Coniferous-broadleaf mixed plantations reshape phosphorus-solubilizing bacterial communities and enhance soil phosphorus bioavailability in subtropical forests

TL;DR

Mixed plantations of coniferous and broadleaf trees improve soil phosphorus availability by changing bacterial communities in subtropical forests.

Contribution

The study reveals how mixed plantations reshape phosphorus-solubilizing bacterial communities and enhance soil phosphorus bioavailability.

Findings

Mixed plantations increased labile phosphorus pools, especially in rhizosphere soils.

Bacterial communities harboring pqqC genes were closely linked to phosphorus fractions.

Soil properties had a stronger influence on rhizosphere phosphorus availability than plant properties.

Abstract

Mixed-species plantations are proven to enhance phosphorus (P) availability in subtropical forest ecosystems. However, the effect of coniferous-broadleaf mixed plantations on soil P cycling dynamics remains poorly understood. Through a long-term field experiment, the study investigated how mixed plantations influence soil P fractions, phoD and pqqC genes, and associated bacterial communities in bulk and rhizosphere soils. Results showed that compared to monocultures, the introduction of broad-leaved trees significantly increased labile P pools, particularly in the rhizosphere. Amplicon-based community profiling of phoD/pqqC genes demonstrated distinct compositional shifts in P-solubilizing bacterial communities across forest types and soil compartments. The pqqC-harboring bacterial communities were more closely related to the P fractions. More importantly, plant properties were important in explaining bulk soil labile P responses, while in rhizosphere soil, labile P was more strongly associated with soil properties, positively affecting labile P. These findings elucidate the complex interplay between tree diversity, microbial functional traits, and soil P transformations. This study underscores the critical role of mixed plantations in promoting microbial-mediated P mobilization and provides valuable insights for designing sustainable forest management strategies to optimize P utilization in subtropical ecosystems.

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