The species richness pattern and its component dependence of two typical secondary forests in central China

Abstract

Secondary forests dominated by Masson pine (Pinus massoniana, MPF) and Chinese fir (Cunninghamia lanceolata, CFF) are widespread in the subtropical areas of China, whereas their biodiversity patterns receive far less attention than biomass patterns. This study aimed to gain insights into the species richness (SR) patterns of the typical natural secondary MPF and CFF in central China, with the old-growth zonal vegetation (evergreen-deciduous broadleaved mixed forest, EDBMF) used as reference. We established 45 plots across the three forest types and surveyed all the stems with a diameter at breast height ≥ 1 cm in each plot. Specifically, we compared the local (plot-level) and rarefied SR among the three forest types; at the metacommunity level, we examined the dependence of the rarefied SR difference between MPF and CFF on the number of individuals (N), species abundance distribution (SAD), and conspecific spatial aggregation (CSA); and we also assessed how local SR changed with N and species dominance within MPF and CFF. Our results showed that MPF had local and rarefied SR levels higher than CFF and closer to EDBMF. Both N and SAD had positive contributions to the high rarefied SR level of MPF (relative to CFF), while CSA had negative contributions. The N contributions were significant and dominated at most scale, the SAD contributions were considerable and significant at large scales, and the CSA contributions were significant at small and intermediate scales. Moreover, within MPF and CFF, local SR changed with N more generally than with species dominance. In conclusion, at both local and metacommunity level, MPF was generally more species-rich than CFF, and this difference remarkably depended on N, suggesting that the habitat conditions of CFF may be stressful for species persistence. Our findings also have several implications for biodiversity research and ecosystem management.