Ex situ species conservation: Predicting plant survival in botanic gardens based on climatic provenance

Abstract

Living collections grown in outdoor landscapes within botanic gardens play an increasingly important role in ex situ species conservation, but there is little work predicting the survival of different plant species in these landscapes. Here we present an approach to predict the survival of plants grown from wild propagules in botanic gardens, based on climatic provenance. We developed mixed effects Cox models to relate plant survival to horticulturally informed measures of climatic differences between botanic garden landscapes and the wild distribution of plants. We fit these models to data on the survival of 1184 plantings of 410 species grown in the Missouri Botanical Garden (MBG, in Saint Louis, Missouri, USA) from wild propagules collected around the world. We detected major effects of growth form, minimum temperature of the coldest month, maximum temperature of the warmest month, and to a lesser extent precipitation of the driest month. Survival at MBG was predicted better by the climate of propagule collection localities than by the overall climatic distribution of species, suggesting local adaptation. However, there was substantial interspecific variation in survival among plants from similar climates. The best models predicted high survival for plants grown at MBG from propagules collected within broad latitudinal bands across non-tropical regions. We explore implications of these findings for the role of botanic gardens in ex situ conservation, and discuss the applicability of the approach we developed to enhance the capacity of living collections to represent species of conservation concern.