ORIGINAL PAPER
In e na ional Jou nal o Biome eo ology (2025) 69:109–122
h ps://doi.o g/10.1007/s00484-024-02796-1
(IPCC 2021), wi h d as ic impac s on en i onmen al p o-
cesses. Among hese impac s, can be included al e a ions
in he phenology o nume ous plan species, gi en ha
phenology has been shown o be especially sensi i e o
empe a u e and ain all (Keenan e al. 2014; Wang e al.
2015, 2022, 2023; Galán e al. 2016; Qiu e al. 2020). Unde
he e ec s o clima e change, bo h o hese a iables show
ends owa ds inc easingly ex eme e en s (IPCC 2021),
and i can hus be expec ed ha al e a ions in plan phenol-
ogy will become mo e ma ked and mo e widesp ead. A he
same ime, he e is e idence ha an inc ease in a mosphe ic
CO2 concen a ions s imula es plan p oduc ion, and conse-
quen ly pollen p oduc ion (Roge s e al. 2006; Albe ine e
al. 2014).
The in e ac ion o all hese p ocesses in he con ex o
clima e change is gene a ing al e a ions in he ai bo ne pol-
len egis e ed om nume ous plan species. Va ia ions in
pollen abundance and seasonally o anemophilous species
In oduc ion
Clima e change is, wi hou doub , one o he majo chal-
lenges acing he 21s cen u y. Human-induced clima e
wa ming has led o an inc ease in he global a e age em-
pe a u e o one deg ee Celsius abo e p e-indus ial le els
Pablo J. Hidalgo
[email p o ec ed]
1 Depa men o In eg a ed Sciences, Cen e o Na u al
Resou ces, Heal h and En i onmen (RENSMA), Uni e si y
o Huel a, Huel a 21007, Spain
2 A mosphe ic Resea ch and Ins umen a ion B anch,
A mosphe ic Sounding S a ion– El A enosillo, Na ional
Ins i u e o Ae ospace Technology (INTA), Mazagón,
Huel a 21130, Spain
3 Depa men o Plan Biology and Ecology, Facul y o
Pha macy, Uni e si y o Se illa, Se illa 41012, Spain
Abs ac
Nume ous s udies ha e shown ha clima e change is impac ing he ai bo ne pollen concen a ion o a ious anemophilous
plan species, bo h he baceous and woody. The aim o his s udy was o de e mine whe he his end, highly ma ked in
Eu ope, is also occu ing in he ci y o Huel a (sou h-wes e n Spain), an a ea wi h a milde Medi e anean clima e. The
ac o s in luencing he main pollen season we e s udied o all local axa accoun ing o mo e han 1% o he o al pollen
collec ed, o e he pe iod 1993–2022, using a olume ic Hi s ype ap o de e mine concen a ion. The s udy included
a end analysis o me eo ological a iables suscep ible o clima e change, speci ically maximum, minimum and a e age
empe a u e, p ecipi a ion and he numbe o hou s o insola ion pe day. Al hough some o he a iables analysed do no
show signi ican ends o mos axa, such as s a da e o peak da e, he o e all esul s indica e a end in he ai bo ne
pollen dynamics o he baceous and woody axa. Six o he eigh woody axa s udied showed a signi ican end owa ds
inc eased pollen concen a ion, some o which a e associa ed wi h empe a u e in p e ious seasons. In con as , h ee o
he i e he baceous axa, which a e mo e sensi i e o sho e m me eo ological a iables, show a signi ican accele a ion
in he end da e o he main pollen season, co ela ed nega i ely wi h empe a u e and insola ion. In conclusion, some
incipien changes a e occu ing, which may be indica i e o u u e consequences on biodi e si y in he Medi e anean
a ea in luenced by he A lan ic Ocean.
Keywo ds Bioclima ology · Clima e change · Ai bo ne pollen · Huel a · Long- e m end
Recei ed: 14 Decembe 2023 / Re ised: 13 Sep embe 2024 / Accep ed: 1 Oc obe 2024 / Published online: 8 No embe 2024
© The Au ho (s) 2024
Pollen season a ia ions among anemophilous species in an A lan ic-
in luenced medi e anean en i onmen : a long e m s udy (1993–
2022)
Nu iaMon iel1· Pablo J.Hidalgo1· José An onioAdame2· F anciscoGonzález-Mine o3
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In e na ional Jou nal o Biome eo ology (2025) 69:109–122
a e especially iden i iable, as his ype o pollen has been
moni o ed o se e al decades in nume ous ci ies a ound
he wo ld (Ziello e al. 2012; Ziska e al. 2019). Long- e m
pollen moni o ing in he ai has enabled many s udies o
link al e a ions in ai bo ne pollen concen a ion o clima e
change (Smi h e al. 2014; Zhang e al. 2015; Ande egg e
al. 2021; Ku ganskiy e al. 2021). The end in he No he n
Hemisphe e seems o indica e an inc ease in he amoun o
pollen eco ded om woody species, such as oli e (Olea
eu opaea), alde (Alnus spp.) and hazel (Co ylus a el-
lana) (Ga cía-Mozo e al. 2014; Hoebeke e al. 2018) while
he amoun o pollen egis e ed om he baceous species,
o ins ance g asses and ne les, shows a dec easing end
(Hoebeke e al. 2018; Rojo e al. 2021). In addi ion, sig-
ni ican changes in he du a ion o he main pollen season
ha e been epo ed, wi h a ia ions in he s a , peak and
end da es (Ga cía-Mozo e al. 2014; Hoebeke e al. 2018;
Ruiz-Valenzuela and Aguile a 2018; Pio owska-We yszko
e al. 2021; Rojo e al. 2021; Adams-G oom e al. 2022).
Howe e , i should be no ed ha hese empo al a ia ions
seem o espond o local clima ic condi ions, wi h di e en
esul s being ob ained acco ding o he egion o coun y
whe e he s udy was loca ed. This si ua ion makes i di icul
o es ablish an exac and unequi ocal global end (Recio e
al. 2009; Galán e al. 2016; Adams-G oom e al. 2022).
This is especially ele an o wo undamen al easons.
In his con ex , i should be s essed ha a ia ions in pol-
len concen a ion ha e a di ec impac on diseases such as
alle gic hini is and as hma. An inc ease in he amoun o
pollen egis e ed and in he du a ion o he lowe ing pe iod,
in combina ion wi h an inc ease in a mosphe ic pollu ion,
will a ec bo h sensi isa ion and symp oma ology (Ziska
e al. 2019; Pacheco e al. 2021). Second, a ia ions in he
ai bo ne pollen om anemophilous species is conside ed
an indica o o he impac o clima e change on ecosys em
in eg i y and species dis ibu ion (Galán e al. 2016; B u -
ae s e al. 2018; Pio owska-We yszko e al. 2021; Adams-
G oom e al. 2022).
This s udy cen ed on he ci y o Huel a, loca ed in he
sou hwes o he Ibe ian Peninsula. The a ea has an oce-
anic Te mo-Medi e anean bioclima e wi h a s ong A lan ic
in luence (Ri as-Ma ínez 1987; Valle 2004; Muñoz-Rod í-
guez e al. 2021). As a esul , he a mosphe ic e ec s o
clima e change (especially empe a u e) can be expec ed o
be mo e a enua ed han in con inen al egions due o he
ma i ime ai masses ha mode a e empe a u es and a e
less ex eme. In addi ion, he biological composi ion o he
ai is cha ac e ized by a p e alence o species ypical o
bo h coas al and con inen al a eas (Muñoz-Rod íguez e al.
2021). Many ae obiological s udies ha e been ca ied ou
in he Medi e anean egion, ocused on long- e m ends
and hei ela ionship wi h clima e o land use changes
(Damialis e al. 2007; Bono iglio e al. 2013; Fe nández-
Llamaza es e al. 2014; Ga cía-Mozo e al. 2014; Galán e
al. 2016; Recio e al. 2018; Ruiz-Valenzuela and Aguile a
2018; C is o olini e al. 2020; López-O ozco e al. 2021),
bu he e a e ew s udies in Medi e anean la i udes which
co e he ype o clima ology di ec ly in luenced by he
A lan ic Ocean (Fe nández-Illescas e al. 2010; Ga cía-
Mozo e al. 2010; Alcáza e al. 2011; Camacho e al. 2020).
Fo his eason, he analysis o pollen a ia ions in he
a mosphe e o Huel a is impo an , since he esul s could
be ep esen a i e o bo h he Gul o Cádiz and he sou he n
and wes e n Po uguese coas s. In ac , hese a eas sha e he
same biogeog aphical p o ince: he Coas al Lusi an-Anda-
lusian P o ince (Ri as-Ma ínez e al. 2017). I is cha ac e -
ized by common siliceous lo a and ege a ion, in pa icula
deg aded hea he sc ublands and na i e o es s o co k and
holm oaks (Ri as-Ma ínez 1988), while also hos ing many
Medi e anean Ibe o-A lan ic endemism.
The main goals o his s udy we e: (i) o explo e changes
in he pa ame e s de ining he main pollen season h ough
analysis o he axa de ec ed in he a mosphe e o Huel a;
(ii) o de e mine whe he he e is a ela ionship be ween
hese ends and he me eo ological a iables in ol ed in
clima e change; and (iii) o p o ide pollen in o ma ion o
use o alle genic pa ien s and o unde s and he in luence o
pollen a ia ions in ag icul u e and o es y managemen .
Ma e ials and me hods
S udy a ea
The ci y o Huel a is loca ed in he sou hwes (SW) o he
Ibe ian Peninsula (37°16’N 6°57’ W), 7 km om he A lan-
ic Ocean as he c ow lies (Fig. 1).
The a ea has an oceanic Medi e anean clima e wi h
a e age annual empe a u es be ween 17 and 19 °C. The
ainy season s e ches om Oc obe o Ap il, wi h an a e -
age annual ain all o a ound 500–700 mm (a e age om
1952 o 2019) (Andalusia Regional Go e nmen 2022; S a e
Me eo ological Agency, 2023). The ci y is si ua ed be ween
he es ua ies o he i e s Tin o and Odiel, such ha he
u ban a ea is su ounded by an ex ensi e ma shland sys-
em. To he SW i bo de s he Odiel Ma shes Na u al A ea,
included in he Na u a 2000 Ne wo k and conside ed bo h a
Biosphe e Rese e and a Ramsa We land, while o he eas
i is bo de ed by he Tin o Ma shes and Ri e side, which
a e also included in he Na u a 2000 Ne wo k (REDIAM
2019). Consequen ly, a la ge numbe o species om he
Ama an haceae amily can be ound, such as A h ocne-
mum sp., Salico nia sp. and Sa coco nia sp., in addi ion
o g asses such as Spa ina sp. ha domina e hese saline
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In e na ional Jou nal o Biome eo ology (2025) 69:109–122
sys ems (Muñoz-Rod íguez e al. 2021). Gi en Huel a’s
p oximi y o he Doñana Na u al Pa k, he composi ion o
ai bo ne pollen is g ea ly in luenced by dune sys ems, as
well as by dehesas (an ag osil opas o al sys em o open
wooded landscapes consis ing mainly o Que cus species),
and pine o es s (Pinus pinea). Mo eo e , he e a e la ge o -
es plan a ions (mainly Eucalyp us sp.), oli e g o es (Olea
eu opaea) and non-i iga ed he baceous c ops (Hidalgo
2021; Muñoz-Rod íguez e al. 2021). Likewise, he ci y o
Huel a has a wide ange o g een spaces wi h na i e ege a-
ion, such as holm oaks (Que cus ilex), co k oaks (Que cus
sube ) and junipe s (Junipe is oxyced us, J. phoenicia), in
addi ion o o namen al ege a ion and many a eas ha a e
ideal o all ypes o he baceous plan s (Fig. 1). In o de o
unde s and he in luence o he su ounding landscape on
pollen concen a ion, an analysis o land use changes (Ka e-
la is e al. 2004), based on CORINE Land Co e (2020),
was ca ied ou o e a 30 km adius. Changes o he su -
ounding a eas o he ci y ha e ecen ly been obse ed, in
pa icula a ela i e educ ion in pine o es s due o wild i es
(15% in 28 yea s) and an inc ease in oli e c ops (53% o e
28 yea s) (Fig. 1).
Ae obiological and me eo ological obse a ions
The ae obiological da a we e aken using a Hi s - ype olu-
me ic ap (Hi s 1952), which collec ed pollen om a oo -
op 12 m a.g.l. (abo e g ound le el) a he Uni e si y o
Huel a’s El Ca men campus. Bo h he collec ion and he
sampling p ocedu e we e ca ied ou ollowing he p o o-
cols o he Spanish Ae obiology Associa ion (Galán Sol-
de illa e al. 2007), and ul illed he minimum equi emen s
es ablished by Galán e al. (2014). The s udy co e s he
pe iod 1993–2022.
The collec ed a mosphe ic pollen his way showed con-
side able biodi e si y, wi h a o al o 38 di e en axa ep-
esen ed (Table S1, supplemen a y ma e ial). In o de o
achie e consis ency ac oss he analyses, we ocused only
on hose axa which accoun ed o mo e han 1% o he o al
pollen collec ed h oughou he ime se ies. This esul ed in
13 axa being selec ed, 8 o which co esponded o woody
species and 5 o he baceous. Be o e es ablishing he da a
ea men , he pollen calenda s o each ype we e p epa ed,
based on daily a e ages o he whole s udied pe iod (Fig.
S2, supplemen a y ma e ial).
Fig. 1 Changes in land use o e a adius o 30 km a ound he ci y o Huel a: 1990 (a) and 2018 (b). Adap ed om CORINE Land Co e 2020
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In e na ional Jou nal o Biome eo ology (2025) 69:109–122
The 90% me hod p oposed by Nilsson and Pe sson
(1981) was used o de e mine he Main Pollen Season
(MPS), by which he s a and end o he MPS a e es ab-
lished when he cumula i e sum o pollen collec ed o ha
yea eaches 5% and 95% o he o al, espec i ely. In addi-
ion, due o he wide phenological a iabili y o he axa
in ol ed, i was decided ha he “Peak” me hod should be
used. This me hod, included in he AeRobiology R so wa e
package (Rojo e al. 2019), consis s in selec ing he day wi h
he highes pollen egis e ( he peak day) o each yea and
o each axon. Once hese ha e been es ablished, six-mon h
pe iods be o e and a e he peak day we e selec ed. The
da a om hose 12 mon hs was be used in he calcula ion
o he MPS o each yea and each axon. The ad an age
o e ed by his echnique is ha i p o ides a mo e ealis ic
analysis o ce ain pollen axa, such as Cup essaceae and
U icaceae, whose pollen seasons usually co e wo di e -
en yea s. The MPS pa ame e s analysed in his s udy we e:
s a day, end day, peak day, alue o peak day, leng h o he
MPS, SPIn (Seasonal Pollen In eg al), calcula ed as he sum
o he daily a e ages du ing he MPS, and APIn (Annual Pol-
len In eg al) (Fig. S3, supplemen a y ma e ial), calcula ed
as he sum o he daily a e ages o he whole 12-mon h
pe iod (Galán e al. 2017; Bas l e al. 2018). Fo missing
da a, he de aul me hod ecommended in he AeRobiology
R package was ollowed: whe e hese da a did no exceed
30 consecu i e days, linea in e pola ion was used (always
ensu ing ha his did no in luence he MPS); in cases whe e
his h eshold was exceeded, he gap in he da a se ies was
main ained (Rojo e al. 2019). The esul ing da ase co e ed
he pe iod om 1993 o 2022, wi h some yea s omi ed om
he s udy (Table 1, column “N”) whene e he a ailabili y
o da a was insu icien o encompass he ull pollen season.
To unde s and how wea he condi ions a ec pollen,
daily su ace me eo ological obse a ions we e used, speci -
ically, he maximum (Tmax), minimum (Tmin) and a e age
(Tmean) empe a u es, ain all (Rain), and daily insola ion
(Insol). The me eo ological eco ds we e ob ained om he
s a e me eo ological obse a o y in Huel a (S a e Me eo o-
logical Agency (AEMET), 2023) which is loca ed 1.5 km
om he pollen moni o ing s a ion. This da abase co e s he
pe iod om 1992 o 2022, o which daily a e ages o each
season and a iable we e aken. Win e was de ined as Janu-
a y o Ma ch, sp ing om Ap il o June, summe om July
o Sep embe and au umn om Oc obe o Decembe .
S a is ical analysis
Fi s , he mean and s anda d de ia ion we e calcula ed o
all ae obiological pa ame e s, a e which he Shapi o-Wilk
no mali y es was applied. This indica ed ha he majo -
i y o he esul s could no be conside ed no mal, and so
Table 1 Taxa accoun ing o mo e han 1% o o al pollen collec ed om he ai o Huel a
Taxa NS a da e Peak da e End da e Lengh APIn SPIn Peak alue
Woody Casua ina 24 266 ± 12 282 ± 19 332 ± 23 68 ± 26 291 ± 175 268 ± 161 51 ± 43
Cup essaceae 21 310 ± 30 48 ± 37 99 ± 32 156 ± 50 1587 ± 1224 1444 ± 1113 108 ± 86
My aceae 22 101 ± 41 181 ± 11 267 ± 38 167 ± 62 461 ± 349 418 ± 316 31 ± 27
Olea 23 114 ± 9 125 ± 13 158 ± 16 44 ± 11 4352 ± 3135 3976 ± 2875 532 ± 426
Pinus 23 58 ± 20 105 ± 18 180 ± 45 123 ± 55 741 ± 506 674 ± 458 81 ± 76
Pla anus 23 67 ± 10 76 ± 7 96 ± 16 30 ± 16 977 ± 911 907 ± 856 161 ± 130
Populus 21 35 ± 39 65 ± 21 94 ± 24 60 ± 50 268 ± 496 249 ± 456 40 ± 87
Que cus 23 60 ± 44 97 ± 11 141 ± 16 82 ± 43 4593 ± 3374 4190 ± 3101 492 ± 380
He baceous Ama an haceae 22 110 ± 10 219 ± 47 276 ± 6 167 ± 12 1549 ± 664 1403 ± 601 71 ± 60
Plan ago 23 84 ± 10 111 ± 18 174 ± 25 91 ± 28 611 ± 433 556 ± 393 44 ± 41
Poaceae 23 102 ± 23 139 ± 9 204 ± 27 104 ± 43 4282 ± 3860 3870 ± 3494 330 ± 354
Rumex 23 53 ± 16 101 ± 27 153 ± 20 101 ± 28 671 ± 500 609 ± 453 35 ± 24
U icaceae 22 362 ± 23 71 ± 18 151 ± 38 155 ± 41 2703 ± 2407 2441 ± 2176 118 ± 121
A e age and s anda d de ia ion o all ae obiological pa ame e s o e he ime se ies. S a , peak and end da es, and leng h o MPS a e exp essed in DOY (days o he yea ). APIn (Annual
Pollen In eg al), SPIn (Seasonal Pollen In eg al) and peak alue a e exp essed in pollen*day/m3. N indica es he numbe s o yea s used in he analyses o each axon (see Sec . 2.2)
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In e na ional Jou nal o Biome eo ology (2025) 69:109–122
Fo example, in he case o My aceae, Que cus, Populus o
Pinus, one, o e en bo h, shows a a ia ion o up o one and
a hal mon hs, while o o he axa he de ia ion is negli-
gible, as can be seen in he case o Ama an haceae, he s a
and end da es o which a e always a ound he same week
o he yea .
T ends in he ae obiological pa ame e s
Table 2 shows he Theil-Sen slope alues and slope de ia-
ion o he pollen season pa ame e s. Wi h espec o s a
da es o he MPS, nei he he woody o he baceous species
seem o show signi ican ends, wi h he excep ion o he
Poaceae g oup (p = 0.034), which shows a end owa ds a
delay in he s a da e. Wi h ega d o peak day, he mos
signi ican end is shown by Casua ina (p = 0.015), which
ends owa ds a delay in he peak da e. Rega ding he end
da e, howe e , he he baceous axa show conside able al e -
a ion. As can be seen in Table 2, he end da e is signi ican ly
ad anced o h ee ou o he i e axa, esul ing in a educ-
ion in he MPS. This is especially e iden in he Poaceae
g oup, whose MPS leng h is he mos signi ican ly educed
(p = 0.001).
The di e ences be ween he baceous and woody axa a e
once again no able in e ms o he amoun o pollen col-
lec ed (APIn, SPIn, and peak day alue) (Table 2). In his
case, Casua ina, Olea, Pinus, Pla anus and Populus show
a signi ican inc ease in pollen concen a ion, while My a-
ceae, shows a dec easing end. He baceous axa, on he
o he hand, do no seem o show any changes in hei pol-
len concen a ion, wi h he excep ion o U icaceae, which
shows a educ ion o SPIn (p = 0.017).
T ends in he me eo ological pa ame e s
Table 3; Fig. 2 show he main a iables likely o be a ec ed
by clima e change. Wi h he excep ion o ain all, all show
signi ican changes o e ime, especially in sp ing (SMJ),
summe (JAS) and au umn (OND). In he case o ain all, a
nega i e end can be de ec ed o e he yea s, especially in
he case o au umn, albei no signi ican .
Co ela ion be ween ae obiological and
me eo ological pa ame e s
Gi en ha he main a ia ions we e ound in he leng h o
he MPS, end da e, and pollen concen a ion (SPIn, APIn
and peak alue), analysis o po en ial co ela ions wi h he
me eo ological a iables ocused on hese h ee pa ame e s.
As he ends o APIn and SPIn we e simila , SPIn was
selec ed o e APIn o i s ad an age in empo ally delimi -
ing he analysis.
non-pa ame ic es s we e used o he subsequen analyses.
The calcula ion o he ends o bo h he ae obiological and
me eo ological pa ame e s was conduc ed using he Mann-
Kendall es and he Theil-Sen es ima o (posi i e Theil-Sen
alues indica e an inc easing end), as hese s a is ical ools
a e conside ed mo e obus o he e ogeneous ime se ies
da a. Special a en ion was paid o he p- alue (p), indica -
ing he signi icance o he analysis, and he Theil-Sen es i-
ma o , which s a es he alue o he slope o he eg ession
line (Hussain and Mahmud 2019).
The ela ionship be ween he ae obiological a iables
and he me eo ological measu emen s was analysed using a
Spea man co ela ion es , which esul ed in wo s a is ical
pa ame e s: he p- alue, indica ing he signi icance o he
es , and he Rho alue, indica ing he ype o co ela ion
(Rho > 0: posi i e co ela ion; Rho < 0: nega i e co ela-
ion) and i s s eng h (Rho = 0: no co ela ion; Rho = 1: pe -
ec co ela ion (Vi anen e al. 2020). The co ela ions we e
made using he ae obiological a iables o each axon, and
he seasonal a e age o he me eo ological a iables o he
en i e du a ion o he MPS, plus wo seasons p io o he
season in ques ion o unde s and he possible in luence on
he pa ame e s o he MPS.
As men ioned abo e, he MPS pa ame e s we e gene -
a ed using he AeRobiology R package (Rojo e al. 2019).
All s a is ical analyses and g aphics we e pe o med using
Py hon ( .3.11). The packages and lib a ies used we e
pyMannKendall (Hussain and Mahmud 2019) o he Mann-
Kendall es , SciPy (Vi anen e al. 2020) o he Spea man
co ela ion es and he Theil-Sen es ima o , and Ma plo lib
(Hun e 2007) and Seabo n (Waskom 2021) o he g aphs.
Resul s
Ae obiological pollen o e iew
Table 1 shows he main esul s o he ae obiological
pa ame e s o e he ime se ies. Rega ding he du a ion o
he main pollen season, he e is conside able a ia ion. Fo
some axa, no ably Ama an haceae and My aceae, he MPS
las se e al mon hs, p obably due o he di e si y o species
ep esen ed, whils o he s, such as he plane ee (Pla anus)
and oli e ee (Olea), ep esen ed by a single species, i is
conside ably sho e , a app oxima ely one mon h.
Wi h espec o he amoun o pollen, he e a e also la ge
a ia ions be ween he di e en axa. In e ms o SPIn, he
axa con ibu ing he la ges amoun s a e Que cus, Olea,
Poaceae and U icaceae, while hose con ibu ing he leas
a e Casua ina and Populus.
Finally, i is wo h no ing he s anda d de ia ion o ce -
ain axa wi h espec o he s a and end da es o he MPS.
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In e na ional Jou nal o Biome eo ology (2025) 69:109–122
Table 2 Theil-Sen slope alues and slope de ia ion o he pollen season pa ame e s o woody and he baceous axa measu ed in Huel a (1993–2022)
Woody axa He baceous axa
Casu. Cup . My . Olea Pinu. Pla . Popu. Que . Ama . Plan. Poac. Rume. U i.
S a
da e
*
0.9 13.4 -18.6 -1.6 1.7 0.4 -4.7 3.3 0.0 2.1 7.1* 2.5 -3.1
± 6.9 ± 16.0 ± 24.4 ± 4.7 ± 6.6 ± 3.9 ± 16.2 ± 12.6 ± 5.8 ± 6.2 ± 9.4 ± 10.1 ± 13.5
Peak
da e
*
11.8 0.6 0.0 2.4 5.6 0.0 -4.3 5.0 4.0 5.0 -3.3 8.0 -2.5
± 8.6 ± 14.1 ± 7.2 ± 7.8 ± 8.5 ± 3.9 ± 10.0 ± 5.0 ± 8.2 ± 9.8 ± 5.6 ± 15.4 ± 12.5
End
da e
+** *
2.7 9.7 17.6 -4.2 -0.6 -0.8 0.0 4.4 2.0 -7.6 -20.0 -5.0 -15.0
± 7.9 ± 9.6 ± 25.6 ± 8.1 ± 29.1 ± 7.7 ± 13.1 ± 9.7 ± 3.3 ± 8.9 ± 10.0 ± 5.8 ± 23.3
Leng h +* **
3.2 -13.3 27.3 -1.9 -1.7 -1.0 10.0 0.9 2.5 -10.0 -31.4 -9.2 -12.0
± 12.7 ± 31.5 ± 39.6 ± 5.4 ± 26.3 ± 5.3 ± 20.6 ± 16.3 ± 6.5 ± 11.5 ± 14.4 ± 13.5 ± 23.5
APIn +*** ** * ** *** *
80.4 378.5 -174.0 1808.5 288.4 547.3 113.6 578.3 22.8 -3.3 -384.0 -77.7 -914.6
± 87.2 ± 510.5 ± 103.4 ± 1247.3 ± 229.3 ± 336.5 ± 115.4 ± 1431.8 ± 425.4 ± 183.6 ± 1628.7 ± 245.4 ± 806.3
SPIn +*** ** * ** *** *
76.4 344.0 -154.0 1668.5 271.1 482.5 105.8 531.3 22.9 -7.037 -344.5 -70.0 -824.1
± 79.0 ± 487.2 ± 95.3 ± 1116.4 ± 208.1 ± 314.8 ± 108.1 ± 1285.5 ± 384.3 ± 167.0 ± 1482.7 ± 212.0 ± 731.6
Peak alue ** ** * * ***
7.0 35.4 -11.4 243.1 32.1 60.0 10.0 46.3 9.4 1.9 0.455 -6.0 -12.0
± 13.5 ± 35.0 ± 9.9 ± 157.0 ± 32.9 ± 50.2 ± 9.2 ± 166.7 ± 18.3 ± 8.1 ± 112.3 ± 8.5 ± 33.4
S a da e, peak da e, end da e and leng h o MPS a e exp essed in days decade-1. APIn (Annual Pollen In eg al), SPIn (Seasonal Pollen In eg al) and peak alues a e exp essed in pollen
decade-1. The p- alue is exp essed as ollows: + p = 0.05; * p < 0.05; ** p < 0.01; *** p < 0.001. The axa a e: Casua ina (Casu.), Cup essaceae (Cup .), My aceae (My .), Olea, Pinu (Pinus),
Pla anus (Pla .), Populus (Popu.), Que cus (Que .), Ama an haceae (Ama .), Plan ago (Plan.), Poaceae (Poac.), Rumex (Rume.) and U icaceae (U i.)
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Table 3 Theil-Sen slope alues and slope de ia ion o me eo ological a iables by season in Huel a (1992–2022)
Seasons Tmax. Tmean. Tmin. Rain Insol.
Win e 0.12 ± 1.4 0.6 ± 1.3 0.9 ± 1.8 0.0 ± 1.6 0.8 ± 1.6
Sp ing 1.8 ± 1.8 1.5 ± 1.4 1.4 ± 1.2 -0.2 ± 0.9 1.9 ± 1.0
Summe 2.1 ± 1.6 1.9 ± 1.0 1.5 ± 0.8 -0.2 ± 0.4 1.6 ± 0.7
Au umn 2.4 ± 1.4 1.6 ± 1.2 1.1 ± 1.7 -0.8 ± 1.9 2.3 ± 1.1
Maximum (Tmax), minimum (Tmin) and a e age (Tmean) empe a u es a e exp essed in ºC season decade-1, ain all (Rain) is exp essed in mm
season decade-1 and insola ion (Insol) is exp essed in h/day season decade-1
Fig. 2 Tempo al e olu ion o he seasonal mean alues o he me eo-
ological pa ame e s and hei end line (1992–2023). The p- alue
is exp essed as ollows: + p = 0.05; * p < 0.05; ** p < 0.01; ***
p < 0.001. The seasons a e di ided in o win e (JFM), sp ing (AMJ),
summe (JAS) and au umn (OND). The me eo ological a iables a e
daily a e ages o each season: Tmax (maximum empe a u e), Tmean
(a e age empe a u e), Tmin (minimum empe a u e), Insol. (Insola-
ion) and Rain ( ain all)
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signi ican co ela ion can be de ec ed among he he ba-
ceous axa be ween hou s o insola ion and ain all and he
pollen concen a ion. A u he posi i e co ela ion can be
seen be ween his pollen concen a ion and win e minimum
empe a u es o U icaceae, Rumex and Plan ago.
Wi h ega d o woody axa, some show a di ec co e-
la ion be ween SPIn and empe a u e and insola ion o he
season p io o he lowe ing pe iod (Fig. 3a). The case o
My aceae is wo h no ing, as i s pa e n is in e se o he es
o he woody axa, showing a nega i e co ela ion be ween
SPIn and summe empe a u e. By con as , a highly
Fig. 3 Resul s o he Spea man co ela-
ion o (a) SPIn, (b) leng h, (c) end da e
wi h seasonal me eo ological a iables
o woody and he baceous axa. The
p- alue is exp essed as ollows: +
p = 0.05; * p < 0.05; ** p < 0.01; ***
p < 0.001. The me eo ological a iables
a e Tmax (maximum empe a u e),
Tmean (a e age empe a u e), Tmin
(minimum empe a u e) exp essed in
ºC, Insol. (Insola ion) exp essed in daily
hou s, and Rain (Rain all) exp essed in
mm
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Fe nández-Llamaza es e al. 2014; Galán e al. 2016; De
Lina es e al. 2017; Ruiz-Valenzuela and Aguile a 2018).
Howe e , hese axa-speci ic ends do no seem o ollow
a gene al pa e n, and espond s ongly o local si ua ions,
di e ences e en being ound wi hin he same a ea by di e -
en s udies (Galán e al. 2016; De Lina es e al. 2017; Ruiz-
Valenzuela and Aguile a 2018). Such di e ences could be
due in pa o land use changes in he p oximi y o he pollen
sample o o si ua ions go e ned by local mic oclima es.
The SPIn o hese woody axa depends chie ly on em-
pe a u e and daily hou s o insola ion in he mon hs lead-
ing up o he s a da e. This e ec , which has al eady been
desc ibed bo h o empe a u e (Ziska e al. 2019; López-
O ozco e al. 2021; Adams-G oom e al. 2022) and o daily
hou s o insola ion in he case o Que cus (Recio e al. 2018;
López-O ozco e al. 2021), Be ula (Hoebeke e al. 2018; De
Wege e al. 2021) and Pla anus (Hoebeke e al. 2018), is
also documen ed in he p esen s udy. This inding shows
ha , despi e being a loca ion close o he ocean, whe e he
bu e ing e ec o he body o wa e plays an essen ial ole,
he e ec s o clima e change on pollen concen a ion a e
signi ican , especially o ce ain axa such as Pinus and
Pla anus (bo h o which display a posi i e end o SPIn,
and a co ela ion o his pa ame e wi h he empe a u e o
p e ious seasons).
In he case o Olea, al hough he e is an e iden co ela-
ion wi h empe a u e, i is no s a is ically signi ican . The
inc ease in SPIn o his axon may be caused by a combina-
ion o he inc ease in empe a u e and changes in land use.
Analysis o he cul i a ion o his ype o c op in he ag i-
cul u al a ea su ounding Huel a e eals ha om 1990 o
2018 land co e inc eased by 53% wi hin a adius o 30 km
a ound he posi ion o he pollen ap (CORINE Land Co e
2020). In addi ion, as o he esea che s ha e poin ed ou ,
he use o i iga ion wi h his ype o c op is associa ed
wi h he disappea ance o he biennial hy hm ha o me ly
cha ac e ised he p oduc ion and emission o pollen in oli e
ees (Díaz de la Gua da e al. 2003). This ci cums ance may
be con ibu ing o he posi i e end ound in he SPIn and
APIn (Díaz de la Gua da e al. 2003; Galán e al. 2016).
Al hough he MPS o he oli e ee is e y limi ed in ime (44
days ± 11 days), Olea pollen is among he mos alle genic,
and an inc ease in emission can ha e a nega i e impac on
he heal h o people sensi i e o his alle gen (Bono iglio e
al. 2013). In Pinus o es s, an opposi e pa e n was ound,
whe eby pollen concen a ion has inc eased despi e a educ-
ion– due mainly o wild i es– in he su ace a ea o his ype
o o es wi hin a 30 km adius o he pollen ap (in ac , he
pe iod 1990–2018 saw a educ ion in he a ea o pine o -
es o 15%, Fig. 1, CORINE Land Co e 2020). Hence, he
inc ease in he SPIn o Pinus pollen can be conside ed as a
The co ela ion be ween he leng h o he MPS and he
me eo ological a iables (Fig. 3b) once again shows ha
he e is a la ge di e ence be ween he esul s ob ained o
he baceous and woody plan s. In he case o woody axa,
ain all is he ac o which co ela es mos s ongly wi h
leng h o MPS, ollowed by empe a u e. He baceous axa,
on he o he hand, show a signi ican co ela ion wi h maxi-
mum and a e age empe a u es, and wi h ain all, depend-
ing on he axa.
Wi h espec o he co ela ion be ween he end o he
pollen season and he me eo ological a iables (Fig. 3c), he
esul s o Rumex and Plan ago a e pa icula ly no ewo -
hy. The end da e closely co ela es wi h empe a u e and
insola ion (and ain all in he case o Plan ago) a he end
o he pollen season. Wi h ega d o a bo eal axa, i seems
ha he e is no ma ked co ela ion wi h me eo ological a i-
ables, excep in he case o Cup essaceae, Olea and Pla a-
nus, whe e he end da e co ela es wi h he empe a u e o
he p e ious mon h.
Discussion
In his s udy, a comp ehensi e analysis o he main ai bo ne
pollen in Huel a was ca ied ou using ime se ies da a om
1993 o 2022. The ci y has some pa icula i ies in ha i
is su ounded by a la ge ma shland sys em and is loca ed
in an a ea o oceanic Medi e anean clima e wi h a s ong
in luence om he A lan ic Ocean. Da a analysis iden i ied
signi ican ends in bo h pollen concen a ion (especially
wi h espec o woody axa) and in he a ious pa ame e s
ha de ine he MPS (pa icula ly in he case o he baceous
axa). In addi ion, se e al o hese ends co ela ed wi h
me eo ological a iables ha a e unde going al e a ions due
o clima e change.
The huge phenological a iabili y o he axa in he
Huel a ai , alongside a compa able a iabili y in hei com-
posi ion, should also be highligh ed. Many o hese axa,
such as Poaceae, a e composed o many species, each wi h a
di e en phenology (De esa e al. 2020). This he e ogenei y
added an ex a laye o complexi y o he s udy and obliged
us o e lec mo e deeply on he esul s ob ained.
Fi s , o e he s udy pe iod he e is a signi ican inc ease
in he concen a ion o ai bo ne pollen de ec ed o Pla a-
nus, Populus, Olea, Casua ina and Pinus. The posi i e
ends in SPIn ound o ou o hese i e axa ha e al eady
been epo ed in o he egions, bo h in he Medi e anean
a ea and in highe la i udes: Olea (Damialis e al. 2007;
Galán e al. 2016; Ruiz-Valenzuela and Aguile a 2018),
Pla anus (Damialis e al. 2007; Alcáza e al. 2011; Galán
e al. 2016; Ruiz-Valenzuela and Aguile a 2018), Popu-
lus (Mak a e al. 2011) and Pinus (Damialis e al. 2007;
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