Alaska is on the front lines of climate change, experiencing the fastest rates of warming of anywhere on this planet. And as temperatures rise within the state's interior — an enormous high-latitude region spanning 113 million acres — the permafrost not only melts, releasing significant amounts of its stored carbon back into the atmosphere. Where it accelerates with increasing temperature, it decelerates. This decomposition has the potential to infuse above- and below-ground food webs with carbon, which might affect the flow of energy between these necessary ecological connections and affect the species they support.
One of those species is the tundra vole, one in all 4 arctic or boreal forest animals identified by Philip Menlick, a research wildlife biologist on the USDA Forest Service Pacific Northwest Research Station in Juneau, Alaska, in recent research published today. Examined as part. Along with colleagues from the University of New Mexico and the University of Texas at Austin, Menlik used a brand new technique to estimate the results of climate change on the energy flow and carbon flow that plants support above ground. , or green, are driven by food webs and microbes. Subterranean, or brown, food webs that two forms of voles, a shrew, and a spider use as a window into a posh world.
“Understanding how energy moves through food webs helps us understand how ecosystems work and how animals can respond to stressors like climate change,” Menlick said. “In arctic and boreal ecosystems, it's well known that the climate is warming, the permafrost is melting, and microbes are flourishing. But we're changing terrestrial food webs and the animals they support. Little is known about the effects of this process on animals.”
A brand new technique with promise
The recent technique at the guts of the study involves measuring the unique carbon isotope “fingerprints” in essential amino acids that only plants, bacteria and fungi can produce. Animals can only obtain these molecules through their weight loss program. This allowed these essential amino acids to act as biomarkers that helped researchers track how carbon was moving between green and brown food webs, ultimately detecting changes. Helped them to put in.
“Scientists often argue about the importance of animals in ecosystem processes such as carbon cycling, but when they consume resources from different food webs, they move carbon between storage pools,” Menlick said. There are,” Menlik said. “In the long run, we predict this tool may very well be used to trace the fate of carbon through food webs to know the lively role of animals in ecosystem functions, resembling nutrient cycling. “
The study analyzed bone collagen from museum specimens of tundra and red-backed voles and masked shrews from the Bonanza Creek Experimental Forest near Fairbanks, Alaska, in 1990 and 2021, a sample that showed long-term climate warming. Represents animals facing. To study the results of short-term climate warming on the animals, researchers sampled arctic wolf spiders near Tulk Lake, Alaska. Some spiders were collected as controls and others exposed to 2°C warming in outdoor compartmentalized habitats called “mesocosms” wherein scientists simulate climate warming with micro-organisms. Can raise the temperature on the dimensions.
At just over 12,000 acres, and spanning interior forests and floodplains, the Bonanza Creek Experimental Forest is a perfect place to check the results of climate change on boreal forests and food webs since it represents a long-term change in interior Alaska. Provides periodic records. . It was established by the USDA Forest Service over 60 years ago and has been a National Science Foundation long-term environmental research site since 1987. For Menlik, the location provides a chance to check how and if these forest changes are affecting the animals that live there. Animals, themselves, forage and influence forest processes through food web dynamics.
Significant change in energy source
Through their isotope analyses, Menlick and his colleagues detected significant changes in carbon assimilation in mammals — specifically a shift from plant-based food webs to fungal-based food webs. In other words, fungi replaced plants because the principal energy source — with small mammals, resembling shrews, absorbing as much as 90 percent of their total carbon intake from fungal carbon, in comparison with historical patterns. There is a rise of greater than 40 percent.
The same was true of arctic wolf spiders. They, too, shifted to plant-based fungus-based food webs as their principal energy source, assimilating greater than 50 percent of brown carbon under warming conditions, in comparison with 26 percent at control sites. Is.
“Our study provides clear evidence that climate warming is changing the dynamics of carbon fluxes and food webs among top consumers in arctic tundra and boreal forest ecosystems — species, ecosystems, and long- and In short-term warming scenarios,” Menlik said. “And we show that these changes are primarily the results of a shift from green, plant-based food webs to brown, microbial-based food webs.”
What is behind the shift?
Scientists suspect that brown carbon is being transferred to top consumers like mammals and spiders in a series of predation events called trophic pathways. Warming ends in increased decomposition of permafrost in each tundra and boreal forests. Fungi feed on this decomposing plant matter and in turn are eaten by arthropods, mites and earthworms that move the fungal carbon up the food web where they, in turn, are eaten by wasps, shrews and spiders.
“Climate warming significantly changes the flow of energy through food webs, as animals that were historically supported by plant-based food webs now rely on fungi,” Menlick said. are supporting oriented food webs which are derived from subterranean decomposition,” Menlick said.
Animals can alter carbon cycling.
Menlick and his colleagues' work indicates that animals act as a crucial link between green and brown food webs. It also suggests that climate warming is changing this link between species in arctic and boreal forests. The potential implications of those climate-induced changes go far beyond the small size of those species.
“Changes in these interactions can have indirect effects on nutrient cycling and ecosystems,” Menlik said.
For example, if voles are getting more of their energy from belowground sources, they could be using fewer plants, which could increase carbon storage in aboveground ecosystems.
“Much of the current work in high latitudes focuses on 'Arctic greening,' or the idea that climate warming is leading to more vegetation and greener ecosystems. We found the exact opposite pattern – – food webs are 'going brown,'” he said.
Moving forward, Menlick plans to check why these patterns differ in plants and animals and what which means for the long run of those rapidly changing ecosystems.