An official website of the United States government
Abstract Consumers play a critical role in mediating plant and ecosystem responses to abiotic stress, yet their influence on belowground processes under changing environmental conditions remains underexplored. Insect consumers are vital components of grassland ecosystems that can shape ecosystem function and stability by mitigating how plant and microbial communities respond to abiotic stress, like drought. This study investigates how small‐bodied consumers influence the magnitude and stability of grassland belowground functions across gradients of abiotic stress. We conducted a fully factorial field experiment manipulating consumer presence and induced drought over a growing season. Our results reveal that the presence of consumers stabilizes bacterial biomass and microbial activity across variable soil moisture conditions. Interestingly, this consumer‐induced increase in ecosystem stability was driven by a destabilization of microbial communities, as indicated by increased variability in bacterial community composition and abundance. Consumer presence also shifted soil bacterial community composition and richness, while fungal communities were less affected. Combined, our results highlight another important dimension of ecosystem stability: community responsiveness and rapid adaptability. Additionally, our findings underscore the critical role of consumers in maintaining belowground ecosystem stability and highlight the need to consider trophic interactions when predicting the impacts of global change on grassland ecosystems.
more »
« less
Microbial community response to a decade of simulated global changes depends on the plant community
Global changes such as increased drought and atmospheric nitrogen deposition perturb both the microbial and plant communities that mediate terrestrial ecosystem functioning. However, few studies consider how microbial responses to global changes may be influenced by interactions with plant communities. To begin to address the role of microbial–plant interactions, we tested the hypothesis that the response of microbial communities to global change depends on the plant community. We characterized bacterial and fungal communities from 395 plant litter samples taken from the Loma Ridge Global Change Experiment, a decade-long global change experiment in Southern California that manipulates rainfall and nitrogen levels across two adjacent ecosystems, a grassland and a coastal sage scrubland. The differences in bacterial and fungal composition between ecosystems paralleled distinctions in plant community composition. In addition to the direct main effects, the global change treatments altered microbial composition in an ecosystem-dependent manner, in support of our hypothesis. The interaction between the drought treatment and ecosystem explained nearly 5% of the variation in bacterial community composition, similar to the variation explained by the ecosystem-independent effects of drought. Unexpectedly, we found that the main effect of drought was approximately four times as strong on bacterial composition as that of nitrogen addition, which did not alter fungal or plant composition. Overall, the findings underscore the importance of considering plant–microbe interactions when considering the transferability of the results of global change experiments across ecosystems.
more »
« less
- Award ID(s):
- 1912525
- PAR ID:
- 10382749
- Date Published:
- Journal Name:
- Elementa: Science of the Anthropocene
- Volume:
- 9
- Issue:
- 1
- ISSN:
- 2325-1026
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Global change alters ecosystems and their functioning, and biotic interactions can either buffer or amplify such changes. We utilized a long‐term nitrogen (N) addition and species removal experiment in the Front Range of Colorado, USA to determine whether a codominant forb and a codominant grass, with different effects on nutrient cycling and plant community structure, would buffer or amplify the effects of simulated N deposition on soil bacterial and fungal communities. While the plant community was strongly shaped by both the presence of dominant species and N addition, we did not find a mediating effect of the plant community on soil microbial response to N. In contrast to our hypothesis, we found a decoupling of the plant and microbial communities such that the soil microbial community shifted under N independently of directional shifts in the plant community. These findings suggest there are not strong cascading effects of N deposition across the plant–soil interface in our system.more » « less
-
Growing season drought can be devastating to crop yields. Soil microbial communities have the potential to buffer yield loss under drought through increasing plant drought tolerance and soil water retention. Microbial inoculation on agricultural fields has been shown to increase plant growth, but few studies have examined the impact of microbial inoculation on plant and soil microbial drought tolerance. We conducted a rainout shelter experiment and subsequent greenhouse experiment to explore 3 objectives. First, we evaluated the performance of a large rainout shelter design for studying drought in agricultural fields. Second, we tested how crop (corn vs. soybean) and microbial inoculation alter the response of soil microbial composition, diversity, and biomass to drought. Third, we tested whether field inoculation treatments and drought exposure altered microbial communities in ways that promote plant drought tolerance in future generations. In our field experiment, the effects of drought on soil bacterial composition depended on crop type, while drought decreased bacterial diversity in corn plots and drought decreased microbial biomass carbon in soybean plots. Microbial inoculation did not alter overall microbial community composition, plant growth, or drought tolerance despite our efforts to address common barriers to inoculation success. Still, a history of inoculation affected growth of future plant generations in the greenhouse. Our study demonstrates the importance of plant species in shaping microbial community responses to drought and the importance of legacy effects of microbial inoculation.more » « less
-
Abstract Global climate and land use change are causing woody plant encroachment in arctic, alpine, and arid/semi‐arid ecosystems around the world, yet our understanding of the belowground impacts of this phenomenon is limited. We conducted a globally distributed field study of 13 alpine sites across four continents undergoing woody plant encroachment and sampled soils from both woody encroached and nearby herbaceous plant community types. We found that woody plant encroachment influenced soil microbial richness and community composition across sites based on multiple factors including woody plant traits, site level climate, and abiotic soil conditions. In particular, root symbiont type was a key determinant of belowground effects, as Nitrogen‐fixing woody plants had higher soil fungal richness, while Ecto/Ericoid mycorrhizal species had higher soil bacterial richness and symbiont types had distinct soil microbial community composition. Woody plant leaf traits indirectly influenced soil microbes through their impact on soil abiotic conditions, primarily soil pH and C:N ratios. Finally, site‐level climate affected the overall magnitude and direction of woody plant influence, as soil fungal and bacterial richness were either higher or lower in woody encroached versus herbaceous soils depending on mean annual temperature and precipitation. All together, these results document global impacts of woody plant encroachment on soil microbial communities, but highlight that multiple biotic and abiotic pathways must be considered to scale up globally from site‐ and species‐level patterns. Considering both the aboveground and belowground effects of woody encroachment will be critical to predict future changes in alpine ecosystem structure and function and subsequent feedbacks to the global climate system.more » « less
-
ABSTRACT Fire is a common ecological disturbance that structures terrestrial ecosystems and biological communities. The ability of fires to contribute to ecosystem heterogeneity has been termed pyrodiversity and has been directly linked to biodiversity (i.e., the pyrodiversity–biodiversity hypothesis). Since climate change models predict increases in fire frequency, understanding how fire pyrodiversity influences soil microbes is important for predicting how ecosystems will respond to fire regime changes. Here we tested how fire frequency‐driven changes in burn patterns (i.e., pyrodiversity) influenced soil microbial communities and diversity. We assessed pyrodiversity effects on soil microbes by manipulating fire frequency (annual vs. biennial fires) in a tallgrass prairie restoration and evaluating how changes in burn patterns influenced microbial communities (bacteria and fungi). Annual burns produced more heterogeneous burn patterns (higher pyrodiversity) that were linked to shifts in fungal and bacterial community composition. While fire frequency did not influence microbial (bacteria and fungi) alpha diversity, beta diversity did increase with pyrodiversity. Changes in fungal community composition were not linked to burn patterns, suggesting that pyrodiversity effects on other ecosystem components (e.g., plants and soil characteristics) influenced fungal community dynamics and the greater beta diversity observed in the annually burned plots. Shifts in bacterial community composition were linked to variation in higher severity burn pattern components (grey and white ash), suggesting that thermotolerance contributed to the observed changes in bacterial community composition and lower beta diversity in the biennially burned plots. This demonstrates that fire frequency‐driven increases in pyrodiversity augment biodiversity and may influence productivity in fire‐prone ecosystems.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1525/elementa.2021.00124
