On the Ecology of Mountainous Forests in a Changing Climate: A ...

238 Appendix
litter^.LN := kInitN[type] * m;
litter^.LNNew := kInitN[type] * m;
litter^.gLign := kLignA + kLignB;
litter^.type := type;
first := litter;
END CreateLitterCohort;
PROCEDURE DeleteLitterCohort( VAR first, cohort, prev: LitterPtr );
(* for efficiency reasons, cohort = NIL is not tested *)
BEGIN
IF prev = NIL THEN (* first element to be deleted *)
first := cohort^.next;
Deallocate( cohort );
cohort := first;
ELSE
prev^.next := cohort^.next;
Deallocate( cohort );
cohort := prev^.next;
END;
END DeleteLitterCohort;
PROCEDURE DeleteAllCohorts( VAR first: LitterPtr );
VAR coh: LitterPtr;
BEGIN
coh := first;
WHILE coh NIL DO
first := coh^.next;
Deallocate( coh );
coh := first;
END; (* WHILE *)
END DeleteAllCohorts;
(*****************************************************)
(* Procedures for decomposition and mineralization *)
(*****************************************************)
PROCEDURE TransferLitterToHumus( VAR litter: LitterPtr );
BEGIN
HNNew := HNNew + litter^.LNNew;
HOMNew := HOMNew + litter^.LOMNew;
DeleteLitterCohort( first, litter, prev );
END TransferLitterToHumus;
PROCEDURE Immobilization;
VAR lignToN, litMDelta, gLeach: REAL;
litter: LitterPtr;
BEGIN
prev := NIL;
litter := first;
WHILE litter NIL DO
WITH litter^ DO
IF (type = wood) OR (type = twigs) THEN
IF type = wood THEN mLoss := 0.03;
ELSE mLoss := 0.2;
END;
litMDelta := mLoss * LOM;
gImmob := kNC * litMDelta; (* nitrogen immobilization *)
litterCO2 := litMDelta; (* CO2 evolution from litter *)
totCO2 := totCO2 + litterCO2;
LOMNew := LOM - litMDelta; (* update state variables *)
LNNew := LN + gImmob; (* no nitrogen leaching *)
totNimmob := totNimmob + gImmob; (* net N immobilization *)
gNMR := (LN + gImmob) / (LOM - litMDelta); (* new nitrogen conc. *)
ELSE
gLeach := kLeach * LN; (* nitrogen leaching *)
gNMR := LN / LOM; (* nitrogen concentration *)
gLign := kLignA + kLignB * LOM/LOMinit;
lignToN := gLign/gNMR;
IF lignToN > k2/k4 THEN
lignToN := k2/k4; (* avoid unreasonable decomposition *)
Warn( "", "Lignin:N ratio is unrealistically high!", "" );
END;
mLoss := ( k1 + k2*uAET - (k3 + k4*uAET)*lignToN )/100.0 * decMlt;
IF mLoss < 0.0 THEN Warn("","Negative decomposition!","") END;
litMDelta := mLoss * LOM; (* LOM change *)
gImmob := kNC * litMDelta; (* nitrogen immobilization *)
gNMR := (LN - gLeach + gImmob) / (LOM-litMDelta); (* new N conc. *)
IF gNMR >= kCritN[type] THEN (* recalculate weight loss *)
mLoss := (kCritN[type] - LN/LOM)
/ (gNMR - LN/LOM) * mLoss;
litMDelta := mLoss * LOM;
gImmob := kNC * litMDelta; (* nitrogen immobilization *)
END;
litterCO2 := litMDelta; (* CO2 evolution from litter *)
totCO2 := totCO2 + litterCO2;
LOMNew := LOM - litMDelta; (* state variables *)
LNNew := LN - gLeach + gImmob;
totNimmob := totNimmob - gLeach + gImmob; (* net N immobilization *)
END;
IF gNMR >= kCritN[type] THEN
TransferLitterToHumus( litter );
ELSE
prev := litter; (* pointer management *)
litter := litter^.next;
END;
END; (* WITH *)
END; (* WHILE *)