Solidago canadensis modifies microbial community and soil physicochemical properties through litter leachates and root exudates

Invasive plant inputs alter soil microbial communities via chemical compounds in litter, root exudates, and leachate, impacting a range of soil processes, but precise effects are poorly understood. We examined Solidago canadensis, a common invasive species in China, and its litter effects on soil microbial communities under natural conditions. Experimental treatments included S. canadensis seedling density (1 and 2 plants/pot) and quantity of litter (10 and 20 g/pot), with control groups that contained no plants or litter. After 120 days, soil samples were analyzed for physico-chemical properties, GC-MS chemical composition, and bacterial community composition using high-throughput sequencing. Results showed that S. canadensis seedlings and litter inputs increased soil pH, organic matter (SOM), and nitrogen (TN), while phosphorus and potassium remained unchanged. We identified 66 chemical compounds, predominantly ketones, alcohol, aldehyde, hydrocarbon, ester, acid, terpenoids, and alkaloids, associated with the presence of the invasive species, alongside shifts in dominant bacterial genera including Sphingomonas, Acidobacteriales, and Gemmatimonas. Rarer genera under the invasive treatment species, such as Candidatus, Rhodoplanes and Novosphingobium, correlated positively with soil TN, pH, and SOM. Collectively, our results demonstrate how the increased presence of allelochemicals from S. canadensis litter significantly impact soil properties and bacterial communities, and may therefore have implications for ecosystem dynamics.