Ex situ cultivation entails high risk of seed dormancy loss on short‐lived wild plant species

Abstract

Abstract Changes in life‐history traits such as seed dormancy during cultivation of wild plant species in ex situ facilities could jeopardize conservation actions including revegetation and plant reintroductions, but the magnitude of these risks and their spread across different plant taxa is unknown. We explored whether plants cultivated in the Botanic Garden Meise differ in seed germination characteristics from plants from natural populations. Using a Bayesian approach of a phylogenetically informed generalized linear mixed model, we analysed germination tests of 72 herbaceous plant species from 27 plant families, originating from the cultivation beds in Meise as well as directly from wild populations. We investigated whether garden‐collected seeds differ in germination percentage, seed dormancy and germination speed from wild‐collected seeds. Furthermore, by analysing literature‐collected information of 24 life‐history traits, we sought to identify potential selection pressures causing these germination changes in order to refine conservation protocols and practices. We found a strong increase of germination percentage and a loss of seed dormancy in garden seeds compared to wild seeds across all species. However, these differences vanished with increasing storage time of the seeds as a result of decreased seed viability with seed ageing over time. Furthermore, traits associated with the life span of the species influenced the germination difference between cultivated and wild seeds, and short‐lived species were particularly vulnerable to the loss of dormancy, while no difference could be detected between wild and cultivated perennial species. Synthesis and applications. Through a multispecies approach, we show that dormancy loss is a common phenomenon in ex situ collections of short‐lived wild plant species. This has wide implications for the use and procedure of ex situ‐reared plant material for restoration and reintroduction measures. We suggest that effective dormancy breaking and temporal distribution of seedling plantation during propagation should be incorporated in restoration and reintroduction protocols to minimize unwanted changes in seed traits. Furthermore, we caution against the use of seeds from cultivated plants for basic seed ecology research such as germination requirements and seed storage behaviour.