Nutrient supply modulates species interactions belowground: dynamics and traits of fine roots in mixed plantations of Eucalyptus and Acacia mangium
Résumé
Aims Belowground interactions are still poorly understood in mixed-species forests. We investigated the effects of soil fertility on belowground processes in mixed planted forests. Methods The dynamics and traits of Eucalyptus and Acacia mangium fine roots (diameter < 2 mm) in plantations with 50% of each species were studied in a randomized block design established in a nutrient depleted soil. Stands with NPK fertilization applied at planting (F+) were compared to unfertilized stands (F-). Results In the 0-15 cm soil layer, Eucalyptus root mass density (RMD) was higher than Acacia RMD by 50% in F+ and 10% in F-, considering both ages. At 34 months of age, Eucalyptus RMD was 94% higher near Acacia trees than near Eucalyptus trees in F-. In this layer, Eucalyptus specific root length (SRL) was 21% higher than Acacia SRL at 16 months of age and was 10% higher in F- than in F+ at 34 months of age. The cumulative Eucalyptus fine root length production between 16 and 34 months was 66% higher in F- than in F+ in the 0-1 m soil layer. Conclusions Fertilization increased the competition between species and led to a partial exclusion of Acacia fine roots from the nutrient-rich topsoil. Soil exploration by Eucalyptus roots in the vicinity of Acacia trees was higher in F- than in F+, which suggests that unfertilized trees benefited from facilitation through higher soil N availability and direct N transfer from Acacia trees.
Auteurs, date et publication :
Auteurs B. Bordron , A. Germon , J-P Laclau , I. R. Oliveira , A. Robin , C. Jourdan , R. R. Paula , R. C. Pinheiro , J. Guillemot , J. L. M. Goncalves , J-P Bouillet
Publication : PLANT AND SOIL
Date : 2021
Volume : 460
Issue : 1-2
Pages : 559-577