Regeneration from seeds in a temperate native flora: A climate???smart and natural???capital???driven germination risk modelling approach

Societal Impact StatementExceptionally rainy winters and hot-dry summers are becoming the new normal around the United Kingdom. The effects of these climatic changes can already be seen in forests and grasslands, agricultural fields and even in our own gardens, as native plants try to keep pace with them. In this study, the seed germination of the native flora of Wakehurst, in the Southeast England, was analysed to identify potential threats to the long-term persistence of selected species, which are part of the natural landscape of this area. Recommendations are provided for ecological restoration interventions which aim to maintain the different potential benefits those plants can provide to people. Seeds play an important role in plant adaptation to human-driven climate change. In this study, we applied a multilevel modelling of thermal germination responses of native temperate plants, to understand how global warming could affect their reproduction and the potential benefits they provide, as part of their natural capital.We identified Wakehurst (Southeast England, UK), as our study system. We modelled thermal seed germination parameters of the native flora as a whole and according to different uses categories (e.g., medicinal or food plants), through a phylogenetic meta-analysis of publicly available data from Kew's Millennium Seed Bank (MSB). We also carried out a comparative germination study for MSB seed lots of 20 selected species. Finally, we quantified the germination risk, by comparing current and predicted environmental temperatures with thermal germination parameters at flora, uses categories and species level.Under future climatic scenarios, germination of the native flora will be at higher risk in spring than in autumn. Fitted quadratic models, although affected by phylogeny, did not show major differences among uses categories. Species with a narrow window of cold germination temperatures could be more at risk than those with warm optimal temperatures. Restoration activities should target species from phylogenetically clustered uses categories, to avoid losing their benefit provisions, and implement climate-smart seed sourcing for high-risk species.This multilevel germination modelling approach, based on collections and available data from conservation seed banks, can be applied to selected floras and regions to inform climate-smart ecological restoration activities, while accounting for their natural capital.