Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2019

Erindi/veggspjald / Talk/poster V62

Woolly willow: an ecosystem engineer in Iceland?

Höfundar / Authors: Þóra Ellen Þórhallsdóttir (1), Kristín Svavarsdóttir (2)

Starfsvettvangur / Affiliations: 1. University of Iceland, 2. Soil Conservation Service of Iceland

Kynnir / Presenter: Vigdís Freyja Helmutsdóttir

The native Icelandic flora contains relatively few woody species, with woolly willow (Salix lanata) being among the most common shrubs. I propose that it may act as an ecosystem engineer, a species with a physiological impact, often beneficial, on other species through modifications of the biotic or abiotic environment. Woolly willow deposits great quantities of leaf litter which may enhance the activity of soil microbes in early successional ecosystems. On land with low vegetation, snow is blown away by strong winds but remains inside and on the lee side of willow bushes. Thicker and longer-lasting snow cover may reduce winter frosts, freeze-thaw cycles and desiccation due to cold winds, significantly ameliorating local microclimate. During the growing season, the bushes may also provide shade and raise the humidity of the surrounding air. To test these hypotheses, two field sites were selected, the early successional outwash plain Skeiðarársandur (80 m a.s.l.) and mid-successional grassland with sparse willow bushes on Skaftafellsheiði (380 m a.s.l.). A standardised approach was used to measure the decay rates of organic material in the soil, called the Teabag index. Temperature and moisture were monitored at ground level last summer, and diurnal temperature fluctuations are recorded this winter on transects at increasing distances from the bushes. The results will contribute to better understanding of woolly willow ecology and promote it’s use for restoration in Iceland.