Distribution and abundance of infective, soilborne <i>Frankia</i> and host symbionts <i>Shepherdia</i>, <i>Alnus</i>, and <i>Myrica</i> in a sand dune ecosystem
Bibliographic record
Abstract
We describe presence, abundance, and distribution of three sympatric nitrogen-fixing shrubs and their symbiotic diazatroph, Frankia, in a sand dune ecosystem differing in successional stage, vegetative cover, edaphic characteristics, and topography. Distribution of actinorhizal Myrica gale L., Alnus incana (L.) Moench subsp. rugosa (Du Roi) Clausen, and Shepherdia canadensis (L.) Nutt. was analyzed among 120 sampling locations representing a gradient of successional stages in a sand dune system along Lake Michigan. In a greenhouse study, seedlings of these species were employed to bioassay the presence and abundance of infective Frankia in soils. Shepherdia-infective Frankia was detected in 80% of the plots, while Alnus- and Myrica-infective Frankia were found in 65% and 64% of the plots, respectively, with no Frankia found in 18% of the plots. Only 14% of the plots supported actinorhizal host-plant species. Infective Frankia were present in soils of young dunes prior to the establishment of any actinorhizal hosts. Shepherdia-infective Frankia were more abundant in soils from drier, earlier successional sites, while Alnus- and Myrica-infective Frankia were more abundant in moister soils of later successional communities. A previous study had revealed that nodular Frankia strains at this site were host specific for Shepherdia and largely so for Myrica and Alnus, which had only a small proportion of shared strains (Huguet et al. 2001). The likelihood of host-plant nodulation by soilborne Frankia was increased by the presence of actinorhizal plants in general, but not by the presence of their respective specific host plants. Submerged soils had no infectious capacity, whereas soils with greater in situ moisture content and soils subject to intermittent saturation tended to have lower infectious capacities overall. Our results suggest that soilborne, infective Frankia genotypes are not only host specific, but are also associated with spatially and chronologically distinct sets of ecological conditions.Key words: speckled alder, sweet gale, Canada buffalo berry, actinorhizal, nitrogen fixation, Frankia, root nodules.
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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 | 0.000 |
| 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 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".