The Role of Low Temperatures in Determining the Northern Range Limit of Kudzu (Pueraria montana var lobata), an Invasive Vine in North America
Bibliographic record
Abstract
Invasive non-indigenous species are among the principle drivers of global change, altering nutrient cycles, changing disturbance regimes, and generally threatening biodiversity. Climate change is widely expected to exacerbate invasions by relaxing abiotic barriers, such as low temperature, but the mechanistic evidence supporting this is limited. Here, I evaluate the hypothesis that low temperatures determine the northern range limit of kudzu (Pueraria montana var. lobata), an invasive Asiatic vine in North America, by assessing freezing and chilling tolerance of kudzu plants in winter, spring, summer, and fall. Kudzu was widely planted throughout the southeastern U.S. in the early 20th Century to prevent erosion. It is winter-deciduous and reproduces primarily from buds on stem nodes. In the last 40 years, kudzu has migrated northward in concert with a northward shift in the -20oC minimum winter temperature isocline, indicating that less severe winter cold is permitting northward migration. Freezing mortality during winter does not explain this correlation. Electrolyte leakage assays demonstrate that above- and belowground kudzu stems can survive to -27oC and -17oC. Insulation provided by soil and snow protects belowground stems from lethal temperatures to well north of kudzu's current range limit. Severe spring chill stops growth and photosynthesis and causes some shoot mortality, but both growth and photosynthesis recover quickly following the chill. Summer growth rates are rapid (up to 22 cm/d), responding within hours to temperature changes, and are unimpaired by nighttime lows. Photosynthesis is reduced at cool temperatures, but on cool days, kudzu leaves tend to be warmer than air temperature, so photosynthesis rates generally remain close to optimal values. In autumn, growth stops below 15oC, but leaves are retained and maintain modest photosynthetic competence until killed by frost in November. In colder climates that occur far north of kudzu's current range, reductions in the length and quality of the growing season could accumulate over time to reduce kudzu's success. There is, however, no strong evidence that low temperatures in any season will prevent kudzu from migrating throughout southern Ontario, making kudzu a good candidate for invasive species regulations.
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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".