Resurvey studies of terricolous bryophytes and lichens indicate a widespread nutrient enrichment in German forests

• Published in: Journal of vegetation science Vol. 34; no. 4
• Main Authors: Diekmann, Martin, Heinken, Thilo, Becker, Thomas, Dörfler, Inken, Heinrichs, Steffi, Leuschner, Christoph, Peppler‐Lisbach, Cord, Osthaus, Magdalena, Schmidt, Wolfgang, Strubelt, Ilka, Wagner, Eva‐Rosa
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.07.2023
• Subjects: Acidic soils; acrocarpous mosses; Aquatic plants; Bryophyta; Bryophytes; Climate change; Coniferous forests; Deciduous forests; Ecological effects; Ellenberg indicator values; Enrichment; Forests; Lichens; liverworts; Mosses; Nitrogen; nitrogen deposition; Nutrient enrichment; Nutrients; Plants; pleurocarpous mosses; Questions; shrub layer; Soils; Species richness; species trend scores; Taxa; tree layer; Vegetation
• ISSN: 1100-9233; 1654-1103
• DOI: 10.1111/jvs.13201

Questions Vegetation resurveys, both single studies and meta‐analyses, have predominantly been based on vascular plant data while bryophytes and lichens have largely been neglected. Our study aims to fill this gap and addresses the following research questions: has the overall species richness of terricolous bryophytes and lichens in forests changed over time? Which are the winners and losers among single species and ecological species groups? Do the results give a signal of the impact of nutrient enrichment, of changes in the light regime and of climate change? Location Deciduous and coniferous forests in Germany. Methods We compiled 35 single resurvey data sets, including 1096 plots in total (each sampled twice). The time interval between initial surveys and resurveys ranged from 10 to 65 years. The differences between old and new plots were analysed with respect to the frequency of single species, total species richness, and the absolute and relative numbers of taxa in the species groups. Trend scores of species were related to ecological indicator values to identify the main environmental drivers behind the observed changes. Results Total species richness did not systematically change, while pleurocarpous mosses had increased at the expense of acrocarpous mosses and, in coniferous forests, of lichens. Weak changes were generally observed in deciduous forests on base‐rich soils. In coniferous forests and in deciduous forests on acid soils, species with high nitrogen demand and high shade tolerance had increased, whereas those being typical for more infertile and open forest sites had decreased. There were trends towards a larger share of taxa with a more oceanic distribution. Conclusions The changes in the vegetation of terricolous bryophytes and lichens in the studied forests indicate nutrient enrichment and increasingly shady conditions in forests on acid soils, likely caused by nitrogen deposition and shrub layer closure. Terricolous bryophytes and lichens have mostly been neglected in forest resurveys. Our study shows that there are pronounced long‐term changes of these species. Just as in vascular plant species, the changes suggest widespread nutrient enrichment and increasingly shady conditions in the forests. In some forest types, there is a trend towards an increase in species with an oceanic distribution. The photograph shows a pine forest dominated by bryophytes. Lichens formerly common in these forests have largely been replaced by pleurocarpous mosses.