Browsing by Subject "woody shrubs"

Due to climate change, the period with snow cover is shortening and the amount of snowfall is decreasing in the boreal region. In Finland, even the probability of snowless winters is increasing in southern and coastal areas of the country. Bilberry (Vaccinium myrtillus) is a keystone species of boreal forests and adapted to overwinter under insulative and protective snow cover. The effects of changing snow cover on bilberry are studied more in Artic and alpine ecosystems but are not well known in forest environments. In this master’s thesis, the effect of snow cover on growth and performance of bilberry was studied in field conditions using snowless treatment area and control area with natural snow cover in a forest environment in Southern Finland. The experiment was carried out during two consecutive winters between the years 2020 and 2022. In the snowless treatment area, the snow shelters prevented snow reaching the ground and shrubs overwintered without protective snow cover, which exposed them to lower air and soil temperatures. Shrubs at the control area overwintered under natural snow cover. Bilberry samples were collected, and field measurements were done in late August 2022. At the field, the number of dead ramets per square meter and the proportion of dead shoots per ramet were counted. In the laboratory, the elongation growth, leaf area and mass, and specific leaf area (SLA) were measured for growing season 2022, and the stem diameter growth was measured for growing seasons 2021 and 2022. After two consecutive snowless winters, the shoot and ramet mortality increased in snowless treatment area compared to control with natural snow cover. The length of an average shoot increased and the number of living shoots per ramet decreased in the treatment area compared to control. The treated ramets also had greater leaf area, leaf mass, and SLA. This indicates changes in bilberry’s resource allocation, and ability to compensatory growth after winter damages. However, increased mortality could lead to decrease in bilberry coverage in forest understory in a long-term. Changes in bilberry growth and performance can have unpredictable and complex effects on forest ecosystems, and there is a need for future research to show how longer snow-free periods and increased cold stress affect this keystone species in boreal forests.