Epsilon Archive for Student Projects

Abstract

In Latvia, Norway spruce Picea abies (L.) Karst. is a common forest tree species. It is often regenerated with planting, mostly using genetically improved stock. Since the middle of the 20th century breeding measures are active aiming for higher productivity and stem quality. However, there is a lack of studies related to possible changes in growth dynamics when using genetically improved material in Latvia. In addition, growth modelling of particularly young stands has gained attention only in recent years.
The aim of the study was to test a Swedish model for individual tree height growth for young Norway spruce stands in Latvian conditions. Data from four young genetic trials in Latvia were used to investigate whether the model based on data from unimproved material could be used to predict the height increment. Stand level projections for full rotation length were done based on the height growth model’s results.
The height growth model intended for non-improved material predicted the height increment for genetically improved Norway spruce in Latvia with sufficient accuracy. No trends over estimated height increment and over improvement level were observed. Mean predicted genetic effect for the highest genetic entries was 0.17. For projected full rotation length, best genetic entries had on average by 11 % higher mean annual increment (MAI) and by 15 % higher net present value. Final felling age was decreased by 9 % comparing to group of the worst performing genetic entries. Rotation length for projected sites varied from 45 to 53 years. Final felling age according to economic maturity was estimated to be reached 5 -14 years earlier than culmination of MAI. First commercial thinning could be applied, when stand was on average 23 years old.