Effects of insect-induced eastern hemlock (Tsuga canadensis) decline on associated macrofungal communities in Kejimkujik National Park and National Historic Site
Bibliographic record
Abstract
Fungi are vital decomposers and mutualists which are key to maintaining thriving forest ecosystems; however, fungal community responses to host tree insect disturbances remain poorly understood, including in old-growth eastern hemlock (Tsuga canadensis L.) forests. Eastern hemlock is a foundation species of the Acadian forest (Wabanaki), which is threatened by the invasive hemlock woolly adelgid (Adelges tsugae Annand) (HWA) in eastern North America, including in Kejimkujik National Park and National Historic Site, Nova Scotia, Canada (KNPNHS).To understand how host tree insect disturbances affect subsequent hemlock macrofungal communities, macrofungal community composition before and after a palewinged grey moth (Iridopsis ephyraria) (PWG) outbreak in eastern hemlock forests of KNPNHS was investigated using new collections and a unique long-term fungarium specimen dataset. This study tested the following hypotheses: 1) A unique fungal community potentially associating with eastern hemlock will be identified; 2) A spatial assay comparing fungal communities of hemlock plots will reveal differences in macrofungal communities according to historic PWG damage levels, and; 3) A temporal assay comparing the past and present fungal communities of hemlock plots affected by PWG will show greater changes in fungal communities of plots with more severe PWG damage than in plots with less severe PWG damage.Macrofungi from hemlock plots with different levels historic PWG disturbance were collected in July – November 2021 – 2023. These, and historic specimens (E. C. Smith Herbarium, Acadia University (ACAD)) collected from the same plots, were identified using ITS rDNA barcoding, phylogenetic analysis, and macro-/ microscopic characteristics. In total, 312 specimens were sequenced—266 newly collected specimens and 46 herbarium vouchers. The 847 specimens collected in the present (2021 – 2023) comprised 300 species from 84 genera. Cortinarius (19%), Russula (7.3%), and Amanita (6.3%) were the most common collections in this period. The 1249 specimens collected in the past (1990, 1991, & 1995) comprised 384 species from 59 genera, and Mycena (8.2%), Lactarius (7.2%), and Cortinarius (6.5%) were most commonly collected. Indicator Species Analysis revealed 25 potential hemlock indicator species across all years, but also showed a reduction in the number of indicator species from the past to the present for many plots. Most of the indicator species named were generalists. Multiple Correspondence Analysis demonstrated differences between fungal communities of plots with different levels of historic PWG damage across space, and showed the greatest change across time occurred in plots with the most severe PWG damage.Our results suggest that as HWA infestations intensify in KNPNHS, T. canadensis ecosystems may lose hemlock-preferring macrofungal species and may shift toward more generalist macrofungal communities. This change may prevent the establishment of new hemlock seedings, induce the loss of bacterial communities associated with hemlock macrofungi, and threaten food sources for many organisms, which could permanently alter the hemlock ecosystems of KNPNHS.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".