An ecological study of the Sitka spruce forest on the west coast of Vancouver Island
Notice bibliographique
Résumé
A forest consisting of almost pure stands of Sitka spruce (Picea sitchensis) occurs in a narrow band varying in width from several feet to approximately 600 feet along the west coast of Vancouver Island. In this area spruce replaces western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata), the dominant species of the region. A comparison of the physical environment of the coastal Sitka spruce forest with that of the hemlock - redcedar forest revealed that ocean spray intensity was the major difference between, the two. Monitoring of ocean spray over a 17 month period indicated that incoming spray is highest during the fall and winter when major storms are frequent in the northern Pacific Ocean. However, the effects of ocean spray on vegetation were at a maximum during late spring and early summer when infrequent precipitation allowed salts to accumulate on the foliage. Young needles of coniferous species were killed by spray during this period. Sitka spruce was found to be much more tolerant than either western hemlock or western redcedar. During the spring and summer the amount of incoming ocean spray varied considerably from site to site depending on the configuration of the coastline, the type of shoreline and the degree of protection provided by vegetation in a seaward direction. The width of the Sitka spruce forest as well as canopy form were closely related to the amounts of incoming ocean spray. Measurements of salt concentrations in throughfall precipitation indicated that significant amounts of sodium, magnesium, calcium and potassium are added to the soil beneath the Sitka spruce forest. These additions improve the nutrient status of the soil but do not accumulate to high levels due to the high precipitation of the region. Retention of these cations in the soil varies considerably with calcium being the highest and sodium the lowest. Studies of the Sitka spruce forest have resulted in the delineation and characterization of seven ecosystematic units on the basis of vegetation, topography, parent material and historical factors. Comparisons of the environmental components of these units strongly suggest ocean spray intensity and water relations to be the most influential factors. An investigation of successional dynamics revealed that Sitka spruce was the dominant climax tree species in most of the forest type, although western hemlock shares this role with spruce in one type. Successional rates and stability of the different forest types are dependent on the geomorphic processes responsible for beach plain expansion and the degree of protection from incoming ocean spray provided by vegetation on the seaward side. Combining the forest types of the alluvial Sitka spruce forest, which were also studied, with those of the coastal Sitka spruce forest, a hierarchic system of classification consisting of plant associations, alliances and orders is proposed for the Sitka spruce forest of the Coastal Western Hemlock Zone on Vancouver Island.
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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 | 0,001 | 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 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 ».