Changes between Version 70 and Version 71 of Documentation/TrunkFunctionality4


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Timestamp:
11/01/20 17:53:01 (20 months ago)
Author:
luyssaert
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  • Documentation/TrunkFunctionality4

    v70 v71  
    329329From a conceptual point of view, ORCHIDEE trunk is all about vegetation dynamics and thus instabilities in the vegetation cover. In ORCHIDEE trunk there are two processes that can deal with dying PFTs including evergreens PFTs. First, ok_recruitment could used. If ok_recruitment = .TRUE. a decrease in the canopy cover will result in more light reaching the forest floor which in turn should trigger recruitment of -for the moment- the same PFT. Generations (cohorts) can take over from each other without loosing the canopy cover entirely. Second, if there are insufficient reserves to grow leaves, there will be no or insufficient gpp, the carbon reserves will be consumed by respiration processes, the plants will be killed, the biomass transferred to the litter pools and the same or another PFT (see section on species change) will be replanted. ORCHIDEE trunk was developed to work with always_init = .FALSE. so this has become the default value, contrary to previous versions of the trunk where always_init = .TRUE. is the default. 
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    331 Temperature is a very consistent climatological variable in the sense that each year the summer is warmer than the winter (even in so-called cold years). This implies that temperature driven phenology is very robust in the sense that the PFT will develop a canopy each year. Soil moisture, however, is much less predictable and in very dry or very yet years the seasonal patterns may differ a lot. Especially when soil moisture criteria are combined with other criteria (pheno model: moigdd) there are years that the criteria are never met and that the PFT never develops leaves. This is not at all observed. Even farmers would plant crops when the conditions are far from optimal (typically because they have to plant the crops before they know that the conditions will be far from optimal). If set the yes, the flag'''ok_force_pheno''' will start the growth of a canopy a predefined number of days (force_pheno_mtc) after the average budbreak data for that PFT at that location. Test simulations over the Americas showed that over a 30 year period forced phenology was used 5 to 10% of the years between 1901 and 1930 for PFT10, 12 and 13. This flag did little or nothing to the phenology of the other PFTs with the pheno model moigdd.      
     331Temperature is a very consistent climatological variable in the sense that each year the summer is warmer than the winter (even in so-called cold years). This implies that temperature driven phenology is very robust in the sense that the PFT will develop a canopy each year. Soil moisture, however, is much less predictable and in very dry or very yet years the seasonal patterns may differ a lot. Especially when soil moisture criteria are combined with other criteria (pheno model: moigdd) there are years that the criteria are never met and that the PFT never develops leaves. This is not at all observed. Even farmers would plant crops when the conditions are far from optimal (typically because they have to plant the crops before they know that the conditions will be far from optimal). If set the yes, the flag'''ok_force_pheno''' will start the growth of a canopy a predefined number of days (force_pheno_mtc) after the average budbreak data for that PFT at that location. Test simulations over the Americas showed that over a 30 year period forced phenology was used 5 to 10% of the years between 1901 and 1930 for PFT10, 12 and 13. This flag did little or nothing to the phenology of the other PFTs with the pheno model moigdd. The variable qc_pheno_event registers if budbreak happened during the year. The variable qc_forced_pheno_event registers if the phenology event had to be forced rather then being simulated as a function of the climatological variables. The ratio of these output variables can be used to plot in which regions and years phenology had to be forced. Not surprisingly it is most used in dry regions of the PFT distribution. 
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