Restoring Enriched Grasslands: Effects of Mowing on Species Richness, Productivity, and Nitrogen Retention
Bibliographic record
Abstract
Species-rich grasslands that become enriched with nitrogen often suffer decreases in species richness, increases in plant biomass, and invasion by weedy exotic species.Suitable techniques to restore enriched grasslands and reestablish native communities are increasingly needed.Here we report results of a 5-yr experiment in enriched coastal prairie grasslands (Bodega Marine Reserve, Bodega Bay, California, USA), to determine the combined effects of mowing and biomass removal on total soil nitrogen, net rates of mineralization, nitrogen retention, and species richness and biomass.We mowed and removed plant biomass from plots in areas where the N-fixing shrub, bush lupine (Lupinus arboreus), had greatly enriched the soil, and where the community was composed of weedy introduced plants.Our goal was to facilitate the establishment of the native grassland assemblage such as was found at nearby low soil nitrogen sites.Mowing and biomass removal resulted in a dramatic change in the species assemblage, from exotic annual grasses to a mixed exotic/native forb community composed primarily of perennials.Species richness was significantly greater in treated plots than in control plots; weedy exotic grasses diminished in abundance, and both native and exotic forb species increased.In mowed vs. control plots, there was significantly less mean aboveground biomass, but significantly greater belowground biomass.This shift in species composition had significant impacts on nitrogen retention.In late fall and winter when plant-available N was highest, much nitrogen leached from the effectively fallow control plots where germination of annual grasses did not peak until midwinter.In contrast, mowed plots retained substantially greater amounts of nitrogen, due to the presence of perennial plants possessing large amounts of belowground biomass early in the season.Despite the cumulative removal of 22 g N/m 2 in biomass over 5 yr, there was no difference between mowed and control plots in total soil N, pool sizes of inorganic N, or net rates of N mineralization.The results indicate that removal of plant biomass by mowing shifted this plant community from an annual grass to a perennial forb assemblage.However, in doing so, N retention by vegetation was increased, making it more difficult to reduce soil N.
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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 | 0.000 | 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 | 0.001 |
| 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".