A~simple model for predicting the global distribution of the N₂ fixing host genus Alnus Mill.: impact of climate change on the global distribution in 2100

Abstract. The importance of N₂-fixing plants has increased in last decades. Alnus (alder) is an important plant group because of its nitrogen fixation ability. Alders are generally distributed in humid locations of boreal, temperate and tropical climate zones, where the nitrogen fixation is an important nitrogen source for other plants. To model the nitrogen fixation by alder, data about the global distribution of alder is absolutely required. In this study a new method and model to predict the distribution of N₂-fixing genus on global scale is presented. Three linear functions were defined for the determination of climate area of alder locations. The distribution model was improved with the aid of the soil units from FAO-Unesco Soil Database, and vegetation types from Schmithüsen's biogeographical atlas. The model (Alnus-Distribution-Model, ADM) was also developed to predict the impact of climate change on alder distribution by using climate data of five relevant climate models (PCM, ECHam4, HadCM3, CSIRO2 and CGCM2), and four IPCC climate scenarios (i.e. A1FI, A2, B1 and B2) in 2100. The model covered basic approaches to understand the climate change effect on plant migration in the future.