{
  "id": 13357314,
  "title": "Stemflow as a Storm-Driven Pathway for Fungal eDNA Transport",
  "url": "https://urgent.news/2026/10/09/stemflow-as-a-storm-driven-pathway-for-fungal-edna-transport",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-09T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.05.756909v1?rss=1"
  },
  "original_language": "en",
  "account": "Stemflow, the water and biological material flowing from tree canopies to the stem base, is a critical pathway for transporting fungal genetic material, known as environmental DNA (eDNA). Researchers have traditionally studied this pathway using microscopy to observe fungal spores called conidia. However, a new study employed a more advanced technique called ITS2 metabarcoding to analyze fungal eDNA in stemflow collected from 15 trees, including five each of American beech, sugar maple, and tulip poplar, in a closed-canopy forest in northeastern Ohio, USA. These samples were collected during eight rain events from November 2024 to May 2025, alongside simulated bark and gutter washes to evaluate the signals near the tree collar and collector.\n\nThe results showed that the fungal communities found in natural stemflow were distinct from both control samples and occupied a larger area in the statistical analysis, known as ordination space. The Ascomycota phylum was the most abundant, with notable genera such as Parafenestella, Cytospora, Microcera, Nectria, and Aureobasidium. Interestingly, 13 out of the 25 most abundant fungal taxa differed significantly between the different tree species. The study identified three major groups of fungi present: woody-plant-associated endophytes, canker fungi, and saprobes, all of which play crucial roles in forest ecosystems.\n\nThe researchers found that storm events accounted for 28.6% of the variation in fungal taxa, indicating that rainfall patterns play a significant role in shaping the fungal community in stemflow. Host tree species, meanwhile, contributed 24.1% to the variation, suggesting that the type of tree influences the fungal community as well. The interaction between host species and storm events explained an additional 10.0% of the variation. When considering the overall composition of fungal communities, the host species had a stronger influence, accounting for 35.4% of the variation, compared to the 20.4% attributed to storm events. This finding highlights that the identity of the tree species is a critical factor in determining the fungal diversity present in stemflow. Additionally, the study detected lichenized fungi and fungi associated with lichens, further emphasizing the diversity of fungal eDNA captured by this method. In conclusion, stemflow provides a minimally invasive and effective means of monitoring the diversity of canopy fungi, while also demonstrating the strong filtering effects of both tree species and storm events on the DNA exported from woody surfaces.",
  "summary": "Stemflow transports water and biological material from forest canopies to the stem base, yet fungal studies of this flux have largely relied on microscopy of conidia. We used ITS2 metabarcoding to characterize fungal environmental DNA (eDNA) in stemflow from 15 trees - five each of American beech (Fagus grandifolia), sugar maple (Acer saccharum), and tulip poplar (Liriodendron tulipifera) in a…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}