Fixes: growth and allometry

[rgknox]

Description:

This PR adds two bug fixes. Bug 1: During plant growth, there is a routine that re-calculates plant diameter in cases where either integration errors or fusion has generated structural biomass that is off-allometry with diameter. After correcting diameter, we were not updating the allometric targets, now we do. Bug 2: In sapwood allometric calculations, the derivative of the sapwood biomass was not being calculated in cases where sapwood was being capped to not exceed structural biomass (ie very small plants).

Collaborators:

@ckoven provided discussion and testing

Expectation of Answer Changes:

This may change answers slightly for very large trees and possibly for very small plants.

Checklist:

• My change requires a change to the documentation.
• I have updated the in-code documentation AND wiki accordingly.
• I have read the CONTRIBUTING document.
• FATES PASS/FAIL regression tests were run
• If answers were expected to change, evaluation was performed and provided

Test Results:

HLM test hash-tag:

19f887d

Test Output:

fates test suite, All PASS

[ckoven]

Chatted about this with @rgknox. It all makes sense to me. Also I've been using this code for ensemble runs that went out successfully for 400 years (when it was dying at year 125 before).

[jenniferholm]

@rgknox - nice job catching these bugs. Regarding the bug #1, now that the allometry targets are updated (after corrected plant diameter), do you think this will have a big effect on reducing the diameter of very large trees? Or only a minimal effect since it sounds like it is only for plants in integration errors or fusion?
I'm asking this because I'm wondering if I should re-run my Manaus simulations after these bug fixes. With the latest code I'm still seeing the resurgence of dominance of really big trees. (But I have also been testing with different canopy spreads and carbon allocation and mortality of large trees, which is helping to reduce the large trees).

[rgknox]

Hi @jenniferholm ,

Its hard to say but I don't expect much difference in results. The benefits will mostly be towards integration stability. Like you said, the differences are going to be on the scale of the integration errors and fusion errors and those aren't very high.
I would not recommend re-running your simulations.

[jenniferholm]

@rgknox - Ok, sounds good! Thanks