Soil Disturbance Affects Plant Productivity via Soil Microbial Community Shifts

Abstract

Recent advances in climate research have discovered that permafrost is particularly vulnerable to the changes occurring in the atmosphere and climate, especially in Alaska where 85% of the land is underlain by mostly discontinuous permafrost. As permafrost thaws, research has shown that natural and anthropogenic soil disturbance causes microbial communities to undergo shifts in membership composition and biomass, as well as in functional diversity. Boreal forests are home to many plants that are integral to the subsistence diets of many Alaska Native communities. Yet, it is unclear how the observed shifts in soil microbes can affect above ground plant communities that are relied on as a major source of food. In this study, we tested the hypothesis that microbial communities associated with permafrost thaw affect plant productivity by growing five plant species found in Boreal forests and Tundra ecosystems, including low-bush cranberry and bog blueberry, with microbial communities from the active layer soils of a permafrost thaw gradient. We found that plant productivity was significantly affected by the microbial soil inoculants. Plants inoculated with communities from above thawing permafrost showed decreased productivity compared to plants inoculated with microbes from undisturbed soils. We used metagenomic sequencing to determine that microbial communities from disturbed soils above thawing permafrost differ in taxonomy from microbial communities in undisturbed soils above intact permafrost. The combination of these results indicates that a decrease in plant productivity can be linked to soil disturbance driven changes in microbial community membership and abundance. These data contribute to an understanding of how microbial communities can be affected by soil disturbance and climate change, and how those community shifts can further influence plant productivity in Boreal forests and more broadly, ecosystem health.

Unearthing Shifts in Microbial Communities Across a Soil Disturbance Gradient

“…The soil samples we collected and used for this study were previously described in Seitz et al, 2021 Linell et al (1973) of varying degrees of soil disturbance. When FPES was established, the first plot, referenced as undisturbed (UD), was left untouched.…”

“…To assess how soil microbial communities are shifting based on previous soil disturbance, we collected a total of 48 soil samples on 28 May 2018, with 16 each from UD, SD, and MD plots. The collection of these cores and their original use was described in Seitz et al (2021). In brief, we extracted cores from a selection of quadrats throughout each disturbance plot to sample the within disturbance level heterogeneity.…”

“…Increasing our understanding of the relationship between active layer soil microbial communities and soil disturbance events, specifically those resulting in deep permafrost thaw including high temperature wildfires, is crucial in the face of the pressures of climate change in the Arctic. In Seitz et al (2021), we observed differences in plant growth associated with microbes from a disturbance gradient. Evidence there suggested that microbes from disturbed soils associated with deep permafrost thaw negatively impacted the productivity of several plants commonly found in boreal ecosystems.…”

“…However, the previous analysis of the soil microbial communities was based on metagenomic sequencing (Seitz et al, 2021), and we wanted to use a measure allowing a closer comparison to other environmental soil microbiome studies (i.e., 16S rRNA amplicon sequencing). Given that studies have demonstrated soil microbial community function shifts with disturbance (Choi et al, 2017;Mackelprang et al, 2011;Santillan et al, 2019), we also aimed to use previously collected metagenomic data to identify any shifts in function that may be leading to the decrease in plant productivity observed in Seitz et al (2021). To further develop our understanding of the potential impacts of soil disturbance events, including permafrost thaw, we analyzed whether within disturbance level variation can predict the growth of plants from an earlier growth experiment described in Seitz et al (2021).…”

“…Given that studies have demonstrated soil microbial community function shifts with disturbance (Choi et al, 2017;Mackelprang et al, 2011;Santillan et al, 2019), we also aimed to use previously collected metagenomic data to identify any shifts in function that may be leading to the decrease in plant productivity observed in Seitz et al (2021). To further develop our understanding of the potential impacts of soil disturbance events, including permafrost thaw, we analyzed whether within disturbance level variation can predict the growth of plants from an earlier growth experiment described in Seitz et al (2021). We hypothesized that within bacterial community diversity will increase with disturbance, and that between community diversity will shift as well.…”