In a study published in Plants, People, Planet, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences revealed that the destructive foraging behavior of Asian elephants (Elephas maximus) can trigger immediate and species-specific changes in how trees release carbon into the soil through their roots.

Root exudates, the primary and secondary metabolites released by plants, are a major source of carbon input to soils and influence whether carbon is stored long-term or rapidly cycled. Asian elephants are regarded as ecosystem engineers. Although their roles in seed dispersal and forest structure are well-documented, their impact on hidden soil processes remains unclear.

In this study, researchers investigated how elephant foraging influenced belowground carbon cycling and soil ecological processes by altering root exudation in tropical forest tree seedlings. To simulate elephant herbivory, they applied three levels (no damage, mild, and severe) of damage to saplings of three tree species commonly consumed by elephants: Macaranga indica, Ficus hispida, and Bauhinia variegata, and measured root exudation rates over a 96-hour period.

Researchers observed significantly different responses of three tree species to the damage. Macaranga indica temporarily doubled its root carbon exudation rate within 24 hours after mild damage, but showed no response to severe damage. Ficus hispida increased its exudation rate significantly, but only 72-96 hours after severe damage, with no change from mild damage. Bauhinia variegata showed no detectable change in exudation in response to either level of damage.

Besides, researchers found that the exudation patterns were linked to specific root traits and local soil properties, supporting a framework where a plant’s physical characteristics and its environment shape its response to the disturbance.

These findings provide scientific support for elephant-friendly forest management, and emphasize the importance of conserving functionally important animal populations and monitoring soil processes in improving climate adaptability.

“This study gives us one more compelling reason to protect ecologically functional elephant populations. Elephants don’t just reshape the forest aboveground, but their foraging sends rapid signals belowground that can shift microbial communities and alter carbon pathways,” said Dr. Ahimsa Campos-Arceiz from XTBG, the corresponding author of the study.

Destructive foraging habits of Asian elephants can cause immediate, species-specific changes in how trees release carbon into the soil through their roots. (Image by Pratibha Khatri)