Integrated in situ and ex situ approach for Gentiana lutea L. ssp. lutea conservation

Gentiana lutea L. subsp lutea (hereafter G. lutea) is a long-lived geophyte, which has high medicinal value for the intensely bitter properties residing mainly in the root, being the main vegetable bitter employed in homeopathy and for the liqueurs production. G. lutea is presented in the Annex V of the Directive 92/43/EEC. In addition, it’s included in the List of endangered medicinal plants in the Annex D to the Council Regulation (EC) No. 338/97 of EU, whose purpose is the protection of plant species by control of their trade. Due to a lack of knowledge on the current G. lutea distributional information in Sardinia, Species Distribution Models (SDMs) could be even an important tool to limit search efforts by selecting the areas where field surveys are to be carried out for guiding discoveries of new localities and to evaluate the influence of extant and extinct localities. Once distribution knowledge was updated, further activities performed on representative localities, including ex situ and in situ studies were carried out. Firstly, our contribution to conserve this specie in Sardinia, included ex situ aspects that provided an alternative and complementary method for preventing immediate extinction and support further interventions. The experimental examination of the time when germination occurs in natural sites, the understanding of the seed behaviour in the soil and the investigation of the germination response under laboratory conditions. In particular, the isolated and on the boundary Sardinian population can differ genetically and morphologically from central populations because of their smaller population size and greater physical and ecological distances from the centre of the range, and may contain genotypes adapted to extreme environmental conditions; it is therefore important to check the effect on seed ecophysiology germination on small and spatial isolated populations. Previous studies have found that the germination of many mountain plants was promoted by cycles of cold-wet stratification that released seed dormancy in transient and permanent seed banks. In this way, dormancy played a key role in optimizing germination success by controlling the timing of germination. Thus, this research would contributed to this species conservation, suggesting the optimal protocol of germination and multiplication and, on the other hand, the information of the different kinds of seed dormancy. G. lutea is reported as being threatened not only by root harvesting practices, but also by global climatic warming due to its distribution, which is restricted mainly to the upper sectors of the mountains. Especially in mountain areas, climate warming is projected to shift species’ ranges to higher elevations. Plant species have responded to global warming through a generally accelerated phenology, enhanced growth and increased reproductive effort. Even fewer studies have addressed such response of the populations at the boundary of species range distributions which are thought to be particularly sensitive to climate change, hence it was evaluated the effect of anomalous temperatures (extremely warm) during the year of 2015 on phenology and reproductive successful. Monitoring the underlying drivers of this variation in phenological shifts will contribute to a mechanistic understanding of the biological effects of climate change. Finally, the criteria established by the IUCN that are widely employed as the gold standard for information on the conservation status of species were applied at regional scale for G. lutea. The assessment through the IUCN Criteria and Categories at global level was updated as Least Concern (LC) and at Italian level as Near Threatened (NT). Considering the regional level, the only previous assessment in Sardinia date to back to 1997 as Critically Endangered (CR), this work will contribute to an implementation of knowledge and conservation management for this taxon. An updating of local conservation status of G. lutea was thus provided by the analysis of its decline and comparing its potential suitable habitats based on the emissions scenarios presented by the Intergovernmental Panel on Climate Change (IPCC) for 2050 and 2070.