Plant community mycorrhization in temperate forests and grasslands: Relations with edaphic properties and plant diversity

Abstract

Questions: Mycorrhizal symbiosis plays a key role in plant communities. Its prevalence in plant communities (mycorrhization) at larger spatial scales has so far been mostly qualitative, while quantitative studies incorporating the mycorrhizal traits of plant species are scarce. This study aims to: (1) determine the variation in general and arbuscular mycorrhization in temperate forests and grasslands, (2) study the effects of soil N, pH and moisture on mycorrhization, and (3) determine the relationships between mycorrhization and plant diversity. Location: Temperate forests and grasslands in Estonia, Northern Europe. Methods: To quantify mycorrhization we used a plant community mycorrhization index - community mean of mycorrhizal status weighted by plant species abundances. The effects of edaphic factors characterized by cumulative Ellenberg values on mycorrhization were analysed using linear mixed models, and the relationship between mycorrhization and diversity was evaluated with partial correlation and variance partitioning. Results: General mycorrhization was higher in forests and lower in grasslands, opposite to arbuscular mycorrhization. Soil N, pH and moisture negatively impacted general mycorrhization, whereas arbuscular mycorrhization was positively affected by soil pH and negatively by soil N and moisture. Plant species richness was negatively correlated with general mycorrhization in forests, whereas arbuscular mycorrhization was positively associated with plant species richness, Shannon and Simpson indices in forests and across ecosystems. Conclusions: Mycorrhization is highly dependent on soil conditions and related to plant diversity, showing its importance for vegetation science. The plant community mycorrhization index used in this study is a promising tool for quantifying the prevalence of mycorrhizal symbiosis along environmental gradients. We assessed the prevalence of mycorrhizal symbiosis in temperate forests and grasslands using plant community mycorrhization index and determined the associations between community mycorrhization, edaphic factors and plant diversity. We found that soil fertility, pH and moisture were significant drivers of community mycorrhization, and the relationship between mycorrhization and plant diversity depended on the type of vegetation and mycorrhizal symbiosis.