TY - JOUR

T1 - Neighbourhood‐mediated shifts in tree biomass allocation drive overyielding in tropical species mixtures

AU - Guillemot, Joannès

AU - Kunz, Matthias

AU - Schnabel, Florian

AU - Fichtner, Andreas

AU - Madsen, Christopher P.

AU - Gebauer, Tobias

AU - Härdtle, Werner

AU - von Oheimb, Goddert

AU - Potvin, Catherine

N1 - The research leading to these results has received funding from the Natural Science and Engineering Research Council of Canada and the Canada Research Chair Programme to CP, as well as site support from the Smithsonian Tropical Research Institute. We acknowledge the continuous support of José Monteza as site manager and of Lady Mancilla, who supported the research team in all administrative aspects. We acknowledge financial support from the French Agricultural Research Centre for International Development (Cirad, CRESI program), the German Centre for Integrative Biodiversity Research (iDiv) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 319936945/GRK2324. We warmly thank Jean‐Paul Laclau (Cirad) and Guerric le Maire (Cirad) for thoughtful discussions and inputs to the field protocol, as well as Divya Sharma (McGill University) and Kathryn E. Barry (iDiv) for English editing. The workers in the photographs of Fig. 1 are Santiago Bonilla (left and right), José Monteza and Felipe Rodriguez (right). Photo credit: FS and JG. We are grateful to Richard Norby and three anonymous referees for their constructive comments that substantially improved the manuscript. © 2020 The Authors. New Phytologist © 2020 New Phytologist Foundation.

PY - 2020/11/1

Y1 - 2020/11/1

N2 - 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.

AB - 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.

KW - Ecosystems Research

KW - biodiversity

KW - carbon sequestration

KW - ecosystem functioning

KW - forest productivity

KW - overyielding

KW - Sardinilla experiment

KW - tree species diversity

KW - tropical plantation forest

KW - biodiversity

KW - carbon sequestration

KW - ecosystem fuctioning

KW - forest productivity

KW - overyielding

KW - Sardinilla experiment

KW - tree species diversity

KW - tropical plantation forest

UR - http://www.scopus.com/inward/record.url?scp=85087675436&partnerID=8YFLogxK

U2 - 10.1111/nph.16722

DO - 10.1111/nph.16722

M3 - Journal articles

C2 - 32496591

VL - 228

SP - 1256

EP - 1268

JO - New Phytologist

JF - New Phytologist

SN - 0028-646X

IS - 4

ER -