Plant intraspecific trait variation (ITV) is known to shape community assembly and ecosystem functioning. However, its influence on rhizosphere organisms, from bacteria and fungi to nematodes, has remained largely unexplored.

In a study published in Plant and Soil, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences have shown that even subtle variations in root characteristics among trees of the same species can restructure the entire microscopic food web in the rhizosphere (the narrow zone of soil directly influenced by root secretions).

The researchers focused on how this “intraspecific trait variation” (ITV) affects soil biodiversity in tropical plantations. They worked within the framework of the Root Economic Space (RES), which classifies roots along two main strategies: collaborative (partnering with soil fungi) and conservative (slower, denser roots). They asked whether these strategies, as they vary from tree to tree, regulate the diversity and interaction networks of bacteria, fungi, and nematodes.

The researchers selected 12 common tree species, half forming partnerships with arbuscular mycorrhizal (AM) fungi and half with ectomycorrhizal (ECM) fungi. They measured fine-root traits such as specific root length (SRL) and root tissue density, along with soil pH and nutrient levels. Then, using high-throughput DNA sequencing and nematode community analysis, they mapped the bacterial, fungal, and nematode communities living in the rhizosphere.

They found that root ITV significantly altered interspecific trait variation within the RES framework. For ECM trees that followed a “do-it-yourself” (high SRL) and “acquisitive” (high root nitrogen) strategy, fungal and nematode diversity jumped markedly. In contrast, for AM trees, higher soil pH was the main factor boosting bacterial diversity. The acquisitive strategy also enhanced nutrient cycling, which in turn strengthened cross-rophic interactions, leading to more complex cooccurrence networks.

Furthermore, high nutrient levels raised nematode diversity in ECM trees, while elevated pH similarly benefited bacterial diversity in AM trees. Interestingly, root exudates from ECM trees were more stable overall but varied more from individual to individual, making their microbial communities more responsive to ITV.

“Plant intraspecific trait variation is a critical driver of community assembly and function,” said XIA Shangwen of XTBG. “This is one of the few studies that simultaneously examines bacteria, fungi, and nematodes within the same root system. Our results underscore the pivotal role of plant phenotypic diversity in shaping belowground communities and highlight its importance for soil biodiversity conservation and ecosystem management.”

Published: 02 July 2026