Ecologists have long understood that biodiversity is paramount to the stability of ecosystems. Until now, however, the majority of ecological research has focused on a single layer of ecological life at a time—for example, plant or animal communities.
In reality, ecological systems have multiple layers that interact continuously. Plants are eaten by herbivores, herbivores are eaten by predators, and the fluctuations at one trophic level, or an organism's specific position in the food chain, can ripple through the entire ecosystem.
To address this knowledge gap, a team of researchers from YOKOHAMA National University, the Chinese Academy of Sciences, Tokyo City University and Inner Mongolia University used three years of cumulative data and structural equation models to assess how species diversity, composition, timing of species dominance, and species stability within plant, herbivore and predator communities were associated with ecosystem stability at various levels of the food chain.
The team published their paper on July 18 in the Journal of Animal Ecology .
“The key question we wanted to answer was … simple but largely unresolved: what actually stabilizes a whole food web through time? We asked whether the mechanisms known to stabilize plant communities also scale up to a more complex, multitrophic system, including plants, herbivores and predators. In particular, we wanted to know whether stability across the food web is driven mainly by plants, by predators or by the [herbivores] that link them,” said Takehiro Sasaki, professor in the Faculty of Environment and Information Sciences at YOKOHAMA National University and primary author of the research study.
The team assessed the stability of a natural grassland in Inner Mongolia at three distinct trophic levels—plants, herbivores and predators—to determine their roles in maintaining the stability at their single community level and of the food chain overall.
The researchers use two complementary approaches to assess the stability of the entire ecosystem: an averaging approach and the multiple-threshold approach. The averaging approach assesses the mean stability across different trophic levels in the food web, but may not reveal differences in stability distribution within trophic groups. Because of this, trophic levels may have similar averages when all trophic levels demonstrate moderate stability or when some trophic levels are markedly stable whereas others are significantly unstable. In contrast, the multiple-threshold approach assesses the extent to which stability persists across all trophic levels.
Overall, the research team found that asynchronous species fluctuations within each trophic group played a central role in stabilizing trophic communities and that multitrophic grassland food webs can be stabilized by herbivore species.
“In our study, the strongest and most consistent predictor of multitrophic stability was not plant species dynamics nor predator species dynamics. It was the fact that different herbivore species fluctuated at different times. When one herbivore species declined, another could increase, creating compensatory dynamics within the herbivore community,” said Sasaki.
The researchers explained that differential responses of herbivore species to environmental change, or their asynchrony over time, is important because herbivores sit at the intermediate trophic level of the food web. They mediate how many and what types of plants are consumed and how consistently resources are supplied to predators. In this way, herbivores act as a biological buffer between plant and predator communities. The study showed that herbivores do not function solely as consumers that destabilize plant communities. Instead, they also function as key stabilizers of biodiversity in the food web.
The current study describes the dynamics between plants, herbivores and predators in a semi-arid grassland, but the team looks forward to investigating the effects of herbivore asynchrony on food web stability in other grasslands, forests, agricultural landscapes and under stronger climate variability. Longer monitoring will also help the researchers determine when herbivore communities buffer ecosystem fluctuations and when that buffering capacity breaks down.
“Our ultimate goal is to move biodiversity science beyond simply asking whether biodiversity matters. We want to identify which parts of biodiversity matter most, where they matter and through what mechanisms they sustain ecosystem functioning. If we can understand the biological architecture of stability, we can better predict which ecosystems are most vulnerable—and which components of biodiversity should be conserved to keep ecosystems functioning in a changing world,” said Sasaki.
Taiki Tachibana, Issei Nishimura, Daichi Makishima, Kousuke Tachibana, Xi Sun, and Yuki Iwachido from the Graduate School of Environment and Information Sciences at YOKOHAMA National University in Kanagawa, Japan; Xiaoming Lu, Xuezhen Zhao and Yongfei Bai from the State Key Laboratory of Vegetation and Environmental Change, in the Institute of Botany at the Chinese Academy of Sciences in Beijing, China; Kei Uchida from the Faculty of Environmental Studies at Tokyo City University in Yokohama, Japan; and Wenhuai Li from the Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology & Observation and the Research Station for the Typical Steppe Ecosystem of the Ministry of Education in the School of Ecology and Environment at Inner Mongolia University in Hohhot, China also contributed to this research.
This work was supported by the Asahi Glass Foundation, the Sumitomo Foundation (2432037), a Grant-in-Aid for Young Scientists A (no. 25712036), a Grant-in-Aid for Scientific Research B (grant no. 22H03791, 24K03127, 25K03306, and 26K03130) from the Ministry of Education, Culture, Sports, Science and Technology of Japan, a grant from the Joint Research Program of Arid Land Research Center, Tottori University (grant no. 06B2005), and a grant from the National Natural Science Foundation of China (31320103916).
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Journal of Animal Ecology
Experimental study
Herbivore species asynchrony underpins multitrophic stability across plants, herbivores and predators
18-Jul-2026