Responses of Reclamation Plants to High Root Zone pH: Effects of Phosphorus and Calcium Availability
Bibliographic record
Abstract
Low phosphorus (P) availability and high pH inhibit plant growth in calcareous soils and some oil sands reclamation sites in northeastern Alberta, Canada. In this study, we used a split‐root hydroponic setup to test the effects of supplemental P with different calcium (Ca) concentrations and root‐zone pH conditions on the growth and physiological response of trees commonly found in the region: paper birch ( Betula papyrifera Marsh.), trembling aspen ( Populus tremuloides Michx.), green alder [ Alnus viridis (Chaix) DC.], and black spruce [ Picea mariana (Mill.) Britton, Sterns & Poggenb.] seedlings. Plant roots were divided and treated with different combinations of P (0.5 and 15 mmol L −1 ), Ca (2 and 50 mmol L −1 ), and pH (5.0 and 9.0) for 6 wk. After that time, we measured seedling height, net photosynthesis and transpiration rates, and the concentration of chlorophyll and different elements in the leaves. Plant responses varied between species; black spruce was most resistant to high pH and high Ca concentrations. We did not find any strong beneficial effects of adding P to plants subjected to high root zone pH and high Ca concentration. However, exposure of part of the root system to low pH alleviated the effects of high pH, likely through the improved supply of micronutrients. Because pH conditions are often not uniform in disturbed sites and reclamation soils, our findings may help improve potential reclamation and phytoremediation strategies for the oil sands, bauxite, and coal‐combustion residue utilization industries. Core Ideas Black spruce was relatively resistant to high pH and high Ca concentrations. Increased P supply did not improve growth of plants exposed to high pH. Partial exposure of roots to low pH alleviated effects of high pH and high Ca concentrations. Revegetation of alkaline sites can be improved if only some roots can reach low pH soil.
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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) | 0.000 | 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".