Nutrients override atrazine effects on riparian and aquatic plant community structure in a <scp>N</scp>orth <scp>A</scp>merican agricultural catchment
Notice bibliographique
Résumé
Summary In agricultural catchments, streams are intimately connected with croplands and are exposed to agrochemicals such as fertilisers and herbicides. In North American streams, the effects of nutrient enrichment on riparian and aquatic plant community structure are not well established and the effects of herbicides are largely unknown. We identified the riparian and aquatic plant community at 12 paired stream/river sites (24 in total, Strahler stream order 3–6) located across a large North American agricultural catchment. Field sites ranged in surrounding agricultural land use (2.7–100% annual crops) and in‐stream June concentrations of reactive phosphate (6–65 μg L −1 as phosphorus) and nitrate (3–3981 μg L −1 as nitrogen). Atrazine, a herbicide commonly used on corn crops in North America, was widespread throughout the catchment with time‐weighted‐average concentrations ranging from 4 to 412 ng L −1 over a 56‐day period. Atrazine concentrations were >100 ng L −1 at over half the field sites. In total, 285 riparian and aquatic plant taxa were identified. Effects of agrochemicals on descriptors of plant communities were assessed by comparing paired sites surrounded by low or high levels of agriculture and examining changes across the catchment. Agrochemicals had no effect on overall species richness. However, the percentage of non‐native species increased across the catchment along a gradient of increasing nitrate. A decline in submerged macrophytes was associated with enrichment of both nitrate and reactive phosphate, whereas no direct effects of atrazine were observed. A floristic quality assessment was used to determine further effects of agrochemicals on riparian and aquatic plant communities. A ranking system, based on native status and tolerance to disturbance, was used to assign coefficient of conservation values to each species. Floristic quality was subsequently calculated as a function of species richness and the average coefficient of conservation value at each site. Overall floristic quality decreased as nitrate increased. Species positively associated with nitrate were typically fast‐growing, weedy, riparian species, whereas species negatively associated with nitrate were characteristic of less disturbed areas and represented a range of growth forms. We conclude that nutrient enrichment, especially of nitrate, has multiple negative effects on riparian and aquatic plant communities that override effects of the herbicide atrazine. Our results highlight the need to reduce inputs of agrochemicals to streams and to regulate nitrogen in addition to phosphorus.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».