Plant Diversity and Soil Microbial Interactions

Plant communities of varying species richness shape the composition, function and resilience of soil microbial assemblages, thereby influencing key ecosystem services such as carbon sequestration, nutrient cycling and soil structure maintenance. Diverse plant stands supply a richer array of organic substrates through litter inputs and root exudation, fostering microbial biomass, altering fungal-to-bacterial ratios and promoting greater enzymatic activity. This enhanced microbial activity accelerates decomposition and stabilises soil organic carbon pools, with quality of inputs often outweighing sheer quantity. Mutualistic associations, notably mycorrhizal fungi and nitrogen-fixing bacteria, underpin nutrient acquisition and plant productivity, while shifts in microbial community structure feedback on soil C:N ratios and soil moisture regimes. The interplay between plant diversity and soil microbes is modulated by climate, soil history and management practices, with profound implications for restoration of degraded lands, optimisation of agricultural systems and mitigation of climate change through soil carbon storage.

Research from Nature Portfolio

Recent studies have demonstrated that plant species richness enhances soil carbon storage predominantly by improving the quality of organic inputs rather than simply increasing biomass returns. In grasslands spanning a broad climatic gradient, diverse plant assemblages elevated soil carbon content and carbon-to-nitrogen ratios most strongly under warm, arid conditions, highlighting the importance of biodiversity for carbon sequestration in a changing climate. A global meta-analysis further revealed consistent positive responses of microbial biomass, bacterial and fungal abundance, and microbial respiration to increases in plant diversity across forests, grasslands and croplands, with older and more species-rich mixtures showing the greatest effects. Long-term experiments on degraded grassland restoration have confirmed that reintroducing high plant diversity can accelerate annual soil carbon accumulation rates two- to three-fold compared with succession under monocultures, underscoring the practical potential of diversity-based management.

Plant Diversity and Soil Microbial Interactions publication trend

The graph below shows the total number of articles in plant diversity and soil microbial interactions across all publications each year (not limited to Nature Index journals).

Technical terms

Soil organic carbon: The carbon stored in soil organic matter, derived from plant and microbial residues, crucial for soil fertility and climate regulation.

Microbial biomass: The living mass of bacteria, fungi and archaea in soil, often estimated to assess microbial contributions to nutrient cycling.

Root exudates: A complex mixture of organic compounds released by plant roots that serve as substrates and signalling molecules for soil microbes.

α-diversity: The diversity of microbial taxa within a single sample or site, reflecting richness and evenness of the community.

Carbon use efficiency: The fraction of assimilated carbon that soil microbes convert into biomass rather than respiring as CO₂, influencing soil carbon retention.

References

1. The positive effect of plant diversity on soil carbon depends on climate. Nature Communications (2023).
2. Tree and shrub richness modifies subtropical tree productivity by regulating the diversity and community composition of soil bacteria and archaea. Microbiome (2023).
3. Abiotic and biotic drivers of tree trait effects on soil microbial biomass and soil carbon concentration. Ecological Monographs (2023).
4. Soil carbon sequestration accelerated by restoration of grassland biodiversity. Nature Communications (2019).
5. Meta-analysis shows positive effects of plant diversity on microbial biomass and respiration. Nature Communications (2019).
6. Root biomass and exudates link plant diversity with soil bacterial and fungal biomass. Scientific Reports (2017).