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1	! =================================================================================================================================
2	! MODULE : stomate_turnover.f90
3	!
4	! CONTACT : orchidee-help _at_ ipsl.jussieu.fr
5	!
6	! LICENCE : IPSL (2006)
7	! This software is governed by the CeCILL licence see ORCHIDEE/ORCHIDEE_CeCILL.LIC
8	!
9	!>\BRIEF This module manages the end of the growing season and calculates herbivory and turnover of leaves, fruits, fine roots.
10	!!
11	!!\n DESCRIPTION: This subroutine calculates leaf senescence due to climatic conditions or as a
12	!! function of leaf age and new LAI, and subsequent turnover of the different plant biomass compartments (sections 1 to 6),
13	!! herbivory (section 7), fruit turnover for trees (section 8) and sapwood conversion (section 9).
14	!!
15	!! RECENT CHANGE(S): None
16	!!
17	!! SVN :
18	!! $HeadURL$
19	!! $Date$
20	!! $Revision$
21	!! \n
22	!_ ================================================================================================================================
23
24	MODULE stomate_turnover
25
26	! modules used:
27	USE xios_orchidee
28	USE ioipsl_para
29	USE stomate_data
30	USE constantes
31	USE pft_parameters
32
33	IMPLICIT NONE
34
35	! private & public routines
36
37	PRIVATE
38	PUBLIC turn, turn_clear
39
40	LOGICAL, SAVE :: firstcall_turnover = .TRUE. !! first call (true/false)
41	!$OMP THREADPRIVATE(firstcall_turnover)
42
43	CONTAINS
44
45
46	!! ================================================================================================================================
47	!! SUBROUTINE : turn_clear
48	!!
49	!>\BRIEF Set flag ::firstcall_turnover to .TRUE., and therefore activate section 1
50	!! of subroutine turn which writes a message to the output.
51	!!
52	!_ ================================================================================================================================
53
54	SUBROUTINE turn_clear
55	firstcall_turnover=.TRUE.
56	END SUBROUTINE turn_clear
57
58
59	!! ================================================================================================================================
60	!! SUBROUTINE : turn
61	!!
62	!>\BRIEF Calculate turnover of leaves, roots, fruits and sapwood due to aging or climatic
63	!! induced senescence. Calculate herbivory.
64	!!
65	!! DESCRIPTION : This subroutine determines the turnover of leaves and fine roots (and stems for grasses)
66	!! and simulates following processes:
67	!! 1. Mean leaf age is calculated from leaf ages of separate leaf age classes. Should actually
68	!! be recalculated at the end of the routine, but it does not change too fast. The mean leaf
69	!! age is calculated using the following equation:
70	!! \latexonly
71	!! \input{turnover_lma_update_eqn1.tex}
72	!! \endlatexonly
73	!! \n
74	!! 2. Meteorological senescence: the detection of the end of the growing season and shedding
75	!! of leaves, fruits and fine roots due to unfavourable meteorological conditions.
76	!! The model distinguishes three different types of "climatic" leaf senescence, that do not
77	!! change the age structure: sensitivity to cold temperatures, to lack of water, or both.
78	!! If meteorological conditions are fulfilled, a flag ::senescence is set to TRUE. Note
79	!! that evergreen species do not experience climatic senescence.
80	!! Climatic senescence is triggered by sensitivity to cold temperatures where the critical
81	!! temperature for senescence is calculated using the following equation:
82	!! \latexonly
83	!! \input{turnover_temp_crit_eqn2.tex}
84	!! \endlatexonly
85	!! \n
86	!! Climatic senescence is triggered by sensitivity to lack of water availability where the
87	!! moisture availability critical level is calculated using the following equation:
88	!! \latexonly
89	!! \input{turnover_moist_crit_eqn3.tex}
90	!! \endlatexonly
91	!! \n
92	!! Climatic senescence is triggered by sensitivity to temperature or to lack of water where
93	!! critical temperature and moisture availability are calculated as above.\n
94	!! Trees in climatic senescence lose their fine roots at the same rate as they lose their leaves.
95	!! The rate of biomass loss of both fine roots and leaves is presribed through the equation:
96	!! \latexonly
97	!! \input{turnover_clim_senes_biomass_eqn4.tex}
98	!! \endlatexonly
99	!! \n
100	!! with ::leaffall(j) a PFT-dependent time constant which is given in
101	!! ::stomate_constants. In grasses, leaf senescence is extended to the whole plant
102	!! (all carbon pools) except to its carbohydrate reserve.
103	!! 3. Senescence due to aging: the loss of leaves, fruits and biomass due to aging
104	!! At a certain age, leaves fall off, even if the climate would allow a green plant
105	!! all year round. Even if the meteorological conditions are favorable for leaf maintenance,
106	!! plants, and in particular, evergreen trees, have to renew their leaves simply because the
107	!! old leaves become inefficient. Roots, fruits (and stems for grasses) follow leaves.
108	!! The ??senescence?? rate varies with leaf age. Note that plant is not declared senescent
109	!! in this case (wchich is important for allocation: if the plant loses leaves because of
110	!! their age, it can renew them). The leaf turnover rate due to aging of leaves is calculated
111	!! using the following equation:
112	!! \latexonly
113	!! \input{turnover_age_senes_biomass_eqn5.tex}
114	!! \endlatexonly
115	!! \n
116	!! Drop all leaves if there is a very low leaf mass during senescence. After this, the biomass
117	!! of different carbon pools both for trees and grasses is set to zero and the mean leaf age
118	!! is reset to zero. Finally, the leaf fraction and leaf age of the different leaf age classes
119	!! is set to zero. For deciduous trees: next to leaves, also fruits and fine roots are dropped.
120	!! For grasses: all aboveground carbon pools, except the carbohydrate reserves are affected:
121	!! 4. Update the leaf biomass, leaf age class fraction and the LAI
122	!! Older leaves will fall more frequently than younger leaves and therefore the leaf age
123	!! distribution needs to be recalculated after turnover. The fraction of biomass in each
124	!! leaf class is updated using the following equation:
125	!! \latexonly
126	!! \input{turnover_update_LeafAgeDistribution_eqn6.tex}
127	!! \endlatexonly
128	!! \n
129	!! 5. Simulate herbivory activity and update leaf and fruits biomass. Herbivore activity
130	!! affects the biomass of leaves and fruits as well as stalks (only for grasses).
131	!! However, herbivores do not modify leaf age structure.
132	!! 6. Calculates fruit turnover for trees. Trees simply lose their fruits with a time
133	!! constant ::tau_fruit(j), that is set to 90 days for all PFTs in ::stomate_constants
134	!! 7. Convert sapwood to heartwood for trees and update heart and softwood above and
135	!! belowground biomass. Sapwood biomass is converted into heartwood biomass
136	!! with a time constant tau ::tau_sap(j) of 1 year. Note that this biomass conversion
137	!! is not added to "turnover" as the biomass is not lost. For the updated heartwood,
138	!! the sum of new heartwood above and new heartwood below after converting sapwood to
139	!! heartwood, is saved as ::hw_new(:). Creation of new heartwood decreases the age of
140	!! the plant ??carbon?? with a factor that is determined by: old heartwood ::hw_old(:)
141	!! divided by the new heartwood ::hw_new(:)
142	!!
143	!! RECENT CHANGE(S) : None
144	!!
145	!! MAIN OUTPUT VARIABLES: ::Biomass of leaves, fruits, fine roots and sapwood above (latter for grasses only),
146	!! ::Update LAI, ::Update leaf age distribution with new leaf age class fraction
147	!!
148	!! REFERENCE(S) :
149	!! - Krinner, G., N. Viovy, N. de Noblet-Ducoudre, J. Ogee, J. Polcher, P.
150	!! Friedlingstein, P. Ciais, S. Sitch and I.C. Prentice (2005), A dynamic global
151	!! vegetation model for studies of the coupled atmosphere-biosphere system, Global
152	!! Biogeochemical Cycles, 19, doi:10.1029/2003GB002199.
153	!! - McNaughton, S. J., M. Oesterheld, D. A. Frank and K. J. Williams (1989),
154	!! Ecosystem-level patterns of primary productivity and herbivory in terrestrial habitats,
155	!! Nature, 341, 142-144, 1989.
156	!! - Sitch, S., C. Huntingford, N. Gedney, P. E. Levy, M. Lomas, S. L. Piao, , Betts, R., Ciais, P., Cox, P.,
157	!! Friedlingstein, P., Jones, C. D., Prentice, I. C. and F. I. Woodward : Evaluation of the terrestrial carbon
158	!! cycle, future plant geography and climate-carbon cycle feedbacks using 5 dynamic global vegetation
159	!! models (dgvms), Global Change Biology, 14(9), 2015â2039, 2008.
160	!!
161	!! FLOWCHART :
162	!! \latexonly
163	!! \includegraphics[scale=0.5]{turnover_flowchart_1.png}
164	!! \includegraphics[scale=0.5]{turnover_flowchart_2.png}
165	!! \endlatexonly
166	!! \n
167	!_ ================================================================================================================================
168
169	SUBROUTINE turn (npts, dt, PFTpresent, &
170	herbivores, &
171	maxmoiavail_lastyear, minmoiavail_lastyear, &
172	moiavail_week, moiavail_month, t2m_longterm, t2m_month, t2m_week, veget_max, &
173	gdd_from_growthinit, leaf_age, leaf_frac, age, lai, biomass, &
174	turnover, senescence,turnover_time)
175
176	!! 0. Variable and parameter declaration
177
178	!! 0.1 Input variables
179
180	INTEGER(i_std), INTENT(in) :: npts !! Domain size - number of grid cells
181	!! (unitless)
182	REAL(r_std), INTENT(in) :: dt !! time step (dt_days)
183	LOGICAL, DIMENSION(npts,nvm), INTENT(in) :: PFTpresent !! PFT exists (true/false)
184	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: herbivores !! time constant of probability of a leaf to
185	!! be eaten by a herbivore (days)
186	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: maxmoiavail_lastyear !! last year's maximum moisture availability
187	!! (0-1, unitless)
188	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: minmoiavail_lastyear !! last year's minimum moisture availability
189	!! (0-1, unitless)
190	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: moiavail_week !! "weekly" moisture availability
191	!! (0-1, unitless)
192	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: moiavail_month !! "monthly" moisture availability
193	!! (0-1, unitless)
194	REAL(r_std), DIMENSION(npts), INTENT(in) :: t2m_longterm !! "long term" 2 meter reference
195	!! temperatures (K)
196	REAL(r_std), DIMENSION(npts), INTENT(in) :: t2m_month !! "monthly" 2-meter temperatures (K)
197	REAL(r_std), DIMENSION(npts), INTENT(in) :: t2m_week !! "weekly" 2 meter temperatures (K)
198	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: veget_max !! "maximal" coverage fraction of a PFT (LAI
199	!! -> infinity) on ground (unitless)
200	REAL(r_std), DIMENSION(npts,nvm), INTENT(in) :: gdd_from_growthinit !! gdd senescence for crop
201
202	!! 0.2 Output variables
203
204	REAL(r_std), DIMENSION(npts,nvm,nparts,nelements), INTENT(out) :: turnover !! Turnover @tex ($gC m^{-2}$) @endtex
205	LOGICAL, DIMENSION(npts,nvm), INTENT(out) :: senescence !! is the plant senescent? (true/false)
206	!! (interesting only for deciduous trees:
207	!! carbohydrate reserve)
208	!! 0.3 Modified variables
209
210	REAL(r_std), DIMENSION(npts,nvm,nleafages), INTENT(inout) :: leaf_age !! age of the leaves (days)
211	REAL(r_std), DIMENSION(npts,nvm,nleafages), INTENT(inout) :: leaf_frac !! fraction of leaves in leaf age class
212	!! (0-1, unitless)
213	REAL(r_std), DIMENSION(npts,nvm), INTENT(inout) :: age !! age (years)
214	REAL(r_std), DIMENSION(npts,nvm), INTENT(inout) :: lai !! leaf area index @tex ($m^2 m^{-2}$)
215	!! @endtex
216	REAL(r_std), DIMENSION(npts,nvm,nparts,nelements), INTENT(inout) :: biomass !! biomass @tex ($gC m^{-2}$) @endtex
217	REAL(r_std), DIMENSION(npts,nvm), INTENT(inout) :: turnover_time !! turnover_time of grasses (days)
218
219	!! 0.4 Local variables
220
221	REAL(r_std), DIMENSION(npts,nvm) :: leaf_meanage !! mean age of the leaves (days)
222	REAL(r_std), DIMENSION(npts) :: dturnover !! Intermediate variable for turnover ??
223	!! @tex ($gC m^{-2}$) @endtex
224	REAL(r_std), DIMENSION(npts) :: moiavail_crit !! critical moisture availability, function
225	!! of last year's moisture availability
226	!! (0-1, unitless)
227	REAL(r_std), DIMENSION(npts) :: tl !! long term annual mean temperature, (C)
228	REAL(r_std), DIMENSION(npts) :: t_crit !! critical senescence temperature, function
229	!! of long term annual temperature (K)
230	LOGICAL, DIMENSION(npts) :: shed_rest !! shed the remaining leaves? (true/false)
231	REAL(r_std), DIMENSION(npts) :: sapconv !! Sapwood conversion @tex ($gC m^{-2}$)
232	!! @endtex
233	REAL(r_std), DIMENSION(npts) :: hw_old !! old heartwood mass @tex ($gC m^{-2}$)
234	!! @endtex
235	REAL(r_std), DIMENSION(npts) :: hw_new !! new heartwood mass @tex ($gC m^{-2}$)
236	!! @endtex
237	REAL(r_std), DIMENSION(npts) :: lm_old !! old leaf mass @tex ($gC m^{-2}$) @endtex
238	REAL(r_std), DIMENSION(npts,nleafages) :: delta_lm !! leaf mass change for each age class @tex
239	!! ($gC m^{-2}$) @endtex
240	REAL(r_std), DIMENSION(npts) :: turnover_rate !! turnover rate (unitless)
241	REAL(r_std), DIMENSION(npts,nvm) :: leaf_age_crit !! critical leaf age (days)
242	REAL(r_std), DIMENSION(npts,nvm) :: new_turnover_time !! instantaneous turnover time (days)
243	INTEGER(i_std) :: j,m,k !! Index (unitless)
244
245	!_ ================================================================================================================================
246
247	IF (printlev>=3) WRITE(numout,*) 'Entering turnover'
248
249	!! 1. first call - output messages
250
251	IF ( firstcall_turnover ) THEN
252
253	WRITE(numout,*) 'turnover:'
254
255	WRITE(numout,*) ' > minimum mean leaf age for senescence (days) (::min_leaf_age_for_senescence) : '&
256	,min_leaf_age_for_senescence
257
258	firstcall_turnover = .FALSE.
259
260
261	ENDIF
262
263	!! 2. Initializations
264
265	!! 2.1 set output to zero
266	turnover(:,:,:,:) = zero
267	new_turnover_time(:,:) = zero
268	senescence(:,:) = .FALSE.
269
270	!! 2.2 Recalculate mean leaf age
271	! Mean leaf age is recalculated from leaf ages of separate leaf age classes. Should actually be recalculated at the
272	! end of this routine, but it does not change too fast.
273	! The mean leaf age is calculated using the following equation:
274	! \latexonly
275	! \input{turnover_lma_update_eqn1.tex}
276	! \endlatexonly
277	! \n
278	leaf_meanage(:,:) = zero
279
280	DO m = 1, nleafages
281	leaf_meanage(:,:) = leaf_meanage(:,:) + leaf_age(:,:,m) * leaf_frac(:,:,m)
282	ENDDO
283
284	!! 3. Climatic senescence
285
286	! Three different types of "climatic" leaf senescence,
287	! that do not change the age structure.
288	DO j = 2,nvm ! Loop over # PFTs
289
290	!! 3.1 Determine if there is climatic senescence.
291	! The climatic senescence can be of three types:
292	! sensitivity to cold temperatures, to lack of water, or both. If meteorological conditions are
293	! fulfilled, a flag senescence is set to TRUE.
294	! Evergreen species do not experience climatic senescence.
295
296	SELECT CASE ( senescence_type(j) )
297
298
299	CASE ('crop' )!for crop senescence is based on a GDD criterium as in crop models
300	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. &
301	( leaf_meanage(:,j) .GT. min_leaf_age_for_senescence(j) ) .AND. &
302	( gdd_from_growthinit(:,j) .GT. gdd_senescence(j)))
303	senescence(:,j) = .TRUE.
304	ENDWHERE
305
306	CASE ( 'cold' )
307
308	!! 3.1.1 Summergreen species: Climatic senescence is triggered by sensitivity to cold temperatures
309	! Climatic senescence is triggered by sensitivity to cold temperatures as follows:
310	! If biomass is large enough (i.e. when it is greater than zero),
311	! AND (i.e. when leaf mean age is above a certain PFT-dependent treshold ::min_leaf_age_for_senescence,
312	! which is given in ::stomate_constants),
313	! AND the monthly temperature is low enough (i.e. when monthly temperature ::t2m_month(:) is below a critical
314	! temperature ::t_crit(:), which is calculated in this module),
315	! AND the temperature tendency is negative (i.e. when weekly temperatures ::t2m_week(:) are lower than monthly
316	! temperatures ::t2m_month(:))
317	! If these conditions are met, senescence is set to TRUE.
318	!
319	! The critical temperature for senescence is calculated using the following equation:
320	! \latexonly
321	! \input{turnover_temp_crit_eqn2.tex}
322	! \endlatexonly
323	! \n
324	!
325	! Critical temperature for senescence may depend on long term annual mean temperature
326	tl(:) = t2m_longterm(:) - ZeroCelsius
327	t_crit(:) = ZeroCelsius + senescence_temp(j,1) + &
328	tl(:) * senescence_temp(j,2) + &
329	tl(:)tl(:) senescence_temp(j,3)
330
331	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. &
332	( leaf_meanage(:,j) .GT. min_leaf_age_for_senescence(j) ) .AND. &
333	( t2m_month(:) .LT. t_crit(:) ) .AND. ( t2m_week(:) .LT. t2m_month(:) ) )
334
335	senescence(:,j) = .TRUE.
336
337	ENDWHERE
338
339	CASE ( 'dry' )
340
341	!! 3.1.2 Raingreen species: Climatic senescence is triggered by sensitivity to lack of water availability
342	! Climatic senescence is triggered by sensitivity to lack of water availability as follows:
343	! If biomass is large enough (i.e. when it is greater than zero),
344	! AND (i.e. when leaf mean age is above a certain PFT-dependent treshold ::min_leaf_age_for_senescence,
345	! which is given in ::stomate_constants),
346	! AND the moisture availability drops below a critical level (i.e. when weekly moisture availability
347	! ::moiavail_week(:,j) is below a critical moisture availability ::moiavail_crit(:),
348	! which is calculated in this module),
349	! If these conditions are met, senescence is set to TRUE.
350	!
351	! The moisture availability critical level is calculated using the following equation:
352	! \latexonly
353	! \input{turnover_moist_crit_eqn3.tex}
354	! \endlatexonly
355	! \n
356	moiavail_crit(:) = &
357	MIN( MAX( minmoiavail_lastyear(:,j) + hum_frac(j) * &
358	( maxmoiavail_lastyear(:,j) - minmoiavail_lastyear(:,j) ), &
359	senescence_hum(j) ), &
360	nosenescence_hum(j) )
361
362	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. &
363	( leaf_meanage(:,j) .GT. min_leaf_age_for_senescence(j) ) .AND. &
364	( moiavail_week(:,j) .LT. moiavail_crit(:) ) )
365
366	senescence(:,j) = .TRUE.
367
368	ENDWHERE
369
370	CASE ( 'mixed' )
371
372	!! 3.1.3 Mixed criterion: Climatic senescence is triggered by sensitivity to temperature or to lack of water
373	! Climatic senescence is triggered by sensitivity to temperature or to lack of water availability as follows:
374	! If biomass is large enough (i.e. when it is greater than zero),
375	! AND (i.e. when leaf mean age is above a certain PFT-dependent treshold ::min_leaf_age_for_senescence,
376	! which is given in ::stomate_constants),
377	! AND the moisture availability drops below a critical level (i.e. when weekly moisture availability
378	! ::moiavail_week(:,j) is below a critical moisture availability ::moiavail_crit(:), calculated in this module),
379	! OR
380	! the monthly temperature is low enough (i.e. when monthly temperature ::t2m_month(:) is below a critical
381	! temperature ::t_crit(:), calculated in this module),
382	! AND the temperature tendency is negative (i.e. when weekly temperatures ::t2m_week(:) are lower than
383	! monthly temperatures ::t2m_month(:)).
384	! If these conditions are met, senescence is set to TRUE.
385	moiavail_crit(:) = &
386	MIN( MAX( minmoiavail_lastyear(:,j) + hum_frac(j) * &
387	(maxmoiavail_lastyear(:,j) - minmoiavail_lastyear(:,j) ), &
388	senescence_hum(j) ), &
389	nosenescence_hum(j) )
390
391	tl(:) = t2m_longterm(:) - ZeroCelsius
392	t_crit(:) = ZeroCelsius + senescence_temp(j,1) + &
393	tl(:) * senescence_temp(j,2) + &
394	tl(:)tl(:) senescence_temp(j,3)
395
396	IF ( is_tree(j) ) THEN
397	! critical temperature for senescence may depend on long term annual mean temperature
398	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. &
399	( leaf_meanage(:,j) .GT. min_leaf_age_for_senescence(j) ) .AND. &
400	( ( moiavail_week(:,j) .LT. moiavail_crit(:) ) .OR. &
401	( ( t2m_month(:) .LT. t_crit(:) ) .AND. ( t2m_week(:) .LT. t2m_month(:) ) ) ) )
402	senescence(:,j) = .TRUE.
403	ENDWHERE
404	ELSE
405
406	turnover_time(:,j) = max_turnover_time(j)
407
408	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. &
409	( leaf_meanage(:,j) .GT. min_leaf_age_for_senescence(j) ) .AND. &
410	( ( moiavail_week(:,j) .LT. moiavail_crit(:) )))
411	turnover_time(:,j) = max_turnover_time(j) * &
412	(1.- (1.- (moiavail_week(:,j)/ moiavail_crit(:)))**2)
413	ENDWHERE
414
415	WHERE ( turnover_time(:,j) .LT. min_turnover_time(j) )
416	turnover_time(:,j) = min_turnover_time(j)
417	ENDWHERE
418
419	WHERE ((( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. &
420	( leaf_meanage(:,j) .GT. min_leaf_age_for_senescence(j) ) .AND. &
421	((t2m_month(:) .LT. t_crit(:)) .AND. (lai(:,j) .GT. lai_max(j)/4.) .OR. &
422	(t2m_month(:) .LT. ZeroCelsius)) .AND. ( t2m_week(:) .LT. t2m_month(:) )))
423	turnover_time(:,j)= leaffall(j)
424	ENDWHERE
425
426	ENDIF
427
428
429	!! Evergreen species do not experience climatic senescence
430	CASE ( 'none' )
431
432
433	!! In case no climatic senescence type is recognized.
434	CASE default
435
436	WRITE(numout,*) ' turnover: don''t know how to treat this PFT.'
437	WRITE(numout,*) ' number (::j) : ',j
438	WRITE(numout,*) ' senescence type (::senescence_type(j)) : ',senescence_type(j)
439
440	CALL ipslerr_p(3,"turn","Dont know how to treat this PFT.","","")
441
442	END SELECT
443
444	!! 3.2 Drop leaves and roots, plus stems and fruits for grasses
445
446	IF ( is_tree(j) ) THEN
447
448	!! 3.2.1 Trees in climatic senescence lose their fine roots at the same rate as they lose their leaves.
449	! The rate of biomass loss of both fine roots and leaves is presribed through the equation:
450	! \latexonly
451	! \input{turnover_clim_senes_biomass_eqn4.tex}
452	! \endlatexonly
453	! \n
454	! with ::leaffall(j) a PFT-dependent time constant which is given in ::stomate_constants),
455	WHERE ( senescence(:,j) )
456
457	turnover(:,j,ileaf,icarbon) = biomass(:,j,ileaf,icarbon) * dt / leaffall(j)
458	turnover(:,j,iroot,icarbon) = biomass(:,j,iroot,icarbon) * dt / leaffall(j)
459	turnover(:,j,ileaf,initrogen) = biomass(:,j,ileaf,initrogen) * dt / leaffall(j)
460	turnover(:,j,iroot,initrogen) = biomass(:,j,iroot,initrogen) * dt / leaffall(j)
461
462
463	ENDWHERE
464
465	ELSE
466
467	!! 3.2.2 In grasses, leaf senescence is extended to the whole plant
468	! In grasses, leaf senescence is extended to the whole plant (all carbon pools) except to its
469	! carbohydrate reserve.
470
471	IF (senescence_type(j) .EQ. 'crop') THEN
472	! 3.2.2.1 crops with 'crop' phenological model
473	WHERE ( senescence(:,j) )
474	turnover(:,j,ileaf,icarbon) = biomass(:,j,ileaf,icarbon) * dt / leaffall(j)
475	turnover(:,j,iroot,icarbon) = biomass(:,j,iroot,icarbon) * dt / leaffall(j)
476	turnover(:,j,isapabove,icarbon) = biomass(:,j,isapabove,icarbon) * dt / leaffall(j)
477	turnover(:,j,ifruit,icarbon) = biomass(:,j,ifruit,icarbon) * dt /leaffall(j)
478
479	turnover(:,j,ileaf,initrogen) = biomass(:,j,ileaf,initrogen) * dt / leaffall(j)
480	turnover(:,j,iroot,initrogen) = biomass(:,j,iroot,initrogen) * dt / leaffall(j)
481	turnover(:,j,isapabove,initrogen) = biomass(:,j,isapabove,initrogen) * dt / leaffall(j)
482	turnover(:,j,ifruit,initrogen) = biomass(:,j,ifruit,initrogen) * dt /leaffall(j)
483	ENDWHERE
484	ELSE
485	! 3.2.2.2 grass or crops based on 'mixed' phenological model
486	WHERE (turnover_time(:,j) .LT. max_turnover_time(j))
487	turnover(:,j,ileaf,icarbon) = biomass(:,j,ileaf,icarbon) * dt / turnover_time(:,j)
488	turnover(:,j,isapabove,icarbon) = biomass(:,j,isapabove,icarbon) * dt / turnover_time(:,j)
489	turnover(:,j,iroot,icarbon) = biomass(:,j,iroot,icarbon) * dt / turnover_time(:,j)
490	turnover(:,j,ifruit,icarbon) = biomass(:,j,ifruit,icarbon) * dt / turnover_time(:,j)
491
492	turnover(:,j,ileaf,initrogen) = biomass(:,j,ileaf,initrogen) * dt / turnover_time(:,j)
493	turnover(:,j,isapabove,initrogen) = biomass(:,j,isapabove,initrogen) * dt / turnover_time(:,j)
494	turnover(:,j,iroot,initrogen) = biomass(:,j,iroot,initrogen) * dt / turnover_time(:,j)
495	turnover(:,j,ifruit,initrogen) = biomass(:,j,ifruit,initrogen) * dt / turnover_time(:,j)
496	ENDWHERE
497	ENDIF
498	ENDIF ! tree/grass
499
500	biomass(:,j,ileaf,:) = biomass(:,j,ileaf,:) - turnover(:,j,ileaf,:)
501	biomass(:,j,isapabove,:) = biomass(:,j,isapabove,:) - turnover(:,j,isapabove,:)
502	biomass(:,j,iroot,:) = biomass(:,j,iroot,:) - turnover(:,j,iroot,:)
503	biomass(:,j,ifruit,:) = biomass(:,j,ifruit,:) - turnover(:,j,ifruit,:)
504
505	biomass(:,j,ilabile,initrogen) = biomass(:,j,ilabile,initrogen) &
506	+ recycle_leaf(j) * turnover(:,j,ileaf,initrogen) &
507	+ recycle_root(j) * turnover(:,j,iroot,initrogen)
508
509	turnover(:,j,ileaf,initrogen) = turnover(:,j,ileaf,initrogen) * ( 1.0 - recycle_leaf(j) )
510	turnover(:,j,iroot,initrogen) = turnover(:,j,iroot,initrogen) * ( 1.0 - recycle_root(j) )
511
512	ENDDO ! loop over PFTs
513
514	!! 4. Leaf fall
515	! At a certain age, leaves fall off, even if the climate would allow a green plant
516	! all year round. Even if the meteorological conditions are favorable for leaf maintenance,
517	! plants, and in particular, evergreen trees, have to renew their leaves simply because the
518	! old leaves become inefficient.
519	! Roots, fruits (and stems) follow leaves. The decay rate varies with leaf age.
520	! Note that plant is not declared senescent in this case (wchich is important for allocation:
521	! if the plant loses leaves because of their age, it can renew them).
522	!
523	! The leaf turnover rate due to aging of leaves is calculated using the following equation:
524	! \latexonly
525	! \input{turnover_age_senes_biomass_eqn5.tex}
526	! \endlatexonly
527	! \n
528	DO j = 2,nvm ! Loop over # PFTs
529
530	!! save old leaf mass
531	lm_old(:) = biomass(:,j,ileaf,icarbon)
532
533	!! initialize leaf mass change in age class
534	delta_lm(:,:) = zero
535
536	IF ( is_tree(j) .OR. (.NOT. natural(j)) ) THEN
537
538	!! 4.1 Trees: leaves, roots, fruits roots and fruits follow leaves.
539
540	!! 4.1.1 Critical age: prescribed for trees
541	leaf_age_crit(:,j) = leafagecrit(j)
542
543	ELSE
544
545	!! 4.2 Grasses: leaves, roots, fruits, sap follow leaves.
546
547	!! 4.2.1 Critical leaf age depends on long-term temperature
548	! Critical leaf age depends on long-term temperature
549	! generally, lower turnover in cooler climates.
550	leaf_age_crit(:,j) = &
551	MIN( leafagecrit(j) * leaf_age_crit_coeff(1) , &
552	MAX( leafagecrit(j) * leaf_age_crit_coeff(2) , &
553	leafagecrit(j) - leaf_age_crit_coeff(3) * &
554	( t2m_longterm(:)-ZeroCelsius - leaf_age_crit_tref ) ) )
555
556	END IF
557
558	! 4.2.2 Loop over leaf age classes
559	DO m = 1, nleafages
560
561	turnover_rate(:) = zero
562
563	WHERE ( leaf_age(:,j,m) .GT. leaf_age_crit(:,j)/2. )
564
565	turnover_rate(:) = &
566	MIN( 0.99_r_std, dt / ( leaf_age_crit(:,j) * &
567	( leaf_age_crit(:,j) / leaf_age(:,j,m) )**quatre ) )
568
569	ENDWHERE
570
571	dturnover(:) = biomass(:,j,ileaf,icarbon) * leaf_frac(:,j,m) * turnover_rate(:)
572	turnover(:,j,ileaf,icarbon) = turnover(:,j,ileaf,icarbon) + dturnover(:)
573	biomass(:,j,ileaf,icarbon) = biomass(:,j,ileaf,icarbon) - dturnover(:)
574
575	! save leaf mass change
576	delta_lm(:,m) = - dturnover(:)
577
578	dturnover(:) = biomass(:,j,iroot,icarbon) * leaf_frac(:,j,m) * turnover_rate(:)
579	turnover(:,j,iroot,icarbon) = turnover(:,j,iroot,icarbon) + dturnover(:)
580	biomass(:,j,iroot,icarbon) = biomass(:,j,iroot,icarbon) - dturnover(:)
581
582	dturnover(:) = biomass(:,j,ifruit,icarbon) * leaf_frac(:,j,m) * turnover_rate(:)
583	turnover(:,j,ifruit,icarbon) = turnover(:,j,ifruit,icarbon) + dturnover(:)
584	biomass(:,j,ifruit,icarbon) = biomass(:,j,ifruit,icarbon) - dturnover(:)
585
586
587	!! for N pools
588	dturnover(:) = biomass(:,j,ileaf,initrogen) * leaf_frac(:,j,m) * turnover_rate(:)
589	turnover(:,j,ileaf,initrogen) = turnover(:,j,ileaf,initrogen) + ( 1.0 - recycle_leaf(j) ) * dturnover(:)
590	biomass(:,j,ilabile,initrogen) = biomass(:,j,ilabile,initrogen) + recycle_leaf(j) * dturnover(:)
591	biomass(:,j,ileaf,initrogen) = biomass(:,j,ileaf,initrogen) - dturnover(:)
592
593	dturnover(:) = biomass(:,j,iroot,initrogen) * leaf_frac(:,j,m) * turnover_rate(:)
594	turnover(:,j,iroot,initrogen) = turnover(:,j,iroot,initrogen) + ( 1.0 - recycle_root(j) ) * dturnover(:)
595	biomass(:,j,ilabile,initrogen) = biomass(:,j,ilabile,initrogen) + recycle_root(j) * dturnover(:)
596	biomass(:,j,iroot,initrogen) = biomass(:,j,iroot,initrogen) - dturnover(:)
597
598	dturnover(:) = biomass(:,j,ifruit,initrogen) * leaf_frac(:,j,m) * turnover_rate(:)
599	turnover(:,j,ifruit,initrogen) = turnover(:,j,ifruit,initrogen) + dturnover(:)
600	biomass(:,j,ifruit,initrogen) = biomass(:,j,ifruit,initrogen) - dturnover(:)
601
602	IF (.NOT. is_tree(j)) THEN
603	dturnover(:) = biomass(:,j,isapabove,icarbon) * leaf_frac(:,j,m) * turnover_rate(:)
604	turnover(:,j,isapabove,icarbon) = turnover(:,j,isapabove,icarbon) + dturnover(:)
605	biomass(:,j,isapabove,icarbon) = biomass(:,j,isapabove,icarbon) - dturnover(:)
606
607	dturnover(:) = biomass(:,j,isapabove,initrogen) * leaf_frac(:,j,m) * turnover_rate(:)
608	turnover(:,j,isapabove,initrogen) = turnover(:,j,isapabove,initrogen) + dturnover(:)
609	biomass(:,j,isapabove,initrogen) = biomass(:,j,isapabove,initrogen) - dturnover(:)
610	ENDIF
611
612	ENDDO
613
614	!! 4.3 Recalculate the fraction of leaf biomass in each leaf age class.
615	! Older leaves will fall more fast than younger leaves and therefore
616	! the leaf age distribution needs to be recalculated after turnover.
617	! The fraction of biomass in each leaf class is updated using the following equation:
618	! \latexonly
619	! \input{turnover_update_LeafAgeDistribution_eqn6.tex}
620	! \endlatexonly
621	! \n
622	!
623	! new fraction = new leaf mass of that fraction / new total leaf mass
624	! = (old fraction*old total leaf mass ::lm_old(:) + biomass change of that fraction ::delta_lm(:,m) ) /
625	! new total leaf mass ::biomass(:,j,ileaf
626	DO m = 1, nleafages
627
628	WHERE ( biomass(:,j,ileaf,icarbon) .GT. zero )
629	leaf_frac(:,j,m) = ( leaf_frac(:,j,m)*lm_old(:) + delta_lm(:,m) ) / biomass(:,j,ileaf,icarbon)
630	ELSEWHERE
631	leaf_frac(:,j,m) = zero
632	ENDWHERE
633
634	ENDDO
635
636	ENDDO ! loop over PFTs
637
638	!! 5. New (provisional) LAI
639	! ::lai(:,j) is determined from the leaf biomass ::biomass(:,j,ileaf,icarbon) and the
640	! specific leaf surface :: sla(j) (m^2 gC^{-1})
641	! The leaf area index is updated using the following equation:
642	! \latexonly
643	! \input{turnover_update_LAI_eqn7.tex}
644	! \endlatexonly
645	! \n
646
647	! lai(:,ibare_sechiba) = zero
648	! DO j = 2, nvm ! Loop over # PFTs
649	! lai(:,j) = biomass(:,j,ileaf,icarbon) * sla(j)
650	! ENDDO
651
652	!! 6. Definitely drop all leaves if there is a very low leaf mass during senescence.
653
654	! Both for deciduous trees and grasses same conditions are checked:
655	! If biomass is large enough (i.e. when it is greater than zero),
656	! AND when senescence is set to true
657	! AND the leaf biomass drops below a critical minimum biomass level (i.e. when it is lower than half
658	! the minimum initial LAI ::lai_initmin(j) divided by the specific leaf area ::sla(j),
659	! ::lai_initmin(j) is set to 0.3 in stomate_data.f90 and sla is a constant that is set to 0.015366 m2/gC),
660	! If these conditions are met, the flag ::shed_rest(:) is set to TRUE.
661	!
662	! After this, the biomass of different carbon pools both for trees and grasses is set to zero
663	! and the mean leaf age is reset to zero.
664	! Finally, the leaf fraction and leaf age of the different leaf age classes is set to zero.
665	DO j = 2,nvm ! Loop over # PFTs
666
667	shed_rest(:) = .FALSE.
668
669	!! 6.1 For deciduous trees: next to leaves, also fruits and fine roots are dropped
670	! For deciduous trees: next to leaves, also fruits and fine roots are dropped: fruit ::biomass(:,j,ifruit)
671	! and fine root ::biomass(:,j,iroot) carbon pools are set to zero.
672	IF ( is_tree(j) .AND. ( senescence_type(j) .NE. 'none' ) ) THEN
673
674	! check whether we shed the remaining leaves
675	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. senescence(:,j) .AND. &
676	( biomass(:,j,ileaf,icarbon) .LT. (lai_initmin(j) / 2.)/slainit(j) ) )
677
678	shed_rest(:) = .TRUE.
679
680	turnover(:,j,ileaf,icarbon) = turnover(:,j,ileaf,icarbon) + biomass(:,j,ileaf,icarbon)
681	turnover(:,j,iroot,icarbon) = turnover(:,j,iroot,icarbon) + biomass(:,j,iroot,icarbon)
682	turnover(:,j,ifruit,icarbon) = turnover(:,j,ifruit,icarbon) + biomass(:,j,ifruit,icarbon)
683
684	biomass(:,j,ileaf,icarbon) = zero
685	biomass(:,j,iroot,icarbon) = zero
686	biomass(:,j,ifruit,icarbon) = zero
687
688	! for N pools
689	turnover(:,j,ileaf,initrogen) = turnover(:,j,ileaf,initrogen) &
690	+ (1.0-recycle_leaf(j)) * biomass(:,j,ileaf,initrogen)
691	turnover(:,j,iroot,initrogen) = turnover(:,j,iroot,initrogen) &
692	+ (1.0-recycle_root(j)) * biomass(:,j,iroot,initrogen)
693	turnover(:,j,ifruit,initrogen) = turnover(:,j,ifruit,initrogen) &
694	+ biomass(:,j,ifruit,initrogen)
695
696	biomass(:,j,ilabile,initrogen) = biomass(:,j,ilabile,initrogen) &
697	+ recycle_leaf(j) * biomass(:,j,ileaf,initrogen) &
698	+ recycle_root(j) * biomass(:,j,iroot,initrogen)
699	biomass(:,j,ileaf,initrogen) = zero
700	biomass(:,j,iroot,initrogen) = zero
701	biomass(:,j,ifruit,initrogen) = zero
702	! reset leaf age
703	leaf_meanage(:,j) = zero
704	lai(:,j) = zero
705	lai(:,j) = zero
706	ENDWHERE
707
708	ENDIF
709
710	!! 6.2 For grasses: all aboveground carbon pools, except the carbohydrate reserves are affected:
711	! For grasses: all aboveground carbon pools, except the carbohydrate reserves are affected:
712	! fruit ::biomass(:,j,ifruit,icarbon), fine root ::biomass(:,j,iroot,icarbon) and sapwood above
713	! ::biomass(:,j,isapabove,icarbon) carbon pools are set to zero.
714	IF ( .NOT. is_tree(j) ) THEN
715
716	! Shed the remaining leaves if LAI very low.
717	WHERE ( ( biomass(:,j,ileaf,icarbon) .GT. zero ) .AND. senescence(:,j) .AND. &
718	( biomass(:,j,ileaf,icarbon) .LT. (lai_initmin(j) / 2.)/slainit(j) ))
719
720	shed_rest(:) = .TRUE.
721
722	turnover(:,j,ileaf,icarbon) = turnover(:,j,ileaf,icarbon) + biomass(:,j,ileaf,icarbon)
723	turnover(:,j,isapabove,icarbon) = turnover(:,j,isapabove,icarbon) + biomass(:,j,isapabove,icarbon)
724	turnover(:,j,iroot,icarbon) = turnover(:,j,iroot,icarbon) + biomass(:,j,iroot,icarbon)
725	turnover(:,j,ifruit,icarbon) = turnover(:,j,ifruit,icarbon) + biomass(:,j,ifruit,icarbon)
726
727	biomass(:,j,ileaf,icarbon) = zero
728	biomass(:,j,isapabove,icarbon) = zero
729	biomass(:,j,iroot,icarbon) = zero
730	biomass(:,j,ifruit,icarbon) = zero
731
732	turnover(:,j,ileaf,initrogen) = turnover(:,j,ileaf,initrogen) &
733	+ (1.0-recycle_leaf(j)) * biomass(:,j,ileaf,initrogen)
734	turnover(:,j,iroot,initrogen) = turnover(:,j,iroot,initrogen) &
735	+ (1.0-recycle_root(j)) * biomass(:,j,iroot,initrogen)
736	turnover(:,j,ifruit,initrogen) = turnover(:,j,ifruit,initrogen) &
737	+ biomass(:,j,ifruit,initrogen)
738
739	biomass(:,j,ilabile,initrogen) = biomass(:,j,ilabile,initrogen) &
740	+ recycle_leaf(j) * biomass(:,j,ileaf,initrogen) &
741	+ recycle_root(j) * biomass(:,j,iroot,initrogen)
742	biomass(:,j,ileaf,initrogen) = zero
743	biomass(:,j,iroot,initrogen) = zero
744	biomass(:,j,ifruit,initrogen) = zero
745
746
747	! reset leaf age
748	leaf_meanage(:,j) = zero
749	lai(:,j) = zero
750	lai(:,j) = zero
751	ENDWHERE
752
753	ENDIF
754
755	!! 6.3 Reset the leaf age structure: the leaf fraction and leaf age of the different leaf age classes is set to zero.
756
757	DO m = 1, nleafages
758
759	WHERE ( shed_rest(:) )
760
761	leaf_age(:,j,m) = zero
762	leaf_frac(:,j,m) = zero
763
764	ENDWHERE
765
766	ENDDO
767
768	ENDDO ! loop over PFTs
769
770	!! 7. Herbivore activity: elephants, cows, gazelles but no lions.
771
772	! Herbivore activity affects the biomass of leaves and fruits as well
773	! as stalks (only for grasses). Herbivore activity does not modify leaf
774	! age structure. Herbivores ::herbivores(:,j) is the time constant of
775	! probability of a leaf to be eaten by a herbivore, and is calculated in
776	! ::stomate_season. following Mc Naughton et al. [1989].
777
778	IF ( ok_herbivores ) THEN
779
780	! If the herbivore activity is allowed (if ::ok_herbivores is true, which is set in run.def),
781	! remove the amount of biomass consumed by herbivory from the leaf biomass ::biomass(:,j,ileaf,icarbon) and
782	! the fruit biomass ::biomass(:,j,ifruit,icarbon).
783	! The daily amount consumed equals the biomass multiplied by 1 day divided by the time constant ::herbivores(:,j).
784	DO j = 2,nvm ! Loop over # PFTs
785
786	IF ( is_tree(j) ) THEN
787
788	!! For trees: only the leaves and fruit carbon pools are affected
789
790	WHERE (biomass(:,j,ileaf,icarbon) .GT. zero)
791	! added by shilong
792	WHERE (herbivores(:,j).GT. zero)
793	dturnover(:) = biomass(:,j,ileaf,icarbon) * dt / herbivores(:,j)
794	turnover(:,j,ileaf,icarbon) = turnover(:,j,ileaf,icarbon) + dturnover(:)
795	biomass(:,j,ileaf,icarbon) = biomass(:,j,ileaf,icarbon) - dturnover(:)
796
797	dturnover(:) = biomass(:,j,ileaf,initrogen) * dt / herbivores(:,j)
798	turnover(:,j,ileaf,initrogen) = turnover(:,j,ileaf,initrogen) + dturnover(:)
799	biomass(:,j,ileaf,initrogen) = biomass(:,j,ileaf,initrogen) - dturnover(:)
800
801
802	dturnover(:) = biomass(:,j,ifruit,icarbon) * dt / herbivores(:,j)
803	turnover(:,j,ifruit,icarbon) = turnover(:,j,ifruit,icarbon) + dturnover(:)
804	biomass(:,j,ifruit,icarbon) = biomass(:,j,ifruit,icarbon) - dturnover(:)
805
806	dturnover(:) = biomass(:,j,ifruit,initrogen) * dt / herbivores(:,j)
807	turnover(:,j,ifruit,initrogen) = turnover(:,j,ifruit,initrogen) + dturnover(:)
808	biomass(:,j,ifruit,initrogen) = biomass(:,j,ifruit,initrogen) - dturnover(:)
809	ENDWHERE
810	ENDWHERE
811
812	ELSE
813
814	! For grasses: all aboveground carbon pools are affected: leaves, fruits and sapwood above
815	WHERE ( biomass(:,j,ileaf,icarbon) .GT. zero )
816	! added by shilong
817	WHERE (herbivores(:,j) .GT. zero)
818	dturnover(:) = biomass(:,j,ileaf,icarbon) * dt / herbivores(:,j)
819	turnover(:,j,ileaf,icarbon) = turnover(:,j,ileaf,icarbon) + dturnover(:)
820	biomass(:,j,ileaf,icarbon) = biomass(:,j,ileaf,icarbon) - dturnover(:)
821
822	dturnover(:) = biomass(:,j,ileaf,initrogen) * dt / herbivores(:,j)
823	turnover(:,j,ileaf,initrogen) = turnover(:,j,ileaf,initrogen) + dturnover(:)
824	biomass(:,j,ileaf,initrogen) = biomass(:,j,ileaf,initrogen) - dturnover(:)
825
826	dturnover(:) = biomass(:,j,isapabove,icarbon) * dt / herbivores(:,j)
827	turnover(:,j,isapabove,icarbon) = turnover(:,j,isapabove,icarbon) + dturnover(:)
828	biomass(:,j,isapabove,icarbon) = biomass(:,j,isapabove,icarbon) - dturnover(:)
829
830	dturnover(:) = biomass(:,j,isapabove,initrogen) * dt / herbivores(:,j)
831	turnover(:,j,isapabove,initrogen) = turnover(:,j,isapabove,initrogen) + dturnover(:)
832	biomass(:,j,isapabove,initrogen) = biomass(:,j,isapabove,initrogen) - dturnover(:)
833
834
835	dturnover(:) = biomass(:,j,ifruit,icarbon) * dt / herbivores(:,j)
836	turnover(:,j,ifruit,icarbon) = turnover(:,j,ifruit,icarbon) + dturnover(:)
837	biomass(:,j,ifruit,icarbon) = biomass(:,j,ifruit,icarbon) - dturnover(:)
838
839	dturnover(:) = biomass(:,j,ifruit,initrogen) * dt / herbivores(:,j)
840	turnover(:,j,ifruit,initrogen) = turnover(:,j,ifruit,initrogen) + dturnover(:)
841	biomass(:,j,ifruit,initrogen) = biomass(:,j,ifruit,initrogen) - dturnover(:)
842	ENDWHERE
843
844	ENDWHERE
845
846	ENDIF ! tree/grass?
847
848	ENDDO ! loop over PFTs
849
850	ENDIF ! end herbivores
851
852	!! 8. Fruit turnover for trees
853
854	! Fruit turnover for trees: trees simply lose their fruits with a time constant ::tau_fruit(j),
855	! that is set to 90 days for all PFTs in ::stomate_constants
856
857	DO k = 1,nelements
858	DO j = 2,nvm ! Loop over # PFTs
859	IF ( is_tree(j) ) THEN
860
861	dturnover(:) = biomass(:,j,ifruit,k) * dt / tau_fruit(j)
862	turnover(:,j,ifruit,k) = turnover(:,j,ifruit,k) + dturnover(:)
863	biomass(:,j,ifruit,k) = biomass(:,j,ifruit,k) - dturnover(:)
864
865	ENDIF
866	ENDDO ! loop over PFTs
867	END DO
868
869	!! 9 Conversion of sapwood to heartwood both for aboveground and belowground sapwood and heartwood.
870
871	! Following LPJ (Sitch et al., 2003), sapwood biomass is converted into heartwood biomass
872	! with a time constant tau ::tau_sap(j) of 1 year.
873	! Note that this biomass conversion is not added to "turnover" as the biomass is not lost!
874	DO j = 2,nvm ! Loop over # PFTs
875
876	IF ( is_tree(j) ) THEN
877
878	!! For the recalculation of age in 9.2 (in case the vegetation is not dynamic ie. ::ok_dgvm is FALSE),
879	!! the heartwood above and below is stored in ::hw_old(:).
880	IF ( .NOT. ok_dgvm ) THEN
881	hw_old(:) = biomass(:,j,iheartabove,icarbon) + biomass(:,j,iheartbelow,icarbon)
882	ENDIF
883
884	!! 9.1 Calculate the rate of sapwood to heartwood conversion
885	! Calculate the rate of sapwood to heartwood conversion with the time constant ::tau_sap(j)
886	! and update aboveground and belowground sapwood ::biomass(:,j,isapabove) and ::biomass(:,j,isapbelow)
887	! and heartwood ::biomass(:,j,iheartabove) and ::biomass(:,j,iheartbelow).
888
889	DO k = 1,nelements
890
891	! Above the ground
892	sapconv(:) = biomass(:,j,isapabove,k) * dt / tau_sap(j)
893	biomass(:,j,isapabove,k) = biomass(:,j,isapabove,k) - sapconv(:)
894	biomass(:,j,iheartabove,k) = biomass(:,j,iheartabove,k) + sapconv(:)
895
896	! Below the ground
897	sapconv(:) = biomass(:,j,isapbelow,k) * dt / tau_sap(j)
898	biomass(:,j,isapbelow,k) = biomass(:,j,isapbelow,k) - sapconv(:)
899	biomass(:,j,iheartbelow,k) = biomass(:,j,iheartbelow,k) + sapconv(:)
900
901	END DO
902
903	!! 9.2 If the vegetation is not dynamic, the age of the plant is decreased.
904	! The updated heartwood, the sum of new heartwood above and new heartwood below after
905	! converting sapwood to heartwood, is saved as ::hw_new(:) .
906	! Creation of new heartwood decreases the age of the plant with a factor that is determined by:
907	! old heartwood ::hw_old(:) divided by the new heartwood ::hw_new(:)
908	IF ( .NOT. ok_dgvm ) THEN
909
910	hw_new(:) = biomass(:,j,iheartabove,icarbon) + biomass(:,j,iheartbelow,icarbon)
911
912	WHERE ( hw_new(:) .GT. zero )
913
914	age(:,j) = age(:,j) * hw_old(:)/hw_new(:)
915
916	ENDWHERE
917
918	ENDIF
919
920	ENDIF
921
922	ENDDO ! loop over PFTs
923
924
925	! WRITE(numout,) '**** turnover_time:',turnover_time(:,:)
926
927	CALL xios_orchidee_send_field("HERBIVORES",herbivores)
928	CALL xios_orchidee_send_field("LEAF_AGE",leaf_meanage)
929
930
931	! Write mean leaf age and time constant of probability of a leaf to be eaten by a herbivore
932	! to the stomate output file.
933	CALL histwrite_p (hist_id_stomate, 'LEAF_AGE', itime, &
934	leaf_meanage, npts*nvm, horipft_index)
935	CALL histwrite_p (hist_id_stomate, 'HERBIVORES', itime, &
936	herbivores, npts*nvm, horipft_index)
937
938	IF (printlev>=4) WRITE(numout,*) 'Leaving turnover'
939
940	END SUBROUTINE turn
941
942	END MODULE stomate_turnover

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