In the intricate tapestry of terrestrial ecosystems, soil functions as both a cradle and a repository of life, intricately woven with threads of organic matter that regulate nutrient cycles, carbon storage, and plant growth. Despite the fundamental role of soil organic matter (SOM) in sustaining ecosystem productivity, the nuanced interactions between plant diversity and the specific fractions of SOM have remained inadequately understood. A groundbreaking study by Angst, Š., Angst, G., Mueller, K.E., and colleagues, published in Nature Communications in 2025, has shed new light on these underexplored linkages, revealing crucial insights into how plant biodiversity influences the partitioning of soil organic matter into particulate and mineral-associated fractions. This revelation has profound implications for ecosystem management, soil carbon sequestration strategies, and our broader understanding of terrestrial biogeochemistry.
Soil organic matter is conventionally partitioned into two principal fractions: particulate organic matter (POM), which consists of visible plant residues and microaggregates, and mineral-associated organic matter (MAOM), where organic compounds are chemically bound to soil minerals at the micro- and nanoscale. These fractions differ not only in origin and turnover rates but also in how they respond to environmental and biological drivers. While POM is generally labile and prone to rapid microbial decomposition, MAOM is often stabilized for centuries to millennia, serving as a long-term carbon sink. The delicate interplay between these fractions influences soil fertility, carbon cycling, and the resilience of ecosystems to climate perturbations.
Previous research has intensely focused on total soil carbon stocks or generalized microbial activity, often disregarding the complex internal dynamics between POM and MAOM and how plant community characteristics might differentially affect these pools. Angst et al.’s study took a holistic approach, combining field surveys spanning gradients of plant diversity with state-of-the-art soil fractionation techniques and molecular analyses. Their work systematically dissected how variations in species richness and composition modulate the quantity and quality of organic matter associated with both particulate and mineral fractions of soils.
One of the key technical achievements in this study was the employment of density fractionation coupled with elemental and isotopic analyses to tease apart the SOM pools. Density fractionation enables the separation of organic matter based on its buoyancy, effectively distinguishing less dense POM from heavier mineral-bound OM. By coupling these physical separations with stable carbon isotope measurements, the research team teased apart fine-scale dynamics of carbon inputs and transformations within each pool, offering unprecedented resolution into organic matter cycling.
The researchers sampled across multiple biomes exhibiting a gradient of plant species richness—from monoculture-dominated plots to rich, diverse communities. Their findings revealed a robust positive correlation between plant diversity and total particulate organic matter content, implicating diverse plant communities in enhancing the inputs of readily decomposable organic residues to the soil. This effect was attributed not only to increased litter quantity but also to a wider array of litter chemical traits provided by diverse species, which may promote heterogeneous microbial processing and aggregate formation.
Conversely, the relationship between plant diversity and mineral-associated organic matter was more complex. While some mineral-associated pools showed moderate increases with diversity, many did not respond directly to diversity per se. Instead, the study suggested that factors such as root exudation patterns, microbial community composition, and mineral surface properties mediate the formation and stabilization of MAOM. This underscores the multifaceted biotic and abiotic controls governing long-term carbon persistence in soils, reinforcing the notion that simple increases in plant diversity do not straightforwardly translate into increased mineral-associated carbon stocks.
Crucially, the research team also employed molecular-level analyses, including nuclear magnetic resonance (NMR) spectroscopy and pyrolysis-GC/MS, to characterize the chemical composition of organic matter within each fraction. These data revealed that particulate fractions were enriched with plant-derived compounds—cellulose, hemicellulose, and lignin—consistent with the presence of fragmented plant tissues. In contrast, mineral-associated organic matter was dominated by microbial-derived compounds such as polysaccharides and peptides, suggesting microbial processing as a critical pathway for OM stabilization on mineral surfaces.
The study further explored how plant diversity influences the microbial consortia responsible for organic matter decomposition and transformation. Through metagenomic sequencing, the authors identified shifts in microbial community diversity and functional potential correlated with plant species richness. Diverse plant communities fostered more diverse and functionally redundant microbial assemblages, potentially facilitating more efficient decomposition and transformation of plant inputs into soil organic matter pools. This microbial mediation could be a pivotal mechanism linking aboveground plant diversity with belowground carbon dynamics.
From an ecological and environmental perspective, these findings hold substantial consequences. With climate change accelerating biodiversity loss, understanding the soil consequences of declining plant diversity becomes imperative. The documented decline in particulate organic matter stocks under low-diversity conditions implies reduced soil fertility and poorer habitat quality for soil biota. Moreover, potential disruptions in MAOM formation could impair long-term carbon storage capabilities, exacerbating positive feedback loops to atmospheric CO2 concentrations.
The authors also discussed practical applications arising from their insights. Restoration ecology and sustainable agriculture stand to benefit from this knowledge by prioritizing diverse plant assemblages not only for aboveground productivity but also for enhancing soil organic matter quantity and stability. Soil management practices fostering plant diversity could be integrated into carbon credit schemes by promoting soils’ ability to sequester carbon in persistent mineral-associated forms.
Technically, this landmark study bridges several knowledge gaps by disaggregating complex soil organic matter pools and linking them with functional aspects of plant diversity and microbial communities. It advances the frontier of biogeochemical research by demonstrating that soil carbon pools cannot be treated as homogenous entities; instead, their responsiveness to biodiversity involves intricate mechanisms operating across scales from molecular to ecosystem levels.
The findings from Angst et al. prompt a reevaluation of how global biogeochemical models incorporate plant biodiversity effects. Most current earth system models simplify soil organic matter as a single pool or subdivide it without adequately capturing biological controls at fine resolution. Incorporating empirical data reflecting diversity-driven variations in POM and MAOM dynamics will refine model predictions of carbon cycling under future scenarios.
Beyond climate change mitigation, this research speaks to biodiversity conservation as a tool for maintaining ecosystem functions critical for human well-being. Soils are the foundation of agriculture, water filtration, and nutrient cycling. Ensuring their health through biodiversity preservation aligns ecological sustainability with socio-economic benefits, reinforcing the interconnectedness of life above and belowground.
Despite its comprehensive approach, the study also opens fresh avenues for inquiry. The specific roles of individual plant functional groups, root traits, and symbiotic relationships in driving soil organic matter stabilization merit further investigation. Moreover, disentangling causal feedbacks between microbial community shifts and soil chemistry dynamics under controlled experimental manipulations could yield mechanistic insights.
In conclusion, the work of Angst and collaborators profoundly enriches our understanding of the underappreciated links between plant diversity and the dual pools of soil organic matter. This nuanced perspective underscores that maintaining and restoring biodiversity extends benefits beyond the visible spectrum of life, deeply embedding itself in the hidden architecture of soil carbon storage and ecosystem resilience. As our planet faces unprecedented environmental changes, such insights illuminate pathways toward sustainable stewardship of both aboveground and belowground biodiversity.
Subject of Research: The study investigates the relationships between plant diversity and the partitioning of soil organic matter into particulate and mineral-associated fractions, focusing on the biogeochemical mechanisms linking aboveground biodiversity with belowground carbon stabilization.
Article Title: Un(der)explored links between plant diversity and particulate and mineral-associated organic matter in soil
Article References:
Angst, Š., Angst, G., Mueller, K.E. et al. Un(der)explored links between plant diversity and particulate and mineral-associated organic matter in soil.
Nat Commun 16, 5548 (2025). https://doi.org/10.1038/s41467-025-60712-6
Image Credits: AI Generated
