss- and lichen cover and the coverage of lingonberry. Factors affecting the height development of pine seedlings were age of the seedling, interactions between seed-tree density and seedling age and the average density of the seedlings on the plot. Height increased clearly best when seed-tree density was 50 stems ha-1. There were no difference between densities 150 stems per hectare and control. The height development was slowest in the density of 250 stems per hectare.