Composition and function of biological soil crust communities along topographic gradients in grasslands of central interior British Columbia (Chilcotin) and southwestern Yukon (Kluane)
Bibliographic record
Abstract
Grasslands in the rainshadow of the Chilcotin (British Columbia) and St. Elias (Kluane, Yukon) mountain ranges of western Canada are characterized by widely spaced clumps of bunchgrass and sage, between which can be found lichen-dominated biological soil crusts (BSC). Our examination of Chilcotin and Kluane grasslands showed differential BSC development along topographic gradients, favoring those sites with lower levels of soil disturbance. Lichen species richness was greatest in upper topographic positions, that is, on valley side terraces in the Chilcotin and esker slopes in Kluane. Common BSC lichens in both grasslands included Acarospora schleicheri, Caloplaca tominii , Collema tenax , Diploschistes muscorum , Fulgensia bracteata , Phaeorrhiza nimbosa , Placidium squamulosum , and Psora decipiens . Chilcotin BSC additionally contained many Cladonia species (e.g., C. carneola , C. chlorophaea , C. pyxidata ), particularly where vegetation had encroached on BSC. The potential for nitrogen fixation by Collema -dominated crusts in Kluane was examined using acetylene reduction assays (ARA) and soil surface microclimate monitoring. ARA activity was highly dependent upon the duration of wetting events, reaching C2H4 levels up to 63 μmol·m–2·h–1after 40 h of hydration. Given the abundance of Collema-dominated crusts in Kluane and the optimal conditions for ARA activity that are reached during wetting–drying transitions, we hypothesized that BSC communities potentially make an important contribution to ecosystem nitrogen budgets. Enrichment in total and mineralizable N, as well as 15N natural abundance values, was consistent with N fixation making an important contribution to soil N pools in these ecosystems. Both Chilcotin and Kluane BSC had similar spongy microstructures that contrasted with the platy microstructures of the underlying surface mineral soils, but only the latter site showed micromorphological evidence of burial of mosses and other BSC components by continuing loess deposition. BSC may have performed similar roles in analogous steppe-like ecosystems that existed under full-glacial conditions in the unglaciated areas of eastern Beringia in Alaska and Yukon.
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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 | 0.002 |
| 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".