Sinking Islands in the Sky: Projecting the future distributions of Ranunculus glacialis, Poa flexuosa and Trisetum spicatum in Jotunheimen, Norway under climate change

• Main Author: Throndsen, Sigbjørn
• Format: Master Thesis
• Language: English
• Published: 2018
• Subjects: species distribution modelling; maxent; alpine ecology; alpine plants; climate change; distributional shift; Norway; Ranunculus glacialis
• Online Access: http://hdl.handle.net/11250/2558111

Department of Environmental Sciences, Faculty of Engineering and Science WESTERN NORWAY UNIVERSITY OF APPLIED SCIENCES Master Thesis in Climate Change Management GE4-304 Introduction Changes in species distributional range as a response to climate change is well documented. The changes are substantial along elevational gradients, and the general trend is that the warming has caused an upward elevational shift for several alpine plants. The aim with this study is to project changes in (1) suitable habitat, (2) elevational range (3) and the level of habitat fragmentation for Ranunculus glacialis, Poa flexuosa and Trisetum spicatum under two different climate change scenarios in Jotunheimen. Method Species presence records and five pre-selected predictors, selected from a set of topographic and climatic variables, were used to model the species distributions. Projections for the year 2070 under climate change scenarios RCP4.5 and RCP8.5 were derived from the models of the current distributions using the Maxent software. Changes in suitable habitat were analyzed using ArcGIS. Results All species were projected to lose suitable habitat with an average reduction of 70 % under RCP8.5 and 48 % under RCP4.5. All species were projected to disappear from their lowest elevations, and the average elevational range contraction for the species was 524 m under RCP8.5 and 243 m under RCP4.5. The level of habitat fragmentation was projected to increase with an average increase in patch number of 72 % and 67 %, and an average reduction in patch size of 82 % and 65 %, under RCP8.5 and RCP4.5 respectively. Discussion All model results have a good or fair predictive performance measured by their AUC values. A sampling bias correction was done using locations of species from the same genus as the focal species (target group) as background points. There was large differences in the future projections between the models with no sampling bias correction and the models with correction. As the corrected models might “over” correct due to ...