The Response of Spore Germination of Sphagnum Mosses to Single and Combined Fire-Related Cues.

Shuayib Yusup,Mamtimin Sulayman,Beibei Fan,Zhao-Jun Bu,Sebastian Sundberg

doi:10.3390/plants11040485

Abstract

Plants in flammable ecosystems have different response strategies to fire, such as increasing germination after exposure to smoke and break of dormancy through heat shock. Peatlands are ecosystems that are more likely to be disturbed by fire with increasing temperatures, but it is not clear how fire affects spore germination of Sphagnum, the dominant plants in peatlands. Here, we hypothesize that Sphagnum spores respond positively to single and combined treatments of moderate heat and smoke (by increased germinability), while spore germinability decreases in response to high temperature. We exposed the Sphagnum spores of four selected species (S. angustifolium, S. fuscum, S. magellanicum and S. squarrosum) collected from peatlands in the Changbai Mountains to heat (40, 60 and 100 °C), on its own and combined with smoke-water treatments. Our results showed that a heat of 100 °C inhibited the spore germination or even killed spores of all species, while spore germination of three (Sphagnum angustifolium, S. fuscum and S. squarrosum) of the four species was promoted by 40 and 60 °C heat compared to the control (20 °C). Hollow species (S. angustifolium and S. squarrosum) showed a stronger positive responsive to heat than hummock species (S. fuscum and S. magellanicum). Sphagnum fuscum spores responded positively to the combined heat and smoke treatment while the other species did not. For the first time, we demonstrate the positive effects of heat on its own and in combination with smoke on spore germination in wetland mosses, which may be important for the establishment and persistence of peatmoss populations after fire.

Highlights

IntroductionMany ecosystems depend on fire to maintain stability and their adaption to fire may determine their fate under the background of climate warming [1,2,3]
Our aim was to test the following hypotheses: (1) Heat will improve the germination of Sphagnum spores; (2) the positive effects of heat on spore germination may be more pronounced when interacting with smoke; and (3) since spores of hollow species (S. angustifolium and S. squarrosum) are more susceptible to fire than those of hummock species (S. fuscum and S. magellanicum) during dry periods, the spores of hollow species may show a more accentuated response than hummock species to heat and smoke
The spore Germination Percentage (GP) of S. angustifolium, S. fuscum and S. squarrosum increased with moderate heat temperature (40 ◦ C and 60 ◦ C)

Summary

Introduction

Many ecosystems depend on fire to maintain stability and their adaption to fire may determine their fate under the background of climate warming [1,2,3]. The survival and reproduction of plants can be directly affected by fire. In the long-term evolution process, vascular plants in fire-prone ecosystems have formed a series of morphological and physiological fire-adapted traits. Pine species in North America can tolerate frequent lightning fires by forming a thick bark and delaying cone cracking [4]; The seeds of Australian Xanthorrhoea gracilis Endl. The fire adaptation strategy of plants makes the populations survive and develop continuously, and the fire-related renewal strategies, such as the response characteristics of propagules (vegetative or sexual) to fire factors, are important for vegetation recovery and change of community structure after fire [7]

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