Effect of forest harvesting on biological processes in headwater streams within the flume creek experimental watershed, British Columbia
Notice bibliographique
Résumé
Effects of forest harvesting on periphyton biomass (measured as Ash Free Dry Mass (AFDM) and Chlorophyll a), benthic organic matter (measured as AFDM) and invertebrate density and diversity were studied in coastal headwater streams in southwestern British Columbia. These aquatic ecosystem variables were also evaluated along the longitudinal gradient of these streams to examine longitudinal patterns. In addition, photosynthetically active solar radiation (PAR), stream water temperatures and chemical concentrations of streamwater were measured and evaluated in order to determine their role in regulating the aforementioned variables. Six headwater streams (1st and 2nd order), three undisturbed and three harvested (3 years postharvest), were sampled over a six-week period during the early summer (May 31 - July 7, 2002). Each stream had nine study reaches (covering a total stream length of 500-700 meters), with harvested streams having three reaches above the harvested area, three reaches within the harvested area and three below - providing for comparisons between forested and harvested stream reaches within streams. Periphyton biomass sampling occurred once a week over the six-week study, while benthic macro invertebrates were sampled over four days during week 3 of the study. Physical and chemical data were also collected once a week for the six-week study period. No significant longitudinal trends were found within the undisturbed streams for any of the studied variables. However, along the harvested streams, Chlorophyll a and stream temperature increased along the downstream longitudinal gradient as the stream flowed through the harvested area and subsequently decreased as the streams flowed back into forested reaches. In addition, incident solar radiation decreased (however not statistically significant) as the streams flowed further into the forested area below the harvested boundary. Incident solar radiation and stream water temperatures were greater in the harvested reaches than in forested reaches of the harvested streams. Periphyton biomass levels were greater within harvested reaches than in forested reaches of the headwater streams. Incident solar radiation was considered to be a primary factor controlling periphyton biomass in these headwater streams, as periphyton biomass increased with increased incident solar radiation. Increased invertebrate density was positively related to periphyton biomass, suggesting bottom-up controls in the aquatic food web. While richness of aquatic invertebrate orders was greater in forested reaches below the harvested area, overall invertebrate diversity was not altered by previous harvesting activities. No differences were seen in benthic organic matter biomass nor were there significant relationships between nutrient concentrations with the aforementioned research variables during the study period.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».