Initial mapping of the Engelmann Spruce - Subalpine Fir (ESSF) zone in British Columbia divided the zone into a forested ESSF (part of the timber harvesting land base) and an ESSF parkland where tree growth is severely limited and forests do not have economic timber value. Eventually, the lower economic value and operability of forests in the upper elevations of the forested ESSF led forest licensees and districts to consider mapping elevation operability lines for forest planning below the parkland boundary. Pacific Inland Resources (a division of West Fraser Mills Ltd.) initiated a pilot project in 1999–2000 to collect data on these high-elevation ecosystems to better inform an operability line for harvesting activities within the Bulkley Timber Supply Area. During the 1999 pilot project, an ecotone between mid-elevation ESSF forests of relatively average productivity and the low-productivity, clumpy forests of the ESSF parkland was recognized. This transitional biogeoclimatic “phase” was characterized by low forest productivity, a continuous but open canopy forest, and understorey species that are more closely associated with ESSF parkland. This transition was initially termed “ESSF Upper Forest phase” (ESSFu), and primarily reflected productivity constraints due to harsh climate and sensitive environments (Trowbridge and Banner 2002). Subsequent provincial correlation recommended that all similar high-elevation ESSF transition zones in the province should be termed “Woodland” subzones or variants (e.g., ESSF##w) (Figure 1). Engelmann Spruce – Subalpine Fir woodland subzones are now recognized throughout British Columbia and continue to be described and mapped as regional field guides are revised and updated. Over the past few years, additional field data and vegetation and environmental analyses in the ESSF zone in the Skeena Region have provided the basis for this revised and expanded woodland ecosystem classification for the ESSFmcw (Moist Cold Woodland), ESSFmkw (Moist Cool Woodland), and ESSFwvw (Wet Very Cold Woodland) subzones. The ESSFmv3w (Moist Very Cold Woodland) ecosystems have not been adequately sampled to provide a woodland classification in this supplement.
E.B. Lilles, R. Trowbridge, W.H. MacKenzie. 2021. Field Guide to Site Identification and Interpretation within the Engelmann Spruce - Subalpine Fir Woodland Subzones of the Skeena Region: Supplement 2 to Land Management Handbook 26: A Field Guide to Site Identification and Interpretation for the Prince Rupert Forest Region. FLNRORD. Land Management Handbook (FLNRORD). LMH26