Habitat suitability modelling of Asphodelus bento-rainhae P. Silva using spatial multicriteria analysis

Asphodelus bento-rainhae P. Silva is a plant species belonging to the order of Liliales. This endemic plant occurs in central Portugal in an area of only 700 hectare on the northern slopes of the Serra da Gardunha (Fundão, Portugal). It is mainly present in north to northeast facing slopes and found in deep soils and open areas, where it is found at higher densities. It occurs along the edges of oak (Quercus robur and Quercus pyrenaica) and chestnut (Castanea sativa) forests, often reaching the herbaceous edges of these woods. Sometimes, it survives in pine forests of Pinus pinaster, mixed woods and slopes or roadsides and in lower abundances in scrubby vegetation. This species survival is threatened by forest fires and the conversion of woodland into cherry orchards, and the fruit growers’ extensive use of herbicides. The tree plantations, as well as urban sprawl, have decreased the extent and quality of its habitat. It is also confronted with invasive plants, such as Acacia dealbata. The mapping of the A. bento-rainhae habitat suitability index results on the integration of a set of biophysical factors using the ArcGIS 10.3 software, based on the Sectorial Plan for Natura 2000 Network and other literature concerning the species ecology. The data used included bioclimatic, soil and topographic variables, based on a digital terrain model (DTM). All the geographic themes (criteria) were classified into three suitability levels: unfavorable, less favorable and favorable. Based on the resulting reclassified themes, the Habitat Suitability Index (HSI) for A. bento-rainhae P. Silva was calculated using the Analytic Hierarchy Process (AHP). The fundamental concept of AHP lies in proceeding from a pairwise comparison of criteria to evaluate the weights that assign relative importance to these criteria. In the end, a map algebra was performed in order to obtain the final theme representing the habitat suitability for A. bento-rainhae. The results regarding the actual species distribution, obtained in the aim of fied work performed in the LIFE-Nature project “Asphodelus bento-rainhae - Measures to manage and preserve it" show a high correlation with the suitability values