Opened 4 years ago

Closed 3 years ago

#413 closed defect (fixed)

Make stomate_prescribe more robust

Reported by: luyssaert Owned by: luyssaert
Priority: major Milestone: IPSLCM6.v2
Component: Biogeochemical processes Version:
Keywords: Cc:

Description

In stomate_prescribe part of the FM code was retained but unnecessarily complex given some more recent changes. An error was made in fitting the self-thinning parameters. When using the new self-thinning parameters it took several decades to reach self-thinning. During those decades the number of individuals remained too high for too long resulting in too little diameter growth.

Change History (2)

comment:1 Changed 4 years ago by luyssaert

  • Owner changed from somebody to luyssaert
  • Status changed from new to assigned

(1) The prescribed number of individuals is no longer used. When establishing a new stand, the number of individuals is calculated from the self-thinning relationship. That way self-thinning starts from day one.

(2) Some of the ORCHIDEE-FM initialization was removed and replaced by a much more simple approach making use of circ_class_dist (that was already used in mortality).

(3) The code still needs some cleaning (nmaxtrees will need to be removed from src_parameters, the comments need to be checked)

(4) Before cleaning, the code needs to be tested more extensively.


comment:2 Changed 3 years ago by luyssaert

  • Resolution set to fixed
  • Status changed from assigned to closed

The following changes were committed in r4815

Point (1) did not work because the self-thinning relationships go to infinity for small trees. If we establish a stand with trees of less than 2 m tall, we get millions of them and it takes decades befor the stand start looking realistic -> conclusion: mortality in very young stands is NOT driven by self-thinng. The old approach with background mortality was retained.

Point (2). OK.

Point (3). stomate_prescribe.f90 and related routines was cleaned and the documentation checked.

Point (4). Quite some testing was done. The small change in the way the circ classes are initialized had considerable effects on for example tree ring width and the difference between the circ classes.

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