Demographic performance of a pioneer tree species during ecological restoration in the soil erosion area of southeastern China

Abstract

Pioneer species are crucial for the ecological restoration of degraded forests, but what drives variation in their demographic performance is still unclear. Here, we studied three populations of the dominant tree, Pinus massoniana , corresponding to three levels (low, medium, high) of ecological restoration of secondary subtropical forests. Vital rates (growth, survival, and reproduction) were censused during 2019–2020, and integral projection models (IPMs) were parameterized to evaluate the population growth rate (λ) of P. massoniana . The results showed that the survival probability of large-sized individuals, stem growth, and λ of P. massoniana increased as the ecological restoration progressed. In contrast, the survival rate of seedlings declined substantially. The reproduction probability of small individuals was more likely at low than medium/high restoration levels. Elasticity analysis showed that survival contributes most to λ and fecundity the least. λ was primarily determined by the high survival of seedlings/small trees and large trees in the low- and high-restoration level populations, respectively. Life table response experiments showed that increases in survival were mostly responsible for augmented λ during ecological restoration; hence, the high-restoration population had the highest λ due to a higher survival rate. This work shows P. massoniana is capable of undergoing life-history strategy shifts. Its high recruitment and survival of small individuals make it a suitable species for restoring forests, whereby large-sized individuals eventually maintain populations at low risk of mortality.