Is there tree senescence? The fecundity evidence.

Abstract

Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current estimates are dominated by overrepresentation of small trees in regression models. We combined global fecundity data, including a substantial representation of large trees. We compared size–fecundity relationships against traditional allometric scaling with diameter and two models based on crown architecture. All allometric models fail to describe the declining rate of increase in fecundity with diameter found for 80% of 597 species in our analysis. The strong evidence of declining fecundity, beyond what can be explained by crown architectural change, is consistent with physiological decline. A downward revision of projected fecundity of large trees can improve the next generation of forest dynamic models. ���Download Appendix (PDF)���Download Dataset_S01 (CSV)���Download Dataset_S02 (CSV)���Download Dataset_S03 (CSV)���Download Dataset_S04 (CSV)

Citation

Tong Qiu, Marie-Claire Aravena, Robert Andrus, Davide Ascoli, Yves Bergeron, Roberta Berretti, Michal Bogdziewicz, Thomas Boivin, Raul Bonal, Thomas Caignard, Rafael Calama, J. Julio Camarero, Connie J. Clark, Benoit Courbaud, Sylvain Delzon, Sergio Donoso Calderon, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Cathryn H. Greenberg, Qinfeng Guo, Janneke Hille Ris Lambers, Kazuhiko Hoshizaki, Ines Ibanez, Valentin Journé, Christopher L. Kilner, Richard K. Kobe, Walter D. Koenig, Georges Kunstler, Jalene M. LaMontagne, Mateusz Ledwon, James A. Lutz, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Chase L. Nuñez, Ian S. Pearse, Łukasz Piechnik, John R. Poulsen, Renata Poulton-Kamakura, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Shubhi Sharma, Miles Silman, Jennifer J. Swenson, Margaret Swift, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas P. Wion, S. Joseph Wright, Kai Zhu, Jess K. Zimmerman, Magdalena Żywiec, and James S. Clark. 2021. Is there tree senescence? The fecundity evidence. Proceedings of the National Academy of Sciences. 118 (34) e2106130118; https://doi.org/10.1073/pnas.2106130118