Abstract: Climate change is expected to alter the population dynamics of pioneer tree species and their planned use in sustainable forest management, but we have a limited understanding of how their demographic rates change in response to climate changes during ecological restoration. Based on 12 years of demographic data for a pioneer tree species (Pinus massoniana) censused in three plots that correspond to three stages of ecological restoration in southeastern China. We built integral projection models (IPMs) to assess vital rates (survival, growth, reproduction) and population growth in each plot, then evaluated demographic changes to simulated changes in seasonal mean temperature and precipitation in the current and previous census period. The plot representing the medium restoration stage had the highest population growth rate (λ = 0.983). Mean population survival probability increased with ecological restoration, and reproduction probability was significantly suppressed at the high restoration stage. Survival is always the most important vital rate for λ, and climate affects λ primarily via survival at each restoration stage. The current spring temperature was the most critical climate variable for λ in the low and medium restoration stages, and previous summer temperature was most critical in the high restoration stage. Simulated warming leads to a decrease in the stochastic population growth rate (λs) of P. massoniana in every stage. These findings suggest that during ecological restoration, P. massoniana responds to habitat change via modified demographic performance, thus altering its response to climate change. Despite diverse responses to climate change, the persistence of P. massoniana populations is facing a widespread threat of warming states at each restoration stages.

Key words: Climate change, Demographic performance, Ecological restoration, Integral projection models, Pioneer tree species