Subversion Repositories public iLand

#ifndef SNAG_H

#define SNAG_H

#include <QList>

#include <QVariant>

class Tree; // forward

class ResourceUnit; // forward

/** CNPool stores a duple of carbon and nitrogen (kg/ha)

    use addBiomass(biomass, cnratio) to add biomass; use operators (+, +=, *, *=) for simple operations.

*/

struct CNPool

{

    CNPool(): C(0.), N(0.) {}

    static void setCFraction(const double fraction) { biomassCFraction = fraction; } ///< set the global fraction of carbon of biomass

    CNPool(const double c, const double n) {C=c; N=n; }

    bool isEmpty() const { return C==0.; } ///< returns true if pool is empty

    double C; // carbon pool (kg C/ha)

    double N; // nitrogen pool (kg N/ha)

    double CN() { return N>0?C/N:0.; } ///< current CN ratio

    void clear() {C=0.; N=0.; }

    /// add biomass to the pool (kg dry mass/ha); CNratio is used to calculate the N-Content, the global C-Fraction of biomass is used to

    /// calculate the amount of carbon of 'biomass'.

    void addBiomass(const double biomass, const double CNratio) { C+=biomass*biomassCFraction; N+=biomass*biomassCFraction/CNratio; }

    // some simple operators

    void operator+=(const CNPool &s) { C+=s.C; N+=s.N; } ///< add contents of a pool

    void operator*=(const double factor) { C*=factor; N*=factor; } ///< Multiply pool with 'factor'

    const CNPool operator+(const CNPool &p2) const { return CNPool(C+p2.C, N+p2.N); } ///< return the sum of two pools

    const CNPool operator*(const double factor) const { return CNPool(C*factor, N*factor); } ///< return the pool multiplied with 'factor'

private:

    static double biomassCFraction;

};

class Snag

{

public:

    Snag();

    void setup( const ResourceUnit *ru); ///< initial setup routine.

    void newYear(); ///< to be executed at the beginning of a simulation year. This cleans up the transfer pools.

    void processYear(); ///< to be called at the end of the year (after tree growth, harvesting). Calculates flow to the soil.

    // access

    bool isStateEmpty() const { return mTotalSnagCarbon == 0.; }

    bool isEmpty() const { return mLabileFlux.isEmpty() && mRefractoryFlux.isEmpty() && isStateEmpty(); }

    CNPool fluxToSoil() const { return mLabileFlux + mRefractoryFlux; }

    // actions

    /// add for a tree with diameter

    void addTurnoverLitter(const Tree *tree, const double litter_foliage, const double litter_fineroot);

    /// adds the 'tree' to the appropriate Snag pools.

    void addMortality(const Tree* tree);

    /// add residual biomass of 'tree' after harvesting.

    /// remove_(stem, branch, foliage)_pct: percentage of biomass compartment that is removed by the harvest operation.

    /// the harvested biomass is collected.

    void addHarvest(const Tree* tree, const double remove_stem_pct, const double remove_branch_pct, const double remove_foliage_pct );

    QList<QVariant> debugList(); ///< return a debug output

private:

    double calculateClimateFactors(); ///< calculate climate factor 're' for the current year

    double mClimateFactor; ///< current mean climate factor (influenced by temperature and soil water content)

    const ResourceUnit *mRU; ///< link to resource unit

    /// access SWDPool as function of diameter (cm)

    int poolIndex(const float dbh) { if (dbh<mDBHLower) return 0; if (dbh>mDBHHigher) return 2; return 1;}

    CNPool mSWD[3]; ///< standing woody debris pool (0: smallest dimater class, e.g. <10cm, 1: medium, 2: largest class (e.g. >30cm)) kg/ha

    double mNumberOfSnags[3]; ///< number of snags in diameter class

    double mTimeSinceDeath[3]; ///< time since death: mass-weighted age of the content of the snag pool

    CNPool mToSWD[3]; ///< transfer pool; input of the year is collected here (by size class)

    CNPool mLabileFlux; ///< flux to labile soil pools (kg/ha)

    CNPool mRefractoryFlux; ///< flux to teh refractory soil pool (kg/ha)

    CNPool mBranches[5]; ///< pool for branch biomass

    int mBranchCounter; ///< index which of the branch pools should be emptied

    double mTotalSnagCarbon; ///< sum of carbon content in all snag compartments (kg/ha)

    CNPool mTotalIn; ///< total input to the snag state (i.e. mortality/harvest and litter)

    CNPool mSWDtoSoil; ///< total flux from standing dead wood -> soil (kg/ha)

    CNPool mTotalToAtm; ///< flux to atmosphere (kg/ha)

    CNPool mTotalToExtern; ///< total flux of masses removed from the site (i.e. harvesting) kg/ha

    static double mDBHLower, mDBHHigher; ///< thresholds used to classify to SWD-Pools

};

#endif // SNAG_H