Tree colonization of sub-Mediterranean grasslands: effects of dispersal limitation and shrub facilitation
Bibliographic record
Abstract
Encroachment of trees into low-productivity grasslands is a serious threat to grassland biodiversity throughout Europe. Although the rate of encroachment of trees into grassland is variable and poorly understood, it is thought to result from variation in tree seedling recruitment, which is limited mainly by the availability of safe sites and the dispersal distances of propagules. In this study, we established spatially explicit models of seedling recruitment for two major sub-Mediterranean trees: Quercus pubescens Willd. and Fagus sylvatica L. We quantified the spatial distribution of Q. pubescens and F. sylvatica seedlings up to 20 years old at three grassland sites. We also quantified the spatial distribution and size of mature trees and of the two dominant species of shrubs, Buxus sempervirens L. and Juniperus communis L., at each of the three sites. Ninety-eight percent of the regeneration took place under shrub canopy. Quercus pubescens seedlings showed higher seedling production per unit of canopy area and longer mean effective dispersal distances than did F. sylvatica seedlings. Quercus pubescens seedlings also had a large advantage over F. sylvatica seedlings for establishment in open areas. Juniperus shrubs were better safe sites for the establishment of Q. pubescens and F. sylvatica seedlings than were Buxus shrubs. We calculated indices of seedling dispersal limitation and safe site availability for recruitment for four dates. In the dolomitic Causse grasslands examined in this study, the availability of safe sites for germination and survival was far more important than seedling dispersal limitation for recruitment of both tree species.
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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 | 0.001 |
| 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) | 0.001 | 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".