Do drought and understory beech interact to influence the nutrition and growth of sugar maple?
Bibliographic record
Abstract
Hardwood forests dominated by sugar maple ( Acer saccharum ) at its northern limit (Quebec) are threatened by rising regional temperatures and recurrent summer drought. In a rainfall exclusion experiment, we imposed artificial drought in six maple stands where American beech ( Fagus grandifolia ) saplings proliferated in the understory (with overstory beech presence) or were absent. Two paired plots were established in sites where beech proliferated vs. those that were beech-free, i.e., covered by rainfall excluders vs. left uncovered for summer 2021 and 2022. Responses to the four resulting treatments were subjected to Bayesian analysis. Dendroclimatological estimates of annual basal area increment (BAI) produced by three canopy maples within 12 plots, together with foliar nutrients of the same mature maple trees and soil nutrient pools (ion-exchange probes, with increasing burial duration), were compared across plots. Comparisons included ordination scores for foliage (DCA1, Detrended Correspondence Analysis) and Principal Component Analysis (PCA: PC1 and PC2) for soils. Soil water content (SWC) beneath excluders was 56% of adjacent rainfall-accessible plots; beneath understory beech saplings, this deficit negatively affected maple BAI, but only in 2022. Diagnosis and Recommendation Integrated System (DRIS) indices indicated foliar Mg insufficiency and Ca sufficiency. Mg insufficiency increased with rainfall exclusion, regardless of beech sapling presence. Rainfall exclusion reduced soil nutrient supply levels relative to controls; some supply rates (total pools, PC1, PC2, acidity) progressively increased over probe burial duration (2021: 14–56 days) in a diffusion-dependent manner under excluders, while reaching a plateau (equilibrium-dependent adsorption) with accessible rainfall. NO 3 -N progressively dominated beech-free soil inorganic-N pools over time, which diminished regardless of rainfall exclusion. Likewise, soil base cations (Ca + Mg + K) remained high in beech’s absence, and vice versa for acidity (Al + Fe + Mn). Modest rainfall manipulations decreased BAI, altered adsorption processes, and shifted soil pools from endo- to ectomycorrhizal dominance. Even short-term moisture deficiency in maple soils may incur further stress in already nutrient-stressed stands, initiating nutrient cycle uncoupling between foliar and soil pools.
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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".