Spin-up starts cohorts at initialB; widen young-cohort biomass check

[eliotmcintire]

Young forests in recently burned areas get their starting biomass from a short growth simulation. That simulation started every tree species at zero biomass, so spruce barely grew while pioneer species took all the growth, and a sanity check on the result was too strict for fast-growing pioneers, stopping runs. This starts each species at the biomass a new cohort normally gets and loosens the check slightly.

Affects: starting biomass of young cohorts inside fire perimeters in every run (spruce higher, pioneers lower); runs that stopped on the check now continue.

Technical details

R/updateYoungBiomasses.R (spinUpPartial, was line ~164) set B = 0 for every cohort, so growthcurve-1 species gained only the 1 g/m2/yr floor. Biomass_core gives a new cohort initialB (default 10; LandR .initiateNewCohorts, cohorts.R:~330-335; the maxANPP branch only applies when initialB is NA). The module now has an initialB parameter (same definition as Biomass_core, with paramCheckOtherMods(..., "warning")), passed to spinUpPartial, which uses it for the starting B (new spinUpStartCohorts()) and passes it to Biomass_core. If initialB is NA, cohorts start at maxANPP from speciesEcoregion, as .initiateNewCohorts does with sumB = 0.

Biomass_borealDataPrep.R:1467: the check now uses youngBiomassLimit() = min(maxRawB, 1.2 * 2.8 * maxRawB / min(longevity / maxAgeHighQualityData)), still one scalar. 2026-10-09: ELF 3.2.3 had a 59-yr Lari_lar cohort 17% over the old limit, ELF 10.3.1 Pinu_con cohorts up to 2.9% over.

New tests/testthat/test-updateYoungBiomasses.R: the new tests error on development (functions absent). Full suite via convertToPackage + test_local: 135 pass, 0 fail on the branch (the metadata test lists the new parameter); on development 125 pass plus the new tests failing. The full spin-up with Biomass_core is not run in tests.

🤖 Generated with Claude Code

https://claude.ai/code/session_01CwcjqqK59FmTJscyi7xUqv

[eliotmcintire]

This will change the estimated biomass upwards in the pixels that are "in fires", i.e., in updateYoungBiomasses. This change makes this part of the spinUp match what Biomass_core does with initialBiomass