The spatial growth pattern and directional properties of Dryas octopetala on Spitsbergen, Svalbard

Abstract: Exposed, well-drained and nutrient poor areas on Spitsbergen are mainly covered by a plant alliance typical for Svalbard, the Caricion nardinae. Caricion nardinae is a circum-polar alliance, which is dominated by the creeping, ever-green dwarf-shrub [i]Dryas octopetala[/i]. On the beach flats of western Spitsbergen, Jonas Åkerman (1983) observed in 1979 the plant [i]Dryas octopetala[/i] growing in an unusual pattern in the form of half-moons. In the summer of 2015, Veiko Lehsten visited the same area as Åkerman documented in the late 1970s, with the purpose to further investigate this vegetation pattern and the factors causing it. Åkerman suggested in 1983 that the wind was the main contributing factor to the unusual growth of [i]Dryas octopetala[/i]. This thesis will attempt to verify this suggestion and also evaluate the likelihood of other factors playing a role in this phenomenon. This will be done by developing a method for assembling images taken by a standard camera, and thereafter describe and investigate the vegetation patterns of [i]Dryas octopetala[/i] as well as its potential changes over time. The results show that [i]Dryas octopetala[/i] was, at the study sites, directed towards north-northeast, with Åkerman’s data from 1979 being directed a little bit more towards northeast than the vegetation in 2015. The vegetation in both study areas grew close to each other and had a dispersed distribution. This thesis was not able to prove that the prominent wind direction is causing the unusual growing forms and pattern of [i]Dryas octopetala[/i] but it is still the most likely cause after reviewing other potential factors. The method for assembling pictures was time consuming and did not give a perfect final image but it resulted in an acceptable approximation of the study area.