Subversion Repositories public iLand

/********************************************************************************************

**    iLand - an individual based forest landscape and disturbance model

**    http://iland.boku.ac.at

**    Copyright (C) 2009-  Werner Rammer, Rupert Seidl

**

**    This program is free software: you can redistribute it and/or modify

**    it under the terms of the GNU General Public License as published by

**    the Free Software Foundation, either version 3 of the License, or

**    (at your option) any later version.

**

**    This program is distributed in the hope that it will be useful,

**    but WITHOUT ANY WARRANTY; without even the implied warranty of

**    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

**    GNU General Public License for more details.

**

**    You should have received a copy of the GNU General Public License

**    along with this program.  If not, see <http://www.gnu.org/licenses/>.

********************************************************************************************/

#include "global.h"

#include "production3pg.h"

#include "resourceunit.h"

#include "species.h"

#include "speciesresponse.h"

#include "model.h"

Production3PG::Production3PG()

{

    mResponse=0;

    mEnvYear = 0.;

}

/**

  This is based on the utilizable photosynthetic active radiation.

  @sa http://iland.boku.ac.at/primary+production

  The resulting radiation is MJ/m2       */

inline double Production3PG::calculateUtilizablePAR(const int month) const

{

    // calculate the available radiation. This is done at SpeciesResponse-Level (SpeciesResponse::calculate())

    // see Equation (3)

    // multiplicative approach: responses are averaged one by one and multiplied on a monthly basis

//    double response = mResponse->absorbedRadiation()[month] *

//                      mResponse->vpdResponse()[month] *

//                      mResponse->soilWaterResponse()[month] *

//                      mResponse->tempResponse()[month];

    // minimum approach: for each day the minimum aof vpd, temp, soilwater is calculated, then averaged for each month

    //double response = mResponse->absorbedRadiation()[month] *

    //                  mResponse->minimumResponses()[month];

    double response = mResponse->utilizableRadiation()[month];

    return response;

}

/** calculate the alphac (=photosynthetic efficiency) for the given month.

   this is based on a global efficiency, and modified per species.

   epsilon is in gC/MJ Radiation

  */

inline double Production3PG::calculateEpsilon(const int month) const

{

    double epsilon = Model::settings().epsilon; // maximum radiation use efficiency

    epsilon *= mResponse->nitrogenResponse() *

               mResponse->co2Response()[month];

    return epsilon;

}

inline double Production3PG::abovegroundFraction() const

{

    double utilized_frac = 1.;

    if (Model::settings().usePARFractionBelowGroundAllocation) {

        // the Landsberg & Waring formulation takes into account the fraction of utilizeable to total radiation (but more complicated)

        // we originally used only nitrogen and added the U_utilized/U_radiation

        utilized_frac = mResponse->totalUtilizeableRadiation() / mResponse->yearlyRadiation();

    }

    double harsh =  1 - 0.8/(1 + 2.5 * mResponse->nitrogenResponse() * utilized_frac);

    return harsh;

}

void Production3PG::clear()

{

    for (int i=0;i<12;i++) {

        mGPP[i] = 0.; mUPAR[i]=0.;

    }

    mEnvYear = 0.;

}

/** calculate the stand-level NPP

  @ingroup core

  Standlevel (i.e ResourceUnit-level) production (NPP) following the 3PG approach from Landsberg and Waring.

  @sa http://iland.boku.ac.at/primary+production */

double Production3PG::calculate()

{

    Q_ASSERT(mResponse!=0);

    // Radiation: sum over all days of each month with foliage

    double year_raw_gpp = 0.;

    clear();

    double utilizable_rad, epsilon;

    // conversion from gC to kg Biomass: C/Biomass=0.5

    const double gC_to_kg_biomass = 1. / (biomassCFraction * 1000.);

    for (int i=0;i<12;i++) {

        utilizable_rad = calculateUtilizablePAR(i); // utilizable radiation of the month ... (MJ/m2)

        epsilon = calculateEpsilon(i); // ... photosynthetic efficiency ... (gC/MJ)

        mUPAR[i] = utilizable_rad ;

        mGPP[i] =utilizable_rad * epsilon * gC_to_kg_biomass; // ... results in GPP of the month kg Biomass/m2 (converted from gC/m2)

        year_raw_gpp += mGPP[i]; // kg Biomass/m2

    }

    // calculate f_env,yr: see http://iland.boku.ac.at/sapling+growth+and+competition

    double f_sum = 0.;

    for (int i=0;i<12;i++)

        f_sum += mGPP[i] / gC_to_kg_biomass; // == uAPar * epsilon_eff

    //  the factor f_ref: parameter that scales response values to the range 0..1 (1 for best growth conditions) (species parameter)

    const double perf_factor = mResponse->species()->saplingGrowthParameters().referenceRatio;

    // f_env,yr=(uapar*epsilon_eff) / (APAR * epsilon_0 * fref)

    mEnvYear = f_sum / (Model::settings().epsilon * mResponse->yearlyRadiation() * perf_factor);

    if (mEnvYear > 1.) {

        if (mEnvYear>1.5) // warning for large deviations

            qDebug() << "WARNING: fEnvYear > 1 for " << mResponse->species()->id() << mEnvYear << "f_sum, epsilon, yearlyRad, refRatio" <<  f_sum << Model::settings().epsilon <<  mResponse->yearlyRadiation() << perf_factor

                     << "check calibration of the sapReferenceRatio (fref) for this species!";

        mEnvYear = 1.;

    }

    // calculate fraction for belowground biomass

    mRootFraction = 1. - abovegroundFraction();

    // global value set?

    double dbg = GlobalSettings::instance()->settings().paramValue("gpp_per_year",0);

    if (dbg) {

        year_raw_gpp = dbg;

        mRootFraction = 0.4;

    }

    // year GPP/rad: kg Biomass/m2

    mGPPperArea = year_raw_gpp;

    return mGPPperArea; // yearly GPP in kg Biomass/m2

}