Predicting allergenic tree species distributions from the Belgian soil map and a gridded presence database of vascular plants

Abstract

Tree pollen are a major source of aeroallergens which trigger allergic reactions in sensitized people. Climate change increases the burden of tree-related allergic diseases as higher temperatures and changes in precipitation patterns increase the duration and intensity of pollination of allergenic tree species such as birch (Betula spp.). Information on the distribution of allergenic tree species may be helpful to quantify the potential exposure to tree allergens but to date such detailed species distribution maps are lacking. To address this issue, we modelled the probability of occurrence of the thirteen most prominent allergenic tree species in Flanders. We used maximum entropy modelling to calculate probabilities of tree species occurrence based on presence-only data sourced from an open access databank of plant species distributions in Flanders and environmental variables related to the potential natural distribution of tree species in Flanders. Soil texture was used as a proxy for soil fertility and soil drainage class as a proxy for soil moisture. Both variables were derived from the Belgian Soil Map resampled to 1×1 km grid cells. We used landscape types from the Biological Valuation Map and average lowest and highest ground water from Ecoplan as additional environmental predictor variables. Species distribution models were more meaningful than a random distribution for all thirteen allergenic tree species. The Area Under Curve (AUC) varied between 0.53 for Salix and 0.92 for Platanus. Texture class and drainage class were consequently among the most important variables contributing to the models. Probabilities of occurrence were converted to distribution maps using varying expert-based thresholds for the different allergenic tree species. A combined alpha diversity map of allergenic tree species shows hotspots of allergenic tree species diversity in the Campine region and a lower diversity in more industrialised or agriculture dominated parts of Flanders.status: publishe