The Habitat of the Neglected Independent Protonemal Stage of Buxbaumia viridis

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.

Population and Conservation Status of Buxbaumia viridis (DC.) Moug. & Nestl. in Romania

“…According to the results from the ensemble modeling, elevation, precipitation of the driest quarter, and mean temperature of the coldest quarter serve as the best indicators of Buxbaumia viridis occurrence. We can observe that the favored high-altitude areas typically correlate with the altitudinal range of mixed and spruce forests; hence there might be a dependence on habitat type, also supported by other studies [ 44 , 45 ]. Using maximum entropy modeling, Číhal [ 44 ] also argues that the found dependency of B. viridis to habitat type is most likely mostly connected to the species’ requirement for a sufficient quantity of decaying wood [ 46 ].…”

“…Our data suggest the same, as precipitation of the driest quarter and mean temperature of the coldest quarter accompanied by precipitation of the warmest quarter are the important consequent variables after elevation. Increased precipitation (in the driest and warmest areas) has a direct influence on avoiding the desiccation of not just sporophytes [ 45 , 46 ] but also of the less tolerant spores [ 48 ]. The reason for the species’ dependency on lower average winter temperatures is uncertain, as also found and stated by Číhal [ 44 ].…”

First report of Cladosporium herbarum ( Capnodiales, Dothideomycetes ) on the rare moss Buxbaumia viridis in Bulgaria

“…In Europe it has been reported also on the dead wood of Fagus sylvatica L. (Wolf 2015;Deme & al. 2020;Brewczyński 2021;Guillet & al. 2021).…”

Possible Effects of Climate Change on the Occurrence and Distribution of the Rare Moss Buxbaumia viridis in Serbia (SE Europe)

“…It is considered a boreal-montane element, and is commonly found in boreal monodominant spruce forests, or less frequently in beech-fir forests. It grows mainly on decaying wood in hygrophilous and shady environments [ 5 ]. The species has a very narrow substrate receptivity, being attached to the deadwood.…”

“…Although a rare and widely protected species, there are recent studies suggesting that its ecology and distribution are still poorly understood and possibly underestimated. Recently, there is relatively new evidence of the protonemal and gemmae stage growing independently without developing sporophyte [ 5 ]. According to the same authors, the sterile protonemal stage extended to the lower elevations in the broad-leaved forests, while sporophytes were observed only in coniferous forests at higher elevations.…”