Frequency‐dependent herbicide effects on rangeland plants and soils exceed those of the invader
Bibliographic record
Abstract
Abstract Invasive species management is a significant challenge and often involves herbicides. Herbicides, however, can have significant nontarget effects and often need to be reapplied to maintain control, which may amplify negative effects. Effects on plant communities are well documented, but less is known about herbicide effects on rangeland soils with respect to application frequency. Given strengthening plant community effects with repeated application, we should see concurrent changes in soil microbiomes and soil functioning. To explore how application frequency affects rangeland plants and soils, we focused on leafy spurge ( Euphorbia esula L.) invasion. Leafy spurge is invasive in North America and causes widespread changes in rangeland ecosystems, with herbicides often the control method of choice. We applied a common broadleaf‐specific herbicide containing aminocyclopyrachlor and metsulfuron‐methyl (Navius FLEX; Envu) either never, once, or in two consecutive years in both invaded and uninvaded areas. We then measured plant biomass and composition, and soil microbial composition, carbon, and nitrogen for 2 or 3 years. One application reduced leafy spurge nearly 90% for two growing seasons, declining to 60% by the third. One application also caused approximately 50% declines in forb biomass and broadleaf species richness, and a 300% increase in nitrate, with limited other soil effects. By year 3, the plots recovered; however, there was also a 45% increase in secondary invasion by exotic grasses. A second application worsened most plant community effects and caused an 85% loss of shrubs. Further, the second application caused changes in the soil microbiome, with a 22% decline in fungal abundances and increased stress in bacteria. The changes in the microbiome are likely due to the loss of good mycorrhizal hosts and belowground carbon allocation, which is supported by a concurrent 25% decline in labile carbon. Conversely, we found no significant differences in plant and soil properties between invaded and uninvaded areas. Herbicide can thus have frequency‐dependent detrimental effects on rangeland ecosystems that become more pronounced with a second application. Overuse of herbicides for invasive control thus has the potential to significantly alter biodiversity and ecosystem structure and may have worse effects than the invasive species themselves.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 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 teacher head, 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".