Direct and indirect effect of seed size on seedling survival along an experimental light availability gradient

Zhen Ma, Charles G. Willis, Huakun Zhou, Chunhui Zhang, Xinquan Zhao, Shikui Dong, Buqing Yao, Xiaotao Huang, Feng Yu Zhao, Guang Jin Yin, Dengxian Wei, Guozhen Du

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Theoretical models of life-history strategies assume a positive relationship between seed size and subsequent offspring survival (seed size–survival relationship). There is limited empirical evidence, however, on how this relationship changes across environments or in relationship to seedling traits. Moreover, characterizing the dynamics of seedling recruitment under natural conditions is central to understanding how seedling recruitment may in turn affect large-scale ecological processes. Here, first-year seedling survival was monitored from emergence for 303 angiosperms species originated from alpine and sub-alpine meadows of the eastern Tibetan Plateau grasslands, across an experimental light gradient consisting of four treatments. We used linear models (LM)and phylogenetic generalized linear models (PGLM)to test for the seed size–survival relationship, and how this relationship differed across light treatments. We also used path analysis (PA)and phylogenetic confirmatory path analysis (PPA)to assess how seed size interacted with other seedling traits (seedling emergence time, specific leaf area, root: shoot biomass ratio, and biomass growth)to either directly or indirectly affect seedling survival. We found seed size to be positively associated with seedling survival only under low to medium light treatments only in LM (not in PGLM). PA and PPA revealed that the positive effect of seed size on seedling survival was indirect, mainly acting via biomass growth. Under low light, larger seeds exhibited greater biomass growth, which in turn increased seedling survival. In contrast, the direct effect of seed size on seedling survival is negative. In sum, the seed size–survival relationship appears to be both environmentally and phylogenetically dependent. The survival advantage of large seeds appears to be the result of their ability of higher biomass growth after emergence in low resource environments. However, our results also suggest there may be an underlying trade-off with larger seeds facing a lesser, but direct risk of increased mortality. The influence of environment on seedling traits, the interaction among traits, and phylogeny should be taking into consideration when modeling the dynamics of seedling recruitment.

Original languageEnglish (US)
Pages (from-to)64-71
Number of pages8
JournalAgriculture, Ecosystems and Environment
Volume281
DOIs
StatePublished - Sep 1 2019

Bibliographical note

Funding Information:
Our thanks and appreciations go to Prof. Kathleen Donohue, Prof. Wei Qi, and Prof. Kun Liu for their valuable comments on earlier versions of the manuscript. This work was supported by National key research and development program of China (2016YFC0501901-03), National Natural Science Foundation of China (31600335; 31702163; 31860668; 31672474), Natural Science Foundation of Qinghai Province of China (2015-ZJ-919Q), The Project of Qinghai Science & Technology Department (2017-ZJ-Y20;2016-ZJ-Y01), and The Open Project of State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University (2017-ZZ-11; 2017-KF-02; 2018-KF-01). We thank members from Prof. Guozhen Du Lab for help with fieldwork and data collection

Funding Information:
Our thanks and appreciations go to Prof. Kathleen Donohue, Prof. Wei Qi, and Prof. Kun Liu for their valuable comments on earlier versions of the manuscript. This work was supported by National key research and development program of China ( 2016YFC0501901-03 ), National Natural Science Foundation of China ( 31600335 ; 31702163 ; 31860668 ; 31672474 ), Natural Science Foundation of Qinghai Province of China ( 2015-ZJ-919Q ), The Project of Qinghai Science & Technology Department ( 2017-ZJ-Y20;2016-ZJ-Y01 ), and The Open Project of State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University ( 2017-ZZ-11; 2017-KF-02 ; 2018-KF-01 ). We thank members from Prof. Guozhen Du Lab for help with fieldwork and data collection

Publisher Copyright:
© 2019

Keywords

  • Life-history traits
  • Light availability
  • Path analysis
  • Phylogenetic path analysis
  • Seed size
  • Seedling survival
  • Seedling traits
  • Tibetan Plateau

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