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

Appendix 231
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(* Procedure TreeEstablishment *)
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PROCEDURE TreeEstablishment( VAR firstSp: SpeciesPtr;
uWiT: REAL; uDD, gLAI, totalTrees, kPatchSize: REAL );
VAR sp: SpeciesPtr;
nrNewTrees: INTEGER;
gAL, kThres, totTrees, browsU, gBirthNr, time: REAL;
gWFlag, gLFlag, gBFlag, gDFlag, gIFlag, birthOK: BOOLEAN;
BEGIN
gBirthNr := FLOAT( TRUNC(kEstNr*kPatchSize + 0.5) );
gAL := Exp( -kLAtt*gLAI ); (* available light on forest floor *)
totTrees := totalTrees;
time := CurrentTime();
browsU := U(); (* random number for browsing *)
sp := firstSp;
WHILE sp NIL DO
WITH sp^ DO
(* criterion 1: winter temperature (Woodward 1987, 1988, Prentice &
Helmisaari 1991) *)
gWFlag := uWiT < p.kWiT;
IF gWFlag THEN INC( limCounter[1] ) END;
(* criterion 2: available light on forest floor (Ellenberg 1986) *)
IF p.kLy < 5 THEN kThres := 0.025*FLOAT(p.kLy - 1);
ELSE kThres := 0.1*FLOAT(p.kLy) - 0.4;
END;
gLFlag := gAL < kThres;
IF gLFlag THEN INC( limCounter[2] ) END;
(* criterion 3: browsing (Kienast 1987, Dengler 1992) *)
gBFlag := browsU < FLOAT(p.kBrow-1)*uBrPr/30.0;
IF gBFlag THEN INC( limCounter[3] ) END;
(* criterion 4: degree-days (Shugart 1984) *)
gDFlag := (uDD < p.kDDMin) OR (uDD > p.kDDMax);
IF gDFlag THEN INC( limCounter[4] ) END;
(* criterion 5: immigration of species *)
gIFlag := time < p.kImmYr;
(* check if birth is inhibited *)
birthOK := NOT gWFlag AND NOT gLFlag AND NOT gBFlag AND
NOT gDFlag AND NOT gIFlag;
(* establish saplings if establishment is possible *)
IF birthOK AND (U() < kEstP ) THEN
nrNewTrees := TRUNC( U()*gBirthNr ) + 1; (* determine number of trees *)
IF (gLAI < 1.0) AND (firstNewCohort NIL) THEN
firstNewCohort^.nrTrees := firstNewCohort^.nrTrees + nrNewTrees;
ELSE
CreateCohort( firstNewCohort, kInitDBH, nrNewTrees );
END; (* IF *)
totTrees := totTrees + FLOAT( nrNewTrees );
ELSE
INC( limCounter[5] ); (* count number of birth inhibitions *)
END; (* IF *)
INC( limCounter[6] ); (* count number of loops *)
END; (* WITH *)
sp := sp^.next;
END; (* WHILE *)
END TreeEstablishment;
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(* Procedure UpdateGap *)
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PROCEDURE UpdateGap( VAR firstSp: SpeciesPtr; uDD, uDrStr: REAL );
VAR sp: SpeciesPtr;
cohort: CohortPtr;
t, DInc: REAL;
BEGIN
t := CurrentTime();
sp := firstSp;
WHILE sp NIL DO
WITH sp^ DO
cohort := firstCohort;
WHILE cohort NIL DO
cohort^.D := cohort^.D + cohort^.DInc;
IF mon.monTreeRings THEN
DInc := cohort^.DInc * 5.0;
(* corresponds to /2 *10; ring width is half of diameter increment and is
converted from cm to mm *)
WriteTreeRings( sp, t, cohort^.nrOfCohort, DInc, uDD, uDrStr );
END; (* IF *)
INC(cohort^.age);
cohort := cohort^.next;
END;
END; (* WITH *)
MergeCohorts( sp );
sp := sp^.next;
END; (* WHILE *)
END UpdateGap;
BEGIN
kFRT[deciduous] := 1.0;
kFRT[coniferous] := 5.0; (* Bossel et al. 1985 *)
END FCPDynamic.