engleski

Niche characteristics of Pedunculate oak (Quercus robur L.) along the species distribution range in Europe

Pedunculate oak (Quercus robur) is a widely distributed and one of the most valuable European hardwood tree species, both economically and ecologically. We here investigated distribution patterns and niche variation of Q. robur over the large geographical scale within the species entire distribution range. To explore which environmental factors influence the species occurrence we first built an ecological niche model for Q. robur based on 239 822 occurrence points obtained from various sources and a set of 14 environmental predictors selected based on their ecological relevance, excluding highly correlated ones. Based on the resulting model, available species distribution maps from literature and species postglacial recolonization history we defined three groups of occurrence points along the northeast- southwest gradient: species distribution centre, north and south range margin. We then explored how niche occupation (realized niche) of Q. robur changes within the available environmental space characterized with the selected variables along the defined gradient. Finally, we compared niche width in the distribution centre with the northern and southern range margins. Niche width was estimated using the range of values for each of the most important environmental variables (selected based on their contribution to the model) across all points occurring in the three distribution areas. We show and discuss ecological niche differences between central and marginal stands of this still ecologically intriguing species.

ecological niche; Quercus robur; range margins; available environmental space

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