Two Sides Of The Same Plant: Mismatched Responses To Warming

Climate warming induces different responses in plant growth patterns above and below ground, potentially disrupting ecosystem stability.

AsianScientist (Dec. 22, 2021) – While a warming climate is known to affect plant growth and seasonal behaviors, it turns out that the aboveground changes are not always the same beneath the surface. These mismatched responses between the shoots and the roots were reported in Nature Climate Change.

Whether plants or animals, nature follows its own clock: humans have sleep-wake cycles, some bird species have migratory periods and plants have seasonal growth patterns. These biological timetables—the study of which is called phenology—are vital not only for an individual organism’s survival, but also the larger ecosystem’s overall stability.

As the planet warms, however, climate variations are altering wildlife growth periods. Scientists have observed many changes above the ground, such as flowers blooming earlier than expected, and assumed these effects were mirrored below the surface as well.

But new findings are challenging this notion, revealing a different growing season between roots underground and the same plants’ shoots up above. The international research team, led by Professor Zhou Xuhui from China’s Northeast Forestry University, synthesized data from 88 published studies to unearth these unsynchronized phenological responses.

This meta-analysis showed that climate warming did not disrupt the belowground phenology of herbaceous plants like grasses and ferns. Meanwhile, the shoot growing season remained unchanged in length, but shifted forward—starting and ending earlier than normal.

In contrast, the team found the opposite results for woody plants like trees and shrubs. While plant growth aboveground was more resistant to the effects of warming and preserved its normal patterns, the roots’ phenological phases became significantly lengthier.

These varying growing periods influence how a plant allocates its resources, such as putting more biomass or carbon in the roots when underground nutrients are limited. In turn, plant responses to climate warming have far-reaching effects on ecological interactions, such as the exchange of carbon, water and nutrients between soil, plants and consumers.

While the study’s data are preliminary and limited by the small sample size, the newfound evidence highlights the need for more extensive investigations into the previously overlooked belowground growing season.

Moreover, these results could prompt revisiting existing ecological models and integrating belowground phenology in mapping carbon, water and energy flows. With detailed data on plant growing seasons, scientists can better predict and devise interventions against the effects of climate change on ecosystem stability.

“Understanding the links between above- and belowground phenology is crucial for predicting whole ecosystem responses in a warming world,” the authors concluded. “Our results encourage future studies to examine both the causes and consequences of mismatches in above- and belowground plant phenology in response to climate warming.”

The article can be found at: Liu et al. (2021) Phenological mismatches between above- and belowground plant responses to climate warming.


Source: East China Normal University; Photo: Shutterstock.
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