Lit-review BEC (biogeoclimatic ecosystem classification) zone shifts under climate change [tracker] #59

Problem

A future cd vignette will cover Biogeoclimatic Ecosystem Classification
(BEC) zone shifts driven by climate departure. This issue is the
placeholder for the lit review backing that future vignette.

Why filed now (but not yet tackled)

Surfaces during the 3-split climate-departure lit-review work
(temperature, precipitation+drying, interpretation framing).
BEC is a separate domain (vegetation classification × climate
envelope) — gets its own issue + ragnar store rather than padding the
climate-departure ones.

Sequence after the 3-split lands:

• Current 3-split lit reviews back interpretation in vignettes that
  already exist (peace-fwcp, kootenay-lake, third regional). BEC
  backs a future vignette that doesn't exist yet.
• Cross-cutting BC papers (Hamann & Wang 2006, ClimateBC stack,
  Mahony novel climates) will surface naturally during Issue 1
  (temperature) and Issue 2 (precip+drying) — anything BC-specific
  hits both. We won't lose BEC-relevant refs during the 3-split.
• By the time we pick this up, the future BEC vignette will be
  scoped — the structure of the lit review will be clearer than it
  is right now.

Starting candidate list (rough — will refine when active)

• Pojar, Klinka, Meidinger 1987 — BEC foundational (Forest Ecology
  and Management)
• Meidinger & Pojar 1991 — Ecosystems of BC (Special Report 6)
• Hamann & Wang 2006 — Potential climate change effects on BC tree
  species + ecosystems
• Wang et al. 2012, 2016 — ClimateBC / ClimateNA downscaling tools
• Mahony et al. 2018 — Novel climates in BC under projected warming
• Murdock & Cannon (PCIC) — projecting BEC zone shifts under climate
  change

Out of scope (until activated)

• Anything covered by the 3-split lit reviews (temp, precip+drying,
  interp framing).
• Implementation of the BEC vignette itself — separate downstream
  issue once this lit review lands.