Stem Volume Increment after Group Shelterwood Cutting in Scots Pine Stands in Myrtillosa Forest Type

There are only a few studies on the reaction of stands after a group shelterwood cutting. The research tasks were to find out whether an additional increment is formed in the retained part of the stand after group shelterwood cutting; after how many years following cutting the gaps does the additional increment of the retained part of the stand begin to form; if there are differences in additional increments for trees located at a variety of distances from the gap edge; if the storm of 2005 has affected the additional increment of trees. The study was done in five Scots pine (pine) stands, each roughly 110 years old and located within Myrtillosa forest type. In each stand, 2-3 gaps were selected. Around each gap four plots were measured in the uncut part of the stand. In each plot pines were sampled with an increment borer. At least 40 trees in 5 control stands were sampled with an increment borer as well. An additional increment method elaborated by I. Liepa was used in order to determine the response of trees to the gaps. In the uncut parts of the stand additional increment was found to be positive in the first years after group shelterwood cutting for trees closer than 7 m from the gap edge. Six years after cutting the cumulative additional increment in the parts of the stand closer than 7 m from the gap were 2 to 5 times greater compared to the parts of the stand at a distance greater than 7 m, and the differences were significant (at the 95 % confidence level) in 4 of 5 stands. There was a trend that in the year 2005 after the storm, additional increment and tree ring width decreases. However, this trend was not significant (p > 0.05), and independent to the distance from the edge of gap.