Establishment of a desert foundation species is limited by exotic plants and light but not herbivory or water
Bibliographic record
Abstract
Abstract Questions The biodiversity of deserts is becoming increasingly threatened due to global change including the introduction of invasive species. Desert shrubs are foundational species that can facilitate native plant communities but can also benefit exotic species. The influence of exotic plants on the establishment of benefactors from seeds or seedlings is a critical knowledge gap. We tested if the establishment, survival, or growth of seedlings for a benefactor shrub species in California was reduced by the invasive grasses that they facilitate in the field. Location San Joaquin Desert, California, USA. Methods We conducted a field survey to determine if a native shrub, Ephedra californica, facilitated the invasive grass Bromus madritensis. Using seed collected from the field, we conducted a competition experiment on Ephedra californica, using a densities series of Bromus madritensis and under manipulated conditions of light, water, and simulated herbivory. We measured seedling establishment, survival, and biomass of Ephedra californica and Bromus madritensis. Results In the field, Ephedra californica facilitated Bromus madritensiswithin the shrub canopy. In the competition experiment, Bromus madritensishad consistent negative effects on Ephedra californica emergence and seedling survival at all resource and herbivory levels. The emergence and survival of Ephedra californica was reduced in low light, but none of the manipulated conditions increased the competitive effect of Bromus madritensis. Conclusions Reciprocal costs of facilitation by shrubs were evident in emergence and seedling survival but not in growth once established. Water, herbivory, and shade did not mitigate these costs, but also did not exacerbate competition from exotics. Direct competition with exotic plant species is the most significant impact tested here on dryland shrub species and manipulations of resources or herbivory may not effectively promote shrub recruitment. Native shrubs are well adapted to variable desert conditions and could be effective foundational species if invasive grasses are reduced.
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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) | 0.002 | 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".