This study investigates the latitudinal patterns of conspecific negative density dependence (CNDD) in forest communities, a phenomenon where plants experience reduced performance when surrounded by similar species. The Janzen-Connell hypothesis posits that CNDD is more pronounced in tropical than in temperate forests, which could enhance community stabilization and species coexistence. However, previous studies have shown methodological limitations due to the use of static data. This study uses dynamic mortality data from 23 forest sites to assess CNDD patterns across different latitudes. Key findings include: 1. **No Latitudinal Gradient in Average CNDD**: While CNDD was widespread, it did not show a significant trend towards stronger CNDD in tropical forests. The average relative annual mortality increase due to conspecific density was 6.64% at all sites, with no significant difference between tropical and temperate forests. 2. **Stronger CNDD for Rare Tropical Species**: In tropical forests, rare and intermediate-abundance species experienced stronger CNDD compared to common species. This pattern was absent in temperate forests. 3. **Interspecific Variation in CNDD**: Interspecific variation in CNDD was high but not significantly different across latitudes, suggesting that CNDD's stabilizing effect on species diversity is not influenced by latitude. The study concludes that while CNDD is widespread and effective in controlling species abundances, its average strength does not increase significantly towards the tropics. However, CNDD plays a more significant role in structuring species abundance distributions in tropical forests, particularly for rare and intermediate-abundance species. These findings suggest that CNDD may contribute more strongly to the maintenance of local tree species diversity in tropical regions.This study investigates the latitudinal patterns of conspecific negative density dependence (CNDD) in forest communities, a phenomenon where plants experience reduced performance when surrounded by similar species. The Janzen-Connell hypothesis posits that CNDD is more pronounced in tropical than in temperate forests, which could enhance community stabilization and species coexistence. However, previous studies have shown methodological limitations due to the use of static data. This study uses dynamic mortality data from 23 forest sites to assess CNDD patterns across different latitudes. Key findings include: 1. **No Latitudinal Gradient in Average CNDD**: While CNDD was widespread, it did not show a significant trend towards stronger CNDD in tropical forests. The average relative annual mortality increase due to conspecific density was 6.64% at all sites, with no significant difference between tropical and temperate forests. 2. **Stronger CNDD for Rare Tropical Species**: In tropical forests, rare and intermediate-abundance species experienced stronger CNDD compared to common species. This pattern was absent in temperate forests. 3. **Interspecific Variation in CNDD**: Interspecific variation in CNDD was high but not significantly different across latitudes, suggesting that CNDD's stabilizing effect on species diversity is not influenced by latitude. The study concludes that while CNDD is widespread and effective in controlling species abundances, its average strength does not increase significantly towards the tropics. However, CNDD plays a more significant role in structuring species abundance distributions in tropical forests, particularly for rare and intermediate-abundance species. These findings suggest that CNDD may contribute more strongly to the maintenance of local tree species diversity in tropical regions.