Physiological and Morphological Variation in Balsam Fir Provenances Growing in New Brunswick, Canada
Bibliographic record
Abstract
There is a need to understand the physio-morphological responses of northern tree species to climate change. The hypothesis of the current study was that provenance and light intensity were both influential in the control of intrinsic water-use efficiency (iWUE). Diameter at breast height (DBH)-increment was hypothesized as being more affected by provenance. Intrinsic water-use efficiency (iWUE), the ratio of photosynthesis (A) to stomatal conductance (gs), was assessed in foliage under two levels of photosynthetically active radiation (PAR; i.e., 300 and 1200 μmol m−2 s−1) in 63-year-old balsam fir [Abies balsamea (L.) Mill.] provenances derived from seed sources from across the species’ natural range (namely, within 44–51° N latitudes and 53–102° W longitudes) and cultivated in a common garden in eastern Canada. Diameter at breast height (DBH) of provenances from the common garden were measured when they were 42 and 58 years old (DBH1998, DBH2014). The results confirmed the hypotheses regarding the roles of provenance on iWUE and DBH (p < 0.05), but showed a diminished role of PAR on iWUE. The lowest and highest mean iWUE and DBH among the provenances ranged between 0.028 and 0.031 and 0.079–0.083 μmol mmol−1 and 11.82–12.78 and 16.38–18.44 cm, respectively. Stomatal conductance of balsam fir had a strong relationship with iWUE at both light settings, whereas A had a weaker relationship with iWUE. There were no significant relationships between iWUE at the two light settings and climatic variables at the provenance source (p > 0.05). Diameter at breast height in 2014 was significantly greater than DBH1998 (p < 0.05). The relationships between DBH2014 and climatic variables at the provenance source were statistically significant (p < 0.05). There was a significant positive relationship between iWUE and DBH measured in 2014. Survivorship of provenances was shown to vary with DBH-increment. The results show that for present-day and future forest management, (i) selection in balsam fir, in relation to iWUE should ideally be based on a criterion of intraspecific stomatal conductance; (ii) shade tolerance of balsam fir, population differentiation, and consistent pace of DBH-growth under variable climatic conditions are important factors in the species’ sustained growth under changes in forest dynamics projected to accompany changes in regional climate; (iii) temperature variables are strong indicators of DBH-increment in balsam fir; (iv) the effect of tree size on its survival is maintained under variable climatic conditions; and (v) there is a clear association between iWUE and the species’ radial growth.
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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".