Understanding how diverse species coexist in tropical forests is a challenging issue in community ecology. One prominent explanation is the density dependent hypothesis. It assumes that the strength of density dependence varies among species and that rare species have survival advantages because they suffer less conspecific neighborhood density effects compared with abundant species, thus it can promote species coexistence. However, we know little about whether or not species inherent ecological strategies drive the variation of density dependence among species. Therefore, we explored the relationship of variation of density dependence among species with species inherent life strategy (growth-mortality trade-off) in the tropical forest of Barro Colorado Island (BCI), Panama.
Results/Conclusions
We found that species with higher growth and mortality rates had stronger negative conspecific neighborhood effects on saplings, and vice versa. But for larger trees, species with faster growth and higher mortality rates showed lower strength of negative conspecific density dependence. A similar pattern was found for the interplay of heterospecific density dependence with the trade-off among species. Species with higher trade-off values were less impacted by negative effects on saplings from heterospecific neighbors. Conversely, faster growing species with higher mortality rates had higher positive heterospecific density dependence for juveniles. We did not find a significant linear relationship for phylogenetic density dependence and growth-mortality trade-off. Additionally, growth-mortality trade-off changed with life stages from saplings to adults. The growth-mortality trade-off for saplings had significant association with that of juveniles, but this association was not significant between saplings and adults. Species with slow-growing saplings can grow fast at juvenile and adult stages. These findings indicate that species life strategies of growth-mortality trade-off change with life stages and can drive the variation of density dependence among species across life stages. Our study contributes to understanding the driving mechanism of tree dynamic change by characterizing the relationship of density dependent survival with species inherent ecological strategies in tropical forests.