Ecohydrological separation in wet, low energy northern environments? A preliminary assessment using different soil water extraction techniques
Bibliographic record
Abstract
Abstract Ecohydrological studies in seasonally dry climatic regions have revealed isotopic separation of the sources of water used by trees and those that generate stream flow, also referred to as the ‘two water worlds’ hypothesis. Here we investigated whether similar separation occurs in a wet, low energy northern (Latitude 57°) environment in Scotland. For two common soil types (Histosols and Podzols) at three soil depths, and at both forested (with Scots Pine (Pinus sylvestris)) and non‐forested sites, we compared the stable isotope composition of soil water held at increasing soil water tensions. These were assessed by different soil water extraction techniques: Rhizon samplers (mobile water), centrifugation at different speeds (representing different tensions), and cryogenic extraction (bulk water). Sampling occurred during a relatively dry summer. Water that was held at increasing tensions appeared more depleted than more mobile water, consistent with older (winter) precipitation. This pattern was independent of soil type, vegetation cover, and time during the growing season, although there was a slight tendency towards less separation with soil depth. Nevertheless, soil waters in this generally wet, low energy environment exhibited only minor evaporative enrichment, limited to the upper soil profile only. Furthermore, stream water showed no deviation from the local meteoric water line. Preliminary sampling for tree xylem water suggested uptake of evaporated soil water from the near surface soil horizons (upper 10 cm) where fine root densities are concentrated. For Histosols in particular, tree water appeared lagged in its isotopic composition compared to the soil water time series. Although more work is needed to fully test the ‘two water worlds’ hypothesis, our initial analyses did not provide clear evidence to support this in wet, low energy northern environments. Copyright © 2015 John Wiley & Sons, Ltd.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".