Environmental niche and distribution of six deciduous tree species in the spanish atlantic region

Abstract

Understanding the influence of environmental factors on the distribution of tree species is essential for developing management actions at regional level. We developed species distribution models for six European tree species to determine their potential niche in the Spanish Atlantic region, where deciduous forests are relatively well preserved. Data from the national Forest Inventory and topo-climatic and soil variables were used to construct distribution models by using Generalized Linear Models. The main factor accounting for the current geografic distribution of the selected species were minimum winter temperature and mineral fertility of soils. Suitable habitats for Quercus petraea and F. sylvatica were mainly high-altitude areas with low minimum temperatures. In contrast, Q. robur and C. sativa were restricted to low altitudes and warmer conditions. Betula pubescens was not influenced by the elevation, probably because its adaptation to Atlantic conditions, though its distribution was associated with low fertility soils. Although the submediterranean Q. pyrenaica was positively influenced by the slope, model performance was poor for this species, possibly because of the truncated environmental range of the species in the study area. The findings suggest that temperature rather than moisture is shaping the distribution of deciduous trees at the southern limit of the Atlantic biogeographic region. Strong elevational difference between the warm coast and the cold mountains may determine the geographical disjunction between Q. robur and Q. petraea in southern Europe.