Strong Janzen-Connell effects caused by specialized natural enemies that prevent species from becoming highly abundant are one of the most famous explanations for high tropical tree diversity. Together with intraspecific resource competition, the effect of specialized pathogens has jointly become known as conspecific negative density dependence (CNDD), and numerous local studies have found CNDD in tropical and temperate tree communities, yet at varying frequency and strength. Recent studies have assessed CNDD at larger spatial scales and claimed signatures of a latitudinal CNDD gradient in static forest structure. These analyses, however, have been criticized for severe statistical and conceptual problems (Hülsmann & Hartig 2018), and dynamic analyses have been suggested as a robust, but globally not well explored alternative. We explore such dynamic CNDD estimates to understand the role of CNDD for biodiversity patterns.

Project team



  • Hülsmann, L., Chisholm R. A. & Hartig, F. (2021). Is variation in conspecific negative density dependence driving tree diversity patterns at large scales? Trends in Ecology and Evolution. 36, 151-163. [journal]
  • Hülsmann, L. & Hartig, F. (2018). Comment on “Plant diversity increases with the strength of negative density dependence at the global scale”. Science, 360. doi: 10.1126/science.aar2435. [journal]