Líffræðifélag Íslands
Líffræðiráðstefnan 2015

Erindi/veggspjald / Talk/poster E26

Plant diversity in Icelandic tundra – no evidence for an effect even 60 years after cessation of sheep grazing

Martin A. Mörsdorf (1,2,3), Virve T. Ravolainen (4), Nigel Gilles Yoccoz (2), Þóra Ellen Þórhallsdóttir (1), Ingibjörg Svala Jónsdóttir (1,3 )

1. University of Iceland, 2. UiT The Arctic University of Norway, 3. University Centre in Svalbard, 4. Norwegian Polar Institute

Kynnir / Presenter: Martin A. Mörsdorf

Tengiliður / Corresponding author: Martin A. Mörsdorf (mam28@hi.is)

Plant communities in Arctic tundra are strongly shaped by topography but topographically driven within- (alpha) and between (beta) community diversity can be modified by grazing ungulates such as sheep. Although the great majority of tundra ecosystems is grazed to some degree, the potential of ungulates to alter diversity structure that is defined by topography is poorly investigated. Here we assessed alpha and beta diversity within Icelandic tundra valleys and compared presently grazed versus un-grazed valleys to address effects of cessation of sheep grazing. Assessments were conducted on different spatial scales, being determined by topography. Topography was the main driver of alpha and beta diversity in our valleys. Landforms of different curvature and contrasting elevations had the strongest effects on species richness. High species richness was associated with a high prevalence of forb species. On the contrary, we found no difference in diversity patterns between grazed and un-grazed valleys, although we assessed the strongest existing grazing contrasts in Icelandic tundra ecosystems. Decades after cessation of grazing, our results suggest slow recovery within those valleys, which has major implications for management and conservation efforts of plant diversity in tundra ecosystems.