ecearth3/sources/lpjg/modules/landcover.cpp

///////////////////////////////////////////////////////////////////////////////////////
/// \file landcover.cpp
/// \brief Functions handling landcover aspects, such as creating or resizing Stands
///
/// Landcover change.
///
/// \author Mats Lindeskog,
/// \Part of code in this file as well as in cropphenology.cpp, cropallocation.cpp and
/// \management.cpp based on LPJ-mL C++ code received from Alberte Bondeau in 2008.
/// $Date$
///
///////////////////////////////////////////////////////////////////////////////////////

#include "config.h"
#include "landcover.h"
#include "guessmath.h"

#define CHECK_NLIM -13
//#define CHECK_NLIM -8
//#define CHECK_NLIM -5

// prevent a check error to terminate the run, this should only be used in a test run.
#define FAIL dprintf
//#define FAIL fail


/// Query whether a date is within a period spanned by two dates.
bool dayinperiod(int day, int start, int end) {

	bool acrossnewyear = false;

	if(day < 0 || start < 0 || end < 0)	// a negative value should not be a valid day
		return false;

	if(start > end)
		acrossnewyear = true;

	if(day >= start && day <= end && !acrossnewyear || (day >= start || day <= end) && acrossnewyear)
		return true;
	else
		return false;
}

/// Step n days from a date.
/** Local proxy to the Date class function in order to simplify call syntax
	from the modules that #includes landcover.h anyway.
  */
int stepfromdate(int day, int step) {

	return Date::stepfromdate(day, step);

}

/// Help function to access two-dimentional arrays that have been created dynamically
int index(int from, int to, int ncols = nst) {

	return from * ncols + to;
}


/// Initial creation of stands when run_landcover==true based on gridcell stand type area fractions.
void landcover_init(Gridcell& gridcell, InputModule* input_module) {

	// Set CFT-specific members of gridcellpft:
	for(unsigned int p = 0; p < gridcell.pft.nobj; p++) {
		Gridcellpft& gcpft = gridcell.pft[p];

		if (gridcell.get_lat() >= 0.0) {
			gcpft.sdate_default = gcpft.pft.sdatenh;
			gcpft.hlimitdate_default = gcpft.pft.hlimitdatenh;
		}
		else {
			gcpft.sdate_default = gcpft.pft.sdatesh;
			gcpft.hlimitdate_default = gcpft.pft.hlimitdatesh;
		}
	}

	// get landcover and crop area fractions from landcover input file(s) or ins-file.
	input_module->getlandcover(gridcell);

	stlist.firstobj();
	while (stlist.isobj) {
		StandType& st = stlist.getobj();
		Gridcellst& gcst = gridcell.st[st.id];

		gcst.frac_old = gcst.frac;

		if(gcst.frac > 0.0) {
			gridcell.create_stand_lu(st, gcst.frac);
		}

		stlist.nextobj();
	}
}

enum {SECONDARY_MATURE, SECONDARY_YOUNG, PRIMARY, NFORESTCLASSES};

/// identifies which stands to reduce in area and sets standtype.nstands
/** Updates frac, frac_change, frac_old and gross_frac_decrease for reduced stands
 *  Updates frac_old and frac_temp for all stands
 *
 *  INTPUT PARAMETERS
 *
 *  \param st_frac_transfer				array with this year's transferred area fractions between the different stand types
 */
void reduce_stands(Gridcell& gridcell, double* st_frac_transfer, forest_st_frac_transfer& forest_st_frac_transfer_s) {

	for(unsigned int i = 0; i < gridcell.st.nobj; i++) {
		Gridcellst& gcst = gridcell.st[i];
		gcst.nstands = 0;
	}

	for(unsigned int i = 0; i < gridcell.nbr_stands(); i++) {
		Stand& stand = gridcell[i];

		stand.frac_old = stand.get_gridcell_fraction();
		stand.frac_temp = stand.frac_old;
		stand.frac_change = 0.0;
		stand.gross_frac_increase = 0.0;
		stand.gross_frac_decrease = 0.0;
		stand.cloned_fraction = 0.0;
		if(stand.transfer_area_st) {
			for(int i=0;i<nst;i++)
				stand.transfer_area_st[i] = 0.0;
		}
		gridcell.st[stand.stid].nstands++;
	}


	for(int from=0; from<nst; from++) {

		StandType& st = stlist[from];
		Gridcellst& gcst = gridcell.st[from];

		if(gcst.gross_frac_decrease > 0.0) {

			if(gcst.nstands > 1) {

/*			Rules for selecting stands:

			natural to cropland: young_stands_first=true
			ifprimary_lc_transfer:
				secondary mature lap: young_stands_first=true, secondary_harvest=true						(will use young -> old secondary stands over age limit)
					restart: young_stands_first=false, secondary_harvest=false, ignore age_limit_reduce		(will use primary stand before age-limited stands)
				(secondary young lap): young_stands_first=true, secondary_harvest=true						(will use young -> old secondary stands over age limit)
					restart: young_stands_first=true, secondary_harvest=false, ignore age_limit_reduce		(will use primary stand before age-limited stands)
				primary lap: young_stands_first=false, secondary_harvest=false								(will use old -> young secondary stands if no more primary stand)
					restart: young_stands_first=false, secondary_harvest=false, ignore age_limit_reduce		(will use age-limited stands)

			natural to natural: young_stands_first=false
			ifprimary_lc_transfer:
				secondary mature lap: young_stands_first=false, secondary_harvest=true						(will use old -> young secondary stands over age limit)
					restart: young_stands_first=false, secondary_harvest=false, ignore age_limit_reduce		(will use primary stand before age-limited stands)
				secondary young lap: young_stands_first=true, secondary_harvest=true						(will use young -> old secondary stands over age limit)
					restart: young_stands_first=true, secondary_harvest=false, ignore age_limit_reduce		(will use age-limited stands before primary stand)
				primary lap: young_stands_first=false, secondary_harvest=false								(will use old -> young secondary stands if no more primary stand)
					restart: young_stands_first=false, secondary_harvest=false, ignore age_limit_reduce		(will use age-limited stands)
*/
				int nlaps = 1;
				if(use_primary_lc_transfer)
					nlaps = NFORESTCLASSES;

				for(int n=0; n<nlaps; n++) {

					for(int to=0; to<nst; to++) {

						if(st_frac_transfer[index(from, to)] > 0.0) {

							double st_change_remain = -st_frac_transfer[index(from, to)];

							bool secondary_harvest = false;
							bool young_stands_first = true;	//convert area from youngest stands first

							if(st.landcover == NATURAL || st.landcover == FOREST) {

								if(stlist[to].landcover == NATURAL || stlist[to].landcover == FOREST)
									young_stands_first = false;
								else
									young_stands_first = true;
							}

							if(use_primary_lc_transfer) {
								if(n == SECONDARY_MATURE) {
									// First reduce secondary (mature) stands (fraction not in primary_st_frac_transfer array + secondary_young_st_frac_transfer[index(from, to))
									st_change_remain += forest_st_frac_transfer_s.primary[index(from, to)] + forest_st_frac_transfer_s.secondary_young[index(from, to)];
									secondary_harvest = true;
								} else if(n == SECONDARY_YOUNG) {
									// Then reduce young secondary stands
									st_change_remain = -forest_st_frac_transfer_s.secondary_young[index(from, to)];
									young_stands_first = true;
									secondary_harvest = true;
								}
								else if(n == PRIMARY) {
									// Finally, reduce primary stands (fraction in primary_st_frac_transfer array)
									st_change_remain = -forest_st_frac_transfer_s.primary[index(from, to)];
									young_stands_first = false;
								}
							}

							bool restart = false;

							while(st_change_remain < 0.0) {

								int count_st = 0;

								for(unsigned int i = 0; i < gridcell.size(); i++) {
									int index;

									double stands_frac_sum = 0.0;

									for(unsigned int j = 0; j < gridcell.nbr_stands(); j++) {
										Stand& stand = gridcell[j];

										if(stand.stid == st.id)
											stands_frac_sum += stand.get_gridcell_fraction();
									}

									if(st_change_remain > -INPUT_RESOLUTION * 0.1 || stands_frac_sum == 0.0) {
										if(st_change_remain <= -INPUT_RESOLUTION && stands_frac_sum == 0.0)
											dprintf("\nWarning: no more stand area left of stand type %d ! Residual reduction demand %.15f ignored.\n", st.id, -st_change_remain);
										st_change_remain = 0.0;
										break;
									}

									if(young_stands_first)
										index = (int) gridcell.size() - 1 - i;
									else
										index = i;

									Stand& stand = gridcell[index];

									if(stand.stid == st.id) {
										count_st++;
										int first_year = max(stand.first_year, stand.clone_year);

										if(secondary_harvest && first_year == 0)
											continue;

										// Don't reduce stands younger than the age limit, unless this is the last stand in the loop or the initial stand has been killed
										if(date.year - first_year < age_limit_reduce && !reduce_all_stands && !restart) 
											continue;
							
										// convert equal percentage of areas from all stands
										if(reduce_all_stands) {
											stand.frac_change += st_change_remain * stand.get_gridcell_fraction() / gcst.frac;
											stand.gross_frac_decrease -= st_change_remain * stand.get_gridcell_fraction() / gcst.frac;
											stand.transfer_area_st[to] = -st_change_remain * stand.get_gridcell_fraction() / gcst.frac;
											stand.set_gridcell_fraction(stand.get_gridcell_fraction() + st_change_remain * stand.get_gridcell_fraction() / gcst.frac);
										}
										else {
											if(stand.get_gridcell_fraction() > 0.0) {

												//all natural landcover decrease is taken from this stand
												if(stand.get_gridcell_fraction() >= -st_change_remain) {
													stand.frac_change += st_change_remain;
													stand.gross_frac_decrease -= st_change_remain;
													stand.transfer_area_st[to] -= st_change_remain;
													stand.set_gridcell_fraction(stand.get_gridcell_fraction() + st_change_remain);

													if(stand.get_gridcell_fraction() < INPUT_RESOLUTION * 0.1) {
														gridcell.landcover.acflux_landuse_change += stand.ccont() * stand.get_gridcell_fraction();
														gridcell.landcover.anflux_landuse_change += stand.ncont() * stand.get_gridcell_fraction();
														stand.set_gridcell_fraction(0.0);
													}

													st_change_remain = 0.0;
													break;
												}
												//more stands will have to be reduced
												else {
													stand.frac_change -= stand.get_gridcell_fraction();
													stand.gross_frac_decrease += stand.get_gridcell_fraction();
													stand.transfer_area_st[to] += stand.get_gridcell_fraction();
													st_change_remain += stand.get_gridcell_fraction();
													stand.set_gridcell_fraction(0.0);	//will be killed below
												}
											}
										}
									}
								}

								// Restart loop and reduce oldest stand first if the rules above precluded reduction of the required area.
								if(st_change_remain < 0.0) {
									if(reduce_all_stands) {
										st_change_remain = 0.0;
									}
									else {
										if(n != SECONDARY_YOUNG)
											young_stands_first = false;
										secondary_harvest = false;
										restart = true;
									}
								}
							}
						}
					}
				}
			}
			else if(gcst.nstands == 1 ) {

				for(unsigned int i = 0; i < gridcell.size(); i++) {

					Stand& stand = gridcell[i];

					if(stand.stid == gcst.id) {

						bool expand_to_new_stand = gridcell.landcover.expand_to_new_stand[stand.landcover];
						if(gcst.gross_frac_decrease > stand.get_gridcell_fraction()) {

							if((gcst.gross_frac_decrease - stand.get_gridcell_fraction() > INPUT_RESOLUTION))
								dprintf("\nYear %d: Warning. no more stand area left of stand type %d ! Residual reduction demand %.15f ignored.\n", date.year, stand.stid, gcst.gross_frac_decrease - stand.get_gridcell_fraction());
							gcst.gross_frac_decrease = stand.get_gridcell_fraction();
						}
						stand.frac_change = -gcst.gross_frac_decrease;
						stand.gross_frac_decrease = gcst.gross_frac_decrease;
						stand.set_gridcell_fraction(stand.get_gridcell_fraction() + stand.frac_change);

						if(stand.get_gridcell_fraction() < INPUT_RESOLUTION && (!gcst.gross_frac_increase || expand_to_new_stand)) {
							gridcell.landcover.acflux_landuse_change += stand.ccont() * stand.get_gridcell_fraction();
							gridcell.landcover.anflux_landuse_change += stand.ncont() * stand.get_gridcell_fraction();
							stand.set_gridcell_fraction(0.0);
						}

						for(int to=0; to<nst; to++) {

							if(st_frac_transfer[index(st.id, to)])
								stand.transfer_area_st[to] = st_frac_transfer[index(st.id, to)];
						}
					}
				}
			}
		}
	}
	for(unsigned int j = 0; j < gridcell.nbr_stands(); j++) {
		Stand& stand = gridcell[j];
		StandType& st = stlist[stand.stid];
		Gridcellst& gcst = gridcell.st[stand.stid];

		if(!gcst.frac && stand.get_gridcell_fraction() < INPUT_RESOLUTION * 100.0) {
			if(stand.get_gridcell_fraction() > INPUT_RESOLUTION * 10.0)
				dprintf("\nYear %d: remaining stand when stand type %d fraction is 0. Residual fraction %.15f ignored. Stand killed.\n", date.year, st.id, stand.get_gridcell_fraction());
			gridcell.landcover.acflux_landuse_change += stand.ccont() * stand.get_gridcell_fraction();
			gridcell.landcover.anflux_landuse_change += stand.ncont() * stand.get_gridcell_fraction();
			stand.set_gridcell_fraction(0.0);
		}
	}
}

/// identifies which stands to expand in area
/** Updates frac, frac_change, frac_old and gross_frac_increase for expanded stands
 * Should be preceded by a call to reduce_stands() and, optionally, transfer_to_new_stand()
 *
 *  INTPUT PARAMETERS
 *
 *  \param st_frac_transfer				array with this year's transferred area fractions between the different stand types
 */
void expand_stands(Gridcell& gridcell, double* st_frac_transfer) {

	// Updated variables are zeroed in reduce_stands()

	for(int i=0; i<nst; i++) {

		StandType& st = stlist[i];
		Gridcellst& gcst = gridcell.st[i];
		landcovertype lc = st.landcover;
		bool expand_to_new_stand = gridcell.landcover.expand_to_new_stand[lc];

		if(gcst.gross_frac_increase > 0.0) {	// Not cloned stands

			if(!expand_to_new_stand) {

				for(unsigned int i = 0; i < gridcell.size(); i++) {

					Stand& stand = gridcell[i];

					if(stand.stid == st.id) {

						// Identify which stands to expand (not secondary stands)

						if(!stand.cloned) {

							stand.frac_change += gcst.gross_frac_increase;
							stand.gross_frac_increase = gcst.gross_frac_increase;
							stand.set_gridcell_fraction(stand.get_gridcell_fraction() + gcst.gross_frac_increase);
						}
					}
				}
			}
		}
	}
}

/// sets land cover transfer matrix from gross land cover change data when no input is available
/** Uses rules to select preferred transfers between land covers
 *  NB. New land cover types must be included in the preference arrays !
 *  Also, PEATLAND, URBAN and BARREN needs to be included when using dynamic fractions for these land cover types.
 *  INPUT PARAMETERS
 *  \param landcoverfrac_change			array with this year's difference in area fractions of the different landcovers
 *
 *  OUTPUT PARAMETERS
 *
 *  \param lc_frac_transfer				array with this year's transferred area fractions between the different land covers
 */
void set_lc_change_array(double landcoverfrac_change[], double lc_frac_transfer[][NLANDCOVERTYPES]) {

	const int NRANK = 6;
	int target_preference[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0};
	int origin_preference[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0};
	double receptor_remain[NLANDCOVERTYPES] = {0.0};
	double donor_remain[NLANDCOVERTYPES] = {0.0};
	int ndonor_lc = 0;
	int nreceptor_lc = 0;

	target_preference[CROPLAND][PASTURE] = 5;
	target_preference[CROPLAND][NATURAL] = 6;
	target_preference[CROPLAND][FOREST] = 4;
	target_preference[CROPLAND][URBAN] = 3;
	target_preference[CROPLAND][BARREN] = 2;
	target_preference[CROPLAND][PEATLAND] = 1;

	target_preference[PASTURE][CROPLAND] = 4;
	target_preference[PASTURE][NATURAL] = 6;
	target_preference[PASTURE][FOREST] = 5;
	target_preference[PASTURE][URBAN] = 3;
	target_preference[PASTURE][BARREN] = 1;
	target_preference[PASTURE][PEATLAND] = 2;

	target_preference[FOREST][CROPLAND] = 4;
	target_preference[FOREST][PASTURE] = 5;
	target_preference[FOREST][NATURAL] = 6;
	target_preference[FOREST][URBAN] = 2;
	target_preference[FOREST][BARREN] = 1;
	target_preference[FOREST][PEATLAND] = 3;

	target_preference[NATURAL][CROPLAND] = 4;
	target_preference[NATURAL][PASTURE] = 5;
	target_preference[NATURAL][FOREST] = 6;
	target_preference[NATURAL][URBAN] = 2;
	target_preference[NATURAL][BARREN] = 1;
	target_preference[NATURAL][PEATLAND] = 3;

	target_preference[URBAN][CROPLAND] = 5;
	target_preference[URBAN][PASTURE] = 4;
	target_preference[URBAN][FOREST] = 2;
	target_preference[URBAN][NATURAL] = 3;
	target_preference[URBAN][BARREN] = 6;
	target_preference[URBAN][PEATLAND] = 1;

	target_preference[BARREN][CROPLAND] = 4;
	target_preference[BARREN][PASTURE] = 5;
	target_preference[BARREN][FOREST] = 2;
	target_preference[BARREN][NATURAL] = 6;
	target_preference[BARREN][URBAN] = 1;
	target_preference[BARREN][PEATLAND] = 3;

	origin_preference[PASTURE][CROPLAND] = 5;
	origin_preference[NATURAL][CROPLAND] = 6;
	origin_preference[FOREST][CROPLAND] = 3;
	origin_preference[BARREN][CROPLAND] = 1;
	origin_preference[URBAN][CROPLAND] = 2;
	origin_preference[PEATLAND][CROPLAND] = 4;

	origin_preference[CROPLAND][PASTURE] = 5;
	origin_preference[NATURAL][PASTURE] = 6;
	origin_preference[FOREST][PASTURE] = 3;
	origin_preference[BARREN][PASTURE] = 1;
	origin_preference[URBAN][PASTURE] = 2;
	origin_preference[PEATLAND][PASTURE] = 4;

	origin_preference[CROPLAND][NATURAL] = 5;
	origin_preference[PASTURE][NATURAL] = 6;
	origin_preference[FOREST][NATURAL] = 4;
	origin_preference[BARREN][NATURAL] = 2;
	origin_preference[URBAN][NATURAL] = 1;
	origin_preference[PEATLAND][NATURAL] = 3;

	origin_preference[CROPLAND][FOREST] = 4;
	origin_preference[PASTURE][FOREST] = 5;
	origin_preference[NATURAL][FOREST] = 6;
	origin_preference[BARREN][FOREST] = 2;
	origin_preference[URBAN][FOREST] = 1;
	origin_preference[PEATLAND][FOREST] = 3;

	origin_preference[CROPLAND][URBAN] = 6;
	origin_preference[PASTURE][URBAN] = 5;
	origin_preference[NATURAL][URBAN] = 4;
	origin_preference[BARREN][URBAN] = 3;
	origin_preference[FOREST][URBAN] = 1;
	origin_preference[PEATLAND][URBAN] = 2;

	origin_preference[CROPLAND][PEATLAND] = 2;
	origin_preference[PASTURE][PEATLAND] = 4;
	origin_preference[NATURAL][PEATLAND] = 5;
	origin_preference[BARREN][PEATLAND] = 6;
	origin_preference[FOREST][PEATLAND] = 3;
	origin_preference[URBAN][PEATLAND] = 1;

	origin_preference[CROPLAND][BARREN] = 6;
	origin_preference[PASTURE][BARREN] = 5;
	origin_preference[NATURAL][BARREN] = 4;
	origin_preference[URBAN][BARREN] = 3;
	origin_preference[FOREST][BARREN] = 1;
	origin_preference[PEATLAND][BARREN] = 2;

	for(int i=0; i<NLANDCOVERTYPES; i++) {

		if(landcoverfrac_change[i] > 0.0) {
			receptor_remain[i] = landcoverfrac_change[i];
			nreceptor_lc++;
		}
		else if(landcoverfrac_change[i] < 0.0){
			donor_remain[i] = -landcoverfrac_change[i];
			ndonor_lc++;
		}
	}


	// Simplest cases: no ambiguities
	if(ndonor_lc == 1 || nreceptor_lc == 1) {

		for(int from=0; from<NLANDCOVERTYPES; from++) {

			if(landcoverfrac_change[from] < 0.0) {

				for(int to=0; to<NLANDCOVERTYPES; to++) {

					if(ndonor_lc == 1) {

						if(landcoverfrac_change[to] > 0.0)
							lc_frac_transfer[from][to] += landcoverfrac_change[to];
					}
					else if(nreceptor_lc == 1) {

						if(landcoverfrac_change[to] > 0.0)
							lc_frac_transfer[from][to] += - landcoverfrac_change[from];
					}
				}
			}
		}
	}
	else {

		for(int score=NRANK*2; score>0; score--) {

			for(int from=0; from<NLANDCOVERTYPES; from++) {

				if(donor_remain[from] > INPUT_RESOLUTION * 0.1) {

					for(int to=0; to<NLANDCOVERTYPES; to++) {

						// Identify receiving land covers:
						if(target_preference[from][to] + origin_preference[from][to] == score && receptor_remain[to] > INPUT_RESOLUTION * 0.1 && donor_remain[from] > INPUT_RESOLUTION * 0.1) {

							// all donor land is put into this land cover
							if(receptor_remain[to] >= donor_remain[from]) {

								lc_frac_transfer[from][to] += donor_remain[from];
								receptor_remain[to] -= donor_remain[from];
								donor_remain[from] = 0.0;
								break;
							}
							// transfer to more land cover types
							else {

								lc_frac_transfer[from][to] += receptor_remain[to];
								donor_remain[from] -= receptor_remain[to];
								receptor_remain[to] = 0.0;
							}
						}
					}
				}
			}
		}
	}
}

/// sets stand type transfer matrix from land cover transfer matrix when no stand type transfer input is available
/** Distributes land cover transfers equally between stand types within a land cover but may use
 *  rules to select preferred transfers between stand types/land covers (see set_lc_change_array()) if
 *  equal_distribution is set to false.
 *
 *  INPUT PARAMETERS
 *  \param lc_frac_transfer				array with this year's transferred area fractions between the different land covers
 *
 *  OUTPUT PARAMETERS
 *
 *  \param st_frac_transfer				array with this year's transferred area fractions between the different stand types
 */
void set_st_change_array(Gridcell& gridcell, double lc_frac_transfer[][NLANDCOVERTYPES], double* st_frac_transfer, forest_lc_frac_transfer& forest_lc_frac_transfer_s, forest_st_frac_transfer& forest_st_frac_transfer_s) {

	double* recip_donor_remain = new double[nst];
	double* recip_receptor_remain = new double[nst];
	double recip_lc_change[NLANDCOVERTYPES] = {0.0};
	double recip_lc_frac_transfer[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};
	double recip_transfer_remain[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};
	double net_transfer_remain[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};
	double net_lc_decrease[NLANDCOVERTYPES] = {0.0};

	for(int i=0;i<nst;i++) {
		recip_donor_remain[i] = 0.0;
		recip_receptor_remain[i] = 0.0;
	}

	// Quantify "reciprocal" lc change (gross lc change - net lc change)

	for(int from=0; from<NLANDCOVERTYPES; from++) {

		for(int to=0; to<NLANDCOVERTYPES; to++) {

			recip_lc_frac_transfer[from][to] = min(lc_frac_transfer[from][to], lc_frac_transfer[to][from]);
			recip_transfer_remain[from][to] = recip_lc_frac_transfer[from][to];
			recip_lc_change[from] += recip_lc_frac_transfer[from][to];
			net_transfer_remain[from][to] = lc_frac_transfer[from][to] - recip_lc_frac_transfer[from][to];
			net_lc_decrease[from] += net_transfer_remain[from][to];
		}
	}

	// Net land cover change

	int nsts[NLANDCOVERTYPES] = {0};
	int nsts_active[NLANDCOVERTYPES] = {0};
	bool multi_st = false;

	for(int lc=0; lc<NLANDCOVERTYPES; lc++) {

		for(int i=0; i<nst; i++) {

			if(lc == stlist[i].landcover) {
				nsts[lc]++;
				if(gridcell.st[i].frac || gridcell.st[i].frac_old)
					nsts_active[lc]++;
			}
		}
		if(nsts[lc] > 1)
			multi_st = true;
	}

	// Net transfers between land covers with only one stand type.

	for(int from=0; from<nst; from++) {

		StandType& st_donor = stlist[from];

		for(int to=0; to<nst; to++) {

			StandType& st_receptor = stlist[to];

			if(nsts[st_receptor.landcover] < 2 && nsts[st_donor.landcover] < 2 && net_transfer_remain[st_donor.landcover][st_receptor.landcover] > INPUT_RESOLUTION * 0.1) {
				st_frac_transfer[index(from, to)] += net_transfer_remain[st_donor.landcover][st_receptor.landcover];
				net_transfer_remain[st_donor.landcover][st_receptor.landcover] = 0.0;
			}
		}
	}

	// Net transfers to and from land covers that have several stand types.

	if(multi_st) {

		double net_lc_receptor_remain[NLANDCOVERTYPES] = {0.0};
		double net_transfer_remain_initial[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};

		for(int from=0; from<NLANDCOVERTYPES; from++) {

			for(int to=0; to<NLANDCOVERTYPES; to++) {

				net_lc_receptor_remain[to] += net_transfer_remain[from][to];
				net_transfer_remain_initial[from][to] = net_transfer_remain[from][to];
			}
		}

		double* influx_st = new double[nst];
		double* outflux_st = new double[nst];

		for(int i=0;i<nst;i++) {
			influx_st[i] = 0.0;
			outflux_st[i] = 0.0;
		}

		for(int from=0; from<nst; from++) {

			for(int to=0; to<nst; to++) {

				if(st_frac_transfer[index(from, to)] > 0.0) {
					influx_st[to] += st_frac_transfer[index(from, to)];
					outflux_st[from] += st_frac_transfer[index(from, to)];
				}
			}
		}

		// Transfer from land covers with more than one stand type:

		double* reduce = new double[nst];
		double* receptor_weight = new double[nst];

		for(int i=0;i<nst;i++) {
			reduce[i] = 0.0;
			receptor_weight[i] = 0.0;
		}

		double exclude_frac = 0.0;
		double exclude_frac_0 = 0.0;
		bool recalc_increase = false;

		for(int from=0; from<nst; from++) {

			StandType& st_donor = stlist[from];
			Gridcellst& gcst_donor = gridcell.st[from];

			if(gridcell.landcover.frac[st_donor.landcover])
				receptor_weight[from] = gcst_donor.frac / gridcell.landcover.frac[st_donor.landcover];
		}

		for(int from_lc=0; from_lc<NLANDCOVERTYPES; from_lc++) {

			double negative = 0.0;
			double reducable_frac = 0.0;
			bool recalc_reduce = false;

			if(!net_lc_decrease[from_lc])
				continue;

			for(int from=0; from<nst; from++) {

				StandType& st_donor = stlist[from];
				Gridcellst& gcst_donor = gridcell.st[from];

				if(st_donor.landcover == from_lc && nsts[st_donor.landcover] >=2) {

					double net_st_increase = net_lc_receptor_remain[st_donor.landcover] * receptor_weight[from];
					double net_st_decrease = net_st_increase - gcst_donor.frac_change;

					reduce[from] = (influx_st[from] - outflux_st[from]) + net_st_decrease;
					if(reduce[from] < 0.0) {
						negative += -reduce[from];
						recalc_reduce = true;
					}
					else {
						reducable_frac += reduce[from];
					}

					double remain = reduce[from] - gcst_donor.frac_old;
					if(remain > INPUT_RESOLUTION * 0.1) {
						exclude_frac_0 += gcst_donor.frac;
						exclude_frac += receptor_weight[from] * net_lc_receptor_remain[st_donor.landcover] - remain;
						if(net_lc_receptor_remain[st_donor.landcover])
							receptor_weight[from] -= remain / net_lc_receptor_remain[st_donor.landcover];
						reduce[from] = gcst_donor.frac_old;
						recalc_increase = true;
					}
				}
			}
			if(recalc_reduce) {

				for(int from=0; from<nst; from++) {

					StandType& st_donor = stlist[from];
					Gridcellst& gcst_donor = gridcell.st[from];

					if(st_donor.landcover == from_lc && reducable_frac && reduce[from] > 0.0) {
						reduce[from] = max(0.0, reduce[from] - negative * reduce[from] / reducable_frac);
					}
					else {
						reduce[from] = 0.0;
					}
				}
			}

			if(recalc_increase) {

				for(int from=0; from<nst; from++) {

					StandType& st_donor = stlist[from];
					Gridcellst& gcst_donor = gridcell.st[from];

					if(st_donor.landcover == from_lc) {

						if(receptor_weight[from] == gcst_donor.frac / gridcell.landcover.frac[st_donor.landcover] && gridcell.landcover.frac[st_donor.landcover] != exclude_frac_0) {
							receptor_weight[from] = gcst_donor.frac / (gridcell.landcover.frac[st_donor.landcover] - exclude_frac_0) * (net_lc_receptor_remain[st_donor.landcover] - exclude_frac) / net_lc_receptor_remain[st_donor.landcover];
							double net_st_increase = net_lc_receptor_remain[st_donor.landcover] * receptor_weight[from];
							double net_st_decrease = net_st_increase - gcst_donor.frac_change;
							reduce[from] = (influx_st[from] - outflux_st[from]) + net_st_decrease;
						}
					}
				}
			}
		}

		for(int from=0; from<NLANDCOVERTYPES; from++) {

			for(int to=0; to<NLANDCOVERTYPES; to++) {

				if(nsts[from] >=2 && net_transfer_remain[from][to] > INPUT_RESOLUTION * 0.1) {

					for(int i=0; i<nst; i++) {

						StandType& st_donor = stlist[i];

						if(st_donor.landcover == from && gridcell.landcover.frac_old[from]) {

							for(int j=0; j<nst; j++) {

								StandType& st_receptor = stlist[j];
								Gridcellst& gcst_receptor = gridcell.st[j];

								if(st_receptor.landcover == to && net_lc_decrease[from] && gridcell.landcover.frac[to]) {

									// This shouldn't happen really...
									if(reduce[i] < 0.0)
										dprintf("Year %d: st %d reduce[from] = %.15f !\n", date.get_calendar_year(), i, reduce[i]);
									double transfer = reduce[i] * net_transfer_remain_initial[from][to] / net_lc_decrease[from] * (gcst_receptor.frac / gridcell.landcover.frac[to]);
									st_frac_transfer[index(i, j)] += transfer;
									net_transfer_remain[from][to] -= transfer;
									net_lc_receptor_remain[to] -= transfer;					
								}
							}
						}
					}
					net_transfer_remain[from][to] = 0.0;
					net_transfer_remain_initial[from][to] = 0.0;
				}
			}
		}

		// Transfer to land covers with more than one stand type:

		for(int from=0; from<nst; from++) {

			StandType& st_donor = stlist[from];
			Gridcellst& gcst_donor = gridcell.st[from];

			for(int to=0; to<nst; to++) {

				StandType& st_receptor = stlist[to];

				if(nsts[st_receptor.landcover] >= 2 && net_transfer_remain_initial[st_donor.landcover][st_receptor.landcover] > INPUT_RESOLUTION * 0.1
					&& gridcell.landcover.frac_old[st_donor.landcover]) {

					double transfer = net_transfer_remain_initial[st_donor.landcover][st_receptor.landcover] * receptor_weight[to] * gcst_donor.frac_old / gridcell.landcover.frac_old[st_donor.landcover];
					st_frac_transfer[index(from, to)] += transfer;
					net_transfer_remain[st_donor.landcover][st_receptor.landcover] -= transfer;
				}
			}
		}

		if(influx_st)
			delete[] influx_st;
		if(outflux_st)
			delete[] outflux_st;
		if(reduce)
			delete[] reduce;
		if(receptor_weight)
			delete[] receptor_weight;

	}


	// Add "reciprocal" lc change (gross-net)
	// Also transitions from primary to secondary natural stands are done here

	double* donated_st = new double[nst];
	double* received_st = new double[nst];

	for(int i=0; i<nst; i++) {
		donated_st[i] = 0.0;
		received_st[i] = 0.0;
	}
	for(int from=0; from<nst; from++) {

		for(int to=0; to<nst; to++) {
			donated_st[from] += st_frac_transfer[index(from, to)];
			received_st[to] += st_frac_transfer[index(from, to)];
		}
	}

	double max_transfer_lc[NLANDCOVERTYPES] = {0.0};
	double max_donor_lc[NLANDCOVERTYPES] = {0.0};
	double max_receptor_lc[NLANDCOVERTYPES] = {0.0};
	for(int i=0; i<nst; i++) {
		StandType& st = stlist[i];
		Gridcellst& gcst = gridcell.st[i];
		max_transfer_lc[st.landcover] += min(gcst.frac - received_st[i], gcst.frac_old - donated_st[i]);
		max_receptor_lc[st.landcover] += gcst.frac - received_st[i];
		max_donor_lc[st.landcover] += gcst.frac_old - donated_st[i];
	}

	for(int lc=0; lc<NLANDCOVERTYPES; lc++) {

		if(!recip_lc_change[lc])
			continue;

		if(max_transfer_lc[lc] >= recip_lc_change[lc]) {

			for(int i=0; i<nst; i++) {

				StandType& st = stlist[i];
				Gridcellst& gcst = gridcell.st[i];

				if(st.landcover == lc && recip_lc_change[st.landcover] > 0.0) {
					double max_transfer_st = min(gcst.frac - received_st[i], gcst.frac_old - donated_st[i]);
					if(max_transfer_lc[st.landcover]) {
						recip_receptor_remain[i] = recip_lc_change[st.landcover] * max_transfer_st / max_transfer_lc[st.landcover];
						recip_donor_remain[i] = recip_lc_change[st.landcover] * max_transfer_st / max_transfer_lc[st.landcover];

						if(gcst.frac_old - donated_st[i] - recip_donor_remain[i] < -1e-13) {
							dprintf("Year %d: not enough room for reciprocal transfer for st %d, %g missing\n", date.get_calendar_year(), i, -(gcst.frac_old - donated_st[i] - recip_donor_remain[i]));
						}
						if(gcst.frac - received_st[i] - recip_receptor_remain[i] < -1e-13) {
							dprintf("Year %d: not enough room for reciprocal transfer for st %d, %g missing\n", date.get_calendar_year(), i, -(gcst.frac - received_st[i] - recip_receptor_remain[i]));
						}
					}
				}
			}
		}
		else {

			for(int i=0; i<nst; i++) {

				StandType& st = stlist[i];
				Gridcellst& gcst = gridcell.st[i];

				if(st.landcover == lc) {

					if(max_receptor_lc[st.landcover]) {
						recip_receptor_remain[i] = recip_lc_change[st.landcover] * (gcst.frac - received_st[i]) / max_receptor_lc[st.landcover];
					}
					if(max_donor_lc[st.landcover]) {
						recip_donor_remain[i] = recip_lc_change[st.landcover] * (gcst.frac_old - donated_st[i]) / max_donor_lc[st.landcover];
					}
				}
			}
		}
	}

	if(donated_st)
		delete[] donated_st;
	if(received_st)
		delete[] received_st;

	for(int from=0; from<nst; from++) {

		StandType& st_donor = stlist[from];
		Gridcellst& gcst_donor = gridcell.st[from];

		if(recip_donor_remain[from] > INPUT_RESOLUTION * 0.1) {

			for(int to=0; to<nst; to++) {

				StandType& st_receptor = stlist[to];
				Gridcellst& gcst_receptor = gridcell.st[to];

				if(recip_transfer_remain[st_donor.landcover][st_receptor.landcover]  > INPUT_RESOLUTION * 0.1 
					&& recip_receptor_remain[to] > INPUT_RESOLUTION * 0.1 && recip_donor_remain[from] > INPUT_RESOLUTION * 0.1) {

					double donor_effective = min(recip_donor_remain[from], recip_transfer_remain[st_donor.landcover][st_receptor.landcover]);
					double receptor_effective = min(recip_receptor_remain[to], recip_transfer_remain[st_donor.landcover][st_receptor.landcover]);

					// all donor land is put into this stand type
					if(receptor_effective >= donor_effective) {

						st_frac_transfer[index(from, to)] += donor_effective;
						recip_receptor_remain[to] -= donor_effective;
						recip_donor_remain[from] -= donor_effective;
						recip_transfer_remain[st_donor.landcover][st_receptor.landcover] -= donor_effective;
					}
					// transfer to more stand types
					else {

						st_frac_transfer[index(from, to)] += receptor_effective;
						recip_donor_remain[from] -= receptor_effective;
						recip_receptor_remain[to] -= receptor_effective;
						recip_transfer_remain[st_donor.landcover][st_receptor.landcover] -= receptor_effective;
					}
				}
			}
		}
	}

	// Balance fractions for stand types within a landcover

	double* change_st = new double[nst];
	double* dif_st = new double[nst];

	for(int from=0; from<nst; from++) {
		change_st[from] = 0.0;
		dif_st[from] = 0.0;
	}

	for(int from=0; from<nst; from++) {

		for(int to=0; to<nst; to++) {

			change_st[from] -= st_frac_transfer[index(from, to)];
			change_st[to] += st_frac_transfer[index(from, to)];
		}
	}

	double dif_lc[NLANDCOVERTYPES] = {0.0};

	for(int from=0; from<nst; from++) {

		Gridcellst& gcst = gridcell.st[from];

		dif_st[from] = gcst.frac - (gcst.frac_old + change_st[from]);	// fraction needed to reach target
		dif_lc[stlist[from].landcover] += fabs(dif_st[from]) / 2.0;
	}

	const double ROUNDING_ERROR = 1.0e-16;

	for(int lc=0; lc<NLANDCOVERTYPES; lc++) {

		// identify land cover with need for st frac adjustment
		if(nsts[lc] >= 2 && dif_lc[lc] >= INPUT_RESOLUTION * 0.1) {
			
			// find second land cover that has most transfers to or from the first land cover (with only one stand type with frac/frac_old > 0)
			bool error = true;

			for(int use_lc=0; use_lc<NLANDCOVERTYPES && error; use_lc++) {

				bool use_donor = true;
				if(nsts_active[use_lc] == 1 && max(lc_frac_transfer[lc][use_lc], lc_frac_transfer[use_lc][lc]) > dif_lc[lc]) {
					// determine whether to use transfer to or from land cover 2
					if(dif_lc[lc] <= lc_frac_transfer[use_lc][lc]) {
						bool skip = false;
						for(int st_help=0; st_help<nst; st_help++) {
							StandType& st_donor = stlist[st_help];
							if(st_donor.landcover == use_lc && (gridcell.st[st_help].frac || gridcell.st[st_help].frac_old)) {
								for(int st_dif=0; st_dif<nst; st_dif++) {
									StandType& st_receptor = stlist[st_dif];
									if(st_receptor.landcover == lc && !(dif_st[st_dif] >= 0.0 || st_frac_transfer[index(st_help, st_dif)] + dif_st[st_dif] > -ROUNDING_ERROR)) {
										skip = true;
										break;
									}
								}
							}
						}
						if(!skip) {
							use_donor = true;
							error = false;
						}
					}

					if(error && dif_lc[lc] <= lc_frac_transfer[lc][use_lc]) {

						bool skip = false;
						for(int st_dif=0; st_dif<nst; st_dif++) {
							StandType& st_donor = stlist[st_dif];
							if(st_donor.landcover == lc) {
								for(int st_help=0; st_help<nst; st_help++) {
									StandType& st_receptor = stlist[st_help];
									if(st_receptor.landcover == use_lc && (gridcell.st[st_help].frac || gridcell.st[st_help].frac_old) && !(dif_st[st_dif] <= 0.0 || st_frac_transfer[index(st_dif, st_help)] - dif_st[st_dif] > -ROUNDING_ERROR)) {
										skip = true;
										break;
									}
								}
							}
						}
						if(!skip) {
							use_donor = false;
							error = false;
						}
					}

					if(!error) {

						for(int st_dif=0; st_dif<nst; st_dif++) {

							StandType& st_donor = stlist[st_dif];

							if(st_donor.landcover == lc && fabs(dif_st[st_dif]) >= INPUT_RESOLUTION * 0.1) {

								for(int st_help=0; st_help<nst; st_help++) {

									StandType& st_receptor = stlist[st_help];

									if(st_receptor.landcover == use_lc && (gridcell.st[st_help].frac || gridcell.st[st_help].frac_old) && fabs(dif_st[st_dif]) >= INPUT_RESOLUTION * 0.1) {

										// after tests above, this should always work (overshoots < ROUNDING_ERROR are zeroed here)
										if(use_donor) {
											st_frac_transfer[index(st_help, st_dif)] += max(-st_frac_transfer[index(st_help, st_dif)], dif_st[st_dif]);
											dif_st[st_dif] = 0.0;
										}
										else {
											st_frac_transfer[index(st_dif, st_help)] -= min(st_frac_transfer[index(st_dif, st_help)], dif_st[st_dif]);
											dif_st[st_dif] = 0.0;
										}
									}
								}
							}
						}
					}
				}
			}

			if(error) {

				// If stand type fractions still unbalanced, try shuffling within a land cover
				for(int from=0; from<nst; from++) {

					StandType& st_donor = stlist[from];

					if(st_donor.landcover == lc && -dif_st[from] > INPUT_RESOLUTION * 0.1) {

						for(int to=0; to<nst; to++) {

							StandType& st_receptor = stlist[to];

							if(st_donor.landcover == st_receptor.landcover && -dif_st[from] > INPUT_RESOLUTION * 0.1 && dif_st[to] >= INPUT_RESOLUTION * 0.1) {

								double donor_effective = -dif_st[from];
								double receptor_effective = dif_st[to];

								// all donor land going to this land cover is put into this stand type
								if(receptor_effective >= donor_effective) {

									st_frac_transfer[index(from, to)] += donor_effective;
									lc_frac_transfer[st_donor.landcover][st_donor.landcover] += donor_effective;
									dif_st[from] += donor_effective;
									dif_st[to] -= donor_effective;
								}
								// transfer to more stand types within this land cover
								else {

									st_frac_transfer[index(from, to)] += receptor_effective;
									lc_frac_transfer[st_donor.landcover][st_donor.landcover] += receptor_effective;
									dif_st[from] += receptor_effective;
									dif_st[to] -= receptor_effective;
								}
							}
						}
					}
				}
			}
		}
	}

	if(change_st)
		delete[] change_st;
	if(dif_st)
		delete[] dif_st;

	// Remove very small transfer values derived from rounding errors in the balancing section above
	for(int from=0; from<nst; from++) {
		for(int to=0; to<nst; to++) {
			if(st_frac_transfer[index(from, to)] < ROUNDING_ERROR)
				st_frac_transfer[index(from, to)] = 0.0;
		}
	}

	for(int from=0; from<nst; from++) {

		StandType& st_donor = stlist[from];
		Gridcellst& gcst_donor = gridcell.st[from];

		for(int to=0; to<nst; to++) {

			StandType& st_receptor = stlist[to];
			Gridcellst& gcst_receptor = gridcell.st[to];
			double transfer_frac = st_frac_transfer[index(from, to)];
			if(transfer_frac > (gcst_donor.frac_old) || transfer_frac > (gcst_receptor.frac)) {
				if((transfer_frac - gcst_receptor.frac) > INPUT_RESOLUTION || (transfer_frac - gcst_receptor.frac) > INPUT_RESOLUTION) {
					dprintf("\nYear %d: st_change_array sum not compatible with st.frac_old/frac values for stand types %d and %d\n", date.year, from, to);
					dprintf("st_change_array=%.15f, st_donor.frac_old=%.15f, st_receptor.frac=%.15f\n", transfer_frac, gcst_donor.frac_old, gcst_receptor.frac);
				}
				if(transfer_frac > (gcst_receptor.frac) && transfer_frac < (gcst_receptor.frac + INPUT_RESOLUTION * 100.0)) {
					if((transfer_frac - gcst_receptor.frac) > INPUT_RESOLUTION)
						dprintf("Removing overshoot in array %.15f\n\n", st_frac_transfer[index(from, to)] - gcst_receptor.frac);
					st_frac_transfer[index(from, to)] = gcst_receptor.frac;
				}
				else if(transfer_frac > (gcst_donor.frac_old) && transfer_frac < (gcst_donor.frac_old + INPUT_RESOLUTION * 100.0)) {
					if((transfer_frac - gcst_donor.frac_old) > INPUT_RESOLUTION)
						dprintf("Removing overshoot in array %.15f\n\n", st_frac_transfer[index(from, to)] - gcst_donor.frac_old);
					st_frac_transfer[index(from, to)] = gcst_donor.frac_old;
				}
			}
		}
	}

	// Set the transfer fraction from primary stands within a stand type (simple case: equal primary/secondary ratio for all stand types in a lc->lc transfer)
	if(use_primary_lc_transfer) {
		for(int from=0; from<nst; from++) {

			StandType& st_donor = stlist[from];

			for(int to=0; to<nst; to++) {

				StandType& st_receptor = stlist[to];


				double primary_frac = 0.0;
				double secondary_young_frac = 0.0;

				if(lc_frac_transfer[st_donor.landcover][st_receptor.landcover] > 0.0) {
					primary_frac = forest_lc_frac_transfer_s.primary[st_donor.landcover][st_receptor.landcover] / lc_frac_transfer[st_donor.landcover][st_receptor.landcover];
					secondary_young_frac = forest_lc_frac_transfer_s.secondary_young[st_donor.landcover][st_receptor.landcover] / lc_frac_transfer[st_donor.landcover][st_receptor.landcover];
				}

				forest_st_frac_transfer_s.primary[index(from, to)] = primary_frac * st_frac_transfer[index(from, to)];
				forest_st_frac_transfer_s.secondary_young[index(from, to)] = secondary_young_frac * st_frac_transfer[index(from, to)];
			}
		}
	}

	if(recip_donor_remain)
		delete[] recip_donor_remain;
	if(recip_receptor_remain)
		delete[] recip_receptor_remain;
}

/// Handles harvest and turnover of reduced stands at landcover change.
/** Sets landcover.updated to true
 *  Stores carbon, nitrogen and water of harvested area in a temporary struct.
 *  Should be followed by a call to stand_dynamics() to kill stands with a new area of 0
 *
 *  INPUT PARAMETERS
 *
 *  \param receiving_fraction				sum of added area to expanding stands
 *  \param landcover_receptor				restriction of donor stands transferring to specified receptor landcover
 *  \param landcover_donor 					restriction of donor stands according to landcover
 *  \param stid_receptor 					restriction of donor stands transferring to specified receptor stand type
 *  \param stid_donor  						restriction of stands according to stand type
 *  \param standid							restriction of donor stand
 *
 *  OUTPUT PARAMETERS
 *  \param landcover_change_transfer        struct containing the following pft-specific public members:
 *   - transfer_litter_leaf
 *   - transfer_litter_sap
 *   - transfer_litter_heart
 *   - transfer_litter_root
 *   - transfer_litter_repr
 *   - transfer_nmass_litter_leaf
 *   - transfer_nmass_litter_root
 *   - transfer_nmass_litter_sap
 *   - transfer_nmass_litter_heart
 *   - transfer_harvested_products_slow
 *   - transfer_harvested_products_slow_nmass
 *											,the following patch-level public members
 *   - transfer_cpool_fast
 *   - transfer_cpool_slow
 *   - transfer_nmass_avail
 *   - transfer_wcont_evap
 *   - transfer_snowpack
 *   - transfer_decomp_litter_mean
 *   - transfer_k_soilfast_mean
 *   - transfer_acflux_harvest
 *   - transfer_anflux_harvest
 *											,the following water soil layer-specific public member:
 *   - transfer_wcont
 *											and the following century soil pool-specific public members:
 *   - transfer_sompool.cmass
 *   - transfer_sompool.fireresist
 *   - transfer_sompool.fracremain
 *   - transfer_sompool.ligcfrac
 *   - transfer_sompool.nmass
 *   - transfer_sompool.ntoc
 */
void donor_stand_change(Gridcell& gridcell, double& receiving_fraction, landcover_change_transfer& to,
		int landcover_receptor = -1, int landcover_donor = -1,
		int stid_receptor = -1, int stid_donor = -1,
		int standid = -1, lc_change_harvest_params* harv_params = NULL) {

	int count = 0;
	Landcover& lc = gridcell.landcover;

	for(unsigned int i=0; i<gridcell.nbr_stands(); i++) {

		Stand& stand = gridcell[i];

		double donor_area = 0.0;

		if(stid_receptor >= 0)
			donor_area = stand.transfer_area_st[stid_receptor];
		else if(landcover_receptor >= 0)
			donor_area = stand.transfer_area_lc((landcovertype)landcover_receptor);
		else
			donor_area = stand.gross_frac_decrease;

		if(donor_area > 0.0 && (stand.id == standid || standid < 0) && (stand.landcover == landcover_donor || landcover_donor < 0) && (stand.stid == stid_donor || stid_donor < 0)) {

			count++;

			stand.frac_temp -= donor_area;
			stand.frac_temp = max(0.0, stand.frac_temp);
			double scale = donor_area / receiving_fraction / (double)stand.nobj;

			// Add non-living C, N and water of stand to transfer struct:
			to.add_from_stand(stand, scale);

			// Harvest and turnover of copies of individuals, add to transfer copy:
			stand.firstobj();
			while(stand.isobj) {
				Patch& patch = stand.getobj();
				Vegetation& vegetation = patch.vegetation;
				vegetation.firstobj();
				while(vegetation.isobj) {

					Harvest_CN cp;

					Individual& indiv = vegetation.getobj();
					Patchpft& patchpft = patch.pft[indiv.pft.id];

					if(indiv.has_daily_turnover())
						cp.copy_from_indiv(indiv, true, false);
					else
						cp.copy_from_indiv(indiv, false, false);

					bool lc_pool = (landcover_receptor == -1) && (stid_receptor == -1);
					bool wood_harvest = false;
					if(stand.landcover == NATURAL || stand.landcover == FOREST) {
						if(lc_pool) {
							if(stand.transfer_area_lc((landcovertype)NATURAL) || stand.transfer_area_lc((landcovertype)FOREST))
								wood_harvest = true;
						}
						else if(landcover_receptor == NATURAL || landcover_receptor == FOREST || stid_receptor > -1 && (stlist[stid_receptor].landcover == NATURAL || stlist[stid_receptor].landcover == FOREST)) {
							wood_harvest = true;
						}
					}

					// Harvest of transferred areas:
					switch (stand.landcover)
					{
					case CROPLAND:
						harvest_crop(cp, indiv.pft, indiv.alive, indiv.cropindiv->isintercropgrass);
						break;
					case PASTURE:
						harvest_pasture(cp, indiv.pft, indiv.alive);
						break;
					case NATURAL:
					case FOREST:
					case URBAN:
					case PEATLAND:
						if(harv_params) {
							harvest_wood(cp, indiv.pft, indiv.alive, 1.0, harv_params->harv_eff, harv_params->res_outtake_twig, harv_params->res_outtake_coarse_root);
						}
						else if(wood_harvest) {
							if(lc_pool) {
								double lu_change_ratio = 1.0 - (stand.transfer_area_lc((landcovertype)NATURAL) + stand.transfer_area_lc((landcovertype)FOREST)) / stand.gross_frac_decrease;
								// Land cover change area: frac_cut=1, harv_eff=1, res_outtake_twig=0.95, res_outtake_coarse_root=0.9
								// Wood harvest area: frac_cut=1, harv_eff=pft.harv_eff, res_outtake_twig=pft.res_outtake, res_outtake_coarse_root=0
								harvest_wood(cp, indiv.pft, indiv.alive, 1.0, 1.0 * lu_change_ratio + indiv.pft.harv_eff * (1.0 - lu_change_ratio), 0.95 * lu_change_ratio + indiv.pft.res_outtake * (1.0 - lu_change_ratio), 0.9 * lu_change_ratio);
							}
							else {
								harvest_wood(cp, indiv.pft, indiv.alive, 1.0, indiv.pft.harv_eff, indiv.pft.res_outtake);
							}
						}
						else {
							harvest_wood(cp, indiv.pft, indiv.alive, 1.0, 1.0, 0.95, 0.9);	// frac_cut=1, harv_eff=1, res_outtake_twig=0.95, res_outtake_coarse_root=0.9
						}
						break;
					case BARREN: // Assuming there is nothing to harvest on barren
						break;
					default:
						fail("Modify code to deal with landcover harvest at landcover change!\n");
					}

					turnover(indiv.pft.turnover_leaf, indiv.pft.turnover_root,
						indiv.pft.turnover_sap, indiv.pft.lifeform, indiv.pft.landcover,
						cp.cmass_leaf, cp.cmass_root, cp.cmass_sap, cp.cmass_heart,
						cp.nmass_leaf, cp.nmass_root, cp.nmass_sap, cp.nmass_heart,
						cp.litter_leaf,
						cp.litter_root,
						cp.nmass_litter_leaf,
						cp.nmass_litter_root,
						cp.nstore_longterm, cp.max_n_storage,
						indiv.alive);


					// In case any vegetation left (eg. cmass_root in pasture or grass in woodland):
					kill_remaining_vegetation(cp, indiv.pft, indiv.alive, indiv.istruecrop_or_intercropgrass(), false);

					//Sum added litter C & N:
					to.transfer_litter_leaf[indiv.pft.id] += cp.litter_leaf * scale;
					to.transfer_litter_root[indiv.pft.id] += cp.litter_root * scale;
					to.transfer_litter_sap[indiv.pft.id] += cp.litter_sap * scale;
					to.transfer_litter_heart[indiv.pft.id] += cp.litter_heart * scale;

					to.transfer_nmass_litter_leaf[indiv.pft.id] += cp.nmass_litter_leaf * scale;
					to.transfer_nmass_litter_root[indiv.pft.id] += cp.nmass_litter_root * scale;
					to.transfer_nmass_litter_sap[indiv.pft.id] += cp.nmass_litter_sap * scale;
					to.transfer_nmass_litter_heart[indiv.pft.id] += cp.nmass_litter_heart * scale;

					// Flux to products
					lc.harvest_product += cp.harvested_products_slow * donor_area / (double)stand.nobj;
					lc.harvest_product_lc[stand.landcover] += cp.harvested_products_slow * donor_area / (double)stand.nobj;
					lc.harvest_product_nmass += cp.harvested_products_slow_nmass * donor_area / (double)stand.nobj;
					lc.harvest_product_nmass_lc[stand.landcover] += cp.harvested_products_slow_nmass * donor_area / (double)stand.nobj;

					// Flux to litter
					lc.acflux_harvest_wood_res += cp.dcflux_harvest_wood_res * donor_area / (double)stand.nobj;
					lc.acflux_harvest_wood_res_lc[stand.landcover] += cp.dcflux_harvest_wood_res * donor_area / (double)stand.nobj;

					// Flux to atm
					lc.dcflux_landuse_change += cp.acflux_harvest * donor_area / (double)stand.nobj; // ecev3 - reset to 0 each day
					lc.acflux_landuse_change += cp.acflux_harvest * donor_area / (double)stand.nobj;
					lc.acflux_landuse_change_lc[stand.landcover] += cp.acflux_harvest * donor_area / (double)stand.nobj;
					lc.anflux_landuse_change += cp.anflux_harvest * donor_area / (double)stand.nobj;
					lc.anflux_landuse_change_lc[stand.landcover] += cp.anflux_harvest * donor_area / (double)stand.nobj;

					// gridcell.acflux_landuse_change += -cp.debt_excess * donor_area / (double)stand.nobj;

					if(ifslowharvestpool) {
						to.transfer_harvested_products_slow[indiv.pft.id] += cp.harvested_products_slow * scale;
						to.transfer_harvested_products_slow_nmass[indiv.pft.id] += cp.harvested_products_slow_nmass * scale;
					}

					vegetation.nextobj();
				}

				stand.nextobj();
			}
		}
	}
}


/// Creates and kills stands at landcover change.
/** Harvest of reduced stands need to be done before with donor_stand_change().
 *  Should be followed by a call to receiving_stand_change() for transfer of
 *  carbon, nitrogen and water.
 *
 */
void stand_dynamics(Gridcell& gridcell) {

	stlist.firstobj();
	while (stlist.isobj) {
		StandType& st=stlist.getobj();
		Gridcellst& gcst = gridcell.st[st.id];
		landcovertype lc = st.landcover;

		bool expand_to_new_stand = gridcell.landcover.expand_to_new_stand[lc];

		if(gcst.gross_frac_increase || gcst.gross_frac_decrease || gcst.frac == 0.0) {

			double stand_sum = 0.0;
			Gridcell::iterator gc_itr = gridcell.begin();
			while (gc_itr != gridcell.end()) {
				Stand& stand = *gc_itr;
				if(stand.stid == st.id)
					stand_sum += stand.get_gridcell_fraction();
				++gc_itr;
			}

			// first stand created
			if((gcst.frac_old == 0.0 || stand_sum == 0.0) && gcst.gross_frac_increase > 0.0) {
				int npatch;
				if(date.year == 0)
					// with npatch=0, number of patches will be chosen in the stand constructor  
					npatch = 0;
				else
					npatch = npatch_secondarystand;
				Stand& stand = gridcell.create_stand_lu(st, gcst.gross_frac_increase, npatch);
			}
			// last stand killed
			else if(gcst.frac_old > 0.0 && !gcst.frac) {
				Gridcell::iterator gc_itr = gridcell.begin();
				while (gc_itr != gridcell.end()) {
					Stand& stand = *gc_itr;
					if(stand.stid == st.id) {
						gridcell.landcover.acflux_landuse_change += stand.ccont() * stand.get_gridcell_fraction();
						gridcell.landcover.anflux_landuse_change += stand.ncont() * stand.get_gridcell_fraction();
						gc_itr = gridcell.delete_stand(gc_itr);
					}
					else {
						++gc_itr;
					}
				}
			}
			else {
				if(expand_to_new_stand) {
					// new stand created from other landcover types (pooled option, not created in transfer_to_new_stand())
					if(gcst.gross_frac_increase > 0.0) {
						// Fewer patches in secondary stands if npatch_secondarystand < npatch:
						Stand& stand = gridcell.create_stand_lu(st, gcst.gross_frac_increase, npatch_secondarystand);
					}
				}
				// secondary stand killed if all of its area converted to other landcover types
				if(gcst.nstands > 1 && gcst.gross_frac_decrease > 0.0) {
					Gridcell::iterator gc_itr = gridcell.begin();
					while (gc_itr != gridcell.end()) {
						Stand& stand = *gc_itr;
						if(stand.stid == st.id && stand.get_gridcell_fraction() == 0) {
							gc_itr = gridcell.delete_stand(gc_itr);
							if(gcst.frac < 1e-14)
								gcst.frac = 0.0;
						}
						else {
							++gc_itr;
						}
					}
				}
			}
		}

		stlist.nextobj();
	}
}


 /// Transfers litter etc. of reduced stands to expanding stands at landcover change.
/** Transfers carbon, nitrogen and water of harvested area to expanded areas from a temporary struct.
 *  Is additive - can be called several times to the same landcover or standtype, if the parameter donorfrac_rel is used
 *
 *  INPUT PARAMETERS
 *
 *  \param landcover_change_transfer& from  struct containing the following pft-specific public members:
 *   - transfer_litter_leaf
 *   - transfer_litter_sap
 *   - transfer_litter_heart
 *   - transfer_litter_root
 *   - transfer_litter_repr
 *   - transfer_nmass_litter_leaf
 *   - transfer_nmass_litter_root
 *   - transfer_nmass_litter_sap
 *   - transfer_nmass_litter_heart
 *   - transfer_harvested_products_slow
 *   - transfer_harvested_products_slow_nmass
 *											,the following patch-level public members:
 *   - transfer_cpool_fast
 *   - transfer_cpool_slow
 *   - transfer_nmass_avail
 *   - transfer_cpool_slow
 *   - transfer_wcont_evap
 *   - transfer_snowpack
 *   - transfer_decomp_litter_mean
 *   - transfer_k_soilfast_mean
 *   - transfer_acflux_harvest
 *   - transfer_anflux_harvest
 *											,the following water soil layer-specific public member:
 *   - transfer_wcont
 *											and the following century soil pool-specific public members:
 *   - transfer_sompool.cmass
 *   - transfer_sompool.fireresist
 *   - transfer_sompool.fracremain
 *   - transfer_sompool.ligcfrac
 *   - transfer_sompool.nmass
 *   - transfer_sompool.ntoc
 *
 *  \param LCchangeCtransfer				whether to transfer carbon, nitrogen and water of reduced stands to expanding stands
 *  \param landcover						restricts receiving stands to a certain landcover, default no restriction
 *  \param stid								restricts receiving stands to a certain standtype, default no restriction
 *  \param donorfrac_rel					relative part of fraction (to a receiving stand) from a particular donor
 *  \param standid							restricts receiving stands to a certain stand, default no restriction
 */
void receiving_stand_change(Gridcell& gridcell, landcover_change_transfer& from,
		bool LCchangeCtransfer, int landcover = -1, int stid = -1,
		double donorfrac_rel = 1.0, int standid = -1) {

	Gridcell::iterator gc_itr = gridcell.begin();
	while (gc_itr != gridcell.end()) {
		Stand& stand = *gc_itr;

		if(stand.gross_frac_increase > 0.0 && (stand.landcover == landcover || landcover < 0) &&
				(stand.stid == stid || stid < 0 && (stand.id == standid || standid < 0))) {

			double old_frac = stand.frac_temp;
			double added_frac = donorfrac_rel * stand.gross_frac_increase;
			double new_frac = old_frac + added_frac;
			stand.frac_temp += added_frac;

			if(LCchangeCtransfer) {
				stand.firstobj();
				while(stand.isobj) {
					Patch& patch=stand.getobj();

					// add litter C & N:
					for (int i=0; i<npft; i++) {
						Patchpft& patchpft = patch.pft[i];

						patchpft.litter_leaf = (patchpft.litter_leaf * old_frac + from.transfer_litter_leaf[i] * added_frac) / new_frac;
						patchpft.litter_sap = (patchpft.litter_sap * old_frac + from.transfer_litter_sap[i] * added_frac) / new_frac;
						patchpft.litter_heart = (patchpft.litter_heart * old_frac + from.transfer_litter_heart[i] * added_frac) / new_frac;
						patchpft.litter_root = (patchpft.litter_root * old_frac + from.transfer_litter_root[i] * added_frac) / new_frac;
						patchpft.litter_repr = (patchpft.litter_repr * old_frac + from.transfer_litter_repr[i] * added_frac) / new_frac;

						patchpft.nmass_litter_leaf = (patchpft.nmass_litter_leaf * old_frac + from.transfer_nmass_litter_leaf[i] * added_frac) / new_frac;
						patchpft.nmass_litter_root = (patchpft.nmass_litter_root * old_frac + from.transfer_nmass_litter_root[i] * added_frac) / new_frac;
						patchpft.nmass_litter_sap = (patchpft.nmass_litter_sap * old_frac + from.transfer_nmass_litter_sap[i] * added_frac) / new_frac;
						patchpft.nmass_litter_heart = (patchpft.nmass_litter_heart * old_frac + from.transfer_nmass_litter_heart[i] * added_frac) / new_frac;

						if(ifslowharvestpool) {
							patchpft.harvested_products_slow = (patchpft.harvested_products_slow * old_frac + from.transfer_harvested_products_slow[i] * added_frac) / new_frac;
							patchpft.harvested_products_slow_nmass = (patchpft.harvested_products_slow_nmass * old_frac + from.transfer_harvested_products_slow_nmass[i] * added_frac) / new_frac;
						}
					}

					// add soil C & N:
					patch.soil.cpool_fast = (patch.soil.cpool_fast * old_frac + from.transfer_cpool_fast * added_frac) / new_frac;
					patch.soil.cpool_slow = (patch.soil.cpool_slow * old_frac + from.transfer_cpool_slow * added_frac) / new_frac;

					for(int i=0; i<NSOMPOOL; i++) {
						patch.soil.sompool[i].cmass = (patch.soil.sompool[i].cmass * old_frac + from.transfer_sompool[i].cmass * added_frac) / new_frac;
						patch.soil.sompool[i].fireresist = (patch.soil.sompool[i].fireresist * old_frac + from.transfer_sompool[i].fireresist * added_frac) / new_frac;
						patch.soil.sompool[i].fracremain = (patch.soil.sompool[i].fracremain * old_frac + from.transfer_sompool[i].fracremain * added_frac) / new_frac;
						patch.soil.sompool[i].ligcfrac = (patch.soil.sompool[i].ligcfrac *old_frac + from.transfer_sompool[i].ligcfrac * added_frac) / new_frac;
						patch.soil.sompool[i].litterme = (patch.soil.sompool[i].litterme * old_frac + from.transfer_sompool[i].litterme * added_frac) / new_frac;
						patch.soil.sompool[i].nmass = (patch.soil.sompool[i].nmass * old_frac + from.transfer_sompool[i].nmass * added_frac) / new_frac;
						patch.soil.sompool[i].ntoc = (patch.soil.sompool[i].ntoc * old_frac + from.transfer_sompool[i].ntoc * added_frac) / new_frac;
					}


					patch.soil.nmass_avail = (patch.soil.nmass_avail * old_frac + from.transfer_nmass_avail * added_frac) / new_frac;

					// ecev3 - check
					const double EPS = 1.0e-16;
					if (patch.soil.nmass_avail < 0.0) {
						if (patch.soil.nmass_avail >= -EPS)
							patch.soil.nmass_avail = 0.0; // Reset to 0 if negative but tiny
						else {
							dprintf("ERROR! Year %d day %d Stand %d: Negative soil.nmass_avail in receiving_stand_change: %.15f\n", date.year, date.day, patch.stand.id, patch.soil.nmass_avail);
							dprintf("%.15f %.15f %.15f\n", from.transfer_nmass_avail, added_frac, new_frac);
						}
					}

					// add other soil stuff:
					for(int i=0; i<NSOILLAYER; i++) {
						patch.soil.wcont[i] = (patch.soil.wcont[i] * old_frac + from.transfer_wcont[i] * added_frac) / new_frac;
					}
					patch.soil.wcont_evap = (patch.soil.wcont_evap * old_frac + from.transfer_wcont_evap * added_frac) / new_frac;

					patch.soil.snowpack = (patch.soil.snowpack * old_frac + from.transfer_snowpack * added_frac) / new_frac;
					patch.soil.snowpack_nmass = (patch.soil.snowpack_nmass * old_frac + from.transfer_snowpack_nmass * added_frac) / new_frac;

					patch.soil.decomp_litter_mean = (patch.soil.decomp_litter_mean * old_frac + from.transfer_decomp_litter_mean * added_frac) / new_frac;
					patch.soil.k_soilfast_mean = (patch.soil.k_soilfast_mean * old_frac + from.transfer_k_soilfast_mean * added_frac) / new_frac;
					patch.soil.k_soilslow_mean = (patch.soil.k_soilslow_mean * old_frac + from.transfer_k_soilslow_mean * added_frac) / new_frac;

					double aaet_5_cp[NYEARAAET] = {0.0};
					patch.aaet_5.to_array(aaet_5_cp);
					for(unsigned int i=0;i<from.transfer_aaet_5.size();i++)
						patch.aaet_5.add((aaet_5_cp[i] * old_frac + from.transfer_aaet_5[i] * added_frac) / new_frac);

					patch.soil.anfix_calc = (patch.soil.anfix_calc * old_frac + from.transfer_anfix_calc * added_frac) / new_frac;

					// save individual C and N content for use in scale_indiv()
					for(unsigned int i=0; i<patch.vegetation.nobj ;i++) {
						Individual& indiv = patch.vegetation[i];

						indiv.save_cmass_luc();
						indiv.save_nmass_luc();
					}

					stand.nextobj();
				}

				// set scaling factor to be used in growth() for scaling vegetation C and N:
				stand.scale_LC_change = (stand.frac_old - stand.gross_frac_decrease + min(0.0, stand.cloned_fraction)) / stand.get_gridcell_fraction();
				gridcell.landcover.updated = true;
			}
		}
		++gc_itr;
	}
}

enum {NONEWSTAND, CLONESTAND, CLONESTAND_KILLTREES, NEWSTAND_KILLALL};

/// contains rules for creation of new stands at land cover change
/** Options CLONESTAND and CLONESTAND_KILLTREES require that the receptor landcover
 *  allows growth of natural grass and/or tree PFTs
 *
 *  INTPUT PARAMETERS
 *
 *  \param landcover_donor				landcover type of donor stand
 *  \param landcover_receptor			landcover type of rexeptor stand
 */
int copy_stand_type(int landcover_donor, int landcover_receptor) {

	int copy_type = NONEWSTAND;

	if(landcover_donor == CROPLAND) {

		if(landcover_receptor == NATURAL || landcover_receptor == FOREST)
			copy_type = NEWSTAND_KILLALL;
	}
	else if(landcover_donor == PASTURE) {

		if(landcover_receptor == NATURAL || landcover_receptor == FOREST)
			copy_type = CLONESTAND;
	}
	else if(landcover_donor == NATURAL || landcover_donor == FOREST) {
		
		if(landcover_receptor == FOREST || landcover_receptor == NATURAL)
			copy_type = CLONESTAND;	// or CLONESTAND_KILLTREES/NEWSTAND_KILLALL for clearcut
	}

	return copy_type;
}

/// Creates unique stands from transfer events if copy_stand_type() returns >= 1 for landcovers combination
/** Either clones donor stand or creates new stand from scratch
 *
 *  INPUT PARAMETERS
 *
 *  \param stid_donor  						donor stand type
 *  \param stid_receptor 					receptor stand type
 */
double transfer_to_new_stand(Gridcell& gridcell, int stid_donor, int stid_receptor) {

	double cloned_area = 0.0;

	for(unsigned int i=0; i<gridcell.nbr_stands(); i++) {

		Stand& stand = gridcell[i];
		double transfer_area = stand.transfer_area_st[stid_receptor];

		if(transfer_area > 0.0 && (stand.stid == stid_donor || stid_donor < 0)) {

			int copy_type = copy_stand_type(stand.landcover, stlist[stid_receptor].landcover);	// NONEWSTAND, CLONESTAND, CLONESTAND_KILLTREES, NEWSTAND_KILLALL

			if(copy_type) {

				if(copy_type == CLONESTAND || copy_type == CLONESTAND_KILLTREES) {

					Stand& new_stand = stand.clone(stlist[stid_receptor], transfer_area);

					if(stand.landcover == NATURAL && (stlist[stid_receptor].naturalveg == ""))
						dprintf("WARNING: cloning natural stand without allowing natural pft:s to grow in the new stand. Was this intended ?\n");

					landcover_change_transfer transfer;

					new_stand.cloned = true;
					new_stand.gross_frac_increase = 0.0;
					new_stand.frac_change = 0.0;
					new_stand.cloned_fraction = transfer_area;
					new_stand.origin = stand.landcover;

					new_stand.firstobj();
					while(new_stand.isobj) {
						Patch& patch = new_stand.getobj();
						Vegetation& vegetation = patch.vegetation;
						vegetation.firstobj();
						while(vegetation.isobj) {

							Individual& indiv = vegetation.getobj();
							Standpft& standpft = new_stand.pft[indiv.pft.id];

							if(!standpft.active) {
								// Treatment of pft individuals not allowed to grow anymore in the new stand:
								// Clearcut
								harvest_wood(indiv, 1.0, 1.0, 0.95, 0.9, true);	// frac_cut=1, harv_eff=1, res_outtake_twig=0.95, res_outtake_coarse_root=0.9
								// Grass killed, C+N goes to soil
								kill_remaining_vegetation(indiv);
								vegetation.killobj();
							}
							else if(copy_type == CLONESTAND_KILLTREES && indiv.pft.lifeform != GRASS) {
								harvest_wood(indiv, 1.0, 1.0, 0.95, 0.9, true);	// frac_cut=1, harv_eff=1, res_outtake_twig=0.95, res_outtake_coarse_root=0.9
								vegetation.killobj();
							}
							else {
								vegetation.nextobj();
							}
						}
						new_stand.nextobj();
					}
				}
				else if(copy_type == NEWSTAND_KILLALL) {

					landcover_change_transfer transfer;

					lc_change_harvest_params harvest_params;

					// default values for natural to cropland transition
					harvest_params.harv_eff = 1.0;
					harvest_params.res_outtake_twig = 0.95;
					harvest_params.res_outtake_coarse_root = 0.9;

					donor_stand_change(gridcell, transfer_area, transfer, -1,-1, stid_receptor, -1, stand.id, &harvest_params);
					Stand& new_stand = gridcell.create_stand_lu(stlist[stid_receptor], transfer_area, npatch_secondarystand);
					receiving_stand_change(gridcell, transfer, true, -1, -1, 1.0, new_stand.id);

					new_stand.cloned = true;
					new_stand.gross_frac_increase = 0.0;
					new_stand.frac_change = 0.0;
					new_stand.cloned_fraction = transfer_area;
				}

				cloned_area += transfer_area;
				stand.cloned_fraction -= transfer_area;
				gridcell.st[stid_donor].gross_frac_decrease -= transfer_area;
				gridcell.st[stid_donor].frac_change += transfer_area;
				stand.gross_frac_decrease -= transfer_area;
				stand.frac_change += transfer_area;
				stand.transfer_area_st[stid_receptor] -= transfer_area;
				gridcell.st[stid_receptor].gross_frac_increase -= transfer_area;
				gridcell.st[stid_receptor].frac_change -= transfer_area;

				if(gridcell.st[stid_donor].gross_frac_decrease < INPUT_RESOLUTION * 0.1)
					gridcell.st[stid_donor].gross_frac_decrease = 0.0;
				if(stand.gross_frac_decrease < INPUT_RESOLUTION * 0.1)
					stand.gross_frac_decrease = 0.0;
				if(stand.transfer_area_st[stid_receptor] < INPUT_RESOLUTION * 0.1)
					stand.transfer_area_st[stid_receptor] = 0.0;
				if(gridcell.st[stid_receptor].gross_frac_increase < INPUT_RESOLUTION * 0.1)
					gridcell.st[stid_receptor].gross_frac_increase = 0.0;
			}
		}
	}

	return cloned_area;
}

/// Simulates gross landcover change by adding a specified fraction to the lc_frac_transfer array
void simulate_gross_lc_transfer(Gridcell& gridcell, double lc_frac_transfer[][NLANDCOVERTYPES]) {

	// Added gross fraction transfer as percentage of the lesser of two stand types belonging to certain landcover types
	double gross_lc_change_frac[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};
	gross_lc_change_frac[CROPLAND][NATURAL] = 0.05;
	gross_lc_change_frac[NATURAL][CROPLAND] = 0.05;
	gross_lc_change_frac[CROPLAND][PASTURE] = 0.05;
	gross_lc_change_frac[PASTURE][CROPLAND] = 0.05;
	gross_lc_change_frac[PASTURE][NATURAL] = 0.05;
	gross_lc_change_frac[NATURAL][PASTURE] = 0.05;
	gross_lc_change_frac[FOREST][NATURAL] = 0.05;
	gross_lc_change_frac[NATURAL][FOREST] = 0.05;
	gross_lc_change_frac[FOREST][PASTURE] = 0.05;
	gross_lc_change_frac[PASTURE][FOREST] = 0.05;

	Landcover& lc = gridcell.landcover;
	for(int from=0; from<NLANDCOVERTYPES; from++) {

		for(int to=0; to<NLANDCOVERTYPES; to++) {

			lc_frac_transfer[from][to] += gross_lc_change_frac[from][to] * min(lc.frac_old[from], lc.frac_old[to]);
		}
	}
}


/// Simulates gross landcover change by adding a specified fraction to the st_frac_transfer array
void simulate_gross_st_transfer(Gridcell& gridcell, double* st_frac_transfer) {

	// Added gross fraction transfer as percentage of the lesser of two stand types belonging to certain landcover types
	double gross_lc_change_frac[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};
	gross_lc_change_frac[CROPLAND][NATURAL] = 0.05;
	gross_lc_change_frac[NATURAL][CROPLAND] = 0.05;
	gross_lc_change_frac[CROPLAND][PASTURE] = 0.05;
	gross_lc_change_frac[PASTURE][CROPLAND] = 0.05;
	gross_lc_change_frac[PASTURE][NATURAL] = 0.05;
	gross_lc_change_frac[NATURAL][PASTURE] = 0.05;
	gross_lc_change_frac[FOREST][NATURAL] = 0.05;
	gross_lc_change_frac[NATURAL][FOREST] = 0.05;
	gross_lc_change_frac[FOREST][PASTURE] = 0.05;
	gross_lc_change_frac[PASTURE][FOREST] = 0.05;

	for(int from=0; from<nst; from++) {

		StandType& st_donor = stlist[from];
		Gridcellst& gcst_donor = gridcell.st[from];

		for(int to=0; to<nst; to++) {

			StandType& st_receptor = stlist[to];
			Gridcellst& gcst_receptor = gridcell.st[to];

			if(gross_lc_change_frac[st_donor.landcover][st_receptor.landcover]) {

				// All stand types with an area:
				st_frac_transfer[index(from, to)] += gross_lc_change_frac[st_donor.landcover][st_receptor.landcover]
					* min(min(gcst_donor.frac_old, gcst_donor.frac), min(gcst_receptor.frac_old, gcst_receptor.frac));
			}
		}
	}
}

/// Called after update of st fraction and transfer values
bool check_fractions(Gridcell& gridcell, double landcoverfrac_change[], double lc_change_array[][NLANDCOVERTYPES], 
		double* st_change_array, bool check_lc_st_transfer = false) {

	bool error = false;

	// Check that landcover sum is 1:
	double lc_frac_sum = 0.0;
	for(int i=0; i<NLANDCOVERTYPES; i++)
		lc_frac_sum += gridcell.landcover.frac[i];

	if(!negligible(lc_frac_sum - 1.0, CHECK_NLIM)) {
		dprintf("\nCheck 1: Year %d: landcover fraction sum: %.15f", date.get_calendar_year(), lc_frac_sum);
		error = true;
	}
	/////////

	// Check that stand type sum is 1:
	double st_frac_sum = 0.0;
	for(int i=0; i<nst; i++)
		st_frac_sum += gridcell.st[i].frac;
	if(fabs(st_frac_sum - 1.0)  > INPUT_RESOLUTION * 10.0) {
		dprintf("\nCheck 2: Year %d: stand type fraction sum: %.15f", date.year, st_frac_sum);
		error = true;
	}
	/////////

	// Test if the sum of gross lcc for a landcover is the same as net lcc:
	double test_lc_change[NLANDCOVERTYPES] = {0.0};

	for(int from=0; from<NLANDCOVERTYPES; from++) {

		for(int to=0; to<NLANDCOVERTYPES; to++) {

			test_lc_change[from] -= lc_change_array[from][to];
			test_lc_change[to] += lc_change_array[from][to];
		}
	}

	for(int i=0; i<NLANDCOVERTYPES; i++) {

		if(fabs(test_lc_change[i] - landcoverfrac_change[i]) > INPUT_RESOLUTION * 10.0) {
			dprintf("\nCheck 3: Year %d: lc_change_array sum not equal to landcoverfrac_change value for landcover %d\n", date.year, i);
			dprintf("dif=%.15f", test_lc_change[i] - landcoverfrac_change[i]);
			error = true;
		}
	}
	////////////

	// Test if the sum of gross lcc for a stand type is the same as net lcc:
	double *test_st_change;
	test_st_change = new double[nst];
	for(int i=0;i<nst;i++) {
		test_st_change[i] = 0.0;
	}

	for(int from=0; from<nst; from++) {

		for(int to=0; to<nst; to++) {

			test_st_change[from] -= st_change_array[index(from, to)];
			test_st_change[to] += st_change_array[index(from, to)];
		}
	}

	for(int i=0; i<nst; i++) {

		StandType& st = stlist[i];
		Gridcellst& gcst = gridcell.st[i];

		if(fabs(test_st_change[i] - gcst.frac_change) > INPUT_RESOLUTION * 10.0) {
			dprintf("\nCheck 4: Year %d: st_change_array sum not equal to st.frac_change value for stand type %d\n", date.year, i);
			dprintf("dif=%.15f", test_st_change[i] - gcst.frac_change);
			error = true;
		}
	}
	if(test_st_change)
		delete[] test_st_change;
	////////////

	// Test if st_change_array is compatible with st.frac_old/frac values
	for(int from=0; from<nst; from++) {

		StandType& st_donor = stlist[from];
		Gridcellst& gcst_donor = gridcell.st[from];

		for(int to=0; to<nst; to++) {

			StandType& st_receptor = stlist[to];
			Gridcellst& gcst_receptor = gridcell.st[to];
			if(st_change_array[index(from, to)] > (gcst_donor.frac_old + INPUT_RESOLUTION) || st_change_array[index(from, to)] > (gcst_receptor.frac + INPUT_RESOLUTION)) {
				dprintf("\nCheck 5: Year %d: st_change_array sum not compatible with st.frac_old/frac values for stand types %d and %d\n", date.year, from, to);
				dprintf("st_change_array=%.15f, st_donor.frac_old=%.15f, st_receptor.frac=%.15f", st_change_array[index(from, to)], gcst_donor.frac_old, gcst_receptor.frac);
				error = true;
			}
		}
	}

	// Test if stand type and landcover transfer matrices match each other:
	if(check_lc_st_transfer) {
		double lc_change[NLANDCOVERTYPES] = {0.0};
		double lc_change_arr[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};

		for(int from=0; from<nst; from++) {

			StandType& st = stlist[from];

			for(int to=0; to<nst; to++) {

				StandType& st_dest = stlist[to];

				lc_change[st.landcover] -= st_change_array[index(from, to)];
				lc_change[st_dest.landcover] += st_change_array[index(from, to)];
				lc_change_arr[st.landcover][st_dest.landcover] += st_change_array[index(from, to)];
			}
		}

		for(int i=0; i<NLANDCOVERTYPES; i++) {

			if(fabs(lc_change[i] - landcoverfrac_change[i]) > INPUT_RESOLUTION * 10.0) {
				dprintf("\nCheck 6: Year %d: st_change_array LC sum not equal to LC value for %d\n", date.year, i);
				dprintf("dif=%.15f", fabs(lc_change[i] - landcoverfrac_change[i]));
				error = true;
			}
		}

		for(int from=0; from<NLANDCOVERTYPES; from++) {

			for(int to=0; to<NLANDCOVERTYPES; to++) {

				if(fabs(lc_change_arr[from][to] - lc_change_array[from][to]) > INPUT_RESOLUTION * 10.0) {
					dprintf("\nCheck 7: Year %d: lc_change_arr sum not equal to lc_change_array value for %d, %d\n", date.year, from, to);
					dprintf("dif=%.15f", lc_change_arr[from][to] - lc_change_array[from][to]);
					error = true;
				}
			}
		}
		// Test that no lc transfers are negative:
		for(int from=0; from<NLANDCOVERTYPES; from++) {

			for(int to=0; to<NLANDCOVERTYPES; to++) {

				if(lc_change_array[from][to] < 0.0) {
					dprintf("\nCheck 7b: Year %d: Negative lc_change_array[%d][%d]: %.15f\n", date.year, from, to, lc_change_array[from][to]);
					error = true;
				}
			}
		}
	}

	if(error)
		dprintf("\n\n");

	return error;
}

/// Called before updating stand.frac (reduce_stands)
bool check_fractions1(Gridcell& gridcell) {

	bool error = false;

	// Test if the stand type reduction is smaller than the remaining stand sum:
	for(int s=0; s<nst; s++) {

		StandType& st = stlist[s];
		Gridcellst& gcst = gridcell.st[s];

		if(gcst.frac_change < 0.0){

			double stands_frac_sum = 0.0;

			for(unsigned int i = 0; i < gridcell.nbr_stands(); i++) {
				Stand& stand = gridcell[i];

				if(stand.stid == st.id)
					stands_frac_sum += stand.get_gridcell_fraction();
			}

			if(-gcst.frac_change - stands_frac_sum > INPUT_RESOLUTION * 10.0) {
				dprintf("\nCheck 8: Year %d: stand type %d fraction reduction bigger than sum of stands\n", date.year, s);
				dprintf("dif=%.15f", -gcst.frac_change - stands_frac_sum);
				error = true;
			}
		}
	}
	if(error)
		dprintf("\n\n");

	return error;
}

/// Called after updating stand.frac and transfer values (reduce_stands)
bool check_fractions2(Gridcell& gridcell, double* st_change_array) {

	bool error = false;

	// Test if stand.transfer_area_st[to] sum for a stand type is equal to st_change_array[from][to)]
	for(int from=0; from<nst; from++) {

		StandType& st = stlist[from];

		for(int to=0; to<nst; to++) {

			double *test_st_change;
			test_st_change = new double[nst];
			for(int i=0;i<nst;i++)
				test_st_change[i] = 0.0;

			for(unsigned int i=0; i<gridcell.nbr_stands(); i++) {

				Stand& stand = gridcell[i];

				if(stand.stid == st.id)
					test_st_change[to] += stand.transfer_area_st[to];
			}

			if(fabs(test_st_change[to] - st_change_array[index(from, to)]) > INPUT_RESOLUTION * 100.0) {
				dprintf("\nCheck 9: Year %d: stand transfer area sum not equal to stand type value for stand types %d and %d\n", date.year, from, to);
				dprintf("dif=%.15f", fabs(test_st_change[to] - st_change_array[index(from, to)]));
				error = true;
			}

			if(test_st_change)
				delete[] test_st_change;
		}
	}
	////////////

	// Test if stand.frac_change for a stand is equal to stand.gross_frac_increase + stand.gross_frac_decrease:
	for(unsigned int i=0; i<gridcell.nbr_stands(); i++) {

		Stand& stand = gridcell[i];

		if(largerthanzero(stand.frac_change - (stand.gross_frac_increase - stand.gross_frac_decrease), CHECK_NLIM+1)) {
			dprintf("\nCheck 10: Year %d: frac_change is not equal to gross_frac_increase + gross_frac_decrease for stand %d\n", date.get_calendar_year(), stand.id);
			dprintf("dif=%.15f\n", fabs(stand.frac_change - (stand.gross_frac_increase - stand.gross_frac_decrease)));
			dprintf("frac_change=%.15f, gross_frac_increase=%.15f, gross_frac_decrease=%.15f", stand.frac_change, stand.gross_frac_increase, stand.gross_frac_decrease);
			error = true;
		}
	}
	////////////

	// Test that no stands remain when stand type fraction is 0 (after reduce_stands, so stands may remain, but with frac 0):
	for(int s=0; s<nst; s++) {

		StandType& st = stlist[s];
		Gridcellst& gcst = gridcell.st[s];

		if(gcst.frac == 0.0) {

			double stands_frac_sum = 0.0;

			for(unsigned int i = 0; i < gridcell.nbr_stands(); i++) {
				Stand& stand = gridcell[i];

				if(stand.stid == st.id)
					stands_frac_sum += stand.get_gridcell_fraction();
			}

			if(stands_frac_sum) {
				dprintf("\nCheck 11: Year %d: remaining stand when stand type %d fraction is 0\n", date.get_calendar_year(), s);
				dprintf("remain=%.20f", stands_frac_sum);
				error = true;
			}
		}
	}

	if(error)
		dprintf("\n\n");

	return error;
}

/// Called after updating stand.frac and transfer values of reduced stands (reduce_stands)
bool check_fractions3(Gridcell& gridcell) {

	bool error = false;

	// Test if sum of stands not equal to stand type value for stand type for reduced stands
	for(int s=0; s<nst; s++) {

		StandType& st = stlist[s];
		Gridcellst& gcst = gridcell.st[s];

		double stands_frac_sum = 0.0;

		for(unsigned int i = 0; i < gridcell.nbr_stands(); i++) {
			Stand& stand = gridcell[i];

			if(stand.stid == st.id)
				stands_frac_sum += stand.get_gridcell_fraction();
		}

		if(gcst.frac_change < 0.0) {
			if(fabs(gcst.frac - stands_frac_sum - gcst.gross_frac_increase) > INPUT_RESOLUTION * 100.0) {
				dprintf("\nCheck 12: Year %d: fraction sum of stands not equal to stand type value for stand type %d\n", date.year, s);
				dprintf("dif=%.15f", fabs(gcst.frac - stands_frac_sum - gcst.gross_frac_increase));
				error = true;
			}
		}
	}
	if(error)
		dprintf("\n\n");

	return error;
}

/// Called after creating new stands (stand_dynamics)
bool check_fractions4(Gridcell& gridcell) {

	bool error = false;

	// Test if sum of stands not equal to stand type value for stand type for increased or new stands
	for(int s=0; s<nst; s++) {

		StandType& st = stlist[s];
		Gridcellst& gcst = gridcell.st[s];

		double stands_frac_sum = 0.0;

		for(unsigned int i = 0; i < gridcell.nbr_stands(); i++) {
			Stand& stand = gridcell[i];

			if(stand.stid == st.id) {
				stands_frac_sum += stand.get_gridcell_fraction();
			}
		}

		if(gcst.frac_change >= 0.0) {
			if(gcst.frac && !stands_frac_sum) {
				dprintf("\nCheck 13a: Year %d: no stand present when fraction is > 0 for stand type %d\n", date.year, s);
				dprintf("st frac=%.15f\n\n", gcst.frac);
			}
			else if(fabs(gcst.frac - stands_frac_sum) > INPUT_RESOLUTION * 100.0) {
				dprintf("\nCheck 13: Year %d: fraction sum of stands not equal to stand type value for stand type %d\n", date.year, s);
				dprintf("dif=%.15f", fabs(gcst.frac - stands_frac_sum));
				error = true;
			}
		}
	}
	if(error)
		dprintf("\n\n");

	return error;
}

/// Gets this year's landcover and crop area fractions, landcover transitions and checks that area changes are significant.
/** Stores changes in area fractions for the stand types
 *
 *  OUTPUT PARAMETERS
 *  \param LCchangeCtransfer				whether to transfer carbon, nitrogen and water of reduced stands to expanding stands
 */
bool lc_changed(Gridcell& gridcell, bool& LCchangeCtransfer, InputModule* input_module) {

	double stfrac_sum_old[NLANDCOVERTYPES] = {0.0};
	double change_stand = 0.0;
	double changeLC = 0.0;
	double change_st = 0.0;
	double transferred_fraction = 0.0;
	double receiving_fraction = 0.0;
	bool change = true;
	bool force_small_change = false;
	Landcover& lc = gridcell.landcover;

	// Get new gridcell.landcoverfrac and/or standtype.frac from LUdata and CFTdata

	input_module->getlandcover(gridcell);	

	// Check if any changes in land fractions have been made

	for(unsigned int i = 0; i < gridcell.st.nobj; i++) {
		Gridcellst& gcst = gridcell.st[i];
		stfrac_sum_old[gcst.st.landcover] += gcst.frac_old;
		if(fabs(gcst.frac_change) && (!gcst.frac || !gcst.frac_old))
			force_small_change = true;
	}


	for(int i=0; i<NLANDCOVERTYPES; i++) {
		changeLC += fabs(lc.frac_change[i]) / 2.0;
	}


	for(int lc=0; lc<NLANDCOVERTYPES; lc++) {

		if(run[lc] && (!frac_fixed[lc] || !lcfrac_fixed)) {

			for(unsigned int i = 0; i < gridcell.st.nobj; i++) {
				Gridcellst& gcst = gridcell.st[i];

				if(gcst.st.landcover == lc) {

					double stfrac_change = gcst.frac_change;

					if(stfrac_change < 0.0)
						transferred_fraction -= stfrac_change;
					else if(stfrac_change > 0.0)
						receiving_fraction += stfrac_change;

					if(stfrac_sum_old[lc] != 0.0) {
						change_st += fabs(stfrac_change) / 2.0;
					}
					else {
						change_st += fabs(stfrac_change);
					}
					change_stand += fabs(stfrac_change) / 2.0;
				}
			}
		}
	}

	double change_gross_lcc = 0.0;
	for(int from=0; from<NLANDCOVERTYPES; from++) {
		if(run[from]) {
			for(int to=0; to<NLANDCOVERTYPES; to++) {
				if(run[to]) {
					change_gross_lcc += lc.frac_transfer[to][from];
				}
			}
		}
	}

	// if no changes, do nothing.
	if(changeLC < INPUT_RESOLUTION * 0.1 && change_st < INPUT_RESOLUTION * 0.1 && change_gross_lcc < INPUT_RESOLUTION * 0.1 && !force_small_change) {
		change = false;
	}
	// check for balance of reduced and increased stand fractions
	else {
		if(fabs(transferred_fraction - receiving_fraction) > 0.0001 || fabs(change_stand-receiving_fraction) > 0.0001) {
			if(run[CROPLAND] && run[NATURAL] && run[PASTURE]) {
				// end program if balance is expected (no landcovers inactivated)
				FAIL("Transferred landcover fractions not balanced ! Abort. \n");
			}
			else {
				// allow program to continue, but inactivate landcover change mass transfer 
				LCchangeCtransfer = false;
				dprintf("Transferred landcover fractions not balanced !\nLandcover change fluxes not calculated.\n");
			}
		}
		change = true;
	}

	return change;
}

/// Transfers harvested forest area to transition matrix
bool transfer_harvested_fractions(Gridcell& gridcell, double lc_frac_transfer[][NLANDCOVERTYPES], forest_lc_frac_transfer& forest_lc_frac_transfer_s) {

	bool transfer_harvest = false;

	if(gridcell.landcover.wood_harvest.prim_frac > 0.0) {
		lc_frac_transfer[NATURAL][NATURAL] += gridcell.landcover.wood_harvest.prim_frac;
		forest_lc_frac_transfer_s.primary[NATURAL][NATURAL] += gridcell.landcover.wood_harvest.prim_frac;
		use_primary_lc_transfer = true;
		transfer_harvest = true;
	}
	if(harvest_secondary_to_new_stand && gridcell.landcover.wood_harvest.sec_mature_frac + gridcell.landcover.wood_harvest.sec_young_frac > 0.0) {
		lc_frac_transfer[NATURAL][NATURAL] += gridcell.landcover.wood_harvest.sec_mature_frac;
		lc_frac_transfer[NATURAL][NATURAL] += gridcell.landcover.wood_harvest.sec_young_frac;
		forest_lc_frac_transfer_s.secondary_young[NATURAL][NATURAL] += gridcell.landcover.wood_harvest.sec_young_frac;
		transfer_harvest = true;
	}

	return transfer_harvest;
}

/// Updates all landcover, stand type and stand area fractions each year, possibly resulting in the creation and killing of stands.
/** Harvests transferred areas and transfers litter etc. of reduced stands to expanding stands and harvested matter to fluxes
 *  and (in the case of wood) to long-lived pools.
 *
 *  Land cover fraction files need to be read together with gross land transition files. Net and gross land cover change is 
 *  expected to be compatible, although rounding errors are handled by the input code.
 *
 *  If instruction file parameter iftransfer_to_new_stand is true, new stands may be created for separate land transfers  
 *  in transfer_to_new_stand(), according to rules in copy_stand_type().
 *
 *  Otherwise, new transferred areas are pooled according to instruction file parameter transfer_level (0: one big pool; 1: land cover-level; 
 *  2: stand type-level) and rules in the gridcell arrays pool_from_all_landcovers[to] and pool_to_all_landcovers[from], set
 *  in the Gridcell constructor.
 *  New stands may then be created in stand_dynamics() from the pooled land if the gridcell array expand_to_new_stand[lc] value for the 
 *  receiving land cover, set in the Gridcell constructor, is true (natural and forest).
 *  If not, soil and litter carbon and nitrogen as well as water is pooled with the receiving stands (cropland, pasture).
 *
 *  Transferred land with living plant mass after land cover change should be put in new stands, using the stand cloning mode in 
 *  transfer_to_new_stand(). Stands with living plant mass should not be pooled with newly transferred land, unconditionally so 
 *  if they contain trees (pasture can be expanded without too much problems). New stands should instead be created, either in stand_dynamics()
 *  or transfer_to_new_stand() as described above.
 */
void landcover_dynamics(Gridcell& gridcell, InputModule* input_module) {

	// ecev3
	int year = date.get_calendar_year();
	if (false && ECEARTH && gridcell.fixedLUafter >= 0 && year >= gridcell.fixedLUafter ) {
		dprintf("Return from landcover_dynamics: fixedLUfter = %d \n", year);
		return;
	}

	double* st_frac_transfer = NULL;
	forest_st_frac_transfer forest_st_frac_transfer_s(nst);
	bool LCchangeCtransfer = true;
	Landcover& lc = gridcell.landcover;

	st_frac_transfer = new double[nst * nst];

	for (int i = 0; i<nst; i++) {

		gridcell.st[i].gross_frac_increase = 0.0;
		gridcell.st[i].gross_frac_decrease = 0.0;
	}

	for(int i=0;i<NLANDCOVERTYPES;i++) {

		lc.frac_change[i] = 0.0;

		for(int j=0;j<NLANDCOVERTYPES;j++) {
			lc.frac_transfer[i][j] = 0.0;
			lc.forest_lc_frac_transfer_s.primary[i][j] = 0.0;
			lc.forest_lc_frac_transfer_s.secondary_young[i][j] = 0.0;
		}
	}
	for(int i=0;i<nst*nst;i++) {
		st_frac_transfer[i] = 0.0;
		forest_st_frac_transfer_s.primary[i] = 0.0;
		forest_st_frac_transfer_s.secondary_young[i] = 0.0;
	}

	gridcell.landcover.updated = false;

	for(unsigned int i=0; i<gridcell.nbr_stands(); ++i)
		gridcell[i].scale_LC_change = 1.0;

	bool no_changes = true;

	// Transfer area to new stands during wood harvest.
	if(transfer_harvested_fractions(gridcell, lc.frac_transfer, lc.forest_lc_frac_transfer_s))
		no_changes = false;

	// Rescale stand fractions so sum is 1
	stlist.firstobj();
	while (stlist.isobj) {
		StandType& st = stlist.getobj();
		Gridcellst& gcst = gridcell.st[st.id];
		double frac_sum = 0.0;

		for(unsigned int s=0;s<gridcell.nbr_stands();s++) {
			Stand& stand = gridcell[s];
			if(stand.stid == st.id)
				frac_sum += stand.get_gridcell_fraction();
		}
		for(unsigned int s=0;s<gridcell.nbr_stands();s++) {
			Stand& stand = gridcell[s];
			if(stand.stid == st.id && frac_sum && gcst.frac)
				stand.set_gridcell_fraction(stand.get_gridcell_fraction() / (frac_sum / gcst.frac));
		}
		stlist.nextobj();
	}

	// Get new landcover and stand type area fractions from input files, read transition arrays.
	if(!all_fracs_const) {
		// this call returns 0, causing this function to return, if no significant landcover changes this year, 
		// sets LCchangeCtransfer to 0 if unbalanced landcover changes (if some landcovers are inactivated), thus inactivating transfer of C and N
		if(lc_changed(gridcell, LCchangeCtransfer, input_module)) {
			no_changes = false;
		}
	}
	//CLN LUCHANGE HERE
	if(no_changes) {
		delete[] st_frac_transfer;
		return;
	}

	// Transfer all landcover changes to stand type transition matrix, if not already done.

	if(gross_land_transfer == 3) {

		// Option to read stand type transitions from file.
		fail("Currently no code for option gross_land_transfer==3\n");
	}
	else if(gross_land_transfer == 2 && gross_input_present) {

		// Option to read landcover transitions from file. Update the st_frac_transfer array.
		set_st_change_array(gridcell, lc.frac_transfer, st_frac_transfer, lc.forest_lc_frac_transfer_s, forest_st_frac_transfer_s);
		if(check_fractions(gridcell, lc.frac_change, lc.frac_transfer, st_frac_transfer, true))
			dprintf("Fraction error after set_st_change_array()\n\n");
	}
	else {

		// Option not to read landcover or stand type transitions or to simulate these.
		// The st_frac_transfer array always needs to be updated.

		const bool simulate_st = true;	// gross lcc simulation at land cover level (false) or stand type level (true)

		set_lc_change_array(lc.frac_change, lc.frac_transfer);

		if(gross_land_transfer && !simulate_st)
			simulate_gross_lc_transfer(gridcell, lc.frac_transfer);
		// The lc_frac_transfer-array may contain overshoots if wood harvest with fraction transfer occurred.
		double dummy;
		adjust_gross_transfers(gridcell, lc.frac_change, lc.frac_transfer, lc.forest_lc_frac_transfer_s, dummy);
		set_st_change_array(gridcell, lc.frac_transfer, st_frac_transfer, lc.forest_lc_frac_transfer_s, forest_st_frac_transfer_s);

		if(check_fractions(gridcell, lc.frac_change, lc.frac_transfer, st_frac_transfer, true))
			dprintf("Fraction error after set_st_change_array()\n\n");

		if(gross_land_transfer && simulate_st)
			simulate_gross_st_transfer(gridcell, st_frac_transfer);
	}

	check_fractions(gridcell, lc.frac_change, lc.frac_transfer, st_frac_transfer);
	check_fractions1(gridcell);

	for(int from=0; from<nst; from++) {

		for(int to=0; to<nst; to++) {

			if(st_frac_transfer[index(from, to)] > 0.0) {
				gridcell.st[to].gross_frac_increase += st_frac_transfer[index(from, to)];
				gridcell.st[from].gross_frac_decrease += st_frac_transfer[index(from, to)];
			}
		}
	}

	double ccont_tot_1 = gridcell.ccont();
	double cflux_tot_1 = gridcell.cflux();
	double ncont_tot_1 = gridcell.ncont();
	double nflux_tot_1 = gridcell.nflux();

	// check how many stands of each stand type exist
	// identify which stands to reduce in area
	// set stand variables frac, frac_old, frac_change and gross_frac_decrease for reduced stands and stand types
	reduce_stands(gridcell, st_frac_transfer, forest_st_frac_transfer_s);

	int error = check_fractions2(gridcell, st_frac_transfer);
	error += check_fractions3(gridcell);
	if(error) {
		FAIL("Fraction error after reduce_stands()\n\n");
	}

	// Create new stands for land cover transitions when natural vegetation remains or when each transition requires a new stand:
	if(iftransfer_to_new_stand) {
		bool new_stand = false;
		for(int from=0; from<nst; from++) {
			for(int to=0; to<nst; to++) {
				if(st_frac_transfer[index(from, to)] > 0.0) {
					double new_stand_frac = transfer_to_new_stand(gridcell, from, to);
					if(new_stand_frac) {
						st_frac_transfer[index(from, to)] -= new_stand_frac;
						if(st_frac_transfer[index(from, to)] < INPUT_RESOLUTION * 0.1)
							st_frac_transfer[index(from, to)] = 0.0;
						new_stand = true;
					}
				}
			}
		}

		if(new_stand) {
			int error = check_fractions(gridcell, lc.frac_change, lc.frac_transfer, st_frac_transfer);
			error += check_fractions2(gridcell, st_frac_transfer);
			if(error)
				dprintf("Fraction error after transfer_to_new_stand()\n\n");
		}
	}

	// set stand variables frac, frac_change and gross_frac_increase for expanding stands and stand types
	expand_stands(gridcell, st_frac_transfer);

	error += check_fractions(gridcell, lc.frac_change, lc.frac_transfer, st_frac_transfer);
	error += check_fractions2(gridcell, st_frac_transfer);
	if(error)
		FAIL("Fraction error after expand_stands()\n");


	// Pooling options
	// transfer_level: 0: one big pool; 1: land cover-level; 2: stand type-level

	if(transfer_level == 0) {	// One big pool for all transfers (as in old code)

		landcover_change_transfer transfer;
		double receiving_fraction = 0.0;

		for(int from=0; from<nst; from++) {

			for(int to=0; to<nst; to++) {

				if(st_frac_transfer[index(from, to)] > 0.0)
					receiving_fraction += st_frac_transfer[index(from, to)];
			}
		}

		 // handle harvest and turnover of reduced stands at landcover change
		donor_stand_change(gridcell, receiving_fraction, transfer);

		// create and kill stands at landcover change
		stand_dynamics(gridcell);
		error += check_fractions4(gridcell);
		if(error)
			fail("Fraction error after stand_dynamics()\n");

		// transfer litter etc. of reduced stands to expanding stands at landcover change
		receiving_stand_change(gridcell, transfer, LCchangeCtransfer);
	}
	else if(transfer_level == 1) {	// Landcover-level pools, larger pools available by the gridcell variables pool_from_all_landcovers and pool_to_all_landcovers (set in gridcell constructor)

		landcover_change_transfer transfer_lc_2d[NLANDCOVERTYPES][NLANDCOVERTYPES];
		landcover_change_transfer transfer_lc[NLANDCOVERTYPES];
		landcover_change_transfer transfer_lc_from[NLANDCOVERTYPES];
		double gross_landcoverfrac_increase[NLANDCOVERTYPES] = {0.0};
		double gross_landcoverfrac_decrease[NLANDCOVERTYPES] = {0.0};
		double gross_landcoverfrac_transfer[NLANDCOVERTYPES][NLANDCOVERTYPES] = {0.0};

		for(int from=0; from<nst; from++) {

			for(int to=0; to<nst; to++) {

				if(st_frac_transfer[index(from, to)] > 0.0) {

					gross_landcoverfrac_increase[stlist[to].landcover] += st_frac_transfer[index(from, to)];
					gross_landcoverfrac_decrease[stlist[from].landcover] += st_frac_transfer[index(from, to)];
					gross_landcoverfrac_transfer[stlist[from].landcover][stlist[to].landcover] += st_frac_transfer[index(from, to)];
				}
			}
		}

		// handle harvest and turnover of reduced stands at landcover change

		// pool all transferred area from one landcover:
		for(int from=0; from<NLANDCOVERTYPES; from++) {

			if(gridcell.landcover.pool_to_all_landcovers[from]) { // alt.c
				if(gross_landcoverfrac_decrease[from] > 0.0) {
					donor_stand_change(gridcell, gross_landcoverfrac_decrease[from], transfer_lc_from[from], -1, from);
				}
			}
		}

		for(int to=0; to<NLANDCOVERTYPES; to++) {

			double receiving_fraction = gross_landcoverfrac_increase[to];

			for(int from=0; from<NLANDCOVERTYPES; from++) {

				double receiving_fraction_2d = gross_landcoverfrac_transfer[from][to];

				if(receiving_fraction_2d > 0.0) {

					if(gridcell.landcover.pool_from_all_landcovers[to]) {
						if(!gridcell.landcover.pool_to_all_landcovers[from]) {	// alt.a
							// Add from->to transfer to to-pool:
							donor_stand_change(gridcell, receiving_fraction, transfer_lc[to], to, from);
						}
						else {	// alt.a+c
							// Add from-pool value to to-pool:
							transfer_lc[to].add(transfer_lc_from[from], receiving_fraction_2d / receiving_fraction);
						}
					}
					else {
						if(!gridcell.landcover.pool_to_all_landcovers[from]) {	// alt.b
							// Add from->to transfer to [from][to] place in 2d-array:
							donor_stand_change(gridcell, receiving_fraction_2d, transfer_lc_2d[from][to], to, from);
						}
						else {	// alt.c
							// Copy from-pool value to [from][to] place in 2d-array:
							transfer_lc_2d[from][to].copy(transfer_lc_from[from]);
						}
					}
				}
			}
		}

		// create and kill stands at landcover change
		stand_dynamics(gridcell);
		error += check_fractions4(gridcell);
		if(error)
			fail("Fraction error after stand_dynamics()\n");

		// transfer litter etc. of reduced stands to expanding stands at landcover change
		for(int to=0; to<NLANDCOVERTYPES; to++) {

			if(gridcell.landcover.pool_from_all_landcovers[to]) {
				// Alt.a: All donor lc:s are pooled into receiving lc:s
				if(gross_landcoverfrac_increase[to] > 0.0) {
					receiving_stand_change(gridcell, transfer_lc[to], LCchangeCtransfer, to);
				}
			}
			else {

				for(int from=0; from<NLANDCOVERTYPES; from++) {

					if(gross_landcoverfrac_transfer[from][to] > 0.0) {
						if(!gridcell.landcover.pool_to_all_landcovers[from]) {
							// Alt.b: Transfers from donors are independent:
							receiving_stand_change(gridcell, transfer_lc_2d[from][to], LCchangeCtransfer, to, -1, gross_landcoverfrac_transfer[from][to] / gross_landcoverfrac_increase[to]);
						}
						else {
							// Alt.c: Donor lc:s are pooled before transfer to recipients:
							receiving_stand_change(gridcell, transfer_lc_from[from], LCchangeCtransfer, to, -1, gross_landcoverfrac_transfer[from][to] / gross_landcoverfrac_increase[to]);
						}
					}
				}
			}
		}
	}
	else if(transfer_level == 2) { // Unique transfers between stand types. Stand type-level pools available by the gridcell variables pool_from_all_landcovers and pool_to_all_landcovers (set in gridcell constructor)

		landcover_change_transfer* transfer_st_2d;
		landcover_change_transfer* transfer_st;
		landcover_change_transfer* transfer_st_from;

		transfer_st_2d = new landcover_change_transfer[nst * nst];
		transfer_st = new landcover_change_transfer[nst];
		transfer_st_from = new landcover_change_transfer[nst];

		// handle harvest and turnover of reduced stands at landcover change

		// pool all transferred area from one landcover:
		for(int from=0; from<nst; from++) {

			StandType& st = stlist[from];
			Gridcellst& gcst = gridcell.st[from];

			// Pooling of donor stands within a stand type
			if(gridcell.landcover.pool_to_all_landcovers[st.landcover] || !(st.landcover == NATURAL || st.landcover == FOREST)) { // alt.c
				if(gcst.gross_frac_decrease > 0.0) {
					donor_stand_change(gridcell, gcst.gross_frac_decrease, transfer_st_from[from], -1, -1, -1, from);
				}
			}
		}

		for(int to=0;to<nst;to++) {

			StandType& st_to = stlist[to];
			Gridcellst& gcst_to = gridcell.st[to];
			double receiving_fraction = gcst_to.gross_frac_increase;

			for(int from=0; from<nst; from++) {

				StandType& st_from = stlist[from];
				Gridcellst& gcst_from = gridcell.st[from];
				double receiving_fraction_2d = st_frac_transfer[index(from, to)];

				if(receiving_fraction_2d > 0.0) {

					if(gridcell.landcover.pool_from_all_landcovers[st_to.landcover]) {
						if(!(gridcell.landcover.pool_to_all_landcovers[st_from.landcover] || !(st_from.landcover == NATURAL || st_from.landcover == FOREST))) {	// alt.a
							// Add from->to transfer to to-pool:
							donor_stand_change(gridcell, receiving_fraction, transfer_st[to], -1, -1, to, from);
						}
						else {	// alt.a+c
							// Add from-pool value to to-pool:
							transfer_st[to].add(transfer_st_from[from], receiving_fraction_2d / receiving_fraction);
						}
					}
					else {
						if(!(gridcell.landcover.pool_to_all_landcovers[st_from.landcover] || !(st_from.landcover == NATURAL || st_from.landcover == FOREST))) {	// alt.b
							// Add from->to transfer to [from][to] place in 2d-array:
							donor_stand_change(gridcell, receiving_fraction_2d, transfer_st_2d[index(from, to)], -1, -1, to, from);
						}
					}
				}
			}
		}

		// create and kill stands at landcover change
		stand_dynamics(gridcell);
		error += check_fractions4(gridcell);
		if(error)
			fail("Fraction error after stand_dynamics()\n");

		// transfer litter etc. of reduced stands to expanding stands at landcover change
		for(int to=0; to<nst; to++) {

			StandType& st = stlist[to];
			Gridcellst& gcst = gridcell.st[to];

			if(gridcell.landcover.pool_from_all_landcovers[st.landcover]) {
				// Alt.a: All donor st:s are pooled into receiving st:s
				if(gcst.gross_frac_increase > 0.0) {
					receiving_stand_change(gridcell, transfer_st[to], LCchangeCtransfer, -1, to);
				}
			}
			else {

				for(int from=0; from<nst; from++) {

					if(st_frac_transfer[index(from, to)] > 0.0) {
						StandType& st_from = stlist[from];
						Gridcellst& gcst_from = gridcell.st[from];
						if(!(gridcell.landcover.pool_to_all_landcovers[st_from.landcover] || !(st_from.landcover == NATURAL || st_from.landcover == FOREST))) {
							// Alt.b: Transfers between donor and receptor st:s are independent:
							receiving_stand_change(gridcell, transfer_st_2d[index(from, to)], LCchangeCtransfer, st.landcover, to, st_frac_transfer[index(from, to)] / gcst.gross_frac_increase);
						}
						else {
							// Alt.c: Donor stands in a stand type are pooled before transfer to recipients:
							receiving_stand_change(gridcell, transfer_st_from[from], LCchangeCtransfer, st.landcover, to, st_frac_transfer[index(from, to)] / gcst.gross_frac_increase);
						}
					}
				}
			}
		}

		if(transfer_st_2d)
			delete[] transfer_st_2d;
		if(transfer_st)
			delete[] transfer_st;
		if(transfer_st_from)
			delete[] transfer_st_from;
	}

	double ccont_tot = 0.0;
	double cflux_tot = gridcell.cflux();

	for(unsigned int i=0; i<gridcell.size(); i++) {
		Stand& stand = gridcell[i];

		double ccont_stand = stand.ccont(stand.scale_LC_change);
		ccont_tot += ccont_stand * stand.get_gridcell_fraction();
	}

	if(!negligible(cflux_tot - cflux_tot_1 + ccont_tot - ccont_tot_1, -11))
		dprintf("WARNING ! C balance after lcc off by %.12f\n",cflux_tot - cflux_tot_1 + ccont_tot - ccont_tot_1);

	double ncont_tot = 0.0;
	double nflux_tot = 0.0;

	for(unsigned int i=0; i<gridcell.size(); i++) {
		Stand& stand = gridcell[i];

		double ncont_stand = stand.ncont(stand.scale_LC_change);
		ncont_tot += ncont_stand * stand.get_gridcell_fraction();
		nflux_tot += stand.nflux() * stand.get_gridcell_fraction();
	}

	nflux_tot_1 = nflux_tot;	// Disregard fluxes not already reset this year and the associated scaling problems
	nflux_tot += gridcell.landcover.anflux_landuse_change + gridcell.landcover.anflux_harvest_slow;

//	if(!negligible(nflux_tot - nflux_tot_1 + ncont_tot - ncont_tot_1, CHECK_NLIM+1))
//		dprintf("WARNING ! N balance after lcc off\n");

	if(st_frac_transfer)
		delete[] st_frac_transfer;
}


////////////////////////////////////////////////////////////////////////////////
// Implementation of landcover_change_transfer member functions
////////////////////////////////////////////////////////////////////////////////

/// landcover_change_transfer constructor
landcover_change_transfer::landcover_change_transfer() {

	transfer_litter_leaf = transfer_litter_sap = transfer_litter_heart = NULL;
	transfer_litter_root = transfer_litter_repr = transfer_harvested_products_slow = NULL;
	transfer_nmass_litter_leaf = transfer_nmass_litter_sap = transfer_nmass_litter_heart = NULL;
	transfer_nmass_litter_root = transfer_harvested_products_slow_nmass = NULL;

	transfer_acflux_harvest = transfer_anflux_harvest = transfer_cpool_fast = 0.0;
	transfer_cpool_slow = transfer_wcont_evap = transfer_decomp_litter_mean = 0.0;
	transfer_k_soilfast_mean = transfer_k_soilslow_mean = transfer_nmass_avail = 0.0;
	transfer_snowpack = transfer_snowpack_nmass = transfer_anfix_calc = 0.0;

	for(int i=0;i<NSOILLAYER;i++)
		transfer_wcont[i] = 0.0;

	for(int i=0; i<NSOMPOOL; i++)
		transfer_sompool[i].ntoc = 0.0;

	allocate();
}

/// landcover_change_transfer deconstructor
landcover_change_transfer::~landcover_change_transfer() {

	if(transfer_litter_leaf) delete[] transfer_litter_leaf;
	if(transfer_litter_sap) delete[] transfer_litter_sap;
	if(transfer_litter_heart) delete[] transfer_litter_heart;
	if(transfer_litter_root) delete[] transfer_litter_root;
	if(transfer_litter_repr) delete[] transfer_litter_repr;
	if(transfer_harvested_products_slow) delete[] transfer_harvested_products_slow;
	if(transfer_nmass_litter_leaf) delete[] transfer_nmass_litter_leaf;
	if(transfer_nmass_litter_sap) delete[] transfer_nmass_litter_sap;
	if(transfer_nmass_litter_heart) delete[] transfer_nmass_litter_heart;
	if(transfer_nmass_litter_root) delete[] transfer_nmass_litter_root;
	if(transfer_harvested_products_slow_nmass) delete[] transfer_harvested_products_slow_nmass;
}

/// allocates memory for landcover_change_transfer object
void landcover_change_transfer::allocate() {

	transfer_litter_leaf = new double[npft];
	transfer_litter_sap = new double[npft];
	transfer_litter_heart = new double[npft];
	transfer_litter_root = new double[npft];
	transfer_litter_repr = new double[npft];
	transfer_harvested_products_slow = new double[npft];

	transfer_nmass_litter_leaf = new double[npft];
	transfer_nmass_litter_sap = new double[npft];
	transfer_nmass_litter_heart = new double[npft];
	transfer_nmass_litter_root = new double[npft];
	transfer_harvested_products_slow_nmass = new double[npft];

	for(int i=0;i<npft;i++) {
		transfer_litter_leaf[i] = 0.0;
		transfer_litter_sap[i] = 0.0;
		transfer_litter_heart[i] = 0.0;
		transfer_litter_root[i] = 0.0;
		transfer_litter_repr[i] = 0.0;
		transfer_harvested_products_slow[i] = 0.0;
		transfer_nmass_litter_leaf[i] = 0.0;
		transfer_nmass_litter_sap[i] = 0.0;
		transfer_nmass_litter_heart[i] = 0.0;
		transfer_nmass_litter_root[i] = 0.0;
		transfer_harvested_products_slow_nmass[i] = 0.0;
	}
}

//////////////////////////////////////////////////////////////////////////////////////////
// REFERENCES
//
// Bondeau A, Smith PC, Zaehle S, Schaphoff S, Lucht W, Cramer W, Gerten D, Lotze-Campen H,
//   Müller C, Reichstein M & Smith B 2007. Modelling the role of agriculture for the 
//   20th century global terrestrial carbon balance. Global Change Biology, 13:679-706.
// Lindeskog M, Arneth A, Bondeau A, Waha K, Seaquist J, Olin S, & Smith B 2013.
//   Implications of accounting for land use in simulations of ecosystem carbon cycling
//   in Africa. Earth Syst Dynam 4:385-407.