The influence of soil conditions on regeneration establishment for degraded secondary forest restoration, Southern China

► We proposed a method based on different species’ function grouping to deal with the contradiction between economic feasibility and ecosystem stability in secondary tropical forest restoration. ► The relationships between soil condition and different function group's species were analyzed and got satisfied results by redundancy analysis. ► We proposed three questions on degraded forest restoration in Southern China, and found a feasible way by solving these problems. ► This analysis could be used to determine suitable soil conditions for different restoration purposes. To assess the impact of soil conditions on regeneration establishment we chose three diversity indexes as quantitative indicators of the understory of degraded secondary tropical forest, and selected two different function groups of species for subsequent restoration management. By applying redundancy analysis (RDA) the factors affecting understory diversity and species richness and number of different function groups were investigated. RDA showed that soil conditions had a positive effect (all contribution rates exceeded 55%) in explaining regeneration diversity, grouped species richness and number. Soil available P were the main factors affecting understory diversity and species richness, while pH value and available K were the main factors affecting species number and target species. The response of regeneration to pH value, available P and available K were different. This analysis could be used to determine suitable soil conditions for different restoration purposes. The results should be useful for effective and scientific management of regeneration restoration in the future.