Low root functional dispersion enhances functionality of plant growth by influencing bacterial activities in European forest soils

Abstract

Current studies show that multispecies forests are beneficial regarding biodiversity and ecosystem functionality. However, there are only little efforts to understand the ecological mechanisms behind these advantages of multispecies forests. Bacteria are among the key plant growth-promoting microorganisms that support tree growth and fitness. Thus, we investigated links between bacterial communities, their functionality and root trait dispersion within four major European forest types comprising multispecies and monospecific plots. Bacterial diversity revealed no major changes across the root functional dispersion gradient. In contrast, predicted gene profiles linked to plant growth activities suggest an increasing bacterial functionality from monospecific to multispecies forest. In multispecies forest plots, the bacterial functionality linked to plant growth activities declined with the increasing functional dispersion of the roots. Our findings indicate that enriched abundant bacterial operational taxonomic units are decoupled from bacterial functionality. We also found direct effects of tree species identity on bacterial community composition but no significant relations with root functional dispersion. Additionally, bacterial network analyses indicated that multispecies forests have a higher complexity in their bacterial communities, which points towards more stable forest systems with greater functionality. We identified a potential of root dispersion to facilitate bacterial interactions and consequently, plant growth activities.

Comparative Analyses of Phyllosphere Bacterial Communities and Metabolomes in Newly Developed Needles of Cunninghamia lanceolata (Lamb.) Hook. at Four Stages of Stand Growth

“…Host-plant-associated bacteria affect the growth, health, and nutrient absorption and cycling of the host plant, especially plant growth-promoting rhizobacteria (Chen et al, 2020 ; Swarnalakshmi et al, 2020 ). Previous studies of forest bacterial communities have focused on belowground processes, such as carbon sequestration, root activity, and litter decomposition (Prada-Salcedo et al, 2020 ; Truu et al, 2020 ; Yokobe et al, 2020 ). Little attention has been paid to the functions of foliar bacterial communities in forest ecosystems.…”

Tree species mixing causes a shift in fine‐root soil exploitation strategies across European forests

“…Molecular data of fungal diversity were obtained by standard total genomic DNA extraction. Sample processing, laboratory analysis and bioinformatics procedures were done according to Prada-Salcedo, Goldmann, et al (2021). We amplified fungal ITS2, using the primers P5-5N-ITS4 and P5-6N-ITS4 together with P7-3N-fITS7 and P7-4N-fITS7 (Gardes & Bruns, 1993;Ihrmark et al, 2012;Leonhardt et al, 2019) and produced libraries using the Nextera XT Illumina index Kit (Illumina), based on the manufacturer's instructions.…”

“…Subsequently, we identified and classified fungal groups and determined fungal richness and diversity using the package phyloseq (McMurdie & Holmes, 2013) in r (R Core Team, 2018). Soil total fungal biomass and specifically mycorrhizal biomass were determined by phospholipid fatty acid analysis method described by Prada-Salcedo, Wambsganss, et al (2021) and Pei et al (2017). After lipids extraction, GC-MS analysis and peak areas conversion to nmol g soil −1 , the biomass was calculated accordantly to fungal biomarkers 18:2ω6,9c, 18:1ω9 and 16:1ω5c.…”

Distinct effects of host and neighbour tree identity on arbuscular and ectomycorrhizal fungi along a tree diversity gradient

“…Typically, plant diversity as well as plantrelated ecosystem functions have predominantly been in the focus [4,5], while cascading effects of biodiversity change at one trophic level to other trophic levels have attracted less attention [6,7]. However, in this context, biotic interactions with plant symbionts, such as mycorrhizal fungi, remain unstudied, although they may be directly linked to plant-resource acquisition and, consequently, to plant competition and coexistence in plant communities [8][9][10]. Moreover, there is still a lack of knowledge of the factors that, besides plant diversity itself, influence plant-symbiont interactions and the impact of different forms of interactions on each other.…”