In recent years, with the intensification of human activities, particularly the increase in fossil fuel combustion and agricultural fertilization, the input of nutrients such as nitrogen and phosphorus into terrestrial ecosystems has significantly increased. It is predicted that global nitrogen deposition will be 1 to 3 times higher in the coming decades compared to current levels, and phosphorus deposition has increased by 44.4% over the past 20 years, especially in Asia and Europe. Although nitrogen and phosphorus additions can alleviate nutrient limitations to some extent and enhance vegetation productivity, an increasing body of research indicates that this nutrient enrichment may exacerbate light and nutrient competition among plants, leading to loss of plant diversity and posing a serious threat to underground biodiversity and ecosystem functioning.
However, there is still a lack of in-depth understanding regarding how nitrogen and phosphorus additions affect the diversity, composition, and network structure of soil fungal communities in semi-arid grasslands. To address this scientific challenge, researchers from the Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, conducted a nine-year nutrient addition experiment in semi-arid grasslands in northern China. The relevant paper was published in the Science of the Total Environment.
After years of research, the scientists found that nitrogen addition significantly reduced fungal diversity and altered community composition, while the effect of phosphorus addition on fungal communities was not significant. This finding reveals the severe negative impact of nitrogen deposition on fungal communities in semi-arid grasslands in northern China, with nitrogen addition showing a more pronounced negative effect compared to phosphorus addition.
"Fungal communities play a crucial role in ecosystems, including aiding in nutrient uptake by plants, organic matter decomposition, and maintenance of soil health and structure. The decrease in complexity and stability of fungal community networks may imply a reduction in the efficiency of these ecological services, which could potentially impact ecosystem multifunctionality," said Dr. Hongling Yang, a postdoctoral researcher at the Northwest Institute, as reported by Chinese Science Bulletin. Furthermore, the decline in fungal network stability may also reduce the resilience of ecosystems to external environmental changes, making them more susceptible to environmental stressors. These potential ecological impacts suggest the need for careful management and use of nitrogen fertilizers to protect and maintain soil ecosystem health and diversity.
Researchers revealed through structural equation modeling that nutrient addition altered the structure of fungal communities through decreases in plant richness and increases in the biomass of perennial herbaceous plants. Loss of plant diversity could lead to weakened ecosystem functions because plant species diversity forms the basis for supporting diverse ecosystem services, such as pollination, pest control, and nutrient cycling. When plant diversity decreases, these ecological services may be affected, thereby influencing the overall health and stability of ecosystems.
"Given the projected continuous increase in global nitrogen and phosphorus deposition, the protection and management of soil fungal communities in semi-arid grasslands are particularly urgent and important. Firstly, we must increase scientific research investment to comprehensively monitor and study the dynamics of nitrogen and phosphorus deposition and their specific effects on fungal communities to guide future conservation strategies," said Dr. Hongling Yang. Additionally, nitrogen and phosphorus fertilizer use in agricultural production should be strictly controlled, especially in areas close to natural ecosystems, by promoting precision agriculture and sustainable agricultural practices to reduce nutrient loss and deposition.
Moreover, public awareness of nitrogen and phosphorus deposition issues should be raised, and strict ecological protection policies should be formulated and implemented, such as emission reduction standards and nutrient management regulations, to legally promote ecosystem protection. Only through comprehensive measures can we effectively protect and manage soil fungal communities in semi-arid grasslands to cope with the challenges of future nitrogen and phosphorus deposition, ensuring the long-term maintenance of ecosystem health and biodiversity. This is not only the task of scientific research but also a goal that requires joint efforts from all sectors of society.
Related Paper Information:
Link to the paper
The structural equation model delineates the direct and indirect effects of nitrogen and phosphorus additions on fungal community structure. Image courtesy of the Northwest Institute of Eco-Environmental Resources.
