Neighbourhood-mediated shifts in tree biomass allocation drive overyielding in tropical species mixtures

• Published in: The New phytologist Vol. 228; no. 4; pp. 1256 - 1268
• Main Authors: Guillemot, Joannès, Kunz, Matthias, Schnabel, Florian, Fichtner, Andreas, Madsen, Christopher P., Gebauer, Tobias, Härdtle, Werner, von Oheimb, Goddert, Potvin, Catherine
• Format: Journal Article
• Language: English
• Published: England Wiley 01.11.2020; Wiley Subscription Services, Inc
• Subjects: Allometry; Architecture; Biodiversity; Biodiversity and Ecology; Biomass; carbon sequestration; Destructive testing; Diameters; ecosystem functioning; Environmental Sciences; Forest biomass; forest productivity; Forests; Lasers; Life Sciences; overyielding; Plant cover; Plant diversity; Productivity; Sardinilla experiment; Size effects; Terrestrial environments; tree species diversity; Trees; Tropical Climate; Tropical forests; tropical plantation forest; Vegetal Biology; overyielding; biodiversity; ecosystem functioning; Sardinilla experiment; carbon sequestration; tree species diversity; forest productivity; tropical plantation forest; Sardinilla
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.16722

• Variations in crown forms promote canopy space-use and productivity in mixed-species forests. However, we have a limited understanding on how this response is mediated by changes in within-tree biomass allocation. Here, we explored the role of changes in tree allometry, biomass allocation and architecture in shaping diversity–productivity relationships (DPRs) in the oldest tropical tree diversity experiment. • We conducted whole-tree destructive biomass measurements and terrestrial laser scanning. Spatially explicit models were built at the tree level to investigate the effects of tree size and local neighbourhood conditions. Results were then upscaled to the stand level, and mixture effects were explored using a bootstrapping procedure. • Biomass allocation and architecture substantially changed in mixtures, which resulted from both tree-size effects and neighbourhood-mediated plasticity. Shifts in biomass allocation among branch orders explained substantial shares of the observed overyielding. By contrast, root-to-shoot ratios, as well as the allometric relationships between tree basal area and aboveground biomass, were little affected by the local neighbourhood. • Our results suggest that generic allometric equations can be used to estimate forest aboveground biomass overyielding from diameter inventory data. Overall, we demonstrate that shifts in tree biomass allocation are mediated by the local neighbourhood and promote DPRs in tropical forests.