Rapid warming has so profoundly impacted northern ecosystems that scientists are increasingly concerned about the region’s ability to recover from climate shocks, according to a new study focused on Arctic plant resilience.
The researchers found that frequent disturbances like wildfires, drought, and deforestation have diminished the resilience of many plant communities in the southern boreal forests.
Plant resilience and carbon storage
This decline in resilience – meaning the plants’ ability to bounce back after environmental stressors – could have serious implications for the Arctic’s role in absorbing carbon dioxide, potentially transforming the region from a carbon sink into a carbon source in the near future.
This shift is particularly troubling because the Arctic and boreal regions have warmed several times faster than other parts of the world, and continued warming is expected.
Yue Zhang is the study’s lead author and a graduate student in earth sciences at the Ohio State University.
“When we talk about the response of forests to climate change, most of the time we’re thinking about the tropical rainforest,” explained Zhang.
“But remote boreal forests are really important in terms of their vast extent, large carbon storage and potential to mitigate climate change.”
Varying levels of plant resilience
Based on historical data from NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE) program, the researchers utilized remote sensing technology to track subtle changes in vegetation greenness in Alaska and western Canada between 2000 and 2019.
The goal was to estimate how quickly vegetation recovered from both small-scale fluctuations and large losses, even in areas where significant damage had not yet occurred.
The results showed that while plant resilience in southern boreal forests had decreased over time, resilience appeared to increase in most of the Arctic tundra, despite areas of greening.
Fires, drought, and heat likely contributed to the declining resilience in the southern regions, while shifts in nutrient availability may have helped vegetation thrive in other parts of the Arctic.
Uncertainty of plant carbon storage
However, even though the release of nutrients could benefit plant growth, rising temperatures threaten to accelerate permafrost melting.
The permafrost stores vast amounts of carbon, and its thawing could release carbon emissions equivalent to those produced by 35 million cars annually, hastening the arrival of climate tipping points.
Zhang emphasized the uncertainty about how much of this carbon will be absorbed by plants versus how much will contribute to further warming.
“That’s pretty concerning, because while greening may indicate that productivity and carbon uptake in these regions is increasing now, resilience decline indicates that it may not be sustainable in the longer term.”
An entire ecosystem at risk
The study’s findings indicate that the entire ecosystem is at risk, as large portions of the southern boreal forests are losing stability. This could lead to widespread forest loss and biome shifts in the future.
Greening regions that simultaneously experience a decline in resilience may be showing signs of distress, suggesting that the ecosystem is struggling to survive before it experiences significant forest loss.
“This is a hot spot of vegetation change where studying it can tell us about the ecosystem stability and what it’s capable of tolerating before it transitions into an alternative state through pervasive forest loss,” warned study senior author Professor Yanlan Liu.
Predicting plant resilience
The experts also found that regions at higher elevations with warm, dry conditions and dense vegetation cover were among the most vulnerable to declining resilience.
Yet, there is still a lack of consensus in current climate models regarding how vegetation change and carbon dynamics interact. The team’s work will help to refine these models by providing information about where vegetation shifts are most likely to occur.
Ultimately, Zhang noted that the research has uncovered more subtle changes in the health of the region’s vegetation than previously reported greening and browning trends. Their methodology also offers a new tool for identifying potential vegetation loss in other regions over the coming decades.
Future research directions
The team plans to continue improving their predictions of ecosystem changes and advocate for more fieldwork to verify their remote sensing data.
“Scientists need to learn to quantify climate-induced risks through diverse lenses,” Liu said. “On top of satellite remote sensing, we need more ground observations to help us identify ways to leverage these findings to inform future resources and risk management strategies.”
As the Arctic and boreal regions warm at alarming rates, this study sheds light on the fragility of these ecosystems and the need for urgent strategies to preserve their resilience amid rapid climate change.
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