Photosynthetic responses of white spruce saplings (<i>Picea glauca</i>) to controlled density gradients of spruce and green alder (<i>Alnus crispa</i>)
Bibliographic record
Abstract
Physiological responses to competitive and facilitative interactions between white spruce (Picea glauca [Moench] Voss) and green alder (Alnus crispa [Ait.] Pursh) grown together in Nelder plots were assessed through measurement of spruce in situ shoot photosynthetic potential, stomatal conductance and measurements of needle chemistry. Neither proximity to alder nor overall plant density were found to impact spruce maximum net photosynthetic rates during midsummer. However, photosynthetic potential declined in spruce saplings grown at low densities at the end of the summer, suggesting that spruce saplings benefited from the microhabitat modification provided by both alder and spruce neighbors at higher densities. Although temperatures and precipitation were normal for interior Alaska, low soil volumetric water content and low needle water content suggested that saplings in all treatments were drought stressed. Path analysis was used to relate above- and below-ground abiotic conditions to photosynthetic rates and stomatal conductances to estimate the relative importance of plant-modified environmental conditions in explaining photosynthetic rates. We found that although both alder and spruce decreased soil water, there were not strong relationships between plant modified soil water content and needle water content, or stomatal conductances. Data from nearby canopy and open plots suggested that lower maximum temperatures and higher minimum humidity under the canopy might improve the water status of spruce growing under the canopy. Increasing density of both spruce and alder increased the soil nitrogen slightly, but needle nitrogen was negatively related to the density of neighbors, suggesting that increased biomass resulted in below-ground competition for nitrogen. We found a direct negative effect of light on maximum net photosynthesis late in the summer, suggesting that neighbors could prevent photoinhibition after cool nights in the fall.
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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".