Nonlinearity of effects of invasive ecosystem engineers on abiotic soil properties and soil biota
Bibliographic record
Abstract
Invasions of non‐indigenous species into natural communities are currently rated as one of the most important threats to biodiversity. Particularly exotic ecosystem engineers such as earthworms potentially have profound impacts on community assembly and functioning. We investigated the impact of invasion by the lumbricid earthworms into an aspen forest of the Canadian Rocky Mountains on soil organic matter, microorganisms and microarthropod communities. Building on the results of previous studies in this forest, we expected positive effects of Lumbricus terrestris middens and negative effects of Octolasion tyrtaeum on soil biota (increase and decrease in soil nutrient concentrations, microbial parameters and soil microarthropod density and diversity, respectively). Further, we expected that earthworm effects change with time. Combined results of previous and the present study suggest a wavelike colonization pattern for Dendrobaena octaedra and O. tyrtaeum and that indeed the impact of earthworms on soil biota changed with time, likely due to changes in earthworm density. Unexpectedly, L. terrestris middens neither affected soil abiotic nor soil biotic properties. By contrast and in contrast to our hypothesis, carbon and nitrogen concentration and C‐to‐N ratio in deeper soil layers increased in presence of O. tyrtaeum , thereby likely enhancing nutrient availability for soil microorganisms and microarthropods. Even though the density of this endogeic species was rather low, presence of O. tyrtaeum resulted in increased densities of a number of microarthropod taxa and increased microarthropod diversity. The results suggest that at low density, invasive ecosystem engineers, such as O. tyrtaeum, cause disturbances of intermediate strength thereby beneficially affecting soil microorganisms and most microarthropods. This contrasts earlier effects during the wavelike invasion of O. tyrtaeum into the aspen forest when densities of O. tyrtaeum were high resulting in generally detrimental effects on soil biota. The results emphasize the nonlinearity of earthworm effects on abiotic and biotic soil properties and call for further long‐term investigations.
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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 | 0.001 | 0.002 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".