The Subarctic Forest–Tundra: The Structure of a Biome in a Changing Climate
Bibliographic record
Abstract
The forest–tundra (FT) is a term coined byClements (1936) to describe the transition zone where the subalpine forest and alpine tundra communities meet. The term has been extended to include the high-latitude subarctic vegetation between the circumpolar boreal forest and the arctic tundra (Marr 1948, Hare 1959, Löve 1970, Hare and Ritchie 1972, Rowe 1972, Larsen 1980, Payette 1983). The vegetation mosaic of the FT is viewed as either an ecotone, a zonal subdivision, or a biome, depending on the scale of perception (Marr 1948, Hare 1959, Britton 1967, Rowe 1972, Nichols 1975, Payette 1983). The term ecotone is now gaining popularity, although the concept is an old one (Clements 1936), and it is now used to describe the structural and functional changes occurring at different spatial scales (Gosz 1993, Risser 1995). In the subarctic FT, forest communities are often confined to wind-protected, well-watered, and seepage sites, whereas upland, exposed, well-drained sites are occupied by treeless communities. Across a south–north gradient, the FT extends from the continuous-forest limit, that is, the limit of the area where all well-drained sites are colonized by forest, to the arctic tree line, that is, the northernmost position of arboreal growth. The contrasted structure of the subarctic FT is the inverted mirror image of the agro-forested landscape, in which forests are typically located on the exposed sites and low-stature agricultural fields are found on the bottomlands and riparian soils. Much like the agro-forested landscape, the subarctic FT is heavily fragmented, with strong edaphic and elevational gradients at the local and regional scales. The subarctic FT in North America covers a large area, mostly on the acidic, nutrient-poor soils of the Precambrian shelf across northern Canada, east and west of Hudson Bay (Figure 1). With its patchy vegetation pattern, the subarctic FT is certainly one major bioclimatic zone that exemplifies the ecotone concept. The subarctic FT is composed of climate-sensitive forests and trees at their northernmost ranges, which may explain why it has been used extensively in paleoecological and ecological studies for the evaluation of the environmental impact of climatic change (Lamb 1985, Ritchie 1987, Gajewski et al. 1993, Spear 1993).
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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 | 0.004 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".