The BWCA still has a roughly 60-year window before fire exclusion makes restoration impossible.

Evidence

Assuming that a program of prescribedburning and lightning fires such as that just outlined could be implemented, one question remains: How much time is there before the successional changes already initiated by fire exclusion will cause fuel accumulations and ecological changes that might preclude restoration of the natural system? Fortunately succession is slow enough in this near-boreal ecosystem so that 10-20 yr, or perhaps even 50, could elapse before fire exclusion causes irretrievable changes. It is true that unnaturally large areas are developing heavy fuel loads duo to stand maturation, succession, budworm epidemics, local blowdowns, and other events related to fire exclusion, but these things are still natural in any given stand. What is unnatural now is mainly the deficiency of those young forests and recent burns that a natural fire regime would have produced in the 60 yr since fire protection became effective. Yet even now, 82% of the virgin forest dates from the fires of 1863-1864 or later (Table 4). Thus most stands are still less than 110 yr old, and large areas are only 60-90 yr old. Such forests are certainly not too old to respond naturally to fire. Research on the Little Sioux burn is already demonstrating this in several vegetation types. — Miron L. Heinselman, Fire in the Virgin Forests of the…, 492

Categorization

• XREF: Connects to the reader’s disturbance-history teaching: the 82% figure dating from the 1863-1864 fires extends and quantifies the chapter’s earlier stand-origin dating methods. — connects to: BWCA management excluded fire despite its dominant ecological role — Miron L. Heinselman, Fire in the Virgin Forests of the…, 25; Restoring the natural regime means burning roughly 4,200 Canoe Area acres yearly — Miron L. Heinselman, Fire in the Virgin Forests of the…, 466; No large BWCA burns since 1936 already eliminated early postfire communities. — Miron L. Heinselman, Fire in the Virgin Forests of the…, 413 (+1 more)
• QUESTION: Worth chasing: whether the natural fire rotation is shortening or lengthening as climate warms in the BWCA today.

Related

• No large BWCA burns since 1936 already eliminated early postfire communities. (similarity 0.90)
• Natural fire rotation in the BWCA was about 100 years (similarity 0.87)
• Virtually every BWCA virgin forest stand burned since 1595. (similarity 0.87)
• Five fire years created nearly three-quarters of today’s forest stands. (similarity 0.86)
• Virtually every BWCA forest stand regenerated after fire since 1595 (similarity 0.85)
• The Canoe Area burned and regenerated on about a 100-year rotation. (similarity 0.85)
• The entire BWCA ecosystem was fire-dependent (similarity 0.85)
• The landscape mosaic remains fire-created even after sixty years of suppression. (similarity 0.84)
• Restoring the natural regime means burning roughly 4,200 Canoe Area acres yearly (similarity 0.84)
• Historic burns of 100,000 acres can no longer be allowed in the Canoe Area (similarity 0.83)
• BWCA management excluded fire despite its dominant ecological role (similarity 0.83)
• Natural fire rotation quantifies fire’s role and grounds fire-management targets. (similarity 0.82)
• Surface fires returned every 36 years on average in surviving pine stands. (similarity 0.82)
• Fire is an intrinsic ecosystem component, not an unnatural disturbance, in the Canoe Area. (similarity 0.82)
• Man-controlled burning can still yield a natural ecosystem (similarity 0.81)

Broader Connections

• The entire BWCA ecosystem was fire-dependent #expands (0.85) — Miron L. Heinselman, Fire in the Virgin Forests of the…, 1