Changes between Version 62 and Version 63 of Documentation/TrunkFunctionality4


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Timestamp:
2020-10-23T20:05:39+02:00 (4 years ago)
Author:
luyssaert
Comment:

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  • Documentation/TrunkFunctionality4

    v62 v63  
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    170171=== Forced clear cut === 
    171172Describes r6614. '''FORCED_CLEAR_CUT''' is a flag used to force ORCHIDEE trunk to clearcut a forest after one year of simulation. This flag is set to TRUE in order to start a new stand at the beginning of the FIN step in ENSEMBLE runs. It helps us to control the stand age at the end of the HIST step. If you want to use this flag for other purposes, do not forget that a clearcut means that the majority of the living biomass is removed (circ_class_biomass for sapwood and heartwood), but the other pools are transferred in the litter pool (leaf, branches, fruit, fine root). Note that if '''FORCED_CLEAR_CUT''' is used, the model will clearcut at the end of every year in that run. The typical set-up should be: 300 years of spin-up with '''FORCED_CLEAR_CUT''' set to FALSE, 1 year with '''FORCED_CLEAR_CUT''' set to TRUE, a simulation with the length similar to the age of the forest with '''FORCED_CLEAR_CUT''' set to FALSE.  
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    230230=== Leaf longevity and turnover === 
    231231Describes r6908. '''Longevity_leaf''' is a prescribed parameter for the longevity of a typical leaf/needle at the average temperature for that PFT. For PFTs where a large range in longevity has been observed, this is accounted for in the calculation of '''leaf_age_crit'''. Leaf_age_crit is thus the location-specific longevity. It the age of a leaf/needle exceeds half the value for crit_leaf_age, leaf, root and sapwood turnover will start. Because of the way leaf_age_crit is calculated the simulated longevity differs from the prescribed longevity. For example, longevity_leaf = 220, leaf_age_crit = 165 at 25C, 220 at 15C and 330 at 5C. Note that turnover starts when leaf age is half this value. Thus at 110 days in the temperate zone which is within the observations. 
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    238 === Leaf and roots === 
     238=== Allocation and plant hydraulic architecture === 
     239When tuning allocation to match observed wood or root masses productivity or their stocks, it may be necessary to change '''longevity_sap''' and '''longevity_root'''. Note that this will affect the ratio between leaf and root mass because Mr = Ml / LF where LF = c0_alloc * KF and c0_alloc = sqrt(k_belowground(pft)/k_sap(pft)*longevity_sap/longevity_root*sapwood_density). Likewise when tuning the hydraulic architecture to match observed transpiration, c0_alloc will change and so will allocation. Note that in c0_alloc '''k_belowground''' is used whereas the calculation of hydraulic architecture uses '''k_root'''. The difference is explained in the code. 
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