Plant diversity as a driver of soil carbon persistence and restoration

Soil hosts the world’s largest terrestrial carbon pool. This is primarily held as soil organic matter (SOM), which is ~60% carbon. While plant diversity is known to influence SOM retention, the strength and mechanisms of this relationship remain uncertain in some contexts, particularly in Australia. Persistence of SOM is influenced by the interplay of physical, chemical, and biological factors. One of the proposed mechanisms involves the diversity of molecules that comprise plant inputs and SOM. It is thought that greater molecular diversity fosters persistence by imposing an energy-gain limitation on soil microbes. Additionally, that molecular diversity may be related to SOM persistence by promoting greater mineral associations, making it inaccessible to microbial decomposition.
This research aims to answer the following questions: 
1) Does greater native plant diversity inhibit mineralisation of SOM by soil microbes in West Australian soils?
2) Does greater native plant diversity result in greater molecular diversity of plant inputs to soil? 
3) What is the contribution of aboveground plant litter inputs to differences in microbial community structure and carbon dynamics?
4) How does molecular diversity change over time from plant inputs to stable SOM?

To address these questions, a 15-month long soil and leaf litter incubation experiment was undertaken for two soil types. Different properties were measured to assess soil carbon dynamics, microbial community functional diversity, molecular diversity of inputs, and molecular diversity of SOM. The expected outcome is that plant diversity will foster soil carbon persistence with significant implications for restoring degraded landscapes. By promoting diverse vegetation, restoration efforts can maximize soil carbon storage and support ecosystem services, such as enhanced biodiversity and improved soil health. This research will inform land managers on strategies to enhance soil carbon storage through greater plant diversity, which has additional ecological value in the provision of other ecosystem services. By linking Australia’s unique plant diversity to broader ecological restoration and carbon management frameworks, these findings provide a scalable model for leveraging biodiversity to enhance soil carbon persistence worldwide.