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Plant Ecology

, Volume 184, Issue 2, pp 237–243 | Cite as

No heat-stimulated germination found in herbaceous species from burned subtropical grassland

  • Gerhard E. OverbeckEmail author
  • Sandra C. Müller
  • Valério D. Pillar
  • Jörg Pfadenhauer
Article

Abstract

Fire has been shown to stimulate seed germination in a number of fire-prone ecosystems, mainly in Mediterranean type shrublands and, though not exclusively, in hardseeded species. Stimulation by heat, or by chemical constituents of charred wood and smoke, have been identified as the main mechanisms breaking dormancy of soil-stored seeds. In this study, we experimentally tested the effect of heat on germination rates of nine herbaceous species (5 grasses, 1 Cyperaceae, 3 forbs) from frequently burned grassland in southern Brazil. Seeds were exposed to temperatures between 50°C and 110°C (to 180°C for two species) for 2 min. Germination of treated seeds was monitored in a germination chamber. The heat treatments did not stimulate germination in any of the species tested. Tolerance of seeds to heat varied between species. Two of the herbs and the three grasses with the smallest seeds were able to germinate at temperatures of 110°C, or even higher. Apparently, no mechanisms directly stimulating germination by heat have developed in herbaceous species from southern Brazil. However, survival of high temperatures can be considered to be an adaptation to fire, possibly allowing for increased germination in the post-burn environment.

Keywords

Fire Germination Grasslands Heat shock Southern Brazil 

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Notes

Acknowledgements

We would like to thank Prof. Dr. Renato Borges de Medeiros and Profa. Dra. Lucia Brandão Franke, both UFRGS Department of Agronomy, for their help and for the opportunity to use equipment at the UFRGS seed laboratory. Further thanks go to Emiliano Santarosa and Alessandra Fidelis for helping with the experiments. An anonymous reviewer gave stimulating comments on the manuscript. G. O. received a PhD scholarship from the German National Academic Foundation, S.M. a CAPES PhD grant, and V.P. CNPQ support. This study received support from the German DFG, CAPES (Brazil) and DAAD (Germany) under a ProBral-cooperation.

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Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  • Gerhard E. Overbeck
    • 1
    Email author
  • Sandra C. Müller
    • 2
  • Valério D. Pillar
    • 2
  • Jörg Pfadenhauer
    • 1
  1. 1.Chair of Vegetation EcologyTechnische Universität MünchenFreising-WeihenstephanGermany
  2. 2.Laboratory of Quantitative EcologyUniversidade Federal do Rio Grande do SulPorto AlegreBrazil

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