Secondary metabolites in leaves of hybrid aspen are affected by the competitive status and early thinning in dense coppices

Key message

Non-selective thinning of a hybrid aspen coppice stands via corridor or cross-corridor cutting impacts residual trees differently depending on their competitive status. Suppressed residual trees’ metabolic profile indicates increased stress level, especially after cross-corridor thinning.

Abstract

Context Early thinning with regular corridor harvests is proposed for the management of post-harvest re-sprouted hybrid aspen (Populus tremula L. × P. tremuloides Michx.) coppice stands. The selection of remaining trees is not size-based and their physiological acclimation to the post-thinning conditions is unknown.
Aims To analyse differences in secondary metabolite profile between thinning treatments and trees competitive status.
Methods We used an HPLC-qTOF mass spectrometer to analyse the leaf extracts of dominant and suppressed trees from stands with different thinning intensities: un-thinned control with basal area of 15.4 ± 1.52 m2 ha−1, corridor thinning with basal area of 8.5 ± 0.46 m2 ha−1 and cross-corridor thinning with basal area of 3.9 ± 0.34 m2 ha−1.
Results Competitive status and thinning treatment both had significant effects on the contents of compounds. Higher exposure to irradiance increased the contents of flavonoids and hydroxycinnamates. Corridor thinning treatments doubled the foliar contents of secondary metabolites and lowered macronutrient contents in competitively suppressed residual trees. Dominant residual trees were not affected in this respect.
Conclusion Forest management practice and competitive status can significantly modify the metabolite profile in tree leaves. After corridor thinning of a young aspen coppice stand, the small-sized residual trees may initially respond with increased allocation to leaf chemical defence rather than to productivity.

Keywords
Growth-defense trade-off; Intraspecific competition; Populus; Forest management; HPLC

Publication
Rusalepp, L., Lutter, R., Hepner, H. et al. Secondary metabolites in leaves of hybrid aspen are affected by the competitive status and early thinning in dense coppices. Annals of Forest Science 78, 1 (2021). https://doi.org/10.1007/s13595-020-01014-3

For the read-only version of the full text:
https://rdcu.be/cdhj6

Data availability
The datasets generated and/or analyzed during the current study are available in the Zenodo repository, https://doi.org/10.5281/zenodo.4095450

Handling Editor
Jean-Michel Leban

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