Changes between Version 20 and Version 21 of DevelopmentActivities/ORCHIDEE-CNP/issues


Ignore:
Timestamp:
2016-08-28T09:32:35+02:00 (8 years ago)
Author:
dgoll
Comment:

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  • DevelopmentActivities/ORCHIDEE-CNP/issues

    v20 v21  
    77The 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 in general problematic. The ORCHIDEE project members are informed but they seem not to care about this.  
    88 
    9 === FUNDAMENTAL ISSUE: Stoichiometric flexibility === 
     9=== FUNDAMENTAL ISSUE?: Stoichiometric flexibility === 
    1010Meyerholdt & 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. However, there is substantial variation in wood nutrient content found along a gradient of soil fertility (Heineman et al., 2016) and the wood N and P concentration correlates with leaf N and P concentration. 
    1111 
    12 Due to this contrasting findngs, I am not sure if we should change the approach of OCN in which cahnges in wood stoichiometry follows leaf stoichiometry. 
     12Due to this contrasting findings, I am not sure if we should change the approach of OCN in which cahnges in wood stoichiometry follows leaf stoichiometry. 
    1313One could argue that changes in stoichiometry due to changing environmental conditions are too fast/strong, but overall the flexibility in stoichiometry is rather narrow. Here more mechanistic based approaches to stoichiometry are needed. This would require a more sensible vegetation/ cost optimization/ etc approaches which are time-consuming to implement/develope. 
    1414 
    15 === ISSUE: mineral N dynamics === 
    16 The mineral N is not leaky enough. Unrealistically high amounts of mineral N can accumulate in the model. 
    17 Issues are partly identified but not yet solved: The implementation of OCN into ORCHIDEE-CN is based on Zaehle & Friend (2010) and does not include the improvements by Zaehle et al (2011). In addition, it is not clear in the code which parts were changed by NV. It should be made sure that the mineral N dynamics follow Zaehle et al. (2011). 
    1815 
    1916 
    20 === ISSUE: vegetation carbon === 
    21 We have unrealistically high vegetation carbon stocks (up to two orders of magnitude). 
    22 The issue is due to the ORCHIDEE-CAN parameter values of the allocation. 
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