Depth of calcium uptake by sugar maple (Acer saccharum Marsh.) and its relationships with climatic extremes
Bibliographic record
Abstract
Sugar maple (Acer saccharum Marsh.) has experienced diebacks in many parts of its range; these declines have caused researchers to consider the many connected factors governing tree health. Altered availability of base cations due to acidic deposition and climatic extremes (drought, late winter freeze-thaw cycles) have been identified as two main causal stressors. To predict the role of climate on Ca nutrition, I investigated the relationship between the climatic factors of temperature, precipitation, water availability and windstorm on temporal changes to depth of Ca source of sugar maple. I hypothesized that the Ca uptake depth would be deeper after windstorms, or under dry or cold conditions, and shallower under warm or wet conditions. The ratio of Ca/Sr can be used to track the source of Ca. Calibration of the relationship between soil and plant Ca/Sr was done by analyzing Ca/Sr ratios in soil extracts of various strengths (H2O, NH4Cl, and ammonium EDTA) and in seedlings of sugar maple grown from natural regeneration on 37 differing sites. The relationships between soil extract Ca/Sr ratios and leaf and stem Ca/Sr ratios were linear, and the slopes of these relationships were different. These findings support the use of Ca/Sr as a tracer to Ca and they highlight the need to calibrate the technique for the plant tissue and the soil extractant used. This technique was then applied to study Ca uptake depth and its relationship with climate in the Hermine watershed, a sugar maple dominated forest in southern Quebec. The Ca/Sr was measured in soil, incremental cores of wood, and leaves. The ratio of Ca/Sr from nine soil profiles decreased with soil depth (r2 = 0.320, p<0.05), providing a signature for depth. Wood cores from ten trees were analysed in five or ten year increments from 1940 to 1999 to provide a long-term trend of Ca nutrition. Sugar maple leaves from 1995-2005 from the same 25 trees were analyzed to determine the annual dynamics of Ca uptake depth and its relationship with climate. Results suggest that the majority of tree Ca is taken from the lowest part of the rooting zone, regardless of the climatic conditions that occurred during this study, although the minor variations were related to the April temperature (r2 = 0.208, p = 0.023) and the June, July and August combined total precipitation (r2 = 0.581, p = 0.006). The effect of the windstorm on Ca uptake depth was only apparent in the area of the forest most visibly affected; Ca uptake was deeper.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".