Douglas Fir and Ponderosa Pine Seed Dormancy as Regulated by Grassland Seedbed Conditions
Bibliographic record
Abstract
Tree encroachment in the ecotone between grassland and forest of interior British Columbia has resulted in decreasing grazing potential of rangelands. The 2 dominant tree species in this region, Douglas fir (Pseudotsuga menziesii var. glauca) and ponderosa pine (Pinus ponderosa), require stratification for seed dormancy release. The objective of this study was to determine whether seeds of these species can be stratified and dormancy released under grassland conditions. Field stratification experiments were conducted over 4 years using 2 Douglas fir and 3 ponderosa pine seed collections. A laboratory experiment was conducted to determine the effect of seedcoat removal, light, and stratification duration on dormancy release. Dormancy in Douglas fir and ponderosa pine was released after 1 to 2 months of stratification under grassland seedbed conditions when seeds were placed in the field in late fall and early winter. Continuous stratification until the following May was correlated with higher germination rate. One week of stratification in the laboratory was sufficient to break dormancy in the 2 species and a similar effect can be achieved by exposure to light. Seed coat removal for ponderosa pine also released dormancy, indicating that this structure imposes dormancy. Therefore, the grassland seedbeds near the forest edge can provide suitable conditions to break dormancy of Douglas fir and ponderosa pine seeds, contributing to tree encroachment into adjacent grasslands. Managements aiming to control tree encroachment should take the interaction between tree seed and grassland seedbed conditions into consideration, and the control should be focused on the elimination of seeds and seedlings but not on the germination stage.
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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 | 0.000 | 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 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".