From current to potential distribution: the case of Taxus baccata(Taxaceae, Pinales) on the island of Sardinia (Italy)

Abstract

Taxus baccata is a relic-declining species, especially at the southern edge of its natural distribution. On the Island of Sardinia, we found 237 locations where yews grow, being indifferent to substrates, preferring moist sites with northern aspects and with an elevation range of 695–1,225 m a.s.l. We applied the Maximum Entropy algorithm (MaxEnt), using 202 field-based sites and 19 bioclimatic variables, to model the present potential distribution. Our model showed high levels of predictive performances with significant values of AUC (training, 0.962; test, 0.963). Annual precipitation, mean temperature of the warmest month and isothermality were the key drivers for the distribution of yew in Sardinia. The response curves showed that T. baccata prefers annual mean temperatures ranging from 8.65 to 12.55 °C and annual mean precipitation from 770 to 1,085 mm. Most potential suitable conditions were found in northern and central Sardinia. We also modelled future habitat suitability for T. baccata under two different scenarios (ssp245 and ssp585), highlighting a predicted drastic reduction, up to >95% in the worst scenario, of the habitat suitability for yews by the end of this century. This is related to climate change and poses increasing concerns about the future of yews in Sardinia.

Keywords:

• Climate change
• common yew
• habitat reduction
• mediterranean
• temperate bioclimate

Acknowledgements

We acknowledge all the people who helped in the field research of yew growing stations, especially Salvatore Barrili, Venanzio Basciu, Mario Brundu, Matteo Cara, Angelino Congiu, Antonello Deidda, Giuseppe Demurtas, Mario and Michele Fancello, Giovanni Manca, Gesuino Muggiri, Ernesto Nieddu, Alessandro Ruggero, Domenico Ruiu, Ciriaco Sannìo, Carmine Scudu, Giovanni Simoncini, Alessia Tatti, Fabrizio Tatti, Giovanni Urrai for reports and help in field search; the Agency FoReSTAS for logistic and staff support. GC gratefully acknowledges Sardinian Regional Government for financially supporting his PhD scholarship (POR Sardegna FSE - Operational Programme of the Autonomous Region of Sardinia, European Social Fund 2014-2020 - Axis III Education and training, Thematic goal 10, Investment Priority 10ii), Specific goal 10.5.12. This research is funded by EU project 101071300 Sustainable Horizons (HORIZON) and by FEDER, Junta de Andalucía-Consejería de Economía y Conocimiento. Proyecto UHU-1262837.

Disclosure statement

No potential conflict of interest was reported by the author(s)

Additional information

Funding

This study is supported by POR Sardegna FSE - Operational Programme of the Autonomous Region of Sardinia, European Social Fund 2014-2020 - Axis III Education and training, Thematic goal 10, Investment Priority 10ii), Specific goal 10.5.12. This research is funded by EU project 101071300 Sustainable Horizons (HORIZON) and by FEDER, Junta de Andalucía-Consejería de Economía y Conocimiento. Proyecto UHU-1262837.