Clima ic Con ol on Plan and Soil d
13
C along an
Al i udinal T ansec o Lushan Moun ain in Sub opical
China: Cha ac e is ics and In e p e a ion o Soil Ca bon
Dynamics
Baoming Du
1
, Chunjiang Liu
1,2
*, Hongzhang Kang
1,2
, Penghua Zhu
2
, Shan Yin
1,2
, Guang ong Shen
1,2
,
Jingli Hou
3
, Hannu Il esniemi
4
1School o Ag icul u e and Biology and Resea ch Cen e o Low-Ca bon Ag icul u e, Shanghai Jiao Tong Uni e si y, Shanghai, China, 2Key Labo a o y o U ban
Ag icul u e (Sou h), Minis y o Ag icul u e, People’s Republic o China, Shanghai, China, 3Ins umen al Analysis Cen e o SJTU, Shanghai Jiao Tong Uni e si y, Shanghai,
China, 4Finnish Fo es Resea ch Ins i u e, Van aa, Finland
Abs ac
Dec easing empe a u e and inc easing p ecipi a ion along al i ude g adien s a e ypical moun ain clima e in sub opical
China. In such a clima e egime, iden i ying he pa e ns o he C s able iso ope composi ion (d
13
C) in plan s and soils and
hei ela ions o he con ex o clima e change is essen ial. In his s udy, he pa e ns o d
13
C a ia ion we e in es iga ed o
ee lea es, li e s, and soils in he na u al seconda y o es s a ou al i udes (219, 405, 780, and 1268 m a.s.l.) in Lushan
Moun ain, cen al sub opical China. Fo he dominan ees, bo h lea and lea -li e d
13
C dec eased as al i ude inc eased
om low o high al i ude, whe eas su ace soil d
13
C inc eased. The lowe lea d
13
C a high al i udes was associa ed wi h he
high mois u e- ela ed disc imina ion, while he high soil d
13
C is a ibu ed o he low empe a u e-induced decay. A each
al i ude, soil d
13
C became en iched wi h soil dep h. Soil d
13
C inc eased wi h soil C concen a ions and al i ude, bu
dec eased wi h soil dep h. A nega i e ela ionship was also ound be ween O-alkyl C and d
13
C in li e and soil, whe eas a
posi i e ela ionship was obse ed be ween a oma ic C and d
13
C. Lowe empe a u e and highe mois u e a high al i udes
a e he p edominan con ol ac o s o d
13
C a ia ion in plan s and soils. These esul s help unde s and C dynamics in he
con ex o global wa ming.
Ci a ion: Du B, Liu C, Kang H, Zhu P, Yin S, e al. (2014) Clima ic Con ol on Plan and Soil d
13
C along an Al i udinal T ansec o Lushan Moun ain in Sub opical
China: Cha ac e is ics and In e p e a ion o Soil Ca bon Dynamics. PLoS ONE 9(1): e86440. doi:10.1371/jou nal.pone.0086440
Edi o : Shuijin Hu, No h Ca olina S a e Uni e si y, Uni ed S a es o Ame ica
Recei ed June 25, 2013; Accep ed Decembe 9, 2013; Published Janua y 23, 2014
Copy igh : ß2014 Du e al. This is an open-access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License, which pe mi s un es ic ed
use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal au ho and sou ce a e c edi ed.
Funding: This wo k was suppo ed by he S a e Key Basic Resea ch and De elopmen Plan o China (2011CB403201) and he CFERN&GENE Awa d Funds on
ecological pape . The unde s had no ole in s udy design, da a collec ion and analysis, decision o publish, o p epa a ion o he manusc ip .
Compe ing In e es s: The au ho s ha e decla ed ha no compe ing in e es s exis .
* E-mail: [email p o ec ed]
In oduc ion
In e es ial plan ecosys ems,
13
C en ichmen is gene ally
g ea e in he soils han in ege a ion due o he di e en
ac iona ion o
13
C and
12
C in he biogeochemical p ocesses [1,2].
In he las h ee decades, he C iso ope echnique has been a use ul
app oach o unde s anding he e ec s o wa e de ici on plan s
[3,4], dynamics o soil o ganic C (SOC) [5,6,7], and local clima e
his o y [8]. d
13
C has been used as an index o s udy ecosys em
esponse o clima e and as a su oga e a iable in modeling C
luxes in e es ial ecosys ems [9,10].
A a si e scale, soil d
13
C is closely associa ed wi h local
ege a ion and clima e his o y, and a ies wi h he soil dep h
owing o i s longe - e m ac iona ion in deepe soil [11]. The
impac o ege a ion on soil d
13
C could a y wi h plan species and
issues. Fo ins ance, C
3
(Cal in cycle pho osyn he ic pa hway)
plan s ha e d
13
C alues o –22% o –35%(a e age –26.5%),
compa ed o C
4
plan s whose d
13
C alues a e in he ange o –8%
o –16%(a e age –12.5%) [8,12]. This di e ence help de e mine
he ela i e p opo ion each ege a ion ype in soil o ganic C
[13,14]. Among plan s issues, d
13
C is ypically en iched by 1% o
2%in celluose and hemicelluloses, bu deple ed in
13
Cby2% o
6%in lignin, in compa ison wi h whole-plan ma e ial [6,15].
A a b oade scale, soil
13
C a ies wi h spa ial g adien s by
al i ude, la i ude, longi ude due o changes o ege a ion and
clima e [16]. Bi d e al. (1996) epo ed ha he a e age d
13
C was
–28.360.6%in low la i ude (0uN o20uN o S), –27.760.6%in
mid la i ude soils (20u o 40u), and –27.360.7%in high la i ude
soils (40u o 90u) [17]. The o e all inc ease o SOC d
13
C om low
o high-la i ude o es s was 21%. In moun ain a eas, clima e
a ies wi h al i ude esul ing in di e en ege a ion, li e inpu
in o soils, and li e decomposi ion a e, and he e o e soil d
13
C.
Wei and Jia (2009) epo ed ha soil d
13
C i s dec eased and hen
inc eased as al i ude inc eased om 1000 m o 3800 m in Moun
Gongga, sou hwes e n China [18]. Consequen ly, ecosys ems in
moun ain a eas a e e y sensi i e o changes in clima e [19,20].
Lushan Moun ain is loca ed in he middle-lowe plain o he
Yang ze Ri e in cen al sub opical China, wi h al i ude om
30 m a.s.l. o 1470 m a.s.l. [21]. Along wi h he change o
ele a ion is he opposi e end o hea and wa e (OHW), i.e.,
empe a u e dec eases and p ecipi a ion inc eases om low o
high ele a ions. Co espondingly, ege a ion changes om e e -
PLOS ONE | www.plosone.o g 1 Janua y 2014 | Volume 9 | Issue 1 | e86440
g een b oadlea o es s a he oo hill o deciduous o es s a he op
o moun ain. The OHW is a common moun ain clima e in
sub opical China and has unique communi y composi ion,
li e all decomposi ion a io, soil C biochemical p ocesses o
explo ing he a ia ions o plan and soil d
13
C wi h al i ude,
pa icula ly in ela ion o clima e change.
In his s udy, we examined he a ia ion o d
13
C in esh plan
lea es, li e , and semi-decomposed and soil humic subs ances in
o de o cha ac e ize soil ca bon dynamics a a local o egional
scale in sub opical o es ecosys ems in Lushan Moun ain, China.
The speci ic objec i es we e o: 1) de e mine he pa e ns o d
13
C
a ia ion in dominan plan species and soil wi h al i ude, 2)
in es iga e how soil d
13
C a ies wi h soil dep h a di e en
al i udes, and 3) examine he e ec s o clima ic ac o s on plan
and soil d
13
C along he ele a ion g adien in Lushan Moun ain.
Ma e ials and Me hods
S udy A ea
S udy a ea is loca ed in he Lushan Na u e Rese e (29u319–
29u419N, 115u519– 116u079E), he sou h o Jiujiang Ci y, Jiangxi
P o ince, China (Fig. 1). Pe mission was g an ed by he Na u e
Rese e o Lushan Jiangxi. Lushan is an isola ed moun ain body
si ua ed in he cen e o he as plain o he middle and lowe
eaches o he Yang ze Ri e , co e ing an a ea o abou 300 km
2
along a al i ude ange om 50 m o 1474 m. This a ea has a
sub opical monsoon clima e. The mean annual p ecipi a ion
(MAP) anges om 1308 mm o 2068 mm, and he mean annual
empe a u e (MAT) om 17.1uC o 11.6uC [21].
Owing o he a ia ions in geology, clima e, and ege a ion
along ele a ion, dominan soil ypes change om Fe ic alisols a
low ele a ions o Haplic alisols a high ele a ions [21] acco ding o
he FAO soil ex u e classi ica ion. The co esponding ege a ion
ypes a e e e g een o es s domina ed by se e al Fagaceae ee
species including Cas anopsis scle ophylla,Cas anopsis ey ei and
Li hoca pus glabe , and some e e g een woodland species and sh ubs
a low al i udes o app oxima ely 50 m o 600 m, e e g een
b oadlea o es s and some deciduous ees a e mid al i udes o
600 m and 1000 m, and Linde a ob usiloba o es consis ing o
Ce asus se ula a,Cas anea seguinii,Tilia b e i adia a, and a ew sh ubs
a abou 1200 m.s.l. (Table S1). Some C yp ome ia japonica
plan a ions we e es ablished abou 50 yea s ago a mid al i udes.
Sample S ands and Collec ion
Pe mission was g an ed by he Na u e Rese e o Lushan
Jiangxi (29u319–29u419N, 115u519–116u079E) o ca y ou ou
s udy. Sample s ands we e chosen a an i egula al i ude in e al
owing o na u al o es agmen a ion in moun ain. In o al, ou
s udy si es we e es ablished a al i udes o 219 m, 405 m, 780 m,
and 1268 m (Fig. 1, Table 1). These s udy si es we e no associa ed
wi h endange ed o p o ec ed species.A each si e, h ee plo s (each
20620 m) we e andomly delinea ed. In each plo , ou 4 m
2
subplo s we e andomly chosen o sh ub laye and ou 1 m
2
subplo s o he baceous laye . In each plo , 100 lea es we e
collec ed om dominan ee (Table S1). Sample we e collec ed
om L (Li e ) and LF (Semi-decomposi ion li e ) ho izons and
mine al soil laye s a 0–10 cm, 10–20 cm, 20–30 cm, 30–40 cm,
40–50 cm, and 50–60 cm dep hs. Fi e soil co es we e andomly
collec ed wi hin each plo using a 2 cm-diame e s ainless s eel
bo e and bulked o make one composi e sample by soil dep h.
Soil samples we e ai d ied, g ound, and passed h ough a
2 mm sie e o emo e coa se li ing oo s and g a el be o e being
g ound and passed h ough a 0.149 mm mesh sie e p io o
chemical analysis. Lea and li e samples we e o en d ied (65uC)
o a week o cons an weigh and g ound o ine powde using a
Teca o sample mill (Subang, Shanghai, China) p io o he
chemical and iso opic analyses.
Chemical Analysis
The C iso ope a io (d
13
C) o lea , li e , and soil samples was
de e mined using an elemen al analysis–s able iso ope a io mass
spec ome e (Va ioElIII/Isop ime, Elemen a , Hanau, Ge many)
ope a ed a he Ins umen al Analysis Cen e o Shanghai Jiao
Tong Uni e si y (SJTU). The esul s a e epo ed as pa s pe
housand (%) de ia ions om he Vienna–Pee Dee Belemni e
(PDB) s anda d (unce ain y o 60.1%unce ain y), which The is
exp essed as ollows:
d13C~
d=d{1

|103
d d
To exp ess he absolu e a ia ion o soil d
13
C en ichmen
ela i e o li e , we de ine an absolu e en ichmen ac o F
A
as
Figu e 1. Loca ion o he s udy a ea and he dis ibu ion o sample s ands in Lushan Moun ain, sub opical China.
doi:10.1371/jou nal.pone.0086440.g001
Clima ic Con ol on Plan and Soil d
13
C
PLOS ONE | www.plosone.o g 2 Janua y 2014 | Volume 9 | Issue 1 | e86440
s anda d
sample
Whe e
is he C a io o he e e ence s anda d (PDB) [22]. C/
is he
sample
C/ C a io o he samples and
anda ds
13 12
13 12
ollows:
FA~d13Csoili{d13Cli e
Whe e d
13
C
soil i
is he d
13
Ca i h soil laye and d
13
C
li e
is he d
13
C
a he li e laye .
The a e o soil d
13
C en ichmen a ies wi h soil dep h [1,2]. To
exp ess he ela i e en ichmen o adjacen soil laye s, we de ine
he ela i e soil d
13
C en ichmen ac o F
R
as ollows:
FR~d13Csoili{d13Csoili{l
Whe e d
13
C
soil i
is he d
13
Ca i h soil laye and d
13
C
soil i-1
is he
d
13
Ca i-1 h soil laye .
To explo e he ela ionship be ween soil d
13
C and SOC
concen a ion, as well as soil C unc ional g oups, wo soil
a iables we e de e mined. The a ia ion pa e ns in SOC
concen a ion and soil C unc ional g oups along he al i ude
g adien in Lushan Moun ain will be p esen ed in ano he pape .
The SOC concen a ions o soil samples om di e en dep hs
we e measu ed using dich oma e oxida ion me hod [23].
The chemical composi ions o C in li e and soil laye s a 0–
10 cm, 30–40 cm, and 50–60 cm dep hs we e analyzed wi h solid-
s a e
13
C c oss-pola iza ion magic angle spinning–nuclea mag-
ne ic esonance (CP/MAS–NMR). The li e samples we e d ied
o cons an weigh a 65uC and g ound in a Wiley mill. The soil
samples we e p e ea ed wi h 10% ( / ) hyd o luo ic acid (HF)
be o e he NMR spec oscopy [24] o educe Fe
3+
and Mn
2+
[25]
and concen a e o ganic C o mo e accu a e signal- o-noise a io
[24]. Abou 10 g o he g ound sample was shaken wi h 50 ml HF
o 2 h. A e cen i uga ion (5,000 pm) o 10 min, he supe na-
an was emo ed. The p ocedu e was epea ed i e imes. The
emaining sedimen was washed i e imes wi h 50 ml deionized
wa e o emo e esidual HF be o e eeze d ying.
The solid-s a e
13
C CP/MAS–NMR spec a o li e and soil
samples we e ob ained a a equency o 100.64 MHz using a
B uke AVANCEIII400 NMR spec ome e (B uke Biospin,
Rheins e en, Ge many) ope a ed a 75.42 MHz o
13
C. The
con ac ime was 1.5 ms, wi h 1 s ecycle delay and he magne ic
angle spinning a e was 5 kHz [24]. Abou 12,000 scans we e
collec ed o soil samples and 10,000 scans o li e samples [26].
The chemical shi egions 0–45 ppm, 45–110 ppm, 110–
160 ppm, and 160–220 ppm we e assigned o alkyl C, O-alkyl
C, a oma ic C, and ca boxylic C, espec i ely [24,27]. The sou ces
o o ganic ca bon a e: Alkyl C is de i ed om lipids, a y acides
and plan alipha ic polyme s, O-alkyl C p ima ily om cellulose
and hemicelluloses, as well as s a ch, p o eins and ca bohyd a es,
a oma ic C om lignin and annins, and ca boxyl C om lipids,
alipha ic es e s, and amide ca boxyls [28,29]. The signal in ensi ies
in he espec i e chemical-shi egions we e exp essed as a
pe cen age o he a ea o he o al spec a. The ela i e con en s o
di e en chemical s uc u es we e he e o e calcula ed [26].
S a is ical Analysis
A i hme ic means and s anda d de ia ion we e calcula ed. A
es (i.e., leas signi ican di e ence) was conduc ed o compa e he
means wi h a p obabili y le el o 0.05 o de ec ing signi ican
di e ences. Linea eg ession analyses we e used o examine he
ela ionships be ween soil d
13
C and MAT, MAP, and SOC
concen a ions. All analyses we e pe o med h ough SigmaPlo
10.0 (Sys a So wa e, Richmond, CA, USA) and SAS V8.1 (SAS
Ins i u e Inc., Ca y, No h Ca olina).
Resul s
Va ia ions o Lea , Li e , and Soil d
13
C wi h Al i ude
The deciduous ee lea d
13
C a 1268 m a.s.l. was –28.29%,
signi ican ly lowe han e e g een ees a lowe al i udes (–
27.65% o 226.98%) (Fig. 2). A simila d
13
C-al i ude ela ionship
was also e iden in lea li e , bu no in semi-decomposed li e .
Compa a i ely, esh lea es had highe d
13
C han lea li e o
Table 1. Fea u es o clima e and ege a ion a di e en al i udes in Lushan Moun ain.
Loca ion
Al i ude
(ma.s.l.)
MAP
a
(mm)
MAT
(6C)
TCM
b
(6C)
THM
c
(6C) G owing season (Days) Vege a ion ypes
d
Tongyuan 219 1429 16.2 3.8 28.5 262 EBF
Saiyang 405 1549 15.3 3.2 27.4 253 EBF
Beiyun 780 1794 13.6 1.9 25.1 234 EBMF
Yang ianping 1268 2112 11.3 0.3 22.2 209 DBF
a
The clima ic da a om yea s 1971 o 2000 we e ob ained om he Lushan Me eo ological Bu eau.
b
Tempe a u e o he coldes mon h.
c
Tempe a u e o he ho es mon h.
d
EBF ep esen s o e e g een b oadlea o es ; EBMF o e e g een b oadlea and needle-lea mixed o es ; and DBF o deciduous b oadlea o es .
Figu e 2. d
13
C alues o lea es, lea li e , and semi-decom-
posed li e in he na u al seconda y b oadlea s ands a
al i udes o 219, 405, 780, and 1268 m in he Lushan Moun ain.
The e o ba s a e he s anda d e o s (n = 3 o lea li e and semi-
decomposed li e , and n = 3 o 300 lea es). Di e en le e s indica e
signi ican di e ences among all classes a he di e en al i udes
(P,0.05).
doi:10.1371/jou nal.pone.0086440.g002
Clima ic Con ol on Plan and Soil d
13
C
PLOS ONE | www.plosone.o g 3 Janua y 2014 | Volume 9 | Issue 1 | e86440
semi-decomposed li e . Fo ins ance, d
13
C dec eased om –
26.98%in esh lea es o –28.65%in lea li e a 219 m a.s.l.
(Fig. 2).
The su ace laye s o soils (0–10 cm, 10–20 cm, and 20–30 cm)
a 1268 m was signi ican ly highe han ha a he o he h ee
lowe al i udes. Ihe deepe soil laye s (30–40 cm, 40–50 cm, and
50–60 cm), howe e , no signi ican di e ence by al i ude occu ed
(Fig. 3).
Soil d
13
C En ichmen wi h Soil Dep h
Soil d
13
C en ichmen was g ea e wi h he inc ease o soil dep h
o all al i udes (Fig. S1). Absolu e en ichmen ac o (F
A
) gene ally
inc eased om semi- decomposed laye , peaked a 30–40 cm, and
emained s able a deepe soil (Fig. 4). The soil F
A
a 1268 m we e
gene ally g ea e han ha a he o he h ee al i udes. Fo
ins ance, he maximum F
A
was 7.39%a 30–40 cm soil dep h and
1268 m al i ude, compa ed o he alues o 3.66% o 5.23%a he
same laye o h ee lowe al i udes. The ela i e en ichmen ac o
(F
R
) was gene ally highe in he su ace soil laye s o 0–10 cm
(1.49% o 4.43%) and 10–20 cm (0.93% o 1.76%) han in he
deepe laye s (Fig. 5).
Rela ionships o Soil d
13
C wi h SOC Concen a ion and
Chemical Composi ion
Soil d
13
C inc eased (Fig. S1) wi h SOC concen a ion a each
al i ude, ollowing a s ong nega i e ela ionship (p,0.01) (Fig. 6).
The ela ionship a he h ee si es o lowe al i udes (219 m, 405 m
and 780 m, all co e ed by e e g een o es s) was di e en om
ha a he si e o highes al i ude (1268 m, co e ed by deciduous
o es s). Soil d
13
C was nega i ely co ela ed wi h O-alkyl C, bu
posi i ely wi h a oma ic C and ca boxyl C (Fig. 7).
Rela ionships be ween Soil d
13
C and he Clima ic Fac o s
In Lushan Moun ain, empe a u e dec eases wi h, whe eas
p ecipi a ion inc eases wi h he inc ease o ele a ion. The soil d
13
C
dec eased wi h MAT and inc eased wi h MAP in he h ee uppe
laye s (0–10 cm, 10–20 cm, and 20–30 cm), whe eas no clea
end exis ed o deepe laye s (Fig. 8).
Discussion
Decoupled Pa e ns o Va ia ions in Plan and Soil d
13
C
along Ele a ion
In e es ial ecosys ems, plan unc ional ypes s ongly a ec
si e-le el soil d
13
C h ough li e inpu s [5,30,31]. Fo ins ance,
Pe i e al. (2012) epo ed ha he soil d
13
CinNo ho agus o es s
was signi ican ly associa ed wi h olia d
13
C, bo h o which
dec eased wi h p ecipi a ion [28]. In he p esen s udy, howe e ,
esh lea and lea li e d
13
C dec eased wi h, whe eas soil d
13
C
inc eased wi h al i ude (Figs. 2 and 3), a pa e n ha canno be
explained alone wi h he inc easing p ecipi a ion by al i ude in
Lushan Moun ain.
Di e en om some p e ious s udies [33,34], he ee lea d
13
C
was signi ican ly lowe a he highes al i ude, likely due o he
special clima e egime in Lushan Moun ain whe e p ecipi a ion
inc eases wi h and empe a u e dec eases wi h al i ude (Fig. 8).
Acco ding o a gene al no ion abou plan
13
C disc imina ion [35],
plan s a mois si es end o ha e high s oma al conduc ance (close
o maximum), low wa e use e iciency, and high in e cellula CO
2
concen a ion. This esul s in inc easing disc imina ion agains
13
CO
2
du ing pho osyn hesis leading o low d
13
C alues, in
compa ison wi h a id si es. In Lushan Moun ain, plan s expe ience
g ea e d ough s ess a lowe al i ude si es owing o low
p ecipi a ion and high empe a u e, esul ing in high issues d
13
C.
In he p esen s udy, soil d
13
C inc eased wi h al i ude, consis en
wi h he pa e n ound in p e ious s udies [7,34,36,37,38]. Fo
example, Townsend e al. (1995) epo ed an inc ease o soil d
13
C
om –26.70 %a 900 m a.s.l. o –25.90 %a 1500 m a.s.l. in he
island o Hawaii [32]. Simila esul s a e also epo ed by
Zimme mann e al. (2012) in a opical o es in Pe u whe e soil
d
13
C alues inc eased wi h ele a ion om –27.16%a 1700 m a.s.l.
o –25.79%a 3030 m a.s.l. [38]. The majo eason o he
al i udinal a ia ion o soil d
13
C in hose s udies is p obably he
in luence o plan communi ies h ough he deposi ion o lea li e ,
dead oo ma e ial, and hizodeposi ion [32]. In Lushan Moun ain,
howe e , inc easing p ecipi a ion and dec easing empe a u e wi h
al i ude may ha e p edominan ly in luence o e soil d
13
C.
Rela i e o he bulk lea d
13
C, suga s, s a ch, cellulose, p o ein,
and o ganic aids a e en iched, whe eas lignin and lipids a e
deple ed in d
13
C [6]. The e o e, o ganic ma e wi h high
concen a ions o suga s, s a ch, and cellulose displays high d
13
C
alues. On he o he hand, howe e , suga s, s a ch, cellulose, and
p o ein, a e mo e easily los h ough li e decomposi ion han
lignin [39,40]. This helps explain he high soil d
13
C o op soil
laye s (0–10 cm, 10–20 cm, and 20–30 cm) a he al i ude o
1268 m (Fig. 3) whe e high mois u e and low empe a u e no only
educes o es p oduc i i y and li e (o ganic ma e ) inpu o he
soil, bu also shows down decomposing ac i i ies o mic obes.This
may ha e led o accumula ion o mo e less-decomposed o ganic
ma e in soils and he e o e high soil d
13
C (accumula ion o
suga s, s a ch, cellulose, and p o ein).
Soil d
13
C En ichmen wi h Soil Dep h by Al i ude
In p e ious s udies, en ichmen ac o s (F
A
in his s udy) we e
used o desc ibe he a ia ion in soil d
13
C en ichmen ela i e o
li e . Howe e , he esul s o his s udy sugges ha he ela i e
en ichmen ac o (F
R
) in oduced in he p esen s udy be e
de ec he di e ence o soil
13
C en ichmen by dep h han F
A
used
by p e ious s udies (Figs. 4 and 5). Fo ins ance, F
R
shows a mo e
apid change om semi-decomposed li e o soil laye s (0–10 cm,
10–20 cm) han F
A
(Fig. 5).
A all al i udes, soil d
13
C was en iched wi h soil dep hs om
li e o O-laye and o mine al soil laye s (Figs. 4 and S1). This
Figu e 3. Soil d
13
C alues o di e en laye s in he na u al
seconda y b oadlea s ands a al i udes o 219, 405, 780, and
1268 m in he Lushan Moun ain. The e o ba s ep esen s anda d
e o s means (n = 3). Di e en le e s indica e signi ican di e ences
among al i udes by soil dep h (P,0.05).
doi:10.1371/jou nal.pone.0086440.g003
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Figu e 4. Absolu e en ichmen ac o o soil d
13
(
F
A
) by soil dep h a al i udes o 219 (A), 405 (B), 780 (C), and 1268 m (D) in he
Lushan Moun ain. In he igu es, SD ep esen s he semi-decomposed li e laye .
doi:10.1371/jou nal.pone.0086440.g004
Figu e 5. Rela i e en ichmen ac o o soil d
13
(
F
R
) by soil dep h a al i udes o 219 (A), 405 (B), 780, (C), and 1268 m (D) in he
Lushan Moun ain.
doi:10.1371/jou nal.pone.0086440.g005
Clima ic Con ol on Plan and Soil d
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inding is consis en wi h he conclusion by p e ious s udies
[1,2,11,39]. In he p esen s udy, he absolu e en ichmen ac o a
1268 m a.s.l. (F
A
=5% o 7.5%) was g ea e han ha a lowe
al i udes (F
A
= 1.5% o 5.5%). Fo example, The F
A
o 0–10 cm a
1268 m a.s.l. was abou 5%nea ly wich o ha o he same soil
dep h a all lowe al i udes (Fig. S1). This esul sugges s ha he
clima ic condi ions (MAP = 2112 mm, MAT = 11.3uC) a 1268 m
a.s.l. suppo a dis inc ac iona ion compa ed o lowe al i udes,
pa icula ly he si es a 219 m a.s.l. wi h MAP = 1429 and
MAT = 16.2. The e o e, he clima e egime lowe empe a u e
and highe mois u e a high al i ude s ongly in luences soil
13
C
en ichmen wi h soil dep h [41,42].
Implica ions o Soil d
13
C in Asce aining SOC S a us
Soil C concen a ions a e s ongly co ela ed wi h d
13
C in o es
soil, ollowing a nega i e ela ionship as demons a ed by p e ious
s udies [1,31,43]. In his s udy, soil d
13
C inc eased wi h soil dep h,
a oma ic C and ca bonyl C, bu dec eased wi h O-alkyl C (Figs. 3
and 7). The inc ease o
13
C and changes o SOC chemical
composi ion wi h soil dep h likely esul om humi ica ion [44,45].
Mic obial ac i i ies in luence iso opic ac iona ion du ing SOC
decomposi ion h ough di e en ia ion use o subs a e by di e en
mic obes [41,42,46] and iso opic e ec s on me abolic syn hesis o
seconda y compounds (e.g., lipids, lignin, cellulose) [4,47]. Howe -
e , lipids and lignin a e deg aded mo e slowly and end o be
13
C
deple ed, whe eas cellulose and ca bohyd a e deg ade mo e apidly
and end o be
13
C en iched [42,48]. The e o e, i is di icul o
es ablish di ec ela ionships be ween d
13
C and SOC chemical
composi ions wi h soil dep h. The dis inc high soil d
13
C a 1268 m
a.s.l. is p obably a ibu ed o he accumula ion o highe
13
C-based
suga s, s a ch, cellulose, p o ein, and o ganic aids, esul ing om
slow li e decomposi ion in he su ace soil laye s (0–10 cm, 10–
20 cm, and 20–30 cm) (Fig. 3). The e o e, he en ichmen
mechanisms o soil
13
C along he al i ude g adien we e di e en
om hose by soil dep h in Lushan Moun ain. The de ail
mechanisms need o be cla i ied in u u e esea ch.
Figu e 6. Rela ionships be ween SOC concen a ion (mg g
21
)
and soil d
13
C by soil dep h o ou al i udes in he Lushan
Moun ain. The i ed models a e: y=870.58+71.82x+1.49x
2
,
2
= 0.76,
and p= 0.0002, o he 219 m si e; y= 1881.58+149.87x+3.03x
2
,
2
= 0.72,
and p,0.0001, o he 405 m si e; y= 1250.35+105.77x+2.25x
2
,
2
= 0.68,
and p= 0.0002, o he 780 m si e; and y= 4265.44+383.58x+8.67x
2
,
2
= 0.57, and p= 0.0041, o he 1268 m si e.
doi:10.1371/jou nal.pone.0086440.g006
Figu e 7. Rela ionships be ween soil d
13
C and Alkyl C (A), O-alkyl C (B), A oma ic C (C), and Ca bonyl C (D) o he s udied s ands a
he ou la i udes in he Lushan Moun ain. Dashed lines ep esen he gene al eg ession lines wi h all da a, wi h signi ican le el o p,0.05,
excep o Alkyl C.
doi:10.1371/jou nal.pone.0086440.g007
Clima ic Con ol on Plan and Soil d
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Concluding Rema ks
The pa e ns o plan and soil d
13
C a ia ions and hei ela ion
o he clima e egime along an al i udinal g adien we e s udied in
Lushan Moun ain o cen al sub opical China. The esul s
indica ed ha ee lea d
13
C dec eased and soil d
13
C inc eased
wi h al i ude. The decoupled pa e n o plan and soil d
13
C was due
o he clima e egime o dec easing empe a u e and inc easing
p ecipi a ion wi h al i ude in he s udy a ea, which esul in
dec eased li e decomposi ion a high-la i ude si es. These esul s
ha e impo an implica ions o unde s anding C dynamics o
sub opical o es ecosys ems in he con ex o global wa ming.
Suppo ing In o ma ion
Figu e S1 Va ia ion o d
13
C wi h li e /soil dep h by
s ands a al i udes o 219, 405, 780, and 1268 m in
Lushan Moun ain.
(DOCX)
Table S1 Si e and s and condi ions o s udied a ea.
(DOCX)
Acknowledgmen s
We hank Li Zhang, Shi Xu, and Jieli Wu o hei assis ance in he sample
analysis, and Jinhao Qian, Qin Zou, Kong an Qian and Ming Du o hei
assis ance wi h ieldwo k. D . Rongzhou Man a On a io Fo es Resea ch
Ins i u e, Canada, is g a e ully acknowledged o his cons uc i e
commen s and language checking. Chemical analyses we e conduc ed in
he Ins umen al Analysis Cen e o SJTU, and he Na u e Rese e o
Lushan Jiangxi.
Au ho Con ibu ions
Concei ed and designed he expe imen s: CL HK. Pe o med he
expe imen s: BD HK PZ. Analyzed he da a: BD JH. Con ibu ed
eagen s/ma e ials/analysis ools: SY GS. W o e he pape : BD CL HI.
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