Aims This study tests whether different spectral regions of sunlight affect the microbial decomposer assemblage in surface leaf litter in a beech understorey over the first 6 months following leaf senescence. Methods We performed a litterbag experiment employing filters attenuating combinations of UV-B, UV-A, blue, and green light as well as the whole spectrum of sunlight. We measured changes in microbial biomass and community structure, litter mass loss and litter chemistry during the first 6 months of decomposition.Results Fungal and total microbial biomass were highest in the treatment excluding UV radiation, blue and green light. Exclusion of UV-B radiation decreased the fungal:bacterial biomass ratio and litter nitrogen content. Bacterial biomass was lower in the dark treatment compared to treatments receiving at least part of the solar spectrum. Our filter treatments affected microbial functional structure from the beginning of the experiment, whereas mass loss was only significantly affected after 6 months of decomposition and no effect was found on litter carbon content. Conclusions This study proves that sunlight, in a spectrally dependent manner, affects both microbial functional structure and biomass in temperate deciduous forests early in the decomposition process, with bacteria tending to dominate in sunlight and fungi in dark conditions. We found sunlight to be important in the decomposition in temperate forest understoreys despite the low irradiance characterizing these environments. However, long-term studies are required to estimate the relative contribution of sunlight among factors affecting the eventual incorporation of decomposing leaf litter into forest soils.

The ability of wild blueberries to adapt to their harsh environment is believed to be closely related to their symbiosis with ericoid mycorrhizal fungi, which produce enzymes capable of organic matter mineralization. Although some of these fungi have been identified and characterized, we still know little about the microbial ecology of wild blueberry. Our study aims to characterize the fungal and bacterial rhizosphere communities of Vaccinium angustifolium (the main species encountered in wild blueberry fields). Our results clearly show that the fungal order Helotiales was the most abundant taxon associated with V. angustifolium. Helotiales contains most of the known ericoid mycorrhizal fungi which are expected to dominate in such a biotope. Furthermore, we found the dominant bacterial order was the nitrogenfixing Rhizobiales. The Bradyrhizobium genus, whose members are known to form nodules with legumes, was among the 10 most abundant genera in the bacterial communities. In addition, Bradyrhizobium and Roseiarcus sequences significantly correlated with higher leaf-nitrogen content. Overall, our data documented fungal and bacterial community structure differences in three wild blueberry production fields.

Plant–soil–microbe interactions play a central role in plant nutrient acquisition and thus ecosystem functioning and nutrient availability in agroecosystems. Adjustments in root morphology, root exudation and associations with micro‐organisms such as arbuscular mycorrhizal fungi are common for phosphorus acquisition. Yet how plant below‐ground functional traits interact with microbial communities for P acquisition remains largely unknown, limiting our understanding of phosphorus availability in agroecosystems. Interactions between below‐ground functional traits and rhizosheath soil microbial communities for P acquisition were investigated across eight herbaceous species with contrasting root traits. Root morphological and physiological traits involved in P acquisition were quantified simultaneously with PLFA (phospholipid fatty acid) and NLFA (neutral lipid fatty acid) microbial bioindicators. Multiple correlations were observed between root morphology, root exudates and rhizosheath fungal and bacterial communities. Root exudates and in particular release of malate and malonate were strongly linked with indicators of Gram‐negative bacteria, which were correlated with changes in rhizosheath soil P concentration and plant P content. Our results suggest that root exudation of carboxylates may play an important role in plant–soil–microbe interactions for P acquisition, underlining their likely role in shaping microbial communities. Incorporating these interactions in biogeochemical models would lead to better predicting power and understanding of P cycling and ecosystem functioning. A free Plain Language Summary can be found within the Supporting Information of this article.

Repeated application of organic fertilizer has unintentionally let to the introduction into surface water and soils of many phytotoxic substances that compromise agricultural production and threaten environmental quality. Recent studies using hydroponic systems have reported that bisphenol A (BPA) affects essential mineral elements contents and root absorptive function, thereby impacting nutrient content in plant. However, in soils, plants develop specific traits related to nutrient acquisition strategies. In order to ensure optimized supply of nutrients, understanding the response of these traits under BPA stress is thus essential. Here, we therefore, investigated how leaf nutrient contents (P, Ca, K), root morphology, P-mobilizing exudates and rhizospheric microbiota biomass respond to BPA soil contamination using wheat (Triticum aestivum) as plant model. After 7 weeks, root and leaf traits were not markedly affected by the exposure to BPA at low and high concentrations (0.1 and 1000 mg. kg-1 soil). Significant change on average root diameter and aerial biomass were only observed at the highest dose. BPA contamination had no influence on nutrients acquisition traits and root associated microbiota. Specific root length, carboxylates exudation and P, Ca, K concentrations in leafs were similar irrespective of the treatments. In addition, total microbial biomass, bacteria and fungi abundance measured by phospholipid fatty acid analysis did not differ among controls and contaminated soils. In summary, this experiment suggests a limited influence of BPA contaminated soils on traits involved in nutrient acquisition in wheat.