Additional comments

The study found that mixed forests have 20% less pest attacks than single species forests, especially in the case of herbivorous pest attacks that target just a few tree species. The reason appears to be that other tree species emit odours and provide visual signals that confound pests when they are looking for their usual host trees to feed or lay their eggs. In addition, mixed forests attract a higher diversity of animals like birds, bats and spiders that predate on these pests and reduce their incidence. The results of the project showed that the functional diversity of tree species that make up the mixed forest stand has a greater impact on the prevention of pest attacks than the number of tree species per se. This is to say that a combination a broadleaf and a coniferous species has a stronger effect than the combination of two coniferous species.

These findings provide a basis for developing new forest management strategies that are more effective in preventing the increasing pest attacks due to climate change.

Additional information

Hervé Jactel, Xoaquín Moreira and Bastien Castagnerol, Tree Diversity and Forest Resistance to Insect Pests: Patterns, Mechanisms and Prospects, Annual Review of Entomology 2021. 66:14.1–14.20, 16 septembre 2020.



DOI : https://doi.org/10.1146/annurev-ento-041720-075234