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Most studies of invasive species have been in highly modffied, lowland environments, with comparatively little attention directed to less disturbed, high-elevation environments. However, increasing evidence indicates that plant invasions do occur in these environments, which often have high conservation value and provide important ecosystem services. Over a thousand non-native species have become established in natural areas at high elevations worldwide, and although many of these are not invasive, some may pose a considerable threat to native mountain ecosystems. Here, we discuss four main drivers that shape plant invasions into high-elevation habitats: (1) the (pre-)adaptation of non-native species to abiotic conditions, (2) natural and anthropogenic disturbances, (3) biotic resistance of the established communities, and (4) propagule pressure. We propose a comprehensive research agenda for tackling the problem of plant invasions into mountain ecosystems, including documentation of mountain invasion patterns at multiple scales, experimental studies, and an assessment of the impacts of non-native species in these systems. The threat posed to high-elevation biodiversity by invasive plant species is likely to increase because of globalization and climate change. However, the higher mountains harbor ecosystems where invasion by nonnative species has scarcely begun, and where science and management have the opportunity to respond in time. [ABSTRACT FROM AUTHOR]

Black-tailed prairie dogs are herbivorous rodents known to have large effects on grassland landscapes in North America. They have considerable impacts on prairie plant communities as the result of repeated clipping of vegetation that can reduce preferred forage species and may indirectly result in increased abundance of disturbance-tolerant species. We investigated plant communities within three different habitat types: Active and inactive prairie dog colonies, and adjacent suitable, but unoccupied, control areas in the Northern Great Plains of Montana, U.S.A. Plant species richness did not vary markedly between the three habitat types. However, plant composition measured as cover of plant life forms (forbs, shrubs, and graminoids), which was further divided into native status (native or introduced), and plant species indicators (plant species associated with a specific habitat) did vary distinctly between the three habitat types. Differences in plant composition between the habitat types suggests black-tailed prairie dog activities result in greater diversity of plant microhabitats at a landscape scale, and prairie dogs are an important component of the overall ecosystem in the Northern Great Plains of North America. [ABSTRACT FROM AUTHOR]

Canada thistle is a pervasive perennial weed, causing challenges to agricultural and natural ecosystems globally. Although research has focused on the phenology, genetics, and control of Canada thistle, little is known about the rhizosphere microbiome and the role plant-microbe interactions play in invasion success. This study investigated the rhizosphere microbiome of Canada thistle across diverse climates, soils, and crops in the U.S. northern Great Plains. Soil and rhizosphere samples were collected and bacterial 16S and fungal ITS2 sequencing were performed to characterize the core microbiome and identify potential factors contributing to invasion success. Amplicon sequencing revealed a stable core microbiome that was detected in the Canada thistle rhizosphere across all locations. The core microbiome was dominated by the bacterial phyla Actinobacteriota and Proteobacteria and fungal phyla Ascomycota and Basidiomycota. Differential abundance analysis showed rhizosphere fungal communities were enriched in pathogen-containing genera with a 1.7-fold greater abundance of Fusaria and a 2.6-fold greater abundance of Gibberella compared to bulk soil. Predictive functional profiling showed rhizosphere communities were enriched (p < 0.05, FDR corrected) in plant pathogen fungal guilds which represented 19% of the fungal community. The rhizosphere microbiome was similar in composition across environments, highlighting the stable association between Canada thistle and specific microbial taxa. This study characterized the core microbiome of Canada thistle, and the findings highlight plant-microbe interactions shaping invasive behavior. These findings are important for understanding the ecological impacts of plant invasion and soil-microbe ecological processes., (© 2024. The Author(s).)

Little knowledge exists on how soil bacteria in agricultural settings are impacted by management practices and environmental conditions in current and predicted climate scenarios. We assessed the impact of soil moisture, soil temperature, weed communities, and disease status on soil bacterial communities in three cropping systems: (i) conventional no-till (CNT) systems utilizing synthetic pesticides and herbicides, (ii) USDA-certified tilled organic (OT) systems, and (iii) USDA-certified organic systems with sheep grazing (OG). Sampling date within the growing season and associated soil temperature and moisture exerted the greatest effect on bacterial communities, followed by cropping system, Wheat streak mosaic virus (WSMV) infection status, and weed community. Soil temperature was negatively correlated with bacterial richness and evenness, while soil moisture was positively correlated with bacterial richness and evenness. Soil temperature and soil moisture independently altered soil bacterial community similarity between treatments. Inoculation of wheat with WSMV altered the associated soil bacteria, and there were interactions between disease status and cropping system, sampling date, and climate conditions, indicating the effect of multiple stressors on bacterial communities in soil. In May and July, cropping system altered the effect of climate change on the bacterial community composition in hotter conditions and in hotter and drier conditions compared to ambient conditions, in samples not treated with WSMV. Overall, this study indicates that predicted climate modifications as well as biological stressors play a fundamental role in the impact of cropping systems on soil bacterial communities. IMPORTANCE Climate change is affecting global moisture and temperature patterns, and its impacts are predicted to worsen over time, posing progressively larger threats to food production. In the Northern Great Plains of the United States, climate change is forecast to increase temperature and decrease precipitation during the summer, and it is expected to negatively affect cereal crop production and pest management. In this study, temperature, soil moisture, weed communities, and disease status had interactive effects with cropping system on bacterial communities. As local climates continue to shift, the dynamics of above- and belowground associated biodiversity will also shift, which will impact food production and increase the need for more sustainable practices., (Copyright © 2020 Ishaq et al.)