Effects of different planting configurations and clones on biomass and carbon storage of a 12-year-old poplar ecosystem in southern China

The main objective of this study was to compare the effects of two densities (278 stems x [ha.sup.-1] with two spacings of 6 m x 6 m or 4.5 m x 8 m, 400 stems x [ha.sup.-1] with two spacings of 5m x 5m or 3m x 8 m) and three poplar clones (NL95, NL895, and NL797) on productivity and carbon (C) sequestration of poplar ecosystems. The results showed that planting density significantly affected the biomass of a single tree. The mean tree biomass of clone NL95 was higher in all spacings than that of the other clones, with a significant difference for the 6 m x 6 m spacing. The biomass of poplar trees ranged from 78.9 to 110.3 Mg x [ha.sup.-1], with the highest tree biomass observed in the square configuration. Soil C concentration (0-100 cm) increased after 12 years of management. Soil C storage ranged from 138.1 to 164.3 Mg C x [ha.sup.-1], and the highest soil C storage was in the NL797 poplar plantation with 6 m x 6 m spacing. Our results suggested that clones NL95 and NL797 should be chosen for planting, with a planting density of 278 stems x [ha.sup.-1] and spacing of 6 m x 6 m. Key words: biomass production, C sequestration, plant density, plant spacing, poplar clone. Le principal objectif de cette etude etait de comparer les effets de deux densites (278 tiges * [ha.sup.-1] avec deux espacements de 6 m x 6 m ou 4,5 m x 8 m, 400 tiges x [ha.sup.-1] avec deux espacements de 5 m x 5 m ou 3 m x 8 m) et de trois clones de peuplier (NL95, NL895 et NL797) sur la productivite et la sequestration du carbone (C) dans les ecosystemes de peuplier. Les resultats montrent que la densite de plantation a eu un impact significatif sur un seul clone. La biomasse moyenne des tiges du clone NL95 etait plus elevee que celle des deux autres clones peu importe l'espacement et la difference etait significative pour l'espacement de 6 m x 6 m. La biomasse des tiges de peuplier variait de 78,9 a 110,3 Mg * [ha.sup.-1] et la biomasse la plus elevee a ete observee dans la configuration carree. La concentration de C dans le sol (0-100 cm) avait augmente apres 12 ans d'amenagement. L'entreposage de C dans le sol variait de 138,1 a 164,3 Mg C * [ha.sup.-1] et la quantite la plus elevee a ete observee dans la plantation du clone NL797 avec un espacement de 6 m x 6 m. Nos resultats indiquent que les clones NL95 et NL797 devraient etre retenus pour etre plantes avec une densite de 278 tiges x [ha.sup.-1] et un espacement de 6 m x 6 m. [Traduit par la Redaction] Mots-cles: production de biomasse, sequestration du C, densite des plants, espacement des plants, clone de peuplier.
1. Introduction The continuous increase in atmospheric carbon dioxide (C[O.sub.2]) concentration is the primary factor of climate change (Zhang et al. 2020). The two main causes of C[O.sub.2] increase are [...]