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

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.

Plant functional trait response to environmental drivers across European temperate forest understorey communities

“…Interestingly, both the proportional cover of woody and of OM species was positively related to temperature, and negatively to Ellenberg soil moisture. A higher abundance of woody plant species (not counting tree and shrub seedlings, which were excluded from the analysis) in the understorey may result in a stronger mycorrhizal fungal network, leading to higher occurrences of species forming mycorrhizal associations (Wang et al, ; Hempel et al, ; Veresoglou, Wulf, & Rillig, ). This might also explain the positive correlation between proportional cover of woody and OM species ( R p = 0.57).…”

Estimation of Fungal Diversity and Identification of Major Abiotic Drivers Influencing Fungal Richness and Communities in Northern Temperate and Boreal Quebec Forests

“…Tedersoo et al (2016), identified that fungal richness was positively affected by herb cover [18]. Several groups of root-inhabiting fungi are related to herbaceous plants and a majority of herbaceous plants are dependent on mycorrhizae to survive especially in phosphorus poor soil [87,88]. Higher density of herbaceous cover could provide more colonizable roots for fungi and results in a higher fungal richness [89].…”

Neighbours of arbuscular‐mycorrhiza associating trees are colonized more extensively by arbuscular mycorrhizal fungi than their conspecifics in ectomycorrhiza dominated stands

“…We start to appreciate, however, that shortages in AMF propagules are common in some habitats, such as agricultural fields subject to intensive farming (Schnoor et al, 2011;Manoharan et al, 2017). Forest habitats in the temperate region might also be occasionally AMF propagule limited (Veresoglou et al, 2017), but to the best of our understanding this has not been shown with empirical data.…”

“…In a recent study, Veresoglou et al (2017) suggested that AM woody species in a temperate forest facilitate the establishment of AM herbaceous species of the understorey. AM woody species might be seen as islands of AM propagules in a large archipelago of non-AMF-associating trees which can support the AMF-associating ones (van der Heijden, 2004).…”

“…AM woody species might be seen as islands of AM propagules in a large archipelago of non-AMF-associating trees which can support the AMF-associating ones (van der Heijden, 2004). The differences between stands dominated with AMF-associating trees and those dominated with woody plants that do not form AMF associations in Veresoglou et al (2017) were inferred from plant community data and there have been no comparable studies assaying in situ AMF availability.…”