Can soil microbes survive in a changing climate?
Organisms across the globe are facing unprecedented levels of stress from climate change, habitat destruction, and many other human-driven changes to the environment. Predicting and mitigating the effects of this increasing stress on organisms, and the environmental services on which we depend, requires understanding why some species can exist in a wide range of environments while others exist in only a few habitats.
In the scientific world of ecology, researchers often try to sort organisms on our planet into two categories: specialists and generalists. Generalists can survive across various environmental conditions and habitats, while specialists are more restricted or limited to specific conditions for survival. The panda bear, for example, feeds only on bamboo within a specific habitat. Not only is their habitat range-restricted, but so is their diet, and if the bamboo plant became extinct, panda bears might become extinct as well.
But what about the microbial world of unseen organisms found everywhere on Earth, from the human gut to the soil under our feet? Into which category do they fall?
To find the answer, a group of graduate and postdoc students in Associate Professor Michelle Afkhami's biology lab at the University of Miami College of Arts and Sciences studied the DNA sequences of prokaryotes, a group of microbes that include all bacteria and archaea.
The findings are in a study, titled "Multidimensional specialization and generalization are pervasive in soil prokaryotes," available in the journal Nature Ecology & Evolution.
"The idea behind the project was to find out whether these microbes can exist within a narrow or broad range of conditions along many different environmental dimensions," said Damian Hernandez, a former graduate student in Afkhami's lab and now a postdoc preparing for a biology fellowship with the National Science Foundation.
"Specifically, we wanted to know whether microbes are typically multidimensional specialists, multidimensional generalists, or use different strategies on different environmental dimensions—and what effect that could have on their roles within communities.
"The environmental dimensions we used to determine whether the microbes are generalists or specialists were based on multiple environmental conditions in the soil in which they live, for example, leaf litter, temperature, water, and nutrients," he added.
In a collaborative effort two years in the making, the team of students analyzed over 200 soil samples collected by the National Ecological Observatory Network (NEON) from sites across the United States. Of the over 1,200 prokaryotes examined, Hernandez and the team found something quite surprising. They found that the majority (90 percent) of the microbes were either multidimensional generalists or multidimensional specialists.
Essentially, if a microbe was a generalist across one environmental axis, it was almost always a generalist across all other axes; and if it was a specialist on one environmental axis, it specialized across all axes. In addition to providing important insight into how microbial communities are structured, this discovery provides some of the first evidence for multidimensional specialization and generalization in any type of organism.
"We found that microbes can be very restricted on where they can exist," said Hernandez, who is the first author of the study. "The generalist microbes are very flexible and can withstand a broader range of conditions. But the specialist microbes are sensitive to many different environmental conditions because they are restricted on multiple environmental axes and thus any changes in the environment may hinder their survival.
"Hypothetically, if an ecosystem is structured by microbes that are specialists, then those ecosystems are more likely to be sensitive to environmental change," he said.
Afkhami confirms that the findings present an interesting argument on how microbes can survive in a changing climate.
"As we learned from the study, microbes that are generalists can live across a wide range of habitats, and this can mean that those microbes may be resilient to climate change or habitat fragmentation because they are likely to tolerate changing environmental conditions. They are also very dominant within microbial communities," she said.
In contrast, the team found that specialist microbes can be very susceptible to environmental change. Microbes categorized as specialists also appear to be important "community organizers" due to their high functionality within the microbial world. For example, the research team discovered that specialist microbes are more likely to be those that can promote plant growth, detoxify the soil, digest complex carbons in the soil, and add nutrients to the soil.
"This is very concerning because what we also learned in the study is that microbial specialists are highly connected within the microbial network and can be considered as keystone species for maintaining and driving the diversity and function of the microbiome," said Afkhami.
"In this study, we can start to understand—across a wider sense in the microbiome community—some of their biological functions, their roles in the microbial community, and how they will respond to global changes on the planet."
More information: Damian J. Hernandez et al, Multidimensional specialization and generalization are pervasive in soil prokaryotes, Nature Ecology & Evolution (2023). DOI: 10.1038/s41559-023-02149-y
Provided by University of Miami Plant life found to determine soil bacteria diversity in the Arctic tundra
New UCF project examines key role soils play in keeping the planet cool
The research, funded by a grant from the USDA National Institute of Food and Agriculture, will examine a method to keep carbon from escaping soils and trapping heat in Earth’s atmosphere.
Grant and Award AnnouncementUNIVERSITY OF CENTRAL FLORIDA
New UCF Project Examines Key Role Soils Play in Keeping the Planet Cool
The research, funded by a grant from the USDA National Institute of Food and Agriculture, will examine a method to keep carbon from escaping soils and trapping heat in Earth’s atmosphere.
ORLANDO, Aug.17, 2023 – A new project from the University of Central Florida is looking to the soils for a way to cool the skies.
Funded by a nearly $750,000 grant from the USDA National Institute of Food and Agriculture, the research will examine a method to keep carbon from escaping soils and becoming the greenhouse gas carbon dioxide. As carbon dioxide accumulates in the atmosphere, it warms the Earth by trapping heat.
The research is important as NASA has reported that the Earth has seen some of the hottest temperatures on record this summer.
“When we talk about climate change, a lot of people have the misperception that most of the Earth’s carbon is stored in the atmosphere,” says Lisa Chambers, the project’s principal investigator and an associate professor in UCF’s Department of Biology. “But the atmospheric carbon pool is actually quite small, relative to the pool of carbon in the soil.”
The research will focus on histosols, or organic rich soils, in the Everglades Agricultural Area located south of Lake Okeechobee in Florida.
Histosols comprise only about 1.3% of Earth’s land surface, but store approximately 23% of its carbon. The nutrient-rich soils are perfect for agriculture, but their drainage and cultivation lead to increased carbon dioxide in the atmosphere.
The research team, which includes Jehangir Bhadha with the University of Florida and Jing Hu with Mississippi State University, will examine adding fine minerals — such as silt and clays — to the histosols to prevent carbon from escaping.
Research has found that mineral-associated organic matter releases less carbon into the atmosphere because it is less susceptible to decomposition by microbes.
“It’s been shown through carbon-14 dating that the carbon that’s associated with these fine silts and clays has remained in the soil the longest,” Chambers says. “Whereas unassociated, loose organic matter only dates back tens to hundreds of years old and is easily decomposed by microbes into CO2, the mineral-associated organic matter has been aged to be millennia.”
She says the Everglades Agricultural Area is the perfect place to perform the research because not only could the work help with climate change, but it could also improve agricultural production and sustainability in the area.
Soil subsidence due to decomposing histosols has become a major problem in the Everglades Agricultural Area, where in some locations soil elevation has dropped as much as six feet over the past 100 years.
“The soil has been so unprotected and oxidizing so fast, that there are places where the soils are almost completely gone, turned back into carbon dioxide in the atmosphere, and they're almost down to bedrock,” she says. “So, it's kind of a precarious situation.”
The four-year project will involve surveying the current status of mineral-associated organic matter in the area, lab experiments to determine the best soil formulations and field-scale trials. Although the project will focus on South Florida, the findings could have applications in other areas where histosols have been drained for agricultural production.
Chambers received her doctorate in wetland biogeochemistry from the University of Florida and joined the Department of Biology in UCF’s College of Sciences in 2015. She is the principal investigator of the Aquatic Biogeochemistry Laboratory and is also a member of UCF’s National Center for Integrated Coastal Research.
CONTACT: Robert H. Wells, Office of Research, robert.wells@ucf.edu
No comments:
Post a Comment