Forests are vital components of global biogeochemical cycles. Previous studies have focused on the effects of environmental factors like climate and topography on soil carbon (C), nitrogen (N), and phosphorus (P) stoichiometry. However, it remains unclear how plant diversity modulates soil nutrient limitations across different environmental contexts.

In a study published in Forest Ecology and Management, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences have revealed how plant species diversity dynamically regulates the relative limitations of soil N and P nutrients on C processes by altering soil C:N:P stoichiometric relationships in natural forest ecosystems.

The researchers established a large-scale sampling framework across six 20-hectare forest dynamics plots along the 101°E longitudinal transect spanning southwest China to Southeast Asia. By integrating vegetation and topographic data, they systematically analyzed spatial variations in soil C, N, and P concentrations and their stoichiometric ratios.

The results showed that plant diversity alleviated nutrient limitations in natural forest ecosystems. Within individual forest sites, higher species diversity was strongly correlated with increased soil phosphorus concentrations. These diverse areas also exhibited lower C:N, C:P, and N:P ratios, indicating a shift toward a more balanced soil nutrient environment.

Notably, the relationship between plant diversity and soil nutrients was heavily dependent on the background level of soil phosphorus. In phosphorus-poor forests, high plant diversity primarily enhanced soil phosphorus content, thereby mitigating phosphorus limitation. In phosphorus-rich forests, however, high diversity promoted the accumulation of carbon and nitrogen, potentially boosting carbon sequestration capacity.

“This systematic shift demonstrates that the diversity–stoichiometry relationship is especially sensitive to soil phosphorus status,” said XIA Shangwen of XTBG. “Where phosphorus is limited, plant diversity helps mobilize or retain this critical nutrient; where phosphorus is abundant, diversity appears to drive organic matter buildup.”

The study also confirmed that climatic factors such as temperature and precipitation primarily shape the large-scale geographical patterns of soil C, N, and P stoichiometry. Meanwhile, topographical heterogeneity (e.g., terrain ruggedness) further modulates local nutrient retention capacity by influencing microenvironments and plant diversity.

The study suggests that maintaining or restoring species diversity is not just about conservation, but about ensuring ecosystem functionality and resilience.

Forest plot in SW China. (Image by XTBG)

Available online: 31 January 2026