COSST: A tool to facilitate seed provenancing for climate-smart ecosystem restoration

Selecting the best seed sources is a key step in ecological restoration planning especially under climate change. Seed-provenancing strategies include composite, aiming to reproduce natural gene flow; predictive, focusing on future climate adaptation; and climate-adjusted, a combination of composite and predictive. Yet, implementing different seed-provenancing principles remains a challenge. To fill this methodological gap, we developed the Climate-Oriented Seed-Sourcing Tool (COSST), a tool built in R capable of suggesting priority areas for seed sourcing according to composite, predictive, or climate-adjusted strategies, as well as the restoration site and focal species. The tool derives its inputs from species distribution models, which require occurrence and climate data only. COSST accommodates multiple climatic variables, weights the variables according to species-specific sensitivities, and accounts for uncertainties between climate forecasts. We demonstrated the flexibility of COSST using Caryocar brasiliense (pequi), a tree native to the Brazilian Cerrado, as a case study. The tool identified optimal areas for collecting C. brasiliense seeds and estimated the proportion of seeds to be sourced from various suppliers. We made available an R code for running COSST along with a Shiny application for data visualization. Synthesis and applications. Our tool can guide where to source seeds for species lacking range-wide information on genetic structure, which is the case for a substantial proportion of the tropical flora, where ecosystem restoration is of paramount importance.