Prevalence of interspecific competition in a mixed poplar/black locust plantation under adverse climate conditions
Résumé
& Key message In a mixed poplar/black locust plantation in central France, adverse conditions have led to a prevalence of
interspecific competition, resulting in a poorer performance than monocultures.
& Context In mixed tree plantations, the presence of woody N2-fixing species is thought to reduce N needs by fertilization.
However, benefits associated to soil nitrogen enrichment have to outweigh the negative effects of interspecific competition. To do
so, co-occurring tree species have to be chosen carefully to promote niche sharing between species and reduce competition. Black
locust and poplar mixtures therefore seem promising since both species are fast growing and have potentially complementary
crown shapes.
& Aims Our objective was to evaluate the impact of the poplar/black locust mixture on the growth, above- and belowground
biomass production, and nitrogen allocation of the two species, as compared to their respective monocultures.
& Methods An experimental plantation mixing poplar and black locust was set up in central France. For five growing seasons,
growth, nitrogen allocation, and carbon allocation were monitored for the two species growing either in mixture or in
monoculture.
& Results After a couple of promising growing seasons, black locust growth and survival slowly declined, mainly in the mixture.
At the stand level, biomass production in the mixed plots was nearly 50%below the most productive monoculture (poplar) by age
5 years.
& Conclusion Under adverse conditions, interspecific competition in the mixture was the preponderant interaction, resulting in
higher mortality and lower biomass production than the two monocultures.
Auteurs, date et publication :
Auteurs N. Marron , P. Priault , C. Gana , D. Gérant , D. Epron
Publication : Annals of Forest Science
Date : 2025
Volume : In press