A icle h ps://doi.o g/10.1038/s41467-023-41367-7
D ough as a possible con ibu o o he
Visigo hic Kingdom c isis and Islamic
expansionin heIbe ianPeninsula
Jon Camue a
1
, F ancisco J. Jiménez-Espejo
1
, José So o-Chica
2
,
Gonzalo Jiménez-Mo eno
3
, An onio Ga cía-Alix
3
, Ma ía J. Ramos-Román
4
,
Leena Ruha
5,6
& Manuel Cas o-P iego
7
TheMuslimexpansionin heMedi e anean basin was one he mos ele an
and apid cul u al changes in human his o y. This expansion eached he
Ibe ian Peninsula wi h he eplacemen o he Visigo hic Kingdom by he
Muslim Umayyad Calipha e and he Muslim Emi a e o Có doba du ing he 8 h
cen u y CE. In his s udy we made a compila ion o wes e n Medi e anean
pollen eco ds o gain insigh abou pas clima e condi ions when his
expansion ook place. The pollen s ack esul s, oge he wi h o he paleohy-
d ological eco ds, a chaeological da a and his o ical sou ces, indica e ha
he s a is ically significan s onges d ough s be ween he mid-5 h and mid-
10 h cen u ies CE (450–950CE)occu eda 545–570, 695–725, 755–770 and
900–935 CE, which could ha e con ibu ed o he ins abili y o he Visigo hic
and Muslim eigns in he Ibe ian Peninsula. Ou s udy suppo s he g ea
sensi i i y o he ag icul u e-based economy and socio-poli ical un es o Ea ly
Medie al kingdoms o clima ic a ia ions.
Th oughou human his o y, ises and alls o empi es, kingdoms, and
coun ies ha e been con olled by economic, social, and poli ical ac-
o s, some o hem pa ially condi ioned by clima e changes1,2,
including he ecen conflic s in he Middle Eas 3,4. The s udy o pas
en i onmen al changes in a specifica eaisessen ial ounde s and
how clima e could ha e a ec ed he poli ical s abili y o a egion.
Nowadays, clima e is becoming a cen al elemen in explaining his-
o ical c ises in he Medi e anean a ea, as has occu ed in ecen
decades a ound he Da k Age Cold Pe iod and i s ela ionship wi h he
appea ance o he Jus inian´s plague5, o wi h he c isis ha a ec ed
u al se lemen s in some pa s o Eu ope du ing hose cen u ies6.One
o he mos in e es ing pe iods, and one ha emains ela i ely
unknown om a clima ic poin o iew, is he pe iod o Islamic
expansioninNo hA ica
7, culmina ing in he conques o he Ibe ian
Peninsula. The o ma ion o al-Andalus (Muslim- uled a ea in he
Ibe ian Peninsula) om 711 CE led o he apid disappea ance o he
Visigo hic Kingdom, in a p ocess ha combined mili a y conques ,
poli ical c isis, e i o ial agmen a ion, and pac s8,9.TheVisigo hic
Kingdom uled he Ibe ian Peninsula o a ound 300 yea s (5 h–8 h
cen u ies CE), eplacing he Roman Empi e ule, un il he beginning o
he Islamic expansion in Ibe ia du ing he ea ly-8 h cen u y CE. This
decline was ma ked by a ci il wa and he in asion o he Muslim
Umayyad Calipha e (Islamic dynas y) in 711 CE un il he final conques
in 726 CE. Al hough he a cheological si es s udied du ing he las
decades o he Visigo hic pe iod p o ide use ul in o ma ion abou
a ming s a egies, u banisms, e i o ial con ol o social
o ganiza ion10, he apid all o he Visigo hic Kingdom is s ill unde
deba e, and he hypo hesis o clima e igge ing he Islamic expansion
om he no he n A ica o he no he n Ibe ia has no been in es i-
ga ed ye 11,12.
Recei ed: 8 No embe 2022
Accep ed: 1 Sep embe 2023
Check o upda es
1
Andalusian Ea h Sciences Ins i u e (IACT), Spanish Na ional Resea ch Council - Uni e si y o G anada (CSIC-UGR), G anada, Spain.
2
Depa men o Medie al
His o y and His o iog aphic Sciences and Techniques, Uni e si y o G anada, G anada, Spain.
3
Depa men o S a ig aphy and Paleon ology, Facul y o
Science, Uni e si y o G anada, G anada, Spain.
4
Facul y o Educa ion, Mid-A lan ic Uni e si y, Mad id, Spain.
5
Na u al Resou ces Ins i u e Finland,
Oulu, Finland.
6
Resea ch Uni o Ma hema ical Sciences, Uni e si y o Oulu, Oulu, Finland.
7
Uni o A chaeology, Depa men o His o y and Philosophy,
Uni e si y o Alcalá, Alcalá de Hena es, Spain. e-mail: Jcamue [email protected];F [email protected]
Na u e Communica ions | (2023) 14:5733 1
1234567890():,;
1234567890():,;
To da e, he sca ci y o bo h high- esolu ion paleoclima e eco ds
and s udies ocusing on he impac o clima e changes in Ea ly Medie al
kingdoms du ing he 5 h–10 h cen u ies CE has p e en ed an assess-
men o whe he clima e changes con olled he decline o he Visi-
go hic Kingdom and he Islamic expansion in Ibe ia. P e ious Holocene
paleoclima ic s udies a decadal- o cen ennial scale showed ha he
main clima e ac o a ec ing he en i onmen al a iabili y in he Med-
i e anean egion is he amoun o p ecipi a ion, which has s ongly
a ec ed he human popula ion and dispe sal in his a ea13,14.He ewe
used a high- esolu ion pollen s ack based on 107 pollen eco ds om
Ibe ia and Mo occo (Fig. 1) along wi h o he paleohyd ological eco ds,
a cheological da a and his o ical sou ces o show how he pe sis en
d ough s, iden ified unde he Scale-no malized Significan Ze o
c ossing (SnSiZe ) s a is ical analysis, could ha e influenced he eco-
nomic, social and poli ical condi ions du ing he Visigo hic Kingdom
and al-Andalus be ween he 5 h and 10 h cen u ies CE.
Resul s and discussion
Recons uc ion o d ough pe iods om Ibe ian/Mo occan
paleoen i onmen al p oxies
The s acks o he a id-adap ed A emisia and xe ophy e axa display an
o e all inc easing end o e he las 5000 yea s, indica ing a p o-
g essi e a idifica ion o e ime (Fig. 2e, ). In addi ion, he esul s o
A emisia a subdecadal-scale esolu ion allow he iden ifica ion o 23
d ough e en s du ing he las 5000 yea s (black a ows in Fig. 2e).
Inc eases in A emisia and xe ophy e da a, indica i e o a id condi ions
in he Ibe ian Peninsula, occu ed a ca. 4900, 4550, 4150, 3900, 3650,
3450, 3200, 2900, 2650, 2400, 2300, 2100, 1950, 1750, 1500, 1400,
1250, 1150, 1000, 850, 700, 500 and 200 cal y BP.
Compa ison o pollen da a wi h iso opic analysis o speleo hems
p o ides a mo e de ailed insigh in o local en i onmen al and egional
paleoclima e changes in he s udy egion15,16. In addi ion, since human
influence on speleo hem eco ds is lowe han on he ege a ion
eco ds, he compa ison be ween hese wo p oxies allows us o co -
obo a e whe he he a idi y pe iods obse ed in pollen eco ds a e
p edominan ly na u al o no . Changes in speleo hem ca bon and
oxygen iso opes can be d i en by di e en ac o s16, including ege-
a ion densi y17, ca e empe a u es18, o he amoun o p ecipi a ion,
among o he s19. The co ela ion analyses be ween he d ough e en s
eco ded by he pollen da a and he high- esolu ion oxygen and ca -
bon iso opic eco ds om ca es in no he n Mo occo (Chaa a ca e,
composi e δ18O)20 and no he n Spain (Cob e, Kai e, and Mayo ca es,
s acked ela i e δ13C)21 show high posi i e co ela ion ( = 0.80
be ween A emisia and δ18O, p= 0.007; = 0.76 be ween A emisia and
δ13C, p= 0.010; o u he de ails, see Me hods) (Fig. 2c–e). This
posi i e co ela ion sugges ha he Mo occan and Ibe ianca es could
ha e been con olled by simila paleohyd ological condi ions. The
inc easing δ18Oandδ13C speleo hem alues om Mo occo and Spain
sugges a educ ioninp ecipi a ion, which al hough subjec ed o small
age unce ain ies, coincides wi h he d ough pe iods eco ded by he
s acked A emisia eco d. Simila δ18O-palaeohyd ological pa e ns
ha e been obse ed in speleo hems and in ecen me eo ic wa e
eco ds om Ibe ia, showing inc easing δ18O alues du ing dec easing
p ecipi a ion condi ions22,23. The high δ13C alues du ing d ough
pe iods could eflec a lowe con ibu ion o he ligh ca bon iso ope
in he speleo hem as a consequence o dec easing ege a ion densi y
su ounding he ca e19,24. These pe iods o spa se ege a ion would
ag ee wi h inc easing A emisia, and he e o e, mo e s eppe axa
(Fig. 2c, e, ). Howe e , o he e ec s esul ing in high δ13Cdu inga id
condi ions canno be uled, such as he inc ease o CO
2
degassing o
he d ipwa e du ing low ain all pe iods (low infil a ion) and low ca e
d ip a es25, o a educ ion o he soil biogenic CO
2
p oduc ion ia
mic obial ac i i y and plan espi a ion, which we e also ela ed o low
humidi y condi ions16.
IBERIAN
IBERIAN
PENINSULA
PENINSULA
AFRICA
AFRICA
MEDITERRANEAN SEA
MEDITERRANEAN SEA
ATLANTIC OCEAN
ATLANTIC OCEAN
CANTABRIAN SEA
CANTABRIAN SEA
ALBORAN
ALBORAN
SEA
SEA
600 km3000
N
34ºN 36ºN 38ºN 40ºN 42ºN 44ºN32ºN
12ºW 10ºW 8ºW 6ºW 4ºW 0º2ºW 2ºE 4ºE14ºW
Ele a ion (m a.s.l.)
-5000
-4000
-2500
-2000
-3000
-1000
-1500
-500
0
-200
50
200
400
600
800
1000
1200
2000
2500
3000
1
2345
6
789
10
11
12
13
14
15
16
17
18 19
20
21
22
23
24
25 26
27-28 29
30
31
32
33
34
35
36
37
38
3940
4142
43
44
45 46
47
48-50
51
52-54 55
60
56-59
61-62
63
64
65
66 67
68-70
71-72
73
74 75 76
77 78 79 80
81
82
83
84 85
86
87 88
89
90 91 92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
Cob e, Kai e and
Mayo ca es Asiul ca e
Bu aca Glo iosa
ca e
G o e de
Pis e ca e
Chaa a
ca e
Fig. 1 | Loca ion o he 107 ossil pollen eco ds (black do s) compiled and used in his s udy. Yellow do s show he Ibe ian and Mo occan ca e eco ds ci ed in he
manusc ip and used o compa ison wi h he pollen esul s. Fo de ailed in o ma ion o he ossil pollen eco ds, see Supplemen a y Da a 1.
A icle h ps://doi.o g/10.1038/s41467-023-41367-7
Na u e Communica ions | (2023) 14:5733 2
The pe iod be ween 450 and 950 CE (1500–1000 cal y BP)
dese es special a en ion, as i p esen s ou a id e en s, one o hem
p esen ing he maximum a idi y peak o he las 5000 yea s a ~700 CE
(1250 cal y BP), shown by he maximum abundance o A emisia and
xe ophy es (Fig. 2e, ). The pe o med SnSiZe s a is ical analysis o he
s acked A emisia eco d be ween mid-5 h and mid-10 h cen u ies CE
(450–950 CE, 1500–1000 cal y BP) iden ified ou s a is ically sig-
nifican ex eme d ough pe iods a : (I) 545–570, (II) 695–725 CE, (III)
755–770 CE, and (IV) 900–935 CE (Fig. 3a, b), co esponding o he
d ough e en s8,7,6,and5o helas 5000yea s(Fig.2e). The
p e iously men ioned δ18O (N Mo occo) and δ13C(NSpain) eco ds
also showed ou e en s o clima ic de e io a ion be ween 450 and 950
CE (Fig. 2c, d). Global-scale dend oclima ological s udies showed ha
he coldes clima e condi ions o he las wo millennia occu ed a
536–565 CE26 in connec ion wi h h ee main olcanic e up ions a 536,
540, and 547 CE27, ma ching wi h ou s a is ically significan d ough
pe iod I (Fig. 3a, b). In addi ion, he speleo hem eco ds om Asiul
(N Spain)28 and Bu aca Glo iosa (Po ugal)29 ca es p esen ed sig-
nifican inc eases in δ18O alues a ca. 540–580 and 700–750 CE and a
ca. 500–600 and 700–770 CE, espec i ely, consis en wi h he mos
a id condi ions iden ified in he pollen da a du ing he d ough pe iods
IandII(Fig.3a, b and Supplemen a y Fig. 1c–e). Ano he speleo hem
1
3
4
5
6
7
8?
9
10
11?
12
13
15?
17
20
21
2
16
18
19
22 14
23
-6.5
-6
-5.5
-5
-4.5
Composi e δ18O
(‰ VPDB) (in e ed axis)
d
Chaa a ca e (N Mo occo)
Age (cal y BP)
01500 50010002500 20004000 3500 30005000 4500
Age (y CE/BCE)
500 1000-500 0-2000 -1500 -1000-3000 -2500 20001500
0
-2
2
In e ed NAO index
HumidA id
a
0.8
0.4
b
0
-0.4
-0.8
To al Sola I adiance
(Wm-2)
2
1
0
-1
S ack Xe ophy es
(in e ed axis) ( his s udy)
This s udy
(1500-1000 cal y BP)
(450-950 y CE)
2
1
0
-1
S ack A emisia
(in e ed axis) ( his s udy)
e
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
17
16
18
19
20
21
22
23
(II)
(III)
(IV)
(I)
Humid
A id
-3
-2
-1
0
1
S acked ela i e δ13C
(in e ed axis)
c
2
3
1
2
3
4?
4?
5
6
7
8
9
10
11
12
13
14
15
17-16?
18
20-19
Cob e, Kai e and Mayo
ca es (N Spain)
Humid
A id
Fig. 2 | Compa ison o clima e p oxies/mechanisms o he las 5000 yea s.
aNAO index econs uc ion (in e ed axis)83.bTo al Sola I adiance (W/m2)84.
cS acked ela i e δ13C eco d (in e ed axis) om Cob e, Kai e, and Mayo ca es (N
Spain)21.dComposi e δ18Ospeleo hem eco d(‰VPDB, in e ed axis) om Chaa a
ca e (N Mo occo)20. In g aphs cand d, he g ay lines show he aw ela i e δ13Cand
δ18O alues, and he black lines he 5-poin mo ing a e ages. e– S acks o A emisia
and xe ophy es (in e ed axes) om his s udy, wi h black lines ep esen ing he
45-poin mo ing a e ages, and he o ange (A emisia) and yellow (xe ophy es) lines
he 15-poin mo ing a e ages. The ex eme d ough s eco ded by he A emisia
da a, and obse ed in he Spanish δ13C and Mo occan δ18O eco ds, a e indica ed
wi h black a ows. In g aph e, he d ough s I, II, III, and IV occu ing du ing he
pe iod o in e es o his s udy (450–950 CE, 1500–1000 cal y BP, yellow e ical
shade) co espond o he d ough e en s 8, 7, 6 and 5 o he las 5000 yea s. The
sou ce da a om g aphs eand a e a ailable in Supplemen a y Da a 2.
A icle h ps://doi.o g/10.1038/s41467-023-41367-7
Na u e Communica ions | (2023) 14:5733 3
eco d om Mo occo, he GP5 speleo hem eco d om G o e de Pis e
ca e30, which eco ded he en i onmen al condi ions be ween 600
and 2010 CE, p esen ed wo hia us su aces linked o a id condi ions a
ca. 620–750 and 900–940 CE. These wo e en s o s alagmi e g ow h
cessa ion ma ch ela i ely well wi h h ee s a is ically significan
d ough pe iods shown by he s a is ical analysis o he s acked A e-
misia, hefi s hia us coinciding he d ough s a 695–725 and 755–770
CE (d ough pe iods II and III), and he second hia us wi h he one a
900–935 CE (d ough pe iod IV).
A ecen quan i a i e p ecipi a ion econs uc ion om he Ibe -
ian Peninsula31 eco ded an annual p ecipi a ion decline o 0–100 mm/
y a 700–800 CE o no he n Ibe ia and o 200 mm/y a 680 CE o
sou he n Ibe ia (Supplemen a y Fig. 1 ). Mo eo e , he palynological
s udy om Medina lake32 and he lake le el econs uc ion o Zoña
lake33, bo h si es loca ed in sou he n Ibe ia, showed simila se e e
d ough condi ions du ing he la e-7 h and ea ly-8 h cen u ies CE. The
analysis o non-pollen palynomo phs om Medina lake o he las
5000 yea s eco ded he highes abundance o Gelasinospo a spo e a
ca. 710 CE, which has been linked o d y lake condi ions34,35,andis
coe al wi h he p esence o A emisia h oughou he en i e eco d,
ein o cing he in e p e a ion o low ain all condi ions du ing he
ea ly-8 h cen u y (Supplemen a y Fig. 1g). In Zoña lake he lowes lake
le el o he las 2500 yea s occu ed a ca. 650–750 CE, which could
also indica e ha he lowes p ecipi a ion condi ions o he las wo
and a hal millennia we e eco ded du ing he la e-7 h and ea ly-8 h
cen u ies CE (Supplemen a y Fig. 1h).
Rela ionship be ween he ou s a is ically significan d ough
pe iods and his o ical sou ces be ween mid-5 h and mid-10 h
cen u ies CE (450–950 CE, 1500–1000 cal y BP)
In he ollowing sec ions, we show he ela ionship be ween he ou
SnSiZe s a is ically significan d ough s obse ed in he A emisia
pollen eco d a (I) 545–570, (II) 695–725, (III) 755–770 CE and (IV)
900–935 CE, and he di e en his o ical e en s collec ed om his o ical
sou ces be ween mid-5 h and mid-10 h cen u ies CE (Fig. 3a, b). In
ecen yea s, he con ibu ions o w i en his o ical sou ces o he
Visigo hic pe iod (5 h–8 h cen u ies CE) ha e been suppo ed by
a cheological da a and, in pa icula , by s udies on inhabi ed u al a eas
and subsis ence esou ces36. Some a cheological esul s ha e also
allowed us o dis inguish di e en o ms o peasan habi a s ( illages,
a ms) and hei pe manence o disappea ance o e ime37,whe eas
o he s udies ha e p o ided new da a abou he ag icul u al p oduc ion
s a egies38, including esea ch on he expansion o sheep and goa
a ming, and changes in c op managemen 39,40. All his ook place in a
changing poli ical con ex , especially om 633 CE onwa ds, and wi h a
econfigu a ion o p oduc ion sys ems and land owne ship, which
would ha e been closely linked o clima e and en i onmen al changes.
D ough pe iod I (545–570 CE)/E up ions, plagues, and Visi-
go hic ci il wa
The fi s d ough pe iod eco ded by he Ibe ian and Mo occan A e-
misia and xe ophy e da a be ween 450 and 950 CE, and s a is ically
significan unde he SnSiZe , occu ed a 545–570 CE (Figs. 2e, and
3a, b).
The his o ical sou ces, such as he Byzan ine his o ian P ocopius,
no ed ha du ing 536–538 CE in he I alian peninsula, inclemen
wea he caused se e e c op damages and unusually ha sh and long
win e s ha las ed h ough he sp ings and summe s, as well as cases
o cannibalism due o amine41.TheRomans a esmanCassiodo us
w o e ha “The hea om he sun was eeble”and “A win e wi hou
s o ms, a sp ing wi hou mildness, and a summe wi hou hea ”42,
leading o p olonged os s and d ough s. This clima ic si ua ion,
which seems o ha e been igge ed by he abo e-men ioned olcanic
e up ions27, could ha e p omo ed ood sho ages and amine, he
ARIDITY
Age (cal y BP)
1150 11001250 12001400 1350 13001500 1450 1050 1000
Age (y CE)
800 850700 750550 600 650450 500 950900
-1
0
1
2
3
S ack A emisia
(3-poin mo . a e .)
a
+
-
2
1.5
1
0.5
0
log10(h)
0.50
0.25
0
-0.25
-0.50
b
(I)
D oug h pe iods (II) (III) (IV)
545 570 695 725 755 770 900 935
+ a idi y
+ a idi y
+ a idi y
+ a idi y
418 CE
c
His o ical
sou ces
Visigo hic Kingdom
Umayyad
Calipha e
Independen Emi a e o Có doba
Calipha e o
Có doba
1031 CE
929 CE756 CE711 CE
Ci il wa Visigo hic c isis Ci il wa s Muladi / Moza abic io s
579549
E up ions
and plagues
536 585 680 713 750 772 880 928
Fig. 3 | The SnSiZe analysis o he A emisia s ack be ween 450 and 950 CE
(1500–1000 cal y BP) o iden i y he s onges d ough pe iods along wi h he
e en s collec ed om his o ical sou ces. a,bThe s ack o A emisia (3-poin
mo ing a e age, in e ed axis) and he SnSiZe g aph wi h h ee smoo hing le els
( ed, blue, and yellow lines in bo h panels). In he SnSiZe g aph (b), ed and blue
colo s sugges s ong inc easing and dec easing ends o A emisia, espec i ely.
The numbe s I, II, III, and IV (bo om o b) indica e he ou s a is ically significan
d ough pe iods iden ified by he SnSiZe (age anges included). cE en s and
du a ion o he compiled his o ical sou ces (black s a s and ho izon al lines). The
sou ce da a om g aph aa e a ailable in Supplemen a y Da a 2.
A icle h ps://doi.o g/10.1038/s41467-023-41367-7
Na u e Communica ions | (2023) 14:5733 4
onse o he La e An ique Li le Ice Age (LALIA), and he ou b eak o he
Jus inian plague in 541–543 CE h ough he Medi e anean2,26,43.The
ch onicle o Vic o o Tunnuna s a ed ha his plague a ec ed His-
pania in 542 CE44. La e on, he Gallo-Roman his o ian G ego y o Tou s
w o e ha du ing 580/581 CE he ambassado s o he king o Neus ia
e u ned om Hispania wi h news abou plagues and amine ha we e
a aging Ca pe ania ( egions su ounding he Tagus alley) and
sp eading o Sep imania (SE o p esen -day F ance)45. The his o ian
also w o e ha du ing 580–585 CE Hispania su e ed s ong os s and
d ough s, coinciding wi h he Visigo hic ci il wa (580–584 CE)
(Fig. 3c). Conside ing hese his o ical sou ces and he pollen esul s,
he s a is ically significan d ough pe iod I eco ded a 545–570 CE
(Fig. 3a, b), which oughly coincides wi h he onse o he LALIA and
p obably linked o he olcanic e up ions and he cold clima e
condi ions2,27, could be conside ed an impo an ac o o he sp ead
o he amine and plagues du ing he mid-6 h cen u y CE in Ibe ia.
A e he d ough pe iod I (545–570 CE), he Visigo hic s a e unde
king Leo igild (Visigo hic king, eign 568/569–586 CE) was able o
consolida e a policy o cen aliza ion, e i o ial expansion, and
s eng hening o he fiscal sys em a e a long pe iod o mone a y
de alua ion46. I is likely ha he clima e amelio a ion could ha e
con ibu ed o an imp o emen o ag icul u e and, he e o e, o he
kingdom adminis a ion and s abili y, which could also ha e con-
ibu ed o a be e economic condi ion o he cons uc ion o new
u ban cen e s, such as Reccopolis (578 CE), Vic o iaco (581 CE) and
Oligicus (621 CE).
D ough pe iod II (695–725 CE)/Visigo hic Kingdom c isis and
Umayyad Calipha e expansion
The A emisia and xe ophy e s acks om Ibe ia and Mo occo show
ha he maximum d ough condi ions o he las 5000 yea s occu ed
a 695–725 CE, indica ed by he highes A emisia alues and iden ified
by he SnSiZe analysis (Figs. 2eand3a, b).
The ege a ion eco ds om he Spanish Cen al Sys em showed
dec easing ee co e , especially in mon ane a eas, and inc easing fi e
ac i i y, which was ela ed wi h he e ec o human ac i i y o ob ain
new pas u es and lands o a ming47,48. Howe e , he changing clima e
condi ions o ced he cul i a ion o cold-adap ed ye (S. ce eale)a
high al i udes, sugges ing ha al hough some ege a ion changes in
pollen eco ds we e a ec ed by human ac i i y47, hese a ia ions
could ha e been o ced a he same ime by cold and d ough condi-
ions. Ac ually, du ing he Visigo hic pe iod, di e en echniques we e
de eloped in u al a eas o adap o d ough condi ions. In sou he n
Ibe ia (Sie a Ne ada ange) hey buil he oldes aqui e echa ge
sys ems in Eu ope, da ed a 636 ± 80 CE49, and popula ion mo ed o
highe ele a ions wi h he consequen inc ease in popula ion in
moun ain egions o sou he n Ibe ia50. This popula ion displacemen
o highlands ook ad an age o he highe al i udinal ain all condi-
ions compa ed o lowlands51. In addi ion, he a cheological e idence
om he Visigo hic ci y o Reccopolis (cen al Ibe ia), such as he
cons uc ion o e aces and he eo ganiza ion o he ag icul u al
sys em, ha e also been ela ed o o es decline and d y condi ions
du ing his pe iod52.
His o ical sou ces sugges he beginning o pe sis en d ough
condi ions a a ound 680 CE in he Ibe ian Peninsula. This is coe al
wi h he inc easing a idi y a e ca. 670 CE in Ana olia and he
Le an , which caused he abandonmen o ag icul u al land and he
collapse o he majo se lemen s53. The XII Council o Toledo,
o ganized in cen al Ibe ia by he king E igio (Visigo hic king, eign
680–687 CE), ook place in No embe 681 CE “ o suppo a wo ld in
collapse”54. Th ee yea s la e , in No embe 684 CE, Ti le III o he
Minu e Book o he XIV Council o Toledo eco ded: “This no e, wi h
all ha has happened, was p esen ed in he wo s momen o a e ible
wea he , when all lands, in he wo s win e momen , a e co e ed by
hea y snow all and glacial empe a u es”55, poin ing in o ha sh
win e condi ions du ing he Au umn season. In addi ion, he
Moza abic ch onicle o 754 CE s a ed ha du ing his pe iod: “E i-
gio was consec a ed in he kingdom o he Go hs. He uled o se en
yea s, and Hispania su e ed a huge amine”56. Du ing he nex eign
o king Egica (Visigo hic king, eign 687–702/703 CE), in pa icula
du ing he yea s 691–692 CE, a bubonic plague ha a ec ed he
Ibe ian Peninsula56 was ela ed o long pe iods o cold/d ough
condi ions, low ood p oduc i i y and amine57–59 (Fig. 3c). The
Moza abic ch onicle also eco ded ha du ing 702–703 and 710–713
CE “The s a a ion and plague a aged Hispania”56. Mo eo e , he
ch onicles poin o pe iods o se e e amine (707–709 CE) imme-
dia ely p io o he pe iod o conques (711 CE)60 and he A abic
Akhbā majmūʿa ch onicle (mid-11 h cen u y) indica ed ha a ound
hal o he popula ion o Hispania died o s a a ion be ween 706
and 710 CE61,62 (Fig. 3c). These ch onicles poin o a clima e change
owa ds mo e a id and colde condi ions du ing la e-7 h and ea ly-
8 h cen u ies CE. The dea h o king Wi iza (Visigo hic king, eign
700–710/711 CE) in 710/711 CE, he consequen ci il wa , and he
Muslim in asion o he Visigo hic Kingdom (711 CE) ook place
du ing he iden ified pe sis en A emisia pollen d ough pe iod II
(695–725 CE) (Fig. 3b, c). In his ega d, bo h he ch onicle o king
Al onso III (Ch is ian king, eign 866–910 CE) and he Moza abic
ch onicle o 754 CE coincided abou he decline o he kingdom
du ing he in asion: “The Go hs pe ished pa by hung y and pa by
he swo d”(ch onicle o Al onso III)63 and “Wi h swo d, amine and
cap i i y, no only Hispania Ul e io bu also Hispania Ci e io was
de as a ed”(Moza abic ch onicle)56. No e ha he inc ease in A e-
misia a 695–725 CE shows a delay wi h espec o he fi s his o ical
sou ces on ha sh clima e condi ions a 680–684 CE. This 15-yea
delay could be ela ed wi h age model limi a ions and/o he esi-
lience o ege a ion biomes p io o he expansion o a id-adap ed
A emisia in he egion.
Despi e he desc ibed ha sh clima e condi ions, he a cheological
eco ds do no show massi e de as a ion o des uc ion o ci ies o
se lemen s du ing he in asion64. In he Ea ly Medie al kingdoms a
leas 60% o he ichness was based on ag icul u al p oduc s. Ag i-
cul u al labo employed a ound 80% o he popula ion65,and he e-
o e, ha sh and a id clima e condi ions would ha e a ec ed he
s abili y o kingdoms. Howe e , in he case o he Visigo hic Kingdom,
he e is no unanimous posi ion on he main ac o s ha could ha e led
o he collapse o he Visigo hic s a e66. The decline o he Himya i e
kingdom and he eme gence and expansion o Islam du ing he 6 h
cen u y CE ac oss he A abian Peninsula has ecen ly been ela ed wi h
a id clima e condi ions and s ong d ough s67. This d ough eco ded
in A abia as well as he one we eco ded in Ibe ia du ing la e-7 h and
ea ly-8 h cen u ies CE mus also ha e a ec ed he No h A ican
egions. These a id condi ions cons i u e a new elemen in poli ical,
economic, and mili a y mo i a ions ha led o he Islamic expansion o
he Ibe ian Peninsula om 711 CE onwa ds. Fo se e al decades, he e
has been a consensus ha Islamic expansion om he Middle Eas and
No h A ica o he Ibe ian Peninsula may ha e been a o ed by he
in oduc ion and di usion o new echnologies, ag icul u al p ac ices,
and p oduc s be e adap ed o d ylands and a id en i onmen al
condi ions68. Howe e , he e is inc easing e idence o he di usion o
p e-Islamic ag icul u al echniques, ools, and c ops adap ed o semi-
a id egions, sugges ing ha he p e- and pos -Islamic Nea Eas and
Medi e anean a eas we e mo e simila o each o he han p e iously
assumed69.
Al hough he Visigo hic social and poli ical c isis could ha e
s a ed p io o he d ough pe iod II eco ded by he pollen da a, we
can conclude ha he ex eme and pe sis en d ough du ing he la e-
7 h and ea ly-8 h cen u ies CE in he Ibe ian Peninsula may ha e had a
nega i e impac on ood p oduc ion, damaging he p ima ily
ag icul u e-based economy and pas o al ac i i ies70, igge ing (a
leas pa ially) he social and poli ical ins abili y ha could ha e
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a ec ed he decline o he Visigo hic Kingdom, and he fi s phases o
he consolida ion o al-Andalus.
D ough pe iods III and IV (755–770 and 900–935 CE)/Islamic
io s and ci il wa s
The d ough pe iod e ealed by he SnSiZe analysis du ing he
inc ease in A emisia a 755–770 CE due o enhanced a idi y in he
egion (d ough pe iod III, Fig. 3a, b), coincides wi h he fi s Muslim
poli ical des abiliza ion a e he es ablishmen o he Umayyad Cali-
pha e in 711 CE.
Muslims a emp ed o expand no hwa d, bu we e s opped by
he F anks a he Ba le o Poi ie s (F ance, 732 CE)71.La e on,in740
CE, he Be be up ising ha s a ed in he No h A ica and in al-
Andalus/Hispania gene a ed se e al ci il wa s, amine, and depopula-
ion o ce ain a eas, p omo ing he up u e o al-Andalus wi h he
Abbasid Calipha e (Islamic dynas y) and becoming an independen
Emi a e (Emi a e o Có doba) in 756 CE72. Acco ding o he Moza abic
ch onicle, du ing he yea s 748–750 CE “Aho ible aminedesola e he
en i e al-Andalus/Hispania”, simila o ha eco ded by he Akhbā
majmūʿa ch onicle o he 750–754 CE “The yea o he Hegi a 132 / 750
CE, God sen a majo d ough and amine o he en i e al-Andalus/His-
pania”and hech onicleo Moissac(11 hcen u y) o he771-772CE“A
de as ing amine a ec all Hispania”73 (Fig. 3c). Bo h he s acked
A emisia eco d and he ch onicles show d ough condi ions du ing
he mid-8 h cen u y CE. The beginning o Abd al-Rahman’s ule
(Muslim king, eign 756–788 CE) was cha ac e ized by se e al socio-
poli ical c ises, which could ha e been a consequence o he d ough
and subsequen amines, and only om 783-784 CE onwa ds shows an
inc ease in mone a y and expanding e i o ial con ol, linked o he
s abiliza ion o axa ion74.
The las s ong d ough pe iod iden ified by he SnSiZe analysis
o pollen da a occu ed a 900–935 CE (d ough pe iod IV, Fig. 3a, b).
This las episode coincides in pa wi h he fi s fi na (Muslim ci il wa ),
a long p ocess o poli ical c isis ha began wi h he mos powe ul
ebellion led by Oma Ibn Ha sun om 880 o 928 CE75 (Fig. 3c). These
con on a ions ha e been linked o he expansion o he p ocess o
con e sion o Islam and he inc ease o he poli ical and e i o ial
con ol o he Emi a e o Có doba76.
The wo s a is ically significan inc eases in he s acked A emisia
eco d and his o ical sou ces sugges ex eme d ough condi ions
du ing he mid-8 h cen u y and he ea ly-10 h cen u y CE. These
d ough s could ha e a ec ed ag icul u e, con ibu ing o low ood
p oduc ion and amines, and hus p omo ing he economic and socio-
poli ical des abiliza ion o al-Andalus. Howe e , his p ocess o mac o
analysis canno igno e he ac ha communi ies esponded o cli-
ma ic and en i onmen al condi ions. In his ega d, he Andalusian
socie y was cha ac e ized by he expansion o new ag icul u al ech-
niques, including i iga ion77.
D ough s in he wes e n Medi e anean egion and possible
clima e mechanisms
Nume ous paleoclima e s udies ha e demons a ed a s ong ela ion-
ship be ween in e nal a mosphe ic dynamics, such as he No h
A lan ic Oscilla ion (NAO), and ex e nal sola ac i i y, including To al
Sola I adiance (TSI)78,79. The NAO index con ols he s eng h and
di ec ion o he wes e lies o e Eu ope and hus he amoun and
sou ce o p ecipi a ion en e ing he wes e n Medi e anean80.
Al hough he NAO econs uc ion o he Ibe ian Peninsula81 does no
ma ch well wi h he pollen da a be ween 450 and 950 CE (Supple-
men a y Fig. 1a, c), he mos a id condi ions shown by he inc ease in
A emisia and xe ophy es a he end o he 7 h and he beginning o he
8 h cen u ies CE occu ed du ing he highes posi i e No h A lan ic
NAO index econs uc ion82,83 and he lowes TSI84 o he las 5000
yea s (Fig. 2a, b, e, ). The low sola i adiance gene a es cold and esh
No h A lan ic Cu en condi ions, a ec ing he s a e o he NAO85.
Howe e , his ela ionship has been a opic o deba e o e he las
decade. Some s udies ha e shown ha a educed sola i adiance
du ing he Holocene may ha e modula ed he nega i e NAO
phases20,86, whe eas o he p oxy eco ds ha e e idenced a ela ionship
be ween low sola i adiance and a id condi ions in he
Medi e anean87–89, which could be ela ed o posi i e decadal- o
cen ennial-scale NAO phases. In his la e case, a low sola i adiance
could ha e p oduced a sou hwa d mo emen o he pola on and a
educ ion in he ad ec ion o wa e masses in he A lan ic, educing
he s o m ac i i y o e he Medi e anean and esul ing in a id clima e
and d ough condi ions88. An excep ion occu ed du ing he cold and
d ou h pe iod o he mid-6 h cen u y CE, in e p e ed as a possible
consequence o h ee olcanic e up ions occu ing in a sho ime
pe iod (536, 540, and 547 CE)27 and coe al wi h he Jus inian plague.
Me hods
Fossil pollen da a
This s udy syn hesized pollen and a cheological da a om Spain, Po -
ugal, Ando a, and Mo occo. Wi h espec o he pollen da a, we
ocused on he analysis o A emisia and o he xe ophy e pollen axa
om lacus ine con inuous sedimen a y eco ds o gain insigh in o he
a idi y c ises o he las 5000 yea s and, in pa icula , o he las
1500–1000 cal y BP (450–950 CE). The ossil pollen da a acquisi ion was
pe o med using he Neo oma da abase (www.neo omadb.o g)and he
Eu opean Pollen Da abase (EPD, www.eu opeanpollenda abase.ne ),
whe eas o he pollen eco ds no included in hese da abases we e
ob ained by p i a ely con ac ing he au ho s o he co esponding s u-
dies (see Re e ences in Supplemen a y Da a 1). We selec ed all he con-
inen al pollen eco ds om Spain, Po ugal, Ando a, and Mo occo
con aining da a-samples du ing he las 5000 yea s, which esul ed in
107 pollen eco ds (Fig. 1). In o de o make he s udy as objec i e as
possible, none o hese eco ds ha e been fil e ed acco ding o he
numbe and/o p ecision o da es. We conside ha fil e ing he da a
based on he numbe o da es and/o hei p ecision would cause sub-
jec i i y in he da a acquisi ion and, he e o e, esul s would lose
c edibili y.
The s acked A emisia eco d is based on 3977 samples whe eas
he xe ophy e eco d is based on 4115 samples. No e ha he numbe
o samples in he A emisia and xe ophy e eco ds is di e en due o
he absence o A emisia in se en eco ds. The de ailed in o ma ion
(Si e no. map,Si ename,Da abase,Si e ID,Da ase ID,La i ude,Long-
i ude,Al i ude,Ch onology sou ce, Da ing and dep hs, Age model de ails,
and Re e ences) o he 107 pollen eco ds a e included in Supplemen-
a y Da a 1, and he s acked A emisia and xe ophy e da a in Supple-
men a y Da a 2.
Age ch onologies
Age ch onologies o he pollen eco ds we e ob ained om da a-
bases, including he ch onologies om he o iginal s udies and he
ch onologies p oduced by he Mapping and Da a Accu acy wo king
g oup (MADCAP) o he EPD90,91. As he calib a ed age di e ence
be ween he di e en calib a ion cu es o he pe iod o in e es
(450–950 CE, 1500–1000 cal y BP) is negligible (<20 calib a ed yea s,
see Supplemen a y Fig. 2), we decided o use he o iginal calib a ion
cu es (i.e., In Cal98, In Cal04, In Cal09, In Cal13 and In Cal20) p o-
ided by he da abases and he au ho s (Supplemen a y Da a 1). Since
each o he ossil eco ds collec ed o he s acked A emisia pollen
cu e has i s own age model, i is no possible o p o ide specificage
unce ain ies o his composi e eco d. This p oblem has been mi i-
ga ed by collec ing a la ge numbe o ossil eco ds (107 eco ds),
which educes he age unce ain ies.
Pollen as a p oxy o p ecipi a ion
Al hough he inc easing abundance o A emisia and o he xe ophy e
axa (such as Ama an haceae and Ephed a) a e well known as
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indica o s o a idi y pe iods in he wes e n Medi e anean du ing he
Qua e na y92–94, we made a calib a ion using he Eu asian Mode n
Pollen Da abase (EMPD 2)95 and he Wo ldClim 2.1 da a (www.
wo ldclim.o g)96 o obse e he ela ionship be ween high pe cen-
ages o A emisia and low p ecipi a ion condi ions. The e o e, he
ecen mean annual p ecipi a ion (mm/y ) and A emisia pe cen ages
om 8217 mode n pollen si es we e used o analyze he ela ionship
be ween he abundance o A emisia and he p ecipi a ion alues
(Supplemen a y Fig. 3). The mode n pollen da abase shows ha si es
wi h p ecipi a ion alues below ca. 400 mm/y p esen mean A emisia
pe cen ages o e 7%, whe eas he mean A emisia pe cen ages
dec ease below 3% wi h p ecipi a ion alues abo e ca. 400 mm/y ,
sugges ing ha he A emisia pollen genus is a good p oxy o in e -
p e ing a id clima e condi ions in his egion. The e o e, pe sis en
d ough s in pas pe iods caused an expansion o he as -g owing and
a id-adap ed he b/g ass species, such as A emisia, esul ing in a
highe p opo ion o hese axa in he ossil eco ds.
The limi a ions o he pollen analysis in paleoclima e in e p e a-
ions ha e o be aken in o accoun , since modifica ions in he ege-
a ion co e caused by human impac could also ha e a ec ed pollen
abundances. Howe e , i is mo e likely ha he human e ec on
ege a ion could ha e had an impac du ing a gi en pe iod in a pa -
icula a ea o he Ibe ian Peninsula and/o Mo occo, bu i is less likely
ha his e ec would ha e a ec ed di e en la ge Ibe ian/Mo occan
a eas a he same ime. The e o e, in o de o educe he human e ec
on ege a ion, we ha e collec ed a la ge numbe o pollen eco ds o e
a la ge e i o y, educing he noise o human dis u bance ha could
ha e a ec ed some pollen eco ds du ing specificpe iods.
Da a no maliza ion
A z-sco e no maliza ion (x–mean/s de ) was pe o med on he ossil
A emisia and xe ophy e da a (indi idually o each eco d) be o e
s acking he da a, esul ing in high- esolu ion A emisia and xe ophy e
s acks o he las 5000 yea s (Fig. 2e, ). A 45-poin and 15-poin mo ing
a e ages we e pe o med on he A emisia and xe ophy e s acks (black
lines and o ange/yellow lines in Fig. 2e, ) o an easie compa ison wi h
o he paleoclima ic eco ds. The no malized s acked A emisia and
xe ophy e eco ds a e included in Supplemen a y Da a 2.
Co ela ion analyses
A Pea son co ela ion analysis was pe o med be ween ou s acked
A emisia, he composi e δ18O om Chaa a ca e (Cha1 and
Cha2 speleo hems, N Mo occo), and he s acked ela i e δ13C om
Cob e, Kai e and Mayo ca es (C11, LV5, and SLX1 speleo hems, N
Spain). The s acked A emisia (las 5000 cal y BP), composi e δ18O
(las 5000 cal y BP), and s acked ela i e δ13C(las 3900caly BP)
eco ds p esen a da a esolu ion da a o 1.3, 4, and 4.5 yea s, espec-
i ely. Be o e pe o ming he co ela ion analyses, A emisia and
composi e δ18O da a we e in e pola ed (linea in e pola ion) o he
lowes da a esolu ion o he δ18O eco d, i.e., 4 yea s, whe eas A e-
misia and s acked ela i e δ13C we e in e pola ed o he lowes da a
esolu ion o he δ13C eco d, i.e., 5 yea s. The esul s show a high
posi i e co ela ion, wi h =0.802 (p= 0.007104) o he s acked
A emisia s composi e δ18O eco ds,and =0.768 (p=0.01058) o
he s acked A emisia s s acked ela i e δ13C eco ds. The co ela ion
analysis was de eloped unde he Pas 4.12b s a is ical so wa e97.
Scale-no malized Significan Ze o c ossing (SnSiZe ) analysis
The Significan Ze o c ossing (SiZe ) analysis is a use ul ool in
paleoecology o assess he ele an h esholds in he da a and o
define whe e s a is ically significan changes occu in a da a se 98.In
his analysis, nonpa ame ic smoo hing is applied o da a using a
sequence o smoo hing le els in o de o e eal salien ea u es in he
signal a all equencies. The Scale-no malized Significan Ze o c oss-
ing (SnSiZe ) analysis99, based on he o iginal SiZe analysis100,has
been used o obse e ends and anomalies in he da a, allowing he
iden ifica ion o s a is ically significan inc eases and dec eases in he
da a. In addi ion, he SnSiZe uses scale-no malized de i a i es101 o
de ec he s a is ically significan changes in he signal and highligh
he in ensi y o inc easing and dec easing changes ( ed and blue),
esul ing in mo e o less in ense colo s in he g aph. Thus, in he
SnSiZe g aph, eading om pas o p esen (i.e., om le o igh ), ed
and blue a eas indica e inc eases and dec eases o A emisia, espec-
i ely (no e he in e ed axis in Fig. 3a), and he e o e, ele an
inc easing and dec easing a idi y ends. Da k g ay a eas ep esen no
significan changes, whe eas he ligh g ay a eas indica e ha he
sampling esolu ion is oo low (Fig. 3b). When a ce ain le el o
smoo hing ( ed, blue, o yellow ho izon al lines in he e ical axis,
Fig. 3b) cu s he ele an inc ease ( ed) o dec ease (blue) in A emisia,
i means ha hose changes a e s ong unde ha smoo hing le el. The
ecen ly de eloped SnSiZe was implemen ed by modi ying he sou ce
code o he size R-package102.Theda awasp ep ocessedusinga
3-poin mo ing a e age smoo he o educe backg ound noise in he
s acked A emisia eco d and he e o o he age ch onologies.
Howe e , such p e-smoo hing may p oduce au oco ela ion in he
da a and cause alse posi i es in he SnSiZe analysis. In o de o
mi iga e he au oco ela ion e ec , he SnSiZe analysis was un unde
he 95% confidence le el.
To define he age anges o d ough pe iods, we ook he onse s o
he A emisia inc eases ( ed a eas in he SnSiZe g aph, Fig. 3b), which
indica e he beginning o he d ough s, un il he onse s o he dec eases
(blue a eas in he SnSiZe g aph), indica ing he end o d ough con-
di ions. The maximum esolu ion o de e mining he onse s/ends o
d ough s is 5 yea s. Since he end o he hi d s ong d ough pe iod
(d oug h pe iod III) is no cha ac e ized by an ab up dec ease in
A emisia (and he e o e, no obse ed in he SnSiZe g aph a he
selec ed smoo hing le els — ed, blue, and yellow lines—), his d ough
was delimi ed by he s ong inc ease in A emisia iden ified by he
SnSiZe analysis be ween 755 and 770 CE (Fig. 3b). The e o e, his
me hodology be ween 450 and 950 CE esul ed in ou s a is ically
significan d ough s a 545–570 (1405–1380 cal y BP), 695–725
(1255–1225 cal y BP), 755–770 (1195–1180 cal y BP) and 900–935 CE
(1050–1015 cal y BP). Al hough he s a is ical significance o hese
e en s canno be wa an ed due o he abo e-men ioned isk o alse
posi i es, hey can be conside ed as s onge d ough s in he da a.
His o ical and a cheological sou ces
His o ical sou ces unde annual/bi-annual esolu ion we e collec ed and
compa ed wi h he pollen and paleoclima e p oxy da a o unde s and
he clima e impac on he Visigo hic and Muslim socie ies. The his o ical
sou ces we e selec ed acco ding o he geog aphical and ch onological
c i e ia and he eliabili y o he sou ce, including he Roman s a eman
Cassiodo us (6 h cen u y), he Gallo-Roman his o ian G ego y o Tou s
(6 h cen u y), he Roman-Byzan ine his o ian Vic o o Tunnuna (6 h
cen u y), he Minu e Books o he XII and XIV Councils o Toledo (7 h
cen u y), he Moza abic ch onicle o 754 CE (8 h cen u y), he Ch is ian
ch onicle o king Al onso III (9 h cen u y), he A abic Akhbā majmūʿa
ch onicle (11 h cen u y) and he ch onicle o Moissac (11 h cen u y). In
addi ion, a e iew o he mos significan a cheological da a has been
ca ied ou . Special emphasis has been placed on u al si es o he
Visigo hic pe iod. Da a om u ban si es om he pe iod be ween he
6 h and 8 h cen u ies CE ha e also been analyzed.
Repo ing summa y
Fu he in o ma ion on esea ch design is a ailable in he Na u e
Po olio Repo ing Summa y linked o his a icle.
Da a a ailabili y
The da a om his s udy, including he de ailed in o ma ion on all he
Ibe ian and Mo occan ossil pollen eco ds and he A emisia and
A icle h ps://doi.o g/10.1038/s41467-023-41367-7
Na u e Communica ions | (2023) 14:5733 7
xe ophy e s acks a e a ailable in Supplemen a y Da a 1 and 2,
espec i ely. The A emisia and xe ophy e s acks (Supplemen a y
Da a 2) a e also a ailable a he Pangaea da a eposi o y (www.
pangaea.de). The aw ossil pollen da a we e ob ained om he open-
access Neo oma da abase (www.neo omadb.o g)and heEu opean
Pollen Da abase (www.eu opeanpollenda abase.ne ), and by con ac -
ing he au ho s p i a ely (Viñuelas, B ezoso, Medina, Zoña , Padul, Río
Seco and Honde a eco ds, see Re e ences in he Supplemen a y
Da a 1). The se en pollen eco ds a e no a ailable in open da abases,
can be ob ained by con ac ing he ollowing au ho s: C. Mo ales-
Molina (Viñuelas and B ezoso), T. Sch öde (Medina), C. Ma ín-
Pue as and P. González-Sampé iz (Zoña ), J. Camue a (Padul), R.S.
Ande son and G. Jiménez-Mo eno (Río Seco), and J.M. Mesa-Fe nández
(Honde a). The sou ce da a om his s udy ha we e used o Figs. 1–3
and Supplemen a y Fig. 1 a e a ailable in Supplemen a y Da a 1 and 2.
Code a ailabili y
The SnSiZe code is a modified e sion o he o iginal SiZe code
published by Chaudhu i and Ma on (1999)100, and de eloped by
modi ying he sou ce code o he size R-package (Sonde egge ,
2020)102. Since he new SnSiZe code has no ye been published, he
code will be a ailable p i a ely upon eques .
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