Grasslands are reacting to climate change nearly instantly, new research suggests.
While all ecosystems experience the effects of climate change, often the signs are delayed. For instance, alterations in forest biodiversity typically lag behind shifts in temperature and rainfall.
In contrast, recent findings from the University of Michigan indicate that grasslands are responding to climate change almost immediately. According to the study’s lead researchers, Kai Zhu and Yiluan Song, “forests are accruing climate debt while grasslands are adjusting right away.”
“Climate change unquestionably impacts our ecosystems. It will manifest, sooner or later,” remarked Song, a postdoctoral fellow at the Michigan Institute for Data and AI in Society. “Grasslands are among the first to react.”
This research aims to enhance the scientific community’s understanding and forecasting of climate change effects, noted Zhu, an associate professor at U-M School for Environment and Sustainability. Additionally, it offers vital insights for restoring grassland vegetation.
“To restore grasslands, you need to consider what species to plant,” Zhu explained. “And to answer this, climate change must at least be factored in.”
The research findings were published in the journal Nature Ecology & Evolution.
The research team, comprising members from over a dozen institutions, compiled years of observational data from grassland communities in the California Floristic Province.
This biodiversity hotspot, stretching along the U.S. West Coast, was studied across 12 sites over several decades. Researchers observed that as the local climate grew hotter and drier, species favoring such conditions became more prevalent in plant communities.
They also incorporated results from long-term global change experiments in the area, demonstrating how climate change can drive community shifts.
“While correlation doesn’t equal causation,” Zhu clarified, “experimental data help us establish cause-and-effect relationships.”
The team identified the climate preferences or niches of various species, enabling them to quantify shifts in plant communities related to changes in temperature and precipitation.
This methodology led to a clear and consistent conclusion across both observational and experimental sites, which Zhu and Song noted is rare in ecological studies.
What was even more striking was the speed of these ecological changes, they said. The rate was rapid and aligned with the changing climate. The researchers emphasized that this swift transformation in plant communities should not be viewed as adaptation—at least not without further research.
“To me, adaptation carries a positive connotation, suggesting the system is evolving to mitigate some negative impacts of climate change,” Song stated. “The quick transitions in grassland communities involve not only the emergence of some species better suited to hotter, drier conditions but also the decline of those favoring cooler and wetter environments. These changes could lead to adverse effects, including the dominance of non-native species and a decline in biodiversity.”
Although their study was localized, Zhu and Song believe the findings will apply to other grasslands, as long as they are examined within the context of each region’s climate dynamics. For instance, if a region is experiencing warmer and wetter conditions, species that thrive in those environments are likely to increase in number at a rate that mirrors the climate changes.
“I would predict that we might observe an even stronger response to climate change in other grasslands worldwide,” Zhu suggested.
Additional contributions to the study came from researchers at California Polytechnic State University, Clark College, East Bay Regional Park District, University of Oregon, University of Washington, University of Western Australia, and Stanford University. Several University of California entities, including UC Berkeley, UC Davis, UC Riverside, UC Santa Barbara, and UC Santa Cruz, also participated in the project, which Zhu and Song initially began.
