Impacts of alien tree species on the abundance and diversity of terricolous bryophytes

Abstract

Bryophytes comprise an important element of temperate forest biodiversity and functioning. Although numerous studies reported impacts of alien tree species on understorey vegetation, few focused on impacts on bryophytes. Here we checked whether three invasive tree species in Europe (Prunus serotina Ehrh., Quercus rubra L. and Robinia pseudoacacia L.) influence terricolous bryophyte communities, alpha and beta diversity, and cover. We used a set of 186 study plots in western Poland with data on the cover of bryophytes species, as well as light availability, soil C:N ratio and pH. We found that light availability was the main driver of bryophyte species richness, cover and composition. Poor Pinus sylvestris L. forests invaded by P. serotina hosted more species and higher species richness than non-invaded P. sylvestris forests, while forests invaded by Q. rubra and R. pseudoacacia hosted fewer species than native forest types. Low differences among forest types studied resulted from small pools of species and the presence of generalist species. Fagus sylvatica L. forest, Q. rubra and R. pseudoacacia forests hosted the smallest number of species, while the most species rich stands were poor P. sylvestris forest invaded by P. serotina and non-invaded P. sylvestris forests. We concluded that light limitation by invasive species might be more important than dominant tree species identity in limiting terricolous bryophyte species richness and abundance. This requires further studies, accounting for varied abundances of invasive tree species. Therefore, the conservation of sites with high terricolous bryophyte biodiversity needs to be focused on canopy cover.

Loss in macronutrient pools in bilberry and lingonberry in mesic Scots pine forests after Northern red oak introduction

“…Lack of differences accounting for vascular plants results from the low cover of the herbaceous layer, and therefore lower species richness. Bryophytes seem to be more sensitive to the limitation of light availability than vascular plants, similarly as in a multi-comparison study on invasive tree species effects on bryophytes (Dyderski and Jagodziński 2020b). Our results confirmed previous findings of shading by red oak (Niinemets 2010;Jagodziński et al 2018;).…”

“…For EIV.L, we used data for vascular plants and bryophytes and vascular plants only, while SLA reflected only the vascular plant community. We decided to analyse EIV.L for both vascular plants and bryophytes, as the latter dominate the understory in AFP and RFP and are also responsive to light availability (Dyderski and Jagodziński 2020b). We used one-way ANOVA followed by Tukey's posteriori test to assess the differences in EIV.L and SLA community-weighted mean values among forest types studied.…”