These Interim Forest Cover Series Maps were produced in 1958 following the first-ever systematic inventory of the province’s forests. The inventory information was collected from 1951 to 1957 with help from federal funding using a combination of aerial photographs (40 chain photos) and ground sampling plots. In total, 5057 clusters of four fixed-radii plots were used to supplement the aerial photo interpretation. Each map is accompanied by an envelope on which estimates of the timber volume within the map sheet were provided. The volume estimates were intended to be accurate to +/- 10% for major tree species. The maps are printed on high-quality paper, and contain colour-coded representations of various classifications of forest cover. Physical copies of the map series are held in the UBC Library’s Map and Atlas Collection in Koerner Library, as well as at the Rare Books and Special Collections Library, within the MacMillan Bloedel Limited fonds.

The maps have been converted to GeoJSON, the index of which can be found here and the GeoJSON data here.

The key references for understanding the inventory information are:

Thrower, James S. 1992. "An Historical Summary of Forest Inventory Sampling Designs in British Columbia." Report of the Timber Inventory Task Force on the Current Timber Inventory with Recommendations for the Future. The Resources Inventory Committee 840.

Continuous Forest Inventory of BC 1957 (In: British Columbia forest inventory statistics 1910-1973.)​

Below is a glossary of forest covers extracted from the 1967 forest inventory. Note that the definitions used in this map series may differ and that this glossary should be interpreted cautiously. 

Mature Forest - Forest land in mature condition, defined as stands containing an acceptable number of trees per acre: 81 years and over for broad-leaved, Lodgepole pine, and Whitebark pine stands; 121 years and over for conifers. Note that pre-1963, mature broad-leaved stands were defined as 41 years and over. 

Immature Forest - Forest land in immature condition, defined as stands containing an acceptable number of trees per acre: 1-80 years for broad-leaved, Lodgepole pine, and Whitebark pine stands; 1-121 years for conifers. Note that pre-1963, mature broad-leaved stands were defined as 1-40 years. 

Not satisfactorily stocked areas - Forest land in not satisfactorily restocked (N.S.R) condition, defined as stands that have been disturbed over 75% by fire, logging, wind, insect, disease or other disturbances, and have not re-stocked with sufficient numbers of commercial species.

Non-productive forests and non-forested lands - Includes all non-merchantable stands which are occupying productive forest land (i.e., non-productive). Non-forest land is land best suited for the growing of crops other than forest trees or which is incapable of supporting a commercial forest.