Epsilon Archive for Student Projects

Abstract

Varje år orsakar rotrötan stora ekonomiska förluster för skogsbruket i Sverige dels genom att grantimmer nedklassas till massaved eller brännved, men även genom de tillväxtförluster som rotrötan orsakar. Att våra skogar drabbas av rotröta är inte något nytt, man kände till detta redan under tidigt 1800-tal. Men hur har dess förekomst i granbestånd förändrats i Norrland respektive Svealand och Götaland förändrats de senaste decennierna? Att undersöka det var syftet med denna studie.
Analyserna i studien gjordes med hjälp av riksskogstaxeringens data. Detta datamaterial samlades in under åren 1983-2013 från deras tillfälliga provytor. På dessa provytor togs borrprov i brösthöjd där man noterade om det förekom röta eller ej. Det datamaterial som användes i analyserna var av bestånd med minst 70 % granvolym och uppdelat i två grupper (områden); Svealand och Götaland respektive Norrland.
Analyserna av datamaterialet som erhölls utfördes i Excel. De analyser som utfördes var trendanalyser med glidande fem-års medelvärdet. Trendanalyser gjordes för att se om det kunde finnas något linjärt samband mellan rötad granvolym och år.
Resultatet av studien påvisade ingen tydlig signifikans på en ökad trend när det kommer till procentuell andel rötad volym. Dock kunde man se att det fanns skillnader i volymen rötad gran, att det har blivit en större volym i Svealand och Götaland, medan det hade blivit lägre i Norrland.

Every year the root rot is causing major economic losses for the forest industry in Sweden, partially because saw logs become downgraded to pulpwood or firewood, but also due to the growth losses that the root rot causes. The fact that our forest is affected by root rot isn’t something new; they knew that already during the early 1800s. But how has its presence in spruce stand changed in Norrland in the recent decades? The aim of this study was to investigate that.
The analyzes in this study were made with the help of the National Forest Inventory data. The data were collected during 1983-2013 from their temporary sample plots. On these plots, the stems were drilled at breast height and it was noted if root rot was present or not. The dataset that were used in the analysis were stands with at least 70 % spruce of the total volume and the dataset were divided into two groups (areas). The first of the two areas were Svealand and Götaland and the other one was Norrland.
The analyzes of the data obtained was performed in Excel. The analyzes that were performed was a trend analysis with moving a five-year average. The trend analysis was done to see if there could be a linear relationship between root rot infected spruce volume and year.
The results of the study showed no clear significance of an increased trend when it comes to the percentage of root rot infected volume. However, you could see that there were a difference in the volume of root rot infected spruce, it has become a larger volume in Svealand and Götaland, whereas it had become lower in the north.