Seed mass diversity along resource gradients: the role of allometric growth rate and size-asymmetric competition

Niv DeMalach*, Ronen Kadmon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The large variation in seed mass among species inspired a vast array of theoretical and empirical research attempting to explain this variation. So far, seed mass variation was investigated by two classes of studies. One class focuses on species varying in seed mass within communities, while the second focuses on variation between communities, most often with respect to resource gradients. Here, we develop a model capable of simultaneously explaining variation in seed mass within and between communities. The model describes resource competition (for both soil and light resources) in annual communities and incorporates two fundamental aspects: light asymmetry (higher light acquisition per unit biomass for larger individuals) and growth allometry (negative dependency of relative growth rate on plant biomass). Results show that both factors are critical in determining patterns of seed mass variation. In general, growth allometry increases the reproductive success of small-seeded species while light asymmetry increases the reproductive success of large-seeded species. Increasing availability of soil resources increases light competition, thereby increasing the reproductive success of large-seeded species and ultimately the community (weighted) mean seed mass. An unexpected prediction of the model is that maximum variation in community seed mass (a measure of functional diversity) occurs under intermediate levels of soil resources. Extensions of the model incorporating size-dependent seed survival and disturbance also show patterns consistent with empirical observations. These overall results suggest that the mechanisms captured by the model are important in determining patterns of species and functional diversity.

Original languageAmerican English
Pages (from-to)2196-2206
Number of pages11
JournalEcology
Volume99
Issue number10
DOIs
StatePublished - Oct 2018

Bibliographical note

Publisher Copyright:
© 2018 by the Ecological Society of America

Keywords

  • community-weighted mean
  • community-weighted variance
  • competition–colonization trade-off
  • disturbance
  • functional diversity
  • functional traits
  • productivity
  • seed size
  • size–number trade-off
  • tolerance–fecundity trade-off

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