Ordination and classification of immature forest ecosystems in the Cowichan Lake area, Vancouver Island
Notice bibliographique
Résumé
The objectives of this study included: 1) classification of immature forest ecosystems surrounding Cowichan Lake on Vancouver Island, 2) investigation of relationships between floristic composition, selected site and soil properties, and ecosystem productivity as estimated by site index (m/100 years) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and 3) evaluation of the usefulness of several multivariate analysis techniques for deriving the classification and investigating relationships. Methods employed included: 1) standard methods used in the biogeoclimatic ecosystem classification system as applied by the B.C. Ministry of Forests, and 2) multivariate analysis techniques, including ordinations (polar,reciprocal averaging, and detrended correspondence analysis) and cluster analysis of the vegetation data, and stepwise discriminant analysis of edatopic indicator species groups (EISG's), and site and soil properties. The classification was finalized after consideration of the environment data and results of multivariate analyses (particularly reciprocal averaging and detrended correspondence analysis) applied to the vegetation data. Three orders, five alliances, and six biogeocoenotic associations (BA's) were established. An objective, repeatable procedure for extracting characteristic combinations of species from summary vegetation tables was developed and applied. A comparison of the summary vegetation tables of three of the immature Cowichan Lake associations to the summary vegetation tables of three (climatically and edaphically) similar mature associations revealed strong similarities in understory species abundance and composition. This suggested that understory plant communities of the immature forest ecosystems had sufficiently stabilized to permit successful identification of probable climax associations. Estimated hygrotope and trophotope values of each plot suggested that axis 1 of the floristic data ordinations corresponded to a complex environmental gradient related to increasing availability of soil moisture and nutrients. This suggestion was supported by the results of indicator plant analysis, and by trends in a limited number of quantitatively assessed site morphological and soil physical and chemical propert ies. Discriminant analysis of EISG's and several site and soil properties selected linear combinations of variables which best characterized differences between the BA's. Soil properties proved more successful than site properties for this purpose. In addition, classification functions were produced which could be used to classify plots not used in the original analysis. Variation in site index values suggested an increase in productivity from BA's 2 to 4 but no differences between BA's 4 and 5. An investigation of relationships between axis 1 scores of detrended correspondence analysis of the floristic data, canonical variable 1 from the discriminant analysis of soil properties, and site index of Douglas-fir suggested that (for the forty-one intermediate plots in BA's 2 to 5): 1) 83% of the variation in understory vegetation was related to differences in the selected soil properties, 2) 78% of the variation in site index was related to changes in understory species abundance and composition, and 3) 71% of the variation in site index was related to changes in the selected soil properties. Mineral soil mineralizable N and exchangeable Ca values were highest, and C:N ratios lowest on the most productive sites. In addition, most of these sites had a mull humus form. This suggested that increases in site productivity were at least partially due to higher N availability. The higher levels of soil Ca on the most productive sites suggested more rapid nitrification rates and more nitrate, a form of N often found to be associated with the best growth of Douglas-fir. It was concluded that multivariate analysis techniques (particularly reciprocal averaging, detrended correspondence analysis, and discriminant analysis) were useful not only for classification purposes, but also for the investigation of trends in environmental properties and site productivity. These techniques provide a rapid, computer-assisted approach to data synthesis, and a more objective basis for interpretations. It was recommended that proponents of the biogeoclimatic system make greater use of these techniques in future studies.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| 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 ».