J Plant Ecol ›› 2019, Vol. 12 ›› Issue (6): 931-940.DOI: 10.1093/jpe/rtz030

• Research Articles • Previous Articles     Next Articles

Influence of smoke, heat and fire on germination of woody species occurring in the dry valleys of southwest China

Mareike Roeder1,2,*, Weidong Yang1 and Kyle W. Tomlinson1   

  1. 1Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
    2Institute of Floodplain Ecology, Karlsruhe Institute of Technology, Josefstraße 1, D – 76437 Rastatt, Germany
    *Correspondence address. Institute of Floodplain Ecology, Karlsruhe Institute of Technology, Josefstraße 1, D – 76437 Rastatt, Germany. Tel: +49 7222 380722; Fax: +49 7222 380799; E-mail: mareike@xtbg.org.cn; mareike.roeder@kit.edu
  • Received:2018-11-13 Revised:2019-05-08 Accepted:2019-05-17 Published:2019-12-01

Abstract:

Aims

Savannahs depend on fire for their persistence. Fire influences regeneration from seeds in several ways: it converts the environment into a more open space which can benefit the establishment of seedlings, and fire itself can also enhance germination by chemical and physical cues, such as smoke and heat. There is limited information as to how seed of Asian savannah species respond to fire, even though Asia has several dry vegetation types that are associated with fire. Our main question was whether fire enhances or triggers the germination of woody species occurring in southwest Chinese dry valleys, which have savannah vegetation.

Methods

We conducted tests with heat (80°C) and smoke solution treatments, and tests with real fire by burning grass on top of sand trays containing seeds. We tested 35 species, including savannah species, and gully and forest species. Depending on seed availability, not all species were tested for all treatments. Twenty-six species had total germination >4% and these were used for analysis.

Important Findings

Heat increased germination of three species (strongest reaction: Dodonaea viscosa), smoke increased germination of five species (strongest reaction: Calotropis gigantea). Both treatments decreased germination for five and seven species, respectively. Real fire was detrimental for most species, except for D. viscosa, which is known to respond positively to heat shock. Even though fire-related cues were not a trigger for germination for most species in our study, fire could still be crucial for regeneration by competition release.

Key words: smoke water, burning, biomass, germination time, Dodonaea viscosa,  Calotropis gigantea, seed mass, water content, dark germination