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An ecological classification of the ponderosa pine stands in the southwestern interior of British Columbia Brayshaw, T. Christopher


In this study 121 stands of Pinus ponderosa in the southwestern interior of British Columbia were examined. Floristic analyses of the stands were made by a system of visual estimates based upon scale values for dominance, abundance, and vigour assigned in the field. These values were later synthesized to produce a formula describing the role of each species in the community. Tables have also been included to show presence and fidelity values for the species of each association. Thus the floristic structure of each community becomes evident. The vigour of tree species was assessed by standard mensuration methods. Climatic data were obtained in some stands over a period of one year. Soil profiles of most of the stands were analysed for pH and texture. The Pinus ponderosa stands are here classified into the following principal communities: A. Pinus ponderosa zone: 1. Pinus — Purshia association with one related subassociation: 1a. Pinus — Aristida subassociation. 2. Pinus — Agropyron association with two related subassocia-tions: 2a. Pinus — Stipa subassociation. 2b. Pinus — Artemisia subassociation. 3. Pinus — Rhus association. B. Pseudotsuga zone: 4. Pseudotsuga — Pinus — Arctostaphylos association. 5. Pseudotsuga — Arctostaphylos — Calarnagrostis association. 6. Pseudotsuga — Calarnagrostis association. 7. Pseudotsuga — Symphoricarpos association. C. Azonal communities: 8. Populus -— Rosa — Cornus (alluvial) complex. All these communities are described individually; their successional relationships discussed; and some recommendations made regarding their utilization. The Agropyron and Arctostaphylos — Calamagrostis associations are thought to represent the climatic climax communities in their respective zones.

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