Issues

SOLVED

MAJOR ISSUE: vegetation runs full of labile carbon

The burning of excess labile carbon and reserve carbon is not like in OCN. The increase in autotrophic respiration when labile carbon stocks get unrealistic high is deactivated by DOFOCO team. When using nutrient this is not acceptable, as vegetation runs full of sugar under nutrient stress on allocation.

MAJOR ISSUE: the soil and litter CN ratios for spinup_analytic

The running averages of the stoichiometry of the respective pools are reset every spinup cycle to zero. Therefore, the running averages are always too small. According to NV, this doesn't happen in his setup. I modified the calculation and ensured that the variables are written out in the restart file in a clean way. The modifications should ensure that the running averages work for all setups.

UNRESOLVED

Reading in N inputs

The variables storing the N inputs in the restart file are all undef. Not quite sure why. I set them all to zero.

Soil type inconsistency in ORCHIDEE-CN-P

The phosphorus model needs soil type specific parameters. Therefore, a new input routine is going to be written which reads in USDA soil orders. According to the soil order the parameter values are set for each grid box.

The problem is that ORCHIDEE already reads in fields of soil texture classes which were originally derived from soil orders. According to the soil texture classes, parameter related to soil hydrology are set. As the original data cannot be found anymore, ORCHIDEE will run with two independent sets of soil order specific parameters. Thereby inconsistencies between the phosphorus related parameters and the the hydrology related parameters can be introduced. The practice of reading in soil texture classes instead of soil orders is also problematic in respect of future developments and I suggest to change that.

Stoichiometric flexibility

Meyerholdt & Zaehle (2015) showed that model predictions best matched available data when the C:N ratios in all ecosystem pools except the wood pool were treated as flexible. Thus, we should make the CNP ratio of wood fixed.

Effect of nutrient stress on root/leaf ratio

The effect of long-term nitrogen stress on the ratio between roots and leaves of O-CN is commented out in the ORCHIDEE-CN. We should reintroduce the effect of nutrient stress on that ratio. This task is hampered by my difficulties to understand how water stress is affecting the ratio in DOFOCO vs ORCHIDEE-CN.

Endless accumualtion of heartwood

I experience that the heartwood pool is still accumulating biomass after 500 yr of simulation. This could be due to the parameter for turnover of sapwood which was changed from 730 days (trunk) to 11680 days (can) or as we use only one size class of trees (ncirc_class=1).