Early cryptogams have recently been considered central engineers to Earth’s current atmosphere and lithosphere. Although historically understudied, recent significance has been placed on their role as biogeochemical drivers through the action of chemical weathering through deep time. Research infers that cryptogams had a significant impact on the evolution of the Earth system starting in the Ordovician when models suggest that there was a strong negative feedback between terrestrial weathering and the first land plants. Data on the magnitude and variation in modern rates and impacts of cryptogam weathering, however, are lacking. We have little knowledge of present-day weathering rates of bryophyte and lichen species. Here, we build on a previous study investigating species-specific weathering of saxicolous (rock dwelling) bryophytes and present the results of a microcosm study of biologically induced weathering by the foliose lichen, Parmelia saxatilis, and the bryophyte, Bucklandiella heterosticha. The objective of this study was to test the hypothesis that a bryophyte and lichen collected from a co-occuring cryptogamic community would have the same net flux of elements weathered into the tissue and environment. Cryptogam species were collected, separated, and incubated for one year on andesite rock growing under natural light and temperature conditions. After one year, cryptogam tissue was removed and rock weathering products were analyzed using ICP-AES and tissue elemental content was analyzed using dry ash analysis.
Results/Conclusions
Our preliminary data suggest that saxicolous cryptogams may be considered to have weathering potential above those that primarily live on other substrates, such as soil. We found that moss species significantly enhanced element weathering compared to controls without mosses and compared to moss weathering values reported in the literature. Additionally, the two cryptogam species also differed in their weathering responses despite appearing to occupy similar ecological niches. These results suggest that saxicolous species may be better adapted to weathering than other cryptogam species and that weathering may be species-specific. Based on our findings we proposed that species specific geochemical weathering should be further explored as a key a functional trait among cryptogams, informing species-specific models of cryptogam impacts on ecosystem biogeochemical cycles. If correlations between modern cryptogamic abundance and diversity and Earth’s first land plant are to be made, more investigations into the patterns of cryptogam weathering are needed. We suggest functional ecology as one way that this could be achieved empirically despite early cryptogams being competitively excluded by modern plants.