Facilitation between woody and herbaceous plants that associate with arbuscular mycorrhizal fungi in temperate European forests.

Stavros D Veresoglou,Matthias C Rillig,Monika Wulf

doi:10.1002/ece3.2757

Abstract

In late‐successional environments, low in available nutrient such as the forest understory, herbaceous plant individuals depend strongly on their mycorrhizal associates for survival. We tested whether in temperate European forests arbuscular mycorrhizal (AM) woody plants might facilitate the establishment of AM herbaceous plants in agreement with the mycorrhizal mediation hypothesis. We used a dataset spanning over 400 vegetation plots in the Weser‐Elbe region (northwest Germany). Mycorrhizal status information was obtained from published resources, and Ellenberg indicator values were used to infer environmental data. We carried out tests for both relative richness and relative abundance of herbaceous plants. We found that the subset of herbaceous individuals that associated with AM profited when there was a high cover of AM woody plants. These relationships were retained when we accounted for environmental filtering effects using path analysis. Our findings build on the existing literature highlighting the prominent role of mycorrhiza as a coexistence mechanism in plant communities. From a nature conservation point of view, it may be possible to promote functional diversity in the forest understory through introducing AM woody trees in stands when absent.

Highlights

Plant communities often contain individuals belonging to different life forms. Sutherland et al (2013) identified as one of 100 fundamental questions in ecology investigating how coexistence of plants with different life forms is possible
We justify this on the basis that while forest management practices in Europe control for community structure of woody plants, forests are rarely managed directly for herbaceous plants
The positive relationship between relative abundance of arbuscular mycorrhizal (AM) herbaceous and AM woody plants were robust to the consideration of environmental parameters

Summary

| INTRODUCTION

Plant communities often contain individuals belonging to different life forms. Sutherland et al (2013) identified as one of 100 fundamental questions in ecology investigating how coexistence of plants with different life forms is possible. There is a considerable number of studies describing temperate forests which shows that biotic interactions represent key modulators of mature tree mortality (Das, Battles, Stephenson, & van Mantgem, 2011), decomposition rates and nutrient cycling (Rouifed, Handa, David, & Hättenschwiler, 2010), and seedling recruitment (Montgomery, Reich, & Palik, 2010; Muhamed, Touzard, Le Bagousse-Pinguet, & Michalet, 2013). These facts highlight the need to focus more on the role of biotic interactions in the understory (Nilsson & Wardle, 2005). We tested whether and to what extent woody plants that associate with AM fungi facilitate the establishment of herbaceous plants of compatible mycorrhizal types in agreement with the mycorrhizal

| MATERIALS AND METHODS

Findings

| DISCUSSION