The Habitat of the Neglected Independent Protonemal Stage of Buxbaumia viridis

Ameline Guillet,Vincent Hugonnot,Florine Pépin

doi:10.3390/plants10010083

Ameline Guillet, Vincent Hugonnot + Show 1 more

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https://doi.org/10.3390/plants10010083

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Abstract

Buxbaumia viridis is a well-known species of decaying deadwood, which is protected in Europe. All previous studies dealing with the ecology of B. viridis rely on the sporophyte generation because the gametophyte generation is allegedly undetectable. Recent advances have shown that the protonemal stage, including gemmae, is recognizable in the field, thereby considerably modifying our perception of the species’ range and habitat. In France, we demonstrate the existence of independent protonemal populations, with the implication that the range of B. viridis is widely underestimated. Sporophytes and sterile protonema do not share the same ecological requirements. The sporophyte stage was found in montane zones, almost exclusively in coniferous forests, and on well-decayed wood. The sterile protonemal stage extends to lower elevations, in broad-leaved forests, and on wood in a less advanced state of decay. Our results suggest that the humidity could be one of the most relevant explanatory variables for the occurrence of sporophytes. Opening of the canopy seems to promote sporophyte development. Previous anomalous observations of B. viridis growing on humus or bark might be explained by the presence of a protonemal population that is able to produce sporophytes under rarely occurring but favorable climatic events.

Highlights

Buxbaumia viridis (Moug. ex Lam. et DC.) Brid. ex Moug. et Nestl. (Buxbaumiaceae) is a hygrophilous, sciaphilous, and acidophilous species, widely distributed in the Northern hemisphere, where it mainly colonizes decaying wood in wet, shaded coniferous montane woodlands [1,2,3]
France, and we study the ecology of the protonemal ecological requirements at two different scales, namely habitat and microstage from a conservation perspective
The gametophytic stage of B. viridis can be recognized in the field (Figure 4) by the combination of a whitish-grey film immersed in wood fibers and discrete combination of a whitish-grey film immersed in wood fibers and discrete chocolate-brown granular masses of protonemal gemmae

Summary

Introduction

Buxbaumia viridis (Moug. ex Lam. et DC.) Brid. ex Moug. et Nestl. (Buxbaumiaceae) is a hygrophilous, sciaphilous, and acidophilous species, widely distributed in the Northern hemisphere, where it mainly colonizes decaying wood in wet, shaded coniferous montane woodlands [1,2,3]. Ecological factors, that have been suggested as relevant in explaining the occurrence of the species, are the amount of available deadwood, the degree of its decomposition, canopy openness, humidity, elevation, aspect, and deadwood composition [3,4,5]. As a species apparently linked to well-preserved forest stands with large accumulations of bulky woody debris, it has been suggested that B. viridis is an indicator of ancient woodland [5]. Over recent decades the species has been assessed in the European Red-list for bryophytes as “vulnerable”, and this has led to a disproportionate increase in the number of targeted studies [3,4,8,9]. Its status has changed to “least concern” in the most recent Red-List [10]

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