Douglas-fir (abbreviated as Fd) is one of the most prevalent and valuable tree species in British Columbia. The CCISS model predicts warmer temperatures will facilitate increased suitability of Fd throughout much of its current range and expansion of suitable range at higher elevations and further north, especially on mesic and drier sites. Fd is predicted to become less suitable in the hottest and driest sites, i.e. valley bottoms of the Southern Interior.
While the CCISS tool offers valuable insights into broad-scale trends, summarized here by species, suitability projections must be interpreted with caution. Many areas of projected change are also areas with high uncertainty in climate predictions. Furthermore, factors such as soil texture, drainage, land-use history, forest health pressures, and biotic interactions (e.g., competition or browsing) can strongly influence actual outcomes on the ground. These nuances emphasize the importance of pairing climate tools with on-the-ground knowledge and site-specific judgement when planning future Douglas-fir management.
Douglas-fir (Fd) is native to the Pacific and Cordilleran regions of Western North America. In BC there are two varieties, interior Douglas-fir (Pseudotsuga menziesii var. glauca) found throughout the Central and Southern Interior and coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) found along the south coast and Vancouver Island. It is most common in the montane zone, but also occurs in the submontane zone and to a lesser extent subalpine zone (Klinka et al., 2000).
Fd is best adapted to cool/warm temperate and cool (warm) mesothermal climates (Klinka et al., 2000), occurring from the humid maritime coastal climate to the semi-arid continental climate of the interior. The distribution of Fd in the interior of BC represents its northernmost latitudinal range, limited by cold temperatures. Fd is also limited by high-elevation and forest-grassland transitions (Griesbauer & Green, 2010).
The growth response of Fd to climate varies over the species’ broad geographic and climatic range. Fd populations growing in relatively warm and dry climates are limited by growing season precipitation and water availability (Case & Peterson, 2005; Griesbauer & Green, 2010; Watson & Luckman, 2002), with trees on drier stands having greater sensitivity to drought conditions (Adams & Kolb, 2005). Meanwhile, Fd populations growing in high-elevation wet and cold climates are limited by snowfall, and cold annual and winter temperatures (Case & Peterson, 2005; Griesbauer & Green, 2010).
Fd has a wide ecological amplitude, but is most commonly found on moderately dry to slightly dry sites with medium soil nutrients (Klinka et al., 2000). Fd is found on a variety of soil types, but grows best on deep well-drained, sandy loams where moisture in the soil is plentiful.
Fd is commonly a pioneer species that regenerates after forest fires, logging or other disturbances, forming single-species even-aged stands. It is also found in un-even aged stands or in mixed-species stands, often with western hemlock, western redcedar, trembling aspen, ponderosa pine, lodgepole pine, or western larch (Klinka et al., 2000). Fd is a major component in old-growth forests in boreal, cool temperate and cool mesothermal climates.
Species environmental suitability during the reference period (1961–1990)In the maps below, each colour represents the species environmental suitability during the historical reference period* of 1961-90 as determined by expert ratings. Green represents a high suitability (E1 rating), blue represents moderate suitability (E2), yellow represents low suitability (E3), and white indicates areas that are unsuitable for the species. See CCISS Documentation tab > Methods > Environmental Suitability Ratings for more detailed definitions and information on the expert rating process.
*Note on terminology: The historical reference period is sometimes referred to as the “baseline” or simply “historical” or “reference” period.
The pie chart to the right depicts the distribution of the total environmentally suitable area of Fd in BC by biogeoclimatic (BGC) zone, based on the climate of the historical reference period (1961–1990).
On the coast, Fd is most abundant in the southern Coastal Western Hemlock (CWH) zone, especially on mesic to wet sites, where it grows alongside western redcedar, grand fir, and bigleaf maple (Egan, 1999). It also occurs in the Coastal Douglas-fir (CDF) zone, which is characterized by Fd, often with grand fir.
In the interior, Fd is a key species in the southern subzones of the Interior Cedar-Hemlock (ICH) and Sub-Boreal Spruce (SBS) zones, and dominates the Interior Douglas-fir (IDF) zone. It can also be found in the Montane Spruce (MS) and the lower southern Engelmann Spruce – Subalpine Fir (ESSF) zones (Government of British Columbia 2025).
On this page, you will find a visual and interpretive synthesis of the environmental suitability projections calculated using the Climate Change Informed Species Selection CCISS tool, including:
Proportion of the historic range that the species is predicted to remain environmentally suitable (i.e. persist) or become newly suitable (i.e. expand) by site type (edatope).
Predicted mean changes in environmental suitability across its geographic range in BC, by future time period and site type (edatope).
Predicted shifts in total suitable area over time across the province and by biogeoclimatic (BGC) zone.
Douglas-fir (Fd) is projected to persist within 70–90% of its historically suitable range under climate change. In addition the climatically suitable range of Fd is projected to expand over time into an area 0.75-2 times the size of the historical range. The projected expansion of Fd’s suitable area is driven by warming temperatures, for example portions of the Engelmann Spruce–Subalpine Fir (ESSF) and Montane Spruce (MS) zones becoming warmer and therefore more suitable for Fd.
Persistence (x-axis) and expansion (y-axis) are subtly different in how they relate to the historical range of the species. Persistence describes the change in environmental suitability within the species historical range. While Expansion describes the change in environmental suitability outside of the species historical range. Calculated as follows:
\[\text{Persistence (\%)} = \frac{\text{future suitable area within historical range of suitability}} {\text{historically suitable area}} \times 100\] \[\text{Expansion (\%)} = \frac{\text{future suitable area outside historical range of suitability}} {\text{historically suitable area}} \times 100\]