Ex situ conservation and species distribution modelling: what the latter can and what cannot predict

The results of ex situ cultivation of rare and threatened species of local flora in botanical gardens can be a viable source of information for assessing the species’ climatic niche and making predictions about species’ potential suitable habitat. This study analyzed a potential niche for species representing three genera: Tulipa, Eremurus , and Allium (23, 25, and 21 species, respectively), for which the results of their cultivation in Tashkent Botanical Garden are known. The analyses had two objectives: (1) to evaluate for each species the possibility of predicting the success of cultivation solely from its occurrence records, and (2) to predict the suitable habitat for the creation of new populations in situ using the location of the garden among the occurrence records. Species distribution modelling (SDM) turned out to be too conservative in predicting the suitability of a garden location for creating living collections to be of practical value. Although neither the set of climatic + topographic + soil variables nor the set of climatic variables only made any false predictions of the garden location suitability for species whose introduction failed, the percentage of their correct predictions of the location suitability for successfully introduced species was well below 50%, suggesting a very low predictive power of this approach. Similarly, none of the environmental variables used in this study could satisfactorily discriminate species whose cultivation was successful from those whose cultivation in the garden failed. In contrast, SDM utilizing garden species cultivation data to predict suitable habitats in situ turned out to be useful. These results show that even a single occurrence point of the garden location, when added to the occurrence points of species natural populations, can significantly increase the area predicted by SDM as suitable. This has important conservation implications because the choice of potential locations for species translocation is always limited, and the species’ environmental requirements are often poorly known.