Test of validity of a dynamic soil carbon model using data from leaf litter decomposition in a West African tropical forest

GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | Geosci. Model De . Discuss., 6, 3003–3032, 2013 www.geosci-model-de -discuss.ne /6/3003/2013/ doi:10.5194/gmdd-6-3003-2013 © Au ho (s) 2013. CC A ibu ion 3.0 License. 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Please e e o he co esponding inal pape in GMD i a ailable. Tes o alidi y o a dynamic soil ca bon model using da a om lea li e decomposi ion in a Wes A ican opical o es G. H. S. Guendehou1,2, J. Liski3, M. Tuomi3, M. Moudachi ou4, B. Sinsin5, and R. Mäkipää2 1Cen e Béninois de la Reche che Scien i ique e Technique, 03 BP 1665 Co onou, Bénin 2Finnish Fo es Resea ch Ins i u e, P.O. Box 18, 01301 Van aa, Finland 3Finnish En i onmen Ins i u e, P.O. Box 140, 00251 Helsinki, Finland 4Labo a oi e de Pha macognosie, Facul é des Sciences e Techniques, Uni e si é d’Abomey-Cala i, 01 BP 918 Co onou, Bénin 5Labo a oi e d’Ecologie Appliquée, Facul é des Sciences Ag onomiques, Uni e si é d’Abomey-Cala i, 01 BP 526 Co onou, Bénin Recei ed: 8 Ap il 2013 – Accep ed: 6 May 2013 – Published: 28 May 2013 Co espondence o: G. H. S. Guendehou ([email p o ec ed], [email protected]) Published by Cope nicus Publica ions on behal o he Eu opean Geosciences Union. 3003 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | Abs ac We e alua ed he applicabili y o he dynamic soil ca bon model Yasso07 in opical condi ions in Wes A ica by simula ing he li e decomposi ion p ocess using as e- qui ed inpu in o he model li e mass, li e quali y, empe a u e and p ecipi a ion col- lec ed du ing a li e bag expe imen . The expe imen was conduc ed o e a six-mon h5 pe iod on lea li e o i e dominan ee species, namely A zelia a icana, Anogeissus leioca pa, Ceiba pen and a, Dialium guineense and Diospy os mespili o mis in a semi- deciduous e isol o es in Sou he n Benin. Since he p edic ions o Yasso07 we e no consis en wi h he obse a ions on mass loss and chemical composi ion o li e , Yasso07 was i ed o he da ase composed o global da a and he new expe imen-10 al da a om Benin. The e-pa ame e ized e sions o Yasso07 had a good p edic i e abili y and e ined he applicabili y o he model in Benin o es ima e soil ca bon s ocks, i s changes and CO2emissions om he e o ophic espi a ion as main ou pu s o he model. The indings o his esea ch suppo he hypo hesis ha he high a ia ion o li e quali y obse ed in he opics is a majo d i e o he decomposi ion and needs15 o be accoun ed in he model pa ame e iza ion. 1 In oduc ion In opical condi ions in A ica, li le a en ion has been paid o li e decomposi ion and quan i ica ion o changes in he soil o ganic ca bon (SOC), hough o es soil in his egion accoun s o 11 % o he wo ld’s soil ca bon pool (FAO, 2010). Quan i ica ion o 20 SOC dynamics in opical A ica is equi ed o imp o e he es ima ion o he global ca - bon balance. The SOC changes a e epo ed unde he Clima e Change Con en ion as a pa o he na ional g eenhouse gas in en o ies o he o es y sec o (UNFCCC, 2008, 2010), bu majo i y o he coun ies in opical A ica ei he epo no changes in SOC s ocks o apply de aul s ock change ac o s o he In e go e nmen al Panel25 on Clima e Change me hodologies (pa ex. IPCC, 2003, 2006) oge he wi h ough 3004 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | es ima ion o he land use and land use change. Unde he Uni ed Na ions F amewo k Con en ion on Clima e Change (UNFCCC) mechanism o he Reducing Emissions om De o es a ion and Fo es Deg ada ion in De eloping Coun ies (REDD), he coun- ies ha e economic incen i es o he conse a ion, he sus ainable managemen and he enhancemen o hei o es ca bon s ocks and obus me hods leading o con iden 5 and e i ied ca bon s ock es ima es a e inc easingly equi ed. A numbe o s udies ha e epo ed SOC s ocks es ima ed om only spo adic soil sampling and digi al maps ( o example Manu e al., 1991; P udencio, 1993; Volko e al., 1999; Hen y e al., 2009) and he epo ed alues in he exis ing da abases in A ica (Ba jes, 1996, 2002, 2005, 2006; FAO, 2008) consis o global es ima es wi h limi ed indica ions on changes and10 dis ibu ion acco ding o ecosys ems. The dynamics o SOC is in luenced by li e quan i y and quali y, clima e and me abolism o decomposing o ganisms and go e ned by o he physical, chemical and biological ac o s, such as soil p ope ies, which all may be di icul o quan i y (Swi and Ande son, 1989; Ae s, 1997; Coû eaux e al., 1998; La elle e al., 1993). O e all15 changes in he SOC s ock may be quan i ied wi h measu emen s, bu epea ed mea- su emen s o soil ca bon s ocks a e labo ious, ime and esou ces consuming e o s wi h he added d awback o he di icul y o p edic ing u u e le els. Also, ex apola - ing only a ew SOC measu emen s o a la ge scale may lead o high unce ain y due o he spa ial a ia ion o SOC. Thus, p ocesses aking place in soil and SOC s ock20 changes a e s udied mos ly h ough he use o decomposi ion models (Coleman and Jenkinson, 1996; Cu ie and Abe , 1997; Ku z and Apps, 1999; Che o e al., 2001; Liski e al., 2005; Sie a e al., 2012). The applica ion o he model-based app oach could also help coun ies o mee SOC epo ing equi emen s in opical A ica, whe e esou ces a e limi ed. Howe e , model esul s and hei applicabili y depend on model25 s uc u e and pa ame e s, as well as on a ailable inpu in o ma ion and assump ions used (Pel oniemi e al., 2007; Palosuo e al., 2012). To ou knowledge, no SOC model calib a ed using li e decomposi ion da a om o es s in A ica is a ailable. The li e quali y is known o be he mos impo an 3005 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | de e minan o he decomposi ion a e a egional scale (e.g. Tian e al., 1992; Be g e al., 1993; La elle e al., 1993; Ae s, 1997; Lo ange e al., 2002; Guendehou e al., 2014) and he plan species ichness o opical o es s yields high a ia ion in he li - e quali y (Goma-Tchimbakala and Be nha d-Re e sa , 2006; Ba bhuiya e al., 2008; Cusack e al., 2009). Howe e , only a ew li e ypes om opical ee species we e5 included in he da ase ha was used o he pa ame e iza ion o he widely applied soil ca bon model (Coleman and Jenkinson, 1996; Che o e al. 2001; Tuomi e al., 2009) and many soil models a e pa ame e ized only o empe a e and bo eal condi ions. In his pape , we assessed he applicabili y o he dynamic soil ca bon model Yasso07 in opical condi ions in Wes A ica, by simula ing he li e decomposi ion10 p ocess using da a on li e mass, li e quali y, empe a u e and p ecipi a ion. The da a was collec ed om a li e bag expe imen conduc ed on lea li e om i e dominan ee species, namely A zelia a icana,Anogeissus leioca pa,Ceiba pen and a,Dialium guineense, and Diospy os mespili o mis, in he na u al semi-deciduous o es Lama in Sou he n Benin. We es ed he hypo heses ha he decomposi ion p ocess in opics15 is a ec ed by he high a ia ion o li e quali y and e-pa ame e iza ion o he Yasso07 model wi h he di e se li e da a om opics imp o es he p ecision o he mass loss p edic ions. 2 Ma e ial and me hods 2.1 Expe imen al si e20 The expe imen al si e is he Lama o es , a na u al semi-deciduous o es loca ed in a humid opical clima e in Sou he n Benin (Nagel e al., 2004) a 6◦550–7◦000N, 2◦040– 2◦120E (Fig. 1). The si e alls wi hin he opical mois zone acco ding o he classi i- ca ion scheme o clima e egions o he IPCC (IPCC, 2006). The highes (38 ◦C) and he lowes (15 ◦C) empe a u es we e usually eco ded in Feb ua y–Ma ch and in De-25 cembe , espec i ely. The mean annual empe a u e is 27 ◦C. The p ecipi a ion shows 3006 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | a bimodal dis ibu ion pa e n. The mean annual p ecipi a ion in he expe imen al si e is 1100 mm; ain all is, in gene al, mo e han 100 mmmon h−1 h oughou he yea , excep in Janua y, Feb ua y and Decembe . Yea s a e di ided in o ou seasons: wo ainy and wo d y seasons. The p incipal ainy season occu s be ween mid-Ma ch and mid-July and he sho e ainy season be ween mid-Sep embe and mid-No embe .5 The mon hly a e age o ela i e humidi y is always mo e han 51 %. Table 1 shows he mon hly clima ic da a eco ded by he na ional me eo ological se ice a he ime o he decomposi ion expe imen . The soil o he Lama o es is epo ed as a a e hyd omo phic clayey e isol (40 o 60 % o clay) in Wes A ica, wi h a poo d ainage and a pH ange o 5–5.5 in he 0–10 30 cm ho izon (Küppe s e al., 1998). The pH inc eases up o 6.5–7 in deepe ho izons due o he appea ance o limes one a a dep h o 150 cm. This soil has been desc ibed as ich in calcium (Ca) and magnesium (Mg) due o a “g ani o-gneissic” pa en ma e ial om he seconda y and e ia y ages. The mean al i ude in he o es is 60 m ( on Bo hme e al., 1986).15 The ee species ichness o he Lama o es was desc ibed by Akoègninou (1984), Mondjannagni (1969), Pa adis and Houngnon (1977). Küppe s e al. (1998) epo ed 67 amilies based on an in en o y ca ied ou in 1998. The a e age densi y in he na u al dense pa o he o es whe e he expe imen ook place is 12 species/400 m2, and he ela i e abundance o dominan ee species is abou 40 ees/400 m2(Küppe s20 e al., 1998). The cu en esea ch ocused on i e dominan ee species including A. a icana,A. leioca pa,C. pen and a,D. guineense and D. mespili o mis ( on Bo hme e al., 1986; Küppe s e al., 1998; Nagel e al., 2004). No human ac i i ies such as ha es ing o e iliza ion a e implemen ed in he expe imen al si e. In Lama o es , he amoun o lea li e all anges om 26 o 42 d y ma e y −1; he li e all ollows25 a unimodal dis ibu ion pa e n, wi h he maximum li e p oduc ion obse ed du ing he d y season, o en in Janua y (Djego, 2006). 3007 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | 2.2 Li e bag expe imen , mass loss measu emen , and chemical analyses The ma e ial used consis ed o lea li e o A. a icana, A. leioca pa, C. pen and a, D. guineense, and D. mespili o mis. Only senescen lea es eady o all om he ees we e collec ed. Lea es we e d ied in open-ai and hen o en-d ied a 75 ◦C o cons an weigh . In o de o use all he amoun o li e collec ed, an ini ial mass o d ied lea es5 o A. a icana (20 g), A. leioca pa (30 g), C. pen and a (20 g), D. guineense (30 g), and D. mespili o mis (30 g) was placed in he li e bags in polyes e (20 cm ×20 cm, mesh size 0.33 mm) on he o es loo . Li e bags we e di ided be ween ou plo s es ab- lished in a nea ly ec angula con igu a ion; he dis ance be ween he plo s (be ween 25 and 30 m) was assumed la ge enough o minimize he spa ial au oco ela ion be-10 ween plo s. In each plo , li e bags we e placed in ows and columns on he o es loo : he e we e i e columns each con aining he i e li e species and six ows each con- aining he six collec ions. In o al, 30 li e bags we e placed in a plo . In each ow, he i e bags we e placed. Bags we e no mo ed un il collec ion da e and no dis u bances occu ed du ing he expe imen . Bags we e collec ed e e y ou weeks om he ou 15 plo s (be ween Feb ua y and July 2010), he emaining li e was d ied in open ai and in he o en a 75 ◦C o cons an weigh . The emaining mass was measu ed and he mass loss es ima ed. The emaining d ied li e was kep in a eeze in a plas ic bag be o e he chemical analyses. The chemical analyses on li e p io o decomposi ion and on decomposed li e 20 we e ca ied ou in he labo a o y o he Finnish Fo es Resea ch Ins i u e. Based on he solubili y di e ence o he essen ial cons i uen s o lea li e in di e en sol en s, he analyses enabled o de e mine he concen a ion o compounds soluble in e hanol, compounds soluble in wa e , compounds hyd olysable in acid, and compounds nei- he soluble no hyd olysable (he eina e e e ed o as Klason lignin). Ex ac ion was25 conduc ed in a sonica ing wa e ba h, i s o 90 min wi h e hanol, hen o 90 min wi h wa e (Ka hu e al., 2010). The e hanol- and wa e ex ac ed esidue was di ided in o acid-hyd olysable (72 % H2SO4) and non-hyd olysable ac ions using he Klason lignin 3008 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | me hod (E land, 1977). Samples we e il e ed, o en-d ied a 75 ◦C o cons an weigh and weighed be ween he ex ac ions, and he amoun s o di e en ac ions we e de- e mined as p opo ions o he mass o o ganic ma e . The ash con en o he samples was de e mined a e keeping he d ied samples in a mu le u nace a 550 ◦C o e nigh . Due o he high numbe o chemical pa ame e s o de e mine on each collec ed sam-5 ples (160 pa ame e s), samples o he same li e species and same collec ion we e pooled o chemical analyses in o de o educe he amoun o wo k, and assuming his yields he a e age chemical composi ion o he ou plo s. 2.3 Model desc ip ion, simula ions o li e decomposi ion p ocess and da a analysis10 In he model Yasso07, esh o ganic ma e in lea , ine oo , and woody li e is di ided in o ou chemically dis inguishable compound g oups: acid-hyd olysable compounds (A), wa e -soluble compounds (W), e hanol-soluble compounds (E), nei he soluble, no hyd olysable compounds (N) ha decompose a hei unique a es (Tuomi e al., 2009). In addi ion, he e is a humus (H) ac ion, assumed o consis o mo e ecalci an 15 compounds, ha ecei es a pa o p oduc s esul ing om he decomposi ion o A, W, E, N (Fig. 2). The decay a es (as measu e o mic obial ac i i y) o he compound g oups depend on he clima ic condi ions desc ibed by empe a u e and p ecipi a ion (Meen emeye , 1978; Be g e al., 1993; Ae s, 1997; Liski e al., 2003; Pa on e al., 2007). The decomposi ion o compound g oups esul s in mass loss om he sys em20 and in mass lows be ween he compound g oups. The mass loss consis s o emo al om he soil as he e o ophic espi a ion (CO2) and leaching while he emaining mass o ms mo e ecalci an compounds, o example humus. Ma hema ically, Yasso07 is a linea compa men al sys em, a se o i s o de di e - en ial equa ions (Tuomi e al., 2011b):25 ˙ x( )=A(C)x( )+b( )−ωiIPa,x(0) =x0(1) 3009 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | whe e x=(xA,xW,xE,xN,xH)Tis a ec o desc ibing he masses o he i e compa - men s as a unc ion o ime ( ); A(C) is a ma ix desc ibing he decomposi ion a es and he mass lows be ween he compa men s as a unc ion o clima ic condi ions (C); ec- o b( ) is he li e inpu o he soil; ωia e ee pa ame e s desc ibing he p ecipi a ion induced leaching a es; I=(1,1,1,1,1)Tis a cons an column ec o ; Pais he annual5 p ecipi a ion. Vec o x0=(xA,0,xW,0,xE,0,xN,0,xH,0) desc ibes he ini ial chemical com- posi ion s a e o he sys em. Ma ix Ais de ined as a p oduc o he mass low ma ix Apand he diagonal decomposi ion coe icien ma ix k(C)=diag(kA,kW,kE,kN,kH)(C), whe e kia e he decomposi ion a e coe icien s o he compa men s (Tuomi e al., 2009).10 Ap=       −1p1p2p30 p4−1p5p60 p7p8−1p90 p10 p11 p12 −1 0 pHpHpHpH−1       whe e pi∈[0,1] a e ela i e mass low pa ame e s be ween he compa men s. p1:. ela i e mass low magni ude, W →A; p2: ela i e mass low magni ude, E →A; p3:. ela i e mass low magni ude, N →A; p4: ela i e mass low magni ude, A →W; p5:. ela i e mass low magni ude, E →W; p6: ela i e mass low magni ude, N →W;15 p7:. ela i e mass low magni ude, A →E; p8: ela i e mass low magni ude, W →E; p9:. ela i e mass low magni ude, N →E; p10: ela i e mass low magni ude, A →N; p11:. ela i e mass low magni ude, W →N; p12: ela i e mass low magni ude, E →N; pH:. mass low o humus. 3010 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | The clima e dependence o he decomposi ion a e ac o s ki o mula ed in Eq. (2) was jus i ied ea lie by Tuomi e al. (2009): ki(C)=αiexpβ1T+β2T2(1 −expγPa) (2) whe e Tis empe a u e (Celsius scale), Pa: annual p ecipi a ion, αi: decomposi ion a e pa ame e , β1and β2: empe a u e dependence pa ame e s, γ: p ecipi a ion de-5 pendence pa ame e . αi,β1,β2, and γa e ee pa ame e s. The s uc u e and ma hema ical o mulas o Yasso07 a e desc ibed in mo e de ail in p e ious publica ions (Tuomi e al., 2009, 2011a). The da a needed o un he model Yasso07 include: li e amoun , li e quali y (dis- ibu ion o li e be ween A, W, E, N) oge he wi h unce ain y da a (exp essed as10 s anda d de ia ions) and clima ic da a ( empe a u e and p ecipi a ion). The simula ion was conduc ed on each indi idual s udied li e species. An ini ial mass o li e wi h i s chemical composi ion (Figs. 3–7) and clima ic da a (Table 1) we e used as inpu s in o he dynamic soil ca bon model Yasso07. The p edic ions o Yasso07 we e compa ed wi h he obse a ions on change in mass, and change in chemical15 composi ion. Then, Yasso07 was i ed o a da ase whe e new da a om Benin we e me ged wi h a global da a ( om Eu ope; Be g e al., 1991a,b, 1993, No he n and Cen al Ame ica, Gholz e al., 2000; T o ymow e al., 1998). Also, Yasso07 was i ed only o he new expe imen al da a om Benin. This esul ed in wo new e sions o he Yasso07: Y07A o e e o Yasso07 i ed o he da ase including global and Benin20 da a, and Y07B o e e o Yasso07 i ed only o new da a om Benin. The p edic ions o hese wo e sions we e compa ed wi h he obse a ions using mean esiduals and s anda d de ia ions he eo . When analysing he da a, he Bayesian in e ence o in o ma ion om he measu e- men s o he pa ame e alues (see o example, Ellison, 2004) was used. Following he25 me hod o Tuomi e al. (2009, 2011a), he Ma ko chain Mon e Ca lo (MCMC) pos e io sampling echnique was used in da a analyses. The eason o selec ing his me hod was i s abili y o p oduce a sample om he pos e io p obabili y densi y o he model 3011 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | Re e ences Ae s, R.: Clima e, lea li e chemis y and lea li e decomposi ion in e es ial ecosys ems: a iangula ela ionship, Oikos, 79, 439–449, 1997. 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Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | Table 1. Mon hly clima ic da a eco ded du ing he li e bag expe imen in 2010 by he me e- o ological s a ions Bohicon ( o empe a u e) and To o ( o p ecipi a ion) closes o he Lama o es . Mon h Tempe a u e P ecipi a ion (◦C) (mm) Feb 31.4 80.1 Ma 30.6 192.4 Ap 30.2 100.3 May 29.0 157.1 Jun 28.1 90.1 Jul 26.6 149.0 3024 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | Table 2. Pa ame e alues o he o iginal calib a ion o Yasso07 and o he pa ame e iza ion o Yasso07 using only da a om Benin and he ea e all da a (global da a and da a om Benin oge he ). Pa ame e Uni Benin da a All da a O iginal calib a ion∗ In e p e a ion MAP 95 % CI MAP 95 % CI MAP 95 % CI αAy −13.97 ±0.74 0.39 ±0.03 0.72 ±0.09 d a e o A αWy −120.55 ±3.10 4.54 ±0.30 5.9 ±0.8 d a e o W αEy −117.00 ±3.50 0.34 ±0.04 0.28 +0.07, −0.04 d a e o E αNy −13.57 ±0.50 0.13 ±0.02 0.031 +0.011, −0.004 d a e o N p1– 0.02 ±0.02 0.00 +0.01, −0.00 0.48 ±0.06 m low, W →A p2– 0.01 +0.04, −0.01 0.01 ±0.01 0.01 +0.15, −0.01 m low, E →A p3– 0.79 ±0.33 0.87 ±0.03 0.83 +0.16, −0.23 m low, N →A p4– 0.71 ±0.15 0.99 ±0.01 0.99 +0.01, −0.05 m low, A →W p5– 0.05 ±0.05 0.05 +0.01, −0.00 0.00 +0.08, −0.00 m low, E →W p6– 0.04 +0.16, −0.04 0.00 +0.01, −0.00 0.01 +0.20, −0.01 m low, N →W p7– 0.05 ±0.05 0.00 +0.01, −0.00 0.00 +0.01, −0.00 m low, A →E p8– 0.06 +0.07, −0.06 0.00 +0.01, −0.00 0.00 +0.01, −0.00 m low, W →E p9– 0.13 ±0.08 0.133 ±0.03 0.02 +0.23, −0.02 m low, N →E p10 – 0.01 +0.04, −0.01 0.01 ±0.01 0.00 +0.01, −0.00 m low, A →N p11 – 0.02 +0.05, −0.02 0.19 ±0.01 0.02 ±0.02 m low, W →N p12 – 0.88 ±0.11 0.44 ±0.01 0.95 +0.05, −0.16 m low, E →N β110−2◦C−10.087 +0.01, −0.00 0.069 ±0.01 0.095 ±0.02 Tdependence β210−3◦C−2−0.0029 +0.01, −0.00 −0.00050 0.001 −0.0014 +0.0006, −0.0009 Tdependence γm−1−2.500 ±0.05 −0.939 ±0.09 −1.21 ±0.14 Pdependence ωEy −1m−1– 0.005 −0.2008 ±0.01 −0.151 ±0.008 Pleaching Eu ope ωAy −1m−1–+0.01, −0.00 −0.0006 ±0.01 0.000 +0.0, −0.002 Pleaching Ame ica ωBy −1m−1−0.061 ±0.19 −0.943 ±0.04 – – Pleaching Benin 3025 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | 21 583 584 Figu e 1: Loca ion o he s udy a ea in Benin 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 Fig. 1. Loca ion o he s udy a ea in Benin. 3026 GMDD 6, 3003–3032, 2013 Soil ca bon modeling in opical o es s G. H. S. Guendehou e al. Ti le Page Abs ac In oduc ion Conclusions Re e ences Tables Figu es J I J I Back Close Full Sc een / Esc P in e - iendly Ve sion In e ac i e Discussion Discussion Pape | Discussion Pape | Discussion Pape | Discussion Pape | 22 614 Figu e 2: Flow diag am o he model Yasso07 and he ela i e magni udes o each mass low be ween 615 labile compound g oups o o ganic ca bon and mo e ecalci an humus; acid-hyd olysable (A), wa e -616 soluble (W), e hanol-soluble (E), and compounds nei he soluble no hyd olysable (N). The ca bon lows 617 whose magni udes di e s a is ically (95% con idence) om ze o (solid a ows) be ween and ou o he 618 A, W, E, and N ac ions (squa e boxes); he small lows (do ed a ows) in o humus (bo om box), each 619 app oxima ely 0.5%; and he mass lows (dashed a ows) whose maximum a pos e io i (MAP) es ima es 620 we e indis inguishable om ze o bu whose 95% Bayesian con idence in e al was b oade han 0.05 621 (Tuomi e al. 2011b). 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 Fig. 2. Flow diag am o he model Yasso07 and he ela i e magni udes o each mass low be ween labile compound g oups o o ganic ca bon and mo e ecalci an humus; acid- hyd olysable (A), wa e -soluble (W), e hanol-soluble (E), and compounds nei he soluble no hyd olysable (N). The ca bon lows whose magni udes di e s a is ically (95 % con idence) om ze o (solid a ows) be ween and ou o he A, W, E, and N ac ions (squa e boxes); he small lows (do ed a ows) in o humus (bo om box), each app oxima ely 0.5 %; and he mass lows (dashed a ows) whose maximum a pos e io i (MAP) es ima es we e indis inguishable om ze o bu whose 95 % Bayesian con idence in e al was b oade han 0.05 (Tuomi e al., 2011b). 3027