Using species environmental niche overlap to quantify value of botanical garden accessions and ex situ habitat suitability

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Christine R Rollinson and Shiven Shah, Center for Tree Science, The Morton Arboretum, Lisle, IL, Shiven Shah, Hinsdale Central High School, IL, Shannon M. Still, UC Davis Arboretum & Public Garden, Davis, CA, Emily Beckman, Global Tree Conservation, The Morton Arboretum, Lisle, IL

Background/Question/Methods
Living collections in botanical gardens and arboreta are often used to demonstrate species biodiversity and ex situ conservation. However, resource limitations and habitat suitability limit the breadth and depth of species that can be captured in their collections. Evaluation of the ecological habitat or species niche diversity plus overlap with growing conditions presented by a garden can facilitate optimization of collections curation protocols. We used ordination methods to quantify the relative niche space of taxonomic collections and calculate the potential value of individual species or populations conservation at The Morton Arboretum in Lisle, IL. In our approach, the value of existing accessions or potential acquisitions is quantified based on their overlap or dissimilarity. Additionally, the habitat suitability of The Morton Arboretum under current and future climate change conditions can be quantified by evaluating the distance in niche ordination space from each potential accession. Here, we will present the results of an ecological valuation approach for The Morton Arboretum’s Quercus, Ulmus, Tilia, and Malus collections using occurrence points from public data repositories combined with global data on soil conditions and climate variability.
Results/Conclusions
A preliminary principal components analysis (PCA) of the soil texture, soil chemistry, precipitation regime, and temperature was performed for 102 Quercus species of interest for conservation in The Morton Arboretum’s living collections. In this PCA, the first two components accounted for 53% of the variance (28% and 25%, respectively) in environmental characteristics of approximately 1 million occurrence points publicly available for these species. PERMANOVA analysis demonstrates species segregation in environmental space, with the first PCA component being primarily controlled by climatic variables and soil conditions more strongly associating with the second component. Dominance of climate variability in explaining variance in the first component indicates that both present and future climate is a key consideration for selecting the suitability of locations for species ex situ conservation. However, appropriateness of this method for determining suitability of ex situ habitat suitability needs to be compared to existing collection occurrence and performance records. As all data used in analyses were from freely available global datasets, this method is potentially useful in maximizing the utility and representation of ecological habitats for botanical collections or other conservation strategies.