Solidago canadensis and its endophytes as a self-degrading system during ex situ decomposition

Background and Aims Solidago canadensis is an invasive herb widespread across Eurasia and Australia, known to decompose faster than native species. However, the mechanisms driving its decomposition, particularly the role of associated microorganisms, remain poorly understood. This study aimed to assess the influence of specific components of soil biota (bacteria and fungi) from invaded and non-invaded mesic meadows on the decomposition of S. canadensis . Methods We conducted an ex situ decomposition experiment using shoots and leaves of S. canadensis . Soil solutions from invaded and non-invaded meadows were prepared and passed through syringe filters of varying pore sizes (variants A–D). We assessed primary decomposer diversity under a light microscope and analysed mass loss using generalized linear mixed models. Results Differences among filtration treatments were minimal, and soil solution origin (invaded vs. non-invaded meadows) had negligible effects on mass loss. Leaves and shoots decomposed at similar rates across all variants. These outcomes indicate that external microbial inputs played no detectable role in driving decomposition. Conclusion Our findings suggest that S. canadensis operates as a largely self-contained holobiont, harbouring an internal consortium of primary decomposers capable of sustaining decomposition independently of external soil communities. This highlights the functional redundancy of surrounding soil biota and may contribute to enhanced nutrient cycling in invaded ecosystems. Such a strategy aligns with invasion facilitation frameworks, including the novel weapon hypothesis, illustrating how S. canadensis can exploit new environments. Additionally, its consistently efficient ex situ decomposition suggests strong potential for valorizing harvested biomass through composting or biogas production.