SIP256 Leaf on/off events

[Alomir]

Summary

• What: Add leaf-on/leaf-off events
• Motivation: Needed by PEcAn

How was this change tested?

List steps taken to test this change, with appropriate outputs if applicable

If changes are needed for any sipnet.out files in the test/smoke subdirectories, then include output from
tools/smoke_check.py by running the commands below and pasting the output at the end of this PR. Note that
this must be run BEFORE submitting changes to any sipnet.out files.

make smoke
python tools/smoke_check.py run verbose <list tests/smoke subdirectories with changed outputs>

Run python tools/smoke_check.py help for more info.

TBD

Related issues

• Fixes Allow leaf on/leaf off to be specified as actual events #256

Checklist

• Related issues are listed above. PRs without an approved, related issue may not get reviewed.
• PR title has the issue number in it ("[#] <concise description of proposed change>")
• Tests added/updated for new features (if applicable)
• Documentation updated (if applicable)
• docs/CHANGELOG.md updated with noteworthy changes
• Code formatted with clang-format (run git clang-format if needed)

---

Note: See CONTRIBUTING.md for additional guidance. This repository uses automated formatting checks; if the pre-commit hook blocks your commit, run git clang-format to format staged changes.

[github-actions]

Cpp-Linter Report ⚠️

Some files did not pass the configured checks!

clang-format (v19.1.1) reports: 4 file(s) not formatted

• src/sipnet/events.c
• src/sipnet/sipnet.c
• tests/sipnet/test_events_types/testEventLeafOnOff.c
• tests/sipnet/test_modeling/testBalance.c

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[Alomir]

@copilot Please update unit tests for these changes by:

1. Update tests/sipnet/test_modeling.c to include the relevant changes
2. Create a new test in tests/sipnet/test_event_types/testEventLeafOnOff.c in the style of the other tests in that directory

[Copilot]

@copilot Please update unit tests for these changes by:

1. Update tests/sipnet/test_modeling.c to include the relevant changes
   ...

Done in commit 73a7611. Here's what was added:

1. tests/sipnet/test_events_types/testEventLeafOnOff.c — tests 5 scenarios: one leaf-on event, two leaf-on events, one leaf-off event (no N cycle), one leaf-off event (with N cycle, verifying N goes to litter), and one leaf-off event without litter pool (verifying C goes to soilC). New event input files events_one_leafon.in, events_two_leafon.in, events_one_leafoff.in, events_two_leafoff.in were also added.

2. tests/sipnet/test_modeling/testBalance.c — added testBalanceLeafEvents() which runs the model with event-based leaf-on (day 46) and leaf-off (day 50) and verifies carbon/nitrogen balance is maintained at each time step.

Three bugs were also fixed in the process:

• resetFluxes() was inside calculateFluxes() which zeroed event fluxes before pool updates — moved to updateState() before processEvents()
• LEAFON/LEAFOFF param parsing used numRead != 0 which incorrectly triggered an error on empty strings (sscanf returns EOF=-1, not 0, for empty input) — changed to numRead > 0
• LEAFOFF event used plantWoodC instead of plantLeafC to compute how much leaf C falls