Researchers from the South China Botanical Garden of the Chinese Academy of Sciences, working with international collaborators, have shown that soil microorganisms in tropical forests are broadly limited by phosphorus availability, with this constraint intensifying at higher elevations.

The findings were recently published in Soil Ecology Letters.

The research was conducted along three representative tropical forest elevational gradients in Guangdong and Hainan provinces, spanning an elevational range of approximately 100 to 1,400 meters. By combining measurements of soil extracellular enzyme activities with ecological stoichiometric analyses, the team quantitatively evaluated microbial metabolic constraints on carbon, nitrogen, and phosphorus across diverse climatic and vegetation conditions.

Results revealed that microbial metabolism was consistently marked by strong phosphorus limitation across all sites. The severity of phosphorus limitation increased significantly at higher, cooler elevations. By contrast, microbial carbon limitation was generally weak and showed no consistent elevational trend.

Further analyses identified temperature as the primary environmental factor governing microbial nutrient limitation. Lower temperatures at higher elevations reduced phosphorus release via organic matter mineralization and mineral weathering, while simultaneously promoting microbial investment in phosphorus-acquiring enzymes. These patterns suggest a trade-off in microbial resource allocation between carbon and phosphorus acquisition.

Elevational gradients provide a useful spatial analogue for evaluating the impacts of climate change. The study implies that future warming may partially relieve phosphorus limitation in tropical forest soils, yet could also intensify microbial carbon limitation—with potential implications for soil organic carbon turnover and long-term carbon stability.

This work improves understanding of belowground microbial processes in tropical forests and their sensitivity to climate change, offering insights for terrestrial carbon-cycle modeling and tropical forest management under global environmental change.