The global expansion of plantation forests is disrupting fundamental ecosystem functions by altering nutrient cycling in soils. As forests transition from diverse natural ecosystems to monocultures of planted trees, the balance of essential elements—carbon (C), nitrogen (N), and phosphorus (P)—is being systematically reconfigured, according to new research published in Forest Ecology and Management.

A research team led by Dr. SUN Tao from the Institute of Applied Ecology, Chinese Academy of Sciences, conducted a comprehensive meta-analysis of 126 peer-reviewed studies across various biomes and climate zones. Their findings reveal that forest conversion affects the chemical composition of leaf litter, soils, and microbial communities in interconnected ways, introducing new feedback loops into terrestrial nutrient cycles.

The study, entitled “Nutrient cycles in transition: C:N:P stoichiometry by forest conversion to plantations”, found that while the C:N:P ratio in bulk soil organic matter remained relatively stable, indicating a form of stoichiometric homeostasis, microbial biomass and enzyme activity exhibited greater sensitivity to changes in litter quality. This suggests that belowground biological processes may be less resilient to environmental shifts than previously assumed.

One of the key insights from the study is that litter quality, especially the nutrient content of fallen leaves and roots, plays a decisive role in driving imbalances in ecosystem element ratios. 

Microbial communities, which regulate decomposition and nutrient turnover, respond to these inputs with adjustments in their own internal C:N:P ratios. In contrast to the soil pool, which exhibited stabilizing feedbacks, microbial systems demonstrated weaker stoichiometric stability, with enzyme activities and microbial C:P ratios diverging under altered resource conditions.

The researchers also identified the key environmental and biological factors driving these patterns. Soil pH and climate variables such as temperature and precipitation primarily influenced the soil's C:N ratio, while plant traits—particularly leaf and root C:N, N:P, and C:P ratios—were the dominant factors affecting microbial and enzymatic responses.

Crucially, the study demonstrates that the shift to plantation forests reconfigures the interactions between decomposer organisms and available resources, establishing a new dynamic balance in nutrient cycling. This reorganization can have lasting implications for soil fertility, carbon storage, and the long-term ecological stability of planted forests.

The research offers practical recommendations for improving nutrient management in plantation systems. By incorporating broad-leaved species with nitrogen-fixing abilities or species that form mycorrhizal associations—such as arbuscular mycorrhizal (AM) or ectomycorrhizal (ECM) fungi—land managers could improve nutrient availability and microbial efficiency, enhancing ecosystem resilience.

Figure 1. Impact of forest conversion on the stoichiometry of plants, soils, and microbial communities (Image by WANG Ying).