'Ulmus laevis' pallas, an endangered native elm

Researchers at the Universidad Politécnica de Madrid have confirmed by using DNA molecular markers that the Ulmus laevis species is native in the Iberian Peninsula.

A detailed study of the elm grove, carried out by the Forest Genetics and Physiology Research Group of the UPM within the Spanish Elm Program, explains the controversial issue of the origins of the Ulmus laevis. It was proved that using molecular makers of Nuclear and chloroplast DNA not only that the genetic variability of this population in our country is similar or even higher than the European population but also this species survived in diverse parts of the Iberian Peninsula during glacial periods, as suggested the presence of exclusive chlorotypes.

The Ulmus laevis is an elm that differs from the Ulmus minor by its fruit and because it is a rare species in Spain. Because of its low frequency, the Flora Ibérica journal considers that it is an introduced species, ascribing its presence to wildlife. However, the study has allowed researchers to locate of a larger number of populations of this species in our country than expected. In addition, other works conducted by the group have determined the distribution area and the ecology of this specie in Spain that were unknown so far.

The results suggest that Ulmos laevis inhabits areas of acid soils and water availability, while the common elm occupies naturally basic soils and overcomes some summer drought. Although this species is very susceptible to Dutch elm disease (a disease that wiped out 99% of the Spanish elm) this pandemic do not mean a high risk for Ulmus laevis due to that the beetles (Scolytus spp.) that spread the disease do not feel attracted by this species.

As a consequence of the fragmentation and the small size of populations caused by the demolition of its habitat by humans, and according to the criteria of the International Union for Conservation of Nature, Ulmus leaves must be considered a species in danger of extinction. Therefore, researchers from the UPM are demanding to develop strategies to preserve this species as its inclusion on the Red List of Spanish Vascular Flora in a way that these populations are protected by the state regulations.

According to the current law, Ulmus laevis is considered a native species, therefore it can be used in restoration projects and environmental improvements of riverbanks even in protected areas by the Natura 2000 network.