Fungal communities can be used as indicators of various environmental processes in forest ecosystems. The diversity of these communities is linked to aboveground plants and soil properties. We assessed fungal diversity at four Norway spruce sampling sites that were growing on fertile mineral soils (Oxalidosa) in northwestern Latvia. Three sites were managed-a three-year-old clear-cut and fifty- and eighty-five-year-old stands; one site was unmanaged-a naturally regenerated site after wind damage in 1969. For metabarcoding, we used a fungal internal transcribed spacer (ITS2) and high throughput sequencing with the Ion Torrent platform. Our results showed high operational taxonomic unit richness in the samples, with notable variation in community composition between individual plots both within and among sites, with the highest being in managed, middle-aged stands and the lowest in unmanaged. Significant differences in the diversity of soil fungal communities were not detected between the sites. Redundancy analysis indicated that pH, soil organic matter, organic carbon, and nitrogen were the most important soil variables that explained the variation in fungal communities. The unmanaged stand differed notably by community composition. This study highlights the importance of monitoring forest soil environmental parameters and fungal communities to gain a more comprehensive assessment of forestry management regimes.

The negative ramifications of invasive alien species (IAS) are considered the second-most cause of biodiversity extinction and endangerment after habitat modification. IAS movements are mainly anthropogenically driven (e.g., transport of shipping containers) and require fast detection to minimize damage and cost. The present study is the first to use molecular biosurveillance of international shipping containers to detect IAS and regulated species identification in Canada. Thirty-eight samples were collected from debris (soil, stems, seeds, individual specimens) found in containers arriving in Canada. A multi-marker approach using COI, ITS, ITS2, and 16S was used to identify four main taxonomic groups: arthropods, fungi, plants, and bacteria, respectively. Eleven IAS species were identified via metabarcoding based on environmental DNA samples, including two arthropods, six fungi, two plants, and one bacteria. The origin of the eDNA detected from each species was linked to their native distribution and country of origin, except for Lymantria dispar. Four physical specimens were also collected from shipping container debris and DNA barcoded, identifying three non-regulated species (two arthropods and one fungus). Altogether, these results demonstrate the importance of integrating molecular identification into current toolkits for the biosurveillance of invasive alien species and provide a set of validated protocols ready to be used in this context. Additionally, it reaffirms international shipping containers as a pathway for multiple invasive aliens and regulated species introduction in Canada. It also highlights the need to establish regular and effective molecular biosurveillance at the Canadian border to avoid new or recurrent invasions. Las ramificaciones negativas de las especies ex & oacute;ticas invasoras (EEI) se consideran la segunda causa de extinci & oacute;n y peligro de la biodiversidad despu & eacute;s de la modificaci & oacute;n del h & aacute;bitat. Los movimientos de EEI son impulsados principalmente por causas antropog & eacute;nicas (por ejemplo, transporte de contenedores de env & iacute;o) y requieren una detecci & oacute;n r & aacute;pida para minimizar da & ntilde;os y costos. El presente estudio es el primero en utilizar biovigilancia molecular de contenedores de env & iacute;o internacionales para detectar EEI y la identificaci & oacute;n de especies reguladas en Canad & aacute;. Se recolectaron treinta y ocho muestras de material (tierra, tallos, semillas, espec & iacute;menes individuales) encontrados en contenedores que llegaron a Canad & aacute;. Se utilizaron m & uacute;ltiples marcadores moleculares, COI, ITS, ITS2 y 16S, para identificar cuatro grupos taxon & oacute;micos principales: artr & oacute;podos, hongos, plantas y bacterias, respectivamente. Se identificaron once especies de EEI mediante matabarcoding basado en ADN ambiental, incluidos dos artr & oacute;podos, seis hongos, dos plantas y una bacteria. El origen del ADN ambiental detectado de cada especie estuvo vinculado a su distribuci & oacute;n nativa y pa & iacute;s de origen, excepto Lymantria dispar. Tambi & eacute;n se recolectaron cuatro espec & iacute;menes en los contenedores de env & iacute;o y se analizaron mediante c & oacute;digo de barras de ADN, identificando tres especies no reguladas (dos artr & oacute;podos y un hongo). En conjunto, estos resultados demuestran la importancia de integrar la identificaci & oacute;n molecular dentro de las herramientas actuales para la biovigilancia de especies ex & oacute;ticas invasoras y proporcionan un conjunto de protocolos validados listos para ser utilizados en este contexto. Adem & aacute;s, reafirma que los contenedores de transporte internacional son una v & iacute;a para la introducci & oacute;n de m & uacute;ltiples especies ex & oacute;ticas invasoras y especies reguladas en Canad & aacute;. Tambi & eacute;n destaca la necesidad de establecer una biovigilancia molecular peri & oacute;dica y eficaz en la frontera canadiense para evitar invasiones nuevas o recurrentes.

Soil suppressiveness can reduce the damage by plant parasitic nematodes (PPN) in agricultural soils and is conveyed by the activity of soil microorganisms. While natural suppressiveness has been reported, it is still poorly understood if soil suppressiveness can be elicited by manipulating the soil microbial community. In the present study we assessed the number of the Pratylenchus penetrans (Pp) and the bacterial and fungal community composition over 7 years in a long-term soil health experiment. The field experiment consisted of an organic and conventional agricultural land management system and three soil health treatments (SHT): an untreated control (CT), anaerobic disinfestation (AD) and a combination of marigold cover cropping, compost and chitin amendment (CB). The land management systems were kept continuously, while the soil health treatments were applied only twice in seven years. The microbial community significantly differed between the organic and conventional system, but there was no significant difference in Pp numbers between the two systems. However, both the CB treatment and to a lesser extent the AD treatment reduced Pp numbers and increased yield with the effect being the strongest in the years immediately after the treatment. Accordingly, both the bacterial and fungal community differed significantly between the treatments, the differences being largest in the years after the treatments. Notably, the CB treatment elicited both long-term changes in the microbial community and a reduction of Pp numbers lasting for at least three years. These results indicated that a combination of treatments can lead to an altered soil microbial community in combination with persisting suppressiveness of Pp.

Root-knot nematodes (RKNs) of the genus Meloidogyne are one of the most damaging genera to cultivated woody plants with a worldwide distribution. The knowledge of the soil and rhizosphere microbiota of almonds infested with Meloidogyne could help to establish new sustainable and efficient management strategies. However, the soil microbiota interaction in deciduous woody plants infected with RKNs is scarcely studied. This research was carried out in six commercial almond groves located in southern Spain and infested with different levels of Meloidogyne spp. within each grove. Several parameters were measured: nematode assemblages, levels and biocontrol agents in Meloidogyne's eggs, levels of specific biocontrol agents in rhizoplane and soil, levels of bacteria and fungi in rhizoplane and soil, fungal and bacterial communities by high-throughput sequencing of internal transcribed spacer (ITS), and 16S rRNA gene in soil and rhizosphere of the susceptible almond hybrid rootstock GF-677 infested with Meloidogyne spp. The studied almond groves showed soil degradation by nematode assemblies and fungi:bacterial ratio. Fungal parasites of Meloidogyne eggs were found in 56.25% of the samples. However, the percentage of parasitized eggs by fungi ranged from 1% to 8%. Three fungal species were isolated from Meloidogyne eggs, specifically Pochonia chlamydosporia, Purpureocillium lilacinum, and Trichoderma asperellum. The diversity and composition of the microbial communities were more affected by the sample type (soil vs rhizosphere) and by the geographical location of the samples than by the Meloidogyne density, which could be explained by the vigorous hybrid rootstock GF-677 and a possible dilution effect. However, the saprotrophic function in the functional guilds of the fungal ASV was increased in the highly infected roots vs the low infected roots. These results indicate that the presence of biocontrol agents in almond fields and the development of new management strategies could increase their populations to control partially RKN infection levels.

The extraradical mycelium of mycorrhizal fungi is among the major carbon pools in soil that is hard to quantitatively assess in-situ. Established method of in-growth mesh bags in temperate ecosystems is difficult to apply in the tropics, where mesh bags are often damaged by termites. Here we introduce a modification of the ingrowth mesh bag technique, in which mesh bags are enforced by stainless steel mesh. Its performance was tested in the Dong Nai (Cat Tien) National Park in Vietnam across two monsoon tropical forests, dominated by tree species associated with either ectomycorrhizal (ECM) or arbuscular mycorrhizal (AM) fungi. Armored ingrowth mesh bags remained intact, while about 60 % of non-armored mesh bags were damaged by termites after 180 days of exposure. The biomass of extraradical mycelium of ectomycorrhizal fungi estimated by PLFA analysis was similar in the armored and non-armored mesh bags and did not differ between studied forests. However, fungal community composition slightly differed between armored and non-armored mesh bags in the ECM-but not in the AM-dominated forest. Fungal mycelium gathered in the AM-dominated forest was depleted in N-15 compared to that collected in the ECM-dominated forest. Overall, our results argue for using armored mesh bags as a robust tool for harvesting the biomass of extraradical mycelium of mycorrhizal fungi in tropical ecosystems.

The retreat of glaciers in Antarctica has increased in the last decades due to global climate change, influencing vegetation expansion, and soil physico-chemical and biological attributes. However, little is known about soil microbiology diversity in these periglacial landscapes. This study characterized and compared bacterial and fungal diversity using metabarcoding of soil samples from the Byers Peninsula, Maritime Antarctica. We identified bacterial and fungal communities by amplification of bacterial 16 S rRNA region V3-V4 and fungal internal transcribed spacer 1 (ITS1). We also applied 14C dating on soil organic matter (SOM) from six profiles. Physicochemical analyses and attributes associated with SOM were evaluated. A total of 14,048 bacterial ASVs were obtained, and almost all samples had 50% of their sequences assigned to Actinobacteriota and Proteobacteria. Regarding the fungal community, Mortierellomycota, Ascomycota and Basidiomycota were the main phyla from 1619 ASVs. We found that soil age was more relevant than the distance from the glacier, with the oldest soil profile (late Holocene soil profile) hosting the highest bacterial and fungal diversity. The microbial indices of the fungal community were correlated with nutrient availability, soil reactivity and SOM composition, whereas the bacterial community was not correlated with any soil attribute. The bacterial diversity, richness, and evenness varied according to presence of permafrost and moisture regime. The fungal community richness in the surface horizon was not related to altitude, permafrost, or moisture regime. The soil moisture regime was crucial for the structure, high diversity and richness of the microbial community, specially to the bacterial community. Further studies should examine the relationship between microbial communities and environmental factors to better predict changes in this terrestrial ecosystem.