Global Ecology and Conse a ion 58 (2025) e03451
A ailable online 22 Janua y 2025
2351-9894/© 2025 The Au ho (s). Published by Else ie B.V. This is an open access a icle unde he CC BY license
(h p://c ea i ecommons.o g/licenses/by/4.0/).
Ra e bu e ly species i ally depend on soil dis u bance by an
ecosys em enginee in abandoned calca eous g asslands
Gwydion Sche e
a,1,*
, B igi e S eanga
b,2
, Thomas Fa mann
a,b,3
a
Depa men o Biodi e si y and Landscape Ecology, Uni e si y o Osnab ück, Ba ba as . 11, Osnab ück 49076, Ge many
b
Ins i u e o Biodi e si y and Landscape Ecology (IBL), An de Kleimannb ücke 98, Müns e 48157, Ge many
ARTICLE INFO
Keywo ds:
Biodi e si y conse a ion
EU Habi a s Di ec i e
Ma sh i illa y (Euphyd yas au inia)
Nicke l’s i illa y (Meli aea au elia)
Succession
Th ea ened insec
Wild boa (Sus sc o a)
ABSTRACT
Ecosys em enginee s like wild boa (Sus sc o a) can ese successional p ocesses in g asslands,
c ea ing open swa ds ich in ba e g ound and exhibi ing a wa m mic oclima e. Howe e , s udies
on he e ec s o soil dis u bance by wild boa (Sus sc o a) on bu e ly species in calca eous
g asslands a e missing. He e, we analysed he e ec s o wild boa oo ing in abandoned calca -
eous g asslands o he Hainich Na ional Pa k, Ge many, on wo a e bu e lies: ma sh i illa y
(Euphyd yas au inia) and Nicke l’s i illa y (Meli aea au elia). We sampled di e en en i on-
men al pa ame e s as well as bu e ly equency and abundance in wild boa oo ings and un-
dis u bed calca eous g assland ege a ion. Ou s udy demons a ed ha wild boa play a i al ole
as soil dis u bing ecosys em enginee s o he pe sis ence o he bu e ly species. They c ea ed
ea ly se al s ages ich in ba e g ound, hence a wa m mic oclima e, and hos plan s. The wo
i illa y species used almos exclusi ely (E. au inia) o e en solely (M. au elia) oo ing pa ches o
ep oduc ion. O e all, occu ence and abundance o he bu e ly species we e bes explained by
a (i) high hos plan abundance/biomass and (ii) wa m mic oclima e. Based on ou s udy, high
densi ies o wild boa and addi ionally wild he bi o ous ungula es, which slow down he
expansion o woody plan s by b owsing, should gene ally be p omo ed in he calca eous g ass-
lands o he na ional pa k. Howe e , o e all, hey canno hal sh ub enc oachmen and hus he
con inuous loss o calca eous g asslands. Acco dingly, we ecommend ac i e g assland manage-
men , e.g. exhaus i e sh ub emo al ollowed by la ge-scale g azing by ca le and ho ses wi h low
s ocking a es.
1. In oduc ion
Tempe a e, semi-na u al g asslands ank among he mos speciose ecosys ems on ou plane (Bona i e al., 2017; Feu dean e al.,
2018; Fa mann, 2024). They hold he wo ld eco d in small-scale plan species ichness and a e ho spo s o insec di e si y (Chy ý
e al., 2015; Fa mann, 2024). Fo example, h ee i hs o he 436 na i e Eu opean bu e ly species use calca eous g asslands as hei
main habi a (Van Swaay e al., 2006). Fo cen u ies, adi ional land managemen has c ea ed and p ese ed such g asslands wi h
* Co esponding au ho .
E-mail add ess: [email p o ec ed] (G. Sche e ).
1
ORCID 0000-0001-9246-5726
2
ORCID 0009-0000-4732-7818
3
ORCID 0000-0002-2050-9221
Con en s lis s a ailable a ScienceDi ec
Global Ecology and Conse a ion
jou nal homepage: www.else ie .com/loca e/gecco
h ps://doi.o g/10.1016/j.gecco.2025.e03451
Recei ed 28 Oc obe 2024; Recei ed in e ised o m 14 Janua y 2025; Accep ed 20 Janua y 2025
Global Ecology and Conse a ion 58 (2025) e03451
2
hei ou s anding biodi e si y (P¨
a el e al., 2005; Bona i e al., 2017; Feu dean e al., 2018; Fa mann, 2024). Howe e , wi h ongoing
indus ialisa ion o a ming p ac ise, especially a e Wo ld Wa II, he a ea o semi-na u al g asslands has se e ely declined. Two
opposi e, la ge-scale p ocesses ha e been esponsible o his de elopmen : (i) land use in ensi ica ion and (ii) abandonmen o
a o es a ion (Squi es e al., 2018; Fa mann, 2024). The o me includes he con e sion o nu ien -poo , semi-na u al g asslands o
imp o ed g asslands o a able ields and has mainly occu ed on p oduc i e soils (L¨
o le e al., 2023). By con as , abandonmen and
a o es a ion has ypically occu ed on ma ginal land (Fumy e al., 2021). Due o hei signi icance o biodi e si y conse a ion and
hei g ea ly h ea ened s a us, many o he semi-na u al g asslands, such as calca eous g asslands, a e legally p o ec ed by he EU
Habi a s Di ec i e (EC, 2013).
Ecosys em enginee s a e o ganisms ha al e hei en i onmen so s ongly ha undamen al ecosys em p ocesses a e changed
(Jones e al., 1994). In pa icula he e ec s o soil-dis u bing ecosys em enginee s, such as he Eu opean mole (Talpa eu opaea), wild
boa (Sus sc o a) o he yellow meadow an (Lasius la us), on biodi e si y ha e only ecen ly been s udied mo e in ensi ely in Cen al
Eu opean g asslands. These ecosys em enginee s ha e been shown o ese successional p ocesses in g asslands, leading o open swa ds
ich in ba e g ound (T eibe , 1997; Daube e al., 2006; S ei be ge e al., 2014, 2017; S ei be ge and Fa mann, 2016; Ho cicko ´
a
e al., 2019; Cabon e al., 2022). As a esul , less compe i i e plan species, o e all plan species ichness and animal species ha
equi e wa m ea ly-successional s ages a e a ou ed.
Pa icula ly, wild boa may ha e s ong e ec s on he composi ion o plan and animal communi ies in g asslands since he a eas
dis u bed by hem can be ela i ely la ge (Ho cicko ´
a e al., 2019; Fe e i e al., 2021; Labadessa and Ancillo o, 2023). Du ing
win e , when abo e-g ound die is e y limi ed o wild boa , hey sea ch o ood by digging he soil up o a dep h o 15 cm (Simon and
Goebel, 1999; Welande , 2000). Among animals, bu e ly, g asshoppe and ep ile species ha e been epo ed o bene i om wild
boa oo ing (de Schae zen e al., 2018; Cabon e al., 2022; Labadessa and Ancillo o, 2023). So a , howe e , s udies on he e ec s o
soil dis u bance by wild boa on bu e ly species in calca eous g asslands we e missing.
Calca eous g asslands a e among he main habi a s o he closely ela ed ma sh i illa y (Euphyd yas au inia) and Nicke l’s i illa y
(Meli aea au elia) in Cen al Eu ope (Eichel and Fa mann, 2008; B ¨
au e al., 2013, Sche e and Fa mann, 2024). Due o s ong
popula ion declines in he las cen u y, hey a e conside ed endange ed and nea h ea ened, espec i ely, in Ge many (Reinha d and
Bolz, 2011). Euphyd yas au inia is addi ionally p o ec ed by he EU Habi a s Di ec i e (EC, 2013). Fo bo h bu e ly species, succession
o calca eous g asslands is a majo h ea in he long un (Eichel and Fa mann, 2008; B ¨
au e al., 2013, Sche e and Fa mann, 2024).
The li e laye p e en s he ge mina ion o hos plan s; s ill p esen hos plan s become o e g own and shaded. In ou s udy a ea,
howe e , su p isingly, he calca eous g asslands in he sou he n pa o he Hainich Na ional Pa k (Cen al Ge many: wes e n
Thu ingia) s ill ha bou s ong popula ions o bo h bu e ly species, al hough hey ha e been abandoned o 30 yea s (own obse -
a ion). The popula ion o E. au inia is p obably e en he la ges in d y habi a s ac oss Ge many. Howe e , he s udy a ea does no only
hos la ge popula ions o he wo bu e ly species bu also o wild boa and he bi o ous ungula es (Klamm e al., 2020; Sche e e al.,
2024). The cu en popula ion densi y o wild boa is es ima ed o be up o 12 indi iduals pe 100 ha (Klamm e al., 2020). Among he
he bi o ous ungula es, pa icula ly ed dee (Ce us elaphus) a e known o b owse woody plan s in ensi ely and, hus, o slow down
he expansion o he woody plan s in he calca eous g asslands (Sche e e al., 2024).
He e, we analysed he e ec s o wild boa oo ing in abandoned calca eous g asslands o he Hainich Na ional Pa k on en i on-
men al condi ions and he wo a e bu e ly species E. au inia and M. au elia. We andomly selec ed 100 plo s o 4 m² size, 50 in wild
boa oo ings and 50 in undis u bed calca eous g assland ege a ion. Pe plo we sampled di e en en i onmen al pa ame e s
(mesoclima ic condi ions, ege a ion s uc u e, hos plan cha ac e is ics) as well as bu e ly equency and abundance. Mo eo e , we
assessed hose en i onmen al pa ame e s ha de e mine he occu ence and densi y o he bu e ly species. In pa icula , we hy-
po hesized ha oo ing by wild boa :
(i) c ea es wa m ea ly-successional s ages,
(ii) a ou s he es ablishmen o hos plan s and
(iii) inc eases he equency and abundance o bo h bu e ly species.
Based on he indings o ou s udy, we gi e ecommenda ions o u u e managemen o he calca eous g asslands.
2. Ma e ial and me hods
2.1. S udy species
Ma sh i illa y (Euphyd yas au inia) and Nicke l’s i illa y (Meli aea au elia) a e closely ela ed nymphalid bu e lies o he
Palaea c ic egion (B ¨
au e al., 2013; Sche e and Fa mann, 2024). The dis ibu ion ange o E. au inia ex ends om he B i ish Isles o
eas e n Asia. By con as , M. au elia is less widesp ead and occu s om Cen al Eu ope (eas e n F ance) up o Cen al Asia. Bo h species
a e uni ol ine and on he wings be ween May and July (B ¨
au e al., 2013). They colonize nu ien -poo g asslands, such as calca eous
g asslands, and equi e a ne wo k o sui able habi a pa ches since hey build me apopula ions (An hes e al., 2003a; Hula e al., 2004;
Eichel and Fa mann, 2008; Ghido i e al., 2018, Sche e and Fa mann, 2022, 2024). Locally hey exhibi a high hos -plan speci ici y
and p e e luxu ian hos plan s ich in biomass wi hin sho swa ds o o iposi ion. In calca eous g asslands, small scabious (Scabiosa
columba ia) is he main hos plan o E. au inia (B ¨
au e al., 2013). Howe e , he less common ield scabious (Knau ia a ensis) and
ulle ’s easel (Dipsacus ullonum) may also be used o o iposi ion (An hes and Nunne , 2006; own obse a ion). By con as , he hos
plan o M. au elia is he hoa y plan ain (Plan ago media) (Eichel and Fa mann, 2008; B ¨
au e al., 2013). In bo h i illa y species, he
G. Sche e e al.
Global Ecology and Conse a ion 58 (2025) e03451
3
emales a ach hei eggs as ba ches o 50–400 eggs on he unde side o he hos plan s’ lea es (An hes e al., 2003b; Eichel and
Fa mann, 2008; Sche e and Fa mann, 2022). The la ae eed g ega iously in a mo e o less dense web a ached o hei hos plan s
un il hey hibe na e wi hin he o h ins a in Sep embe . In sp ing, a e hibe na ion, la ae o E. au inia esume o aging g ega iously
and dispe se soli a ily when eaching he i h ins a . By con as , la ae o M. au elia al eady sepa a e sho ly be o e hibe na ion
(Sche e and Fa mann, 2024). Pupa ion occu s in bo h species in he cou se o May in li e o ege a ion.
2.2. S udy a ea
The s udy a ea is loca ed in he Hainich Na ional Pa k in wes e n Thu ingia (Cen al Ge many; 51◦03’ N, 10◦42’ E). The na ional
pa k has a size o abou 7.500 ha and an ele a ional ange o he 330–425 m a.s.l. The clima e is subcon inen al, wi h an a e age
annual empe a u e o 8.5 ◦C and an a e age annual p ecipi a ion o 600–800 mm (long- e m a e age 1989–2018; K onenbe g e al.,
2021). Due o shell limes one sedimen s, he soils a e alkaline (G oßmann, 2018). The s udy a ea has a size o 152 ha.
Mos o he na ional pa k is co e ed by deciduous o es s domina ed by beech. Howe e , he sou he n pa , including he s udy
a ea, s ill con ains la ge emnan s o calca eous g asslands, o igina ing om cen u ies o o me la ge-scale sheep g azing (G oßmann,
2018). O he o al 827 ha o calca eous g asslands, 517 ha a e si ua ed in he sou he n pa . Low-in ensi y land use has s ongly
declined ac oss he egion du ing he las cen u y, and la ge pa s o he p esen na ional pa k ha e been a o es ed. Howe e , he
calca eous g asslands in he sou h o he na ional pa k ha e pe sis ed due o mili a y managemen and aining ac i i ies. Since 1930,
he Weh mach and la e on he So ie A my kep he a ea open h ough la ge-scale sheep g azing, clea -cu ing and mili a y ac i i ies
un il he ea ly 1990s. Since he es ablishmen o he na ional pa k in 1997, an h opogenic in luence has ceased. Today, a e nea ly 30
yea s o abandonmen , he g asslands a e cha ac e ised by sh ub enc oachmen . Ne e heless, some o he g assland pa ches, espe-
cially on sou h- acing slopes, ha e su p isingly emained la gely open. The easons o he slow succession a e he shallow d y soils and
he s ong e ec s o b owsing wild ungula es (Sche e e al., 2024). Fallow dee (Dama dama), ed dee (Ce us elaphus) and oe dee
Fig. 1. The s udy a ea wi hin he s ic ly p o ec ed zone (co e zone) o he Hainich Na ional Pa k in wes e n Thu ingia (Cen al Ge many; inlay).
Displayed a e he loca ions o he ou suba eas wi h he h ee di e en ypes o plo s.
G. Sche e e al.
Global Ecology and Conse a ion 58 (2025) e03451
4
(Cap eolus cap eolus) exhibi high abundances in he s udy a ea. Pa icula ly, ed dee a e known o b owse woody plan s in ensi ely
and, hus, supp ess he expansion o he mos equen wood plan s in he calca eous g asslands: black ho n (P unus spinosa) and
haw ho n (C a aegus spp.). O e all, he calca eous g asslands s ill hos s ong popula ions o E. au inia and M. au elia (own obse -
a ion). Those o E. au inia a e p obably e en he la ges in d y habi a s wi hin Ge many.
2.3. Sampling design
2.3.1. Plo selec ion
The s udy a ea consis ed o ou pa ches o calca eous g asslands (17–63 ha) sepa a ed by a leas 50 m o woodland. These ou
pa ches (he eina e e e ed o as suba eas) con ained he s onges popula ions o E. au inia in he na ional pa k and we e in ensi ely
oo ed by wild boa o an equal deg ee (own obse a ion). All plo s we e equally di ided ac oss he ou suba eas, excluding a eas
domina ed by sh ubs o ees (Fig. 1). Because oo ing beha iou is no comple ely andom, some a eas migh be oo ed mo e o en, e.
g. loca ions close o hideou s like la ge sh ub enc oachmen s, a eas wi h high concen a ions o speci ic ood sou ces o al eady oo ed
a eas (Ho cicko ´
a e al., 2019). To educe bias by o e sampling a eas wi h a high concen a ion o oo ings and because we did no
ind la ge un oo ed a eas, we decided o conduc a andomized sampling app oach. We andomly selec ed 100 plo s o 4 m²
(2 m ×2 m) size, 50 in wild boa oo ings (he eina e e e ed o as oo ing plo s) and 50 in undis u bed calca eous g assland
ege a ion (he eina e e e ed o as con ol plo s) (Fig. 1). Al hough oo ings we e o en la ge , we chose hese measu es o s an-
da dize he i egula shape o he oo ings. Loca ions o hese plo s we e chosen using a digi al as e laye wi h nume a ed
20 m ×20 m g id cells ac oss he ou suba eas, c ea ed in A cGIS P o 3. We andomly selec ed 50 g id cells pe plo ype wi h a
minimum numbe o a leas 12 plo s pe ype in each suba ea. Random selec ion was epea ed i he selec ed g id cell only con ained
sh ubs o ees. Con ol plo s we e es ablished a he cen e o he selec ed g id cells. To selec oo ing plo s, he nea es wild boa
oo ing o a leas 4 m² size o he cen e o he selec ed g id cell was chosen. Mo eo e , i was always loca ed in he cen e o he
espec i e oo ing.
To assess wild boa oo ing in ensi y, we addi ionally es ablished ou andomly selec ed 100 m ×100 m (1 ha) plo s (he eina e
e e ed o as oo ing in ensi y plo s), one in each suba ea. To selec plo s, we used he same me hod as desc ibed abo e wi h
nume a ed 100 m ×100 m g id cells. Each plo had o con ain a leas one oo ing and one con ol plo , o he wise andom selec ion
was epea ed.
2.3.2. Sampling o bu e lies and en i onmen al condi ions
All sampling was done in 2022. Du ing July and Augus , all oo ing and con ol plo s we e sys ema ically sea ched o egg ba ches
o la al webs (he eina e we only e e o la al webs o easons o simplici y) o E. au inia and M. au elia and hei numbe s we e
coun ed. Mo eo e , pe plo , we eco ded he used hos plan and he numbe o webs.
A e bu e ly sampling, we eco ded se e al en i onmen al pa ame e s o all oo ing and con ol plo s. Fo oo ing and con ol
plo s, we measu ed daily sunshine du a ion wi h he help o a ho izon oscope (Sche e e al., 2021) as well as aspec and slope using a
compass wi h an inclinome e . The wo la e pa ame e s we e used o calcula e he hea load index (McCune and Keon, 2002). We
es ima ed he co e o ba e g ound, mosses, li e , g asses, he bs and sh ubs wi hin each plo . The heigh s o he he baceous and sh ub
laye we e measu ed using a olding ule a h ee andomly chosen poin s wi hin he plo and a e aged o u he analysis. We coun ed
he numbe and es ima ed he co e o a ailable hos plan s (D. ullonum, K. a ensis P. media and S. columba ia) sepa a ely o each
species. Addi ionally, o he wo main hos plan s, S. columba ia and P. media, we coun ed he numbe o lea es and measu ed he
diame e o he ose e o h ee andomly chosen plan s pe plo as a p oxy o hei biomass. Fo u he analysis, he alues o he
numbe o lea es and diame e o he h ee plan s we e a e aged.
Pe oo ing in ensi y plo , we mapped all oo ings on he basis o high esolu ion ae ial pho og aphs (1: 300) in he ield. La e we
digi ized hem using A cGIS P o 3 and calcula ed hei numbe and size.
2.4. S a is ical analysis
All s a is ical analyses we e pe o med using R 4.3.2 (R De elopmen Co e Team, 2023). To assess signi ican di e ences in
en i onmen al condi ions as well as in la al web equency and abundance be ween oo ing and con ol plo s, we used pai wise
compa isons conduc ed by gene alized linea mixed-e ec models (GLMMs). Fo di e en da a ypes we used he ollowing e o
s uc u es: coun da a – Poisson; in e al scaled da a – gamma; pe cen age da a – binomial. To accoun o possible spa ial au oco -
ela ion, we used suba ea as a andom ac o .
To assess he en i onmen al pa ame e s ha de e mine la al web equency and abundance, we i ed mul i a iable GLMMs wi h
binomial ( equency) and Poisson (abundance) e o s uc u e, espec i ely. Since E. au inia occu ed in bo h oo ing and con ol plo s,
we calcula ed models o e all 100 plo s (= ull models) and solely o he 50 oo ing plo s (= oo ing models). By con as , M. au elia
was only p esen in oo ing plo s. Acco dingly, we only pe o med oo ing models o his species. Be o e he analyses, we conduc ed
se e al es s o inc ease model obus ness and ans o med o excluded some a iables. To educe model o e i ing, we checked all
p edic o s o in e co ela ions using Spea man’s ank co ela ion (
S
). The numbe o hos plan s (abundance) was always s ongly
in e co ela ed wi h he co e o hos plan s (
S
>0.9, P<0.005). Since he abundance was p ecisely coun ed while co e was
es ima ed, we excluded he la e . To accoun o hos plan biomass, we me ged hos plan diame e and lea coun in o a new a iable
called “biomass” ia p incipal componen analysis (PCA). In e co ela ions be ween bo h a iables we e high in bo h plan species
(S. columba ia:
S
=0.8, P<0.005 P. media:
S
=0.9, P<0.005). To u he p e en mul icollinea i y, we calcula ed he a iance
G. Sche e e al.
Global Ecology and Conse a ion 58 (2025) e03451
5
in la ion ac o (VIFs) o all selec ed a iables. Fo all emaining a iables, he VIF was below 10; acco dingly, no a iables we e
emo ed. To u he inc ease model obus ness, we limi ed he numbe o in oduced a iables pe model by n/10 and added suba ea
as a andom ac o . All p edic o a iables we e scaled p io o he calcula ions o ensu e he compa abili y o he model coe icien s.
When conduc ing he GLMMs, we used model a e aging based on an in o ma ion- heo e ic app oach using he ‘d edge’ unc ion (R
package MuMIn; Ba on, 2023) o iden i y he mos impo an p edic o s (Bu nham and Ande son, 2004; G uebe e al., 2011). To
allow all emaining a iables wi hin model selec ion, we in oduced he co ela ion ma ix in o he models. I a iables we e in e -
co ela ed (|
S
| >0.6), only one o he in e co ela ed p edic o s was allowed wi hin each model. Fo he binomial oo ing model o
E. au inia, comple e sepa a ion impeded he models due he in e ac ion o some a iables pe ec ly p edic ing he ou come. We sol ed
he p oblem by conduc ing wo sepa a e models, one con aining all hos plan pa ame e s (=hos plan model) and he o he one
con aining he o he en i onmen al pa ame e s (=mesoclima e/ ege a ion s uc u e model) (Table A1). A e wa ds, we pe o med a
syn hesis model con aining only he signi ican pa ame e s o he wo p io models. O e all, he numbe o p edic o a iables used in
he models a ied be ween 12 and 14 (Table A2). The esul ing a e aged models only included he op- anked models wi h ΔAICC <3
(G uebe e al., 2011). Finally, he explana o y powe o he models (depic ed as a span o a e aged models) was assessed by
calcula ing ma ginal ( a iance explained by ixed e ec s; R²
m
) and condi ional R² ( a iance explained by bo h ixed and andom
e ec s; R²c) (Nakagawa e al., 2017).
To isualize en i onmen al di e ences be ween oo ing and con ol plo s, we applied non-me ic mul idimensional scaling (NMDS;
R package egan; Oksanen e al., 2022). We i ed he da a acco ding o hei en i onmen al pa ame e s using he B ay-Cu is dis ance
as a dis ance measu e and a maximum numbe o 100 andom s a s.
3. Resul s
3.1. En i onmen al condi ions
The oo ing in ensi y plo s o 1 ha size con ained 24–45 oo ings, which co e ed 14–18 % o he o al plo a ea. The mean size
(±SE) o he oo ings was 51 ±5 m² ( ange: 2–450 m²).
Table 1.
Mesoclima ic condi ions, ege a ion s uc u e and hos plan pa ame e s in oo ing (n=50) and con ol plo s (n=50). Pai wise compa isons we e
conduc ed by GLMMs using suba ea as a andom ac o . Fo di e en da a ypes we used he ollowing e o s uc u es: coun da a – Poisson, in e al
scaled da a – gamma, pe cen age da a – binomial. Pl. =plan s. *P<0.05, **P<0.01, ***P<0.001; n.s., no signi ican .
Pa ame e Roo ing Con ol P
Mean ±SE Range Mean ±SE Range
Mesoclima e     
Sunshine du a ion (h) 13.8 ±0.2 10–15 14.0 ±0.3 8–15 n.s.
Hea load index 0.87 ±0.01 0.71–0.93 0.85 ±0.01 0.68–0.91 *
Vege a ion s uc u e     
Co e (%)     
Ba e g ound 41.7 ±3.3 5–90 1.9 ±0.4 0–10 ***
Mosses 0.5 ±0.3 0–10 51.8 ±5.1 0–100 ***
Li e 21.4 ±1.9 5–75 71.3 ±2.1 30–100 ***
G asses 38.5 ±2.9 5–80 78.0 ±2.5 15–100 ***
He bs 43.5 ±2.3 15–80 36.4 ±2.3 10–75 *
Sh ubs 15.7 ±2.5 0–70 18.5 ±3.4 0–80 n.s.
Heigh (cm)     
He baceous laye 43.1 ±1.7 15–66 51.2 ±2.5 13–110 **
Sh ub laye 120.8 ±21.1 50–400 99.1 ±14.5 50–337 n.s.
Hos plan s     
Dipsacus ullonum     
F equency (%) 22 ±6.0 0/100 2 ±2.0 0/100 **
Co e (%) 1.2 ±0.5 0–20 0.2 ±0.1 0–1 **
K. a ensis     
F equency (%) 56 ±7.0 0/100 32 ±7.0 0/100 *
Co e (%) 7.8 ±1.7 0–50 1.7 ±0.5 0–10 ***
Plan ago media     
F equency (%) 86 ±5.0 0/100 12 ±4.6 0/100 ***
Abundance (pl./4 m²) 11.1 ±1.5 0–53 0.3 ±0.2 0–7 ***
Co e (%) 8.5 ±1.3 1–40 0.2 ±0.1 1–2.5 **
Diame e (cm) 14.6 ±0.4 9.6–19.3 12.8 ±1.2 9.5–16.5 n.s.
No. lea es 8.6 ±0.4 4–15.5 5.1 ±0.6 3.3–7 ***
Scabiosa columba ia     
F equency (%) 82 ±5.5 0/100 54 ±7.1 0/100 *
Abundance (pl./4 m²) 10.6 ±1.7 0–45 6.3 ±1.2 0–32 **
Co e (%) 9.9 ±1.4 1–40 3.8 ±0.9 1–25 **
Diame e (cm) 13.7 ±0.7 8–27.3 11.2 ±0.8 2.8–28.0 *
No. lea es 9.5 ±0.7 4–24.3 6.1 ±0.5 3.3–14 ***
G. Sche e e al.

Global Ecology and Conse a ion 58 (2025) e03451
6
O e all, oo ing and con ol plo s s ongly di e ed in en i onmen al condi ions (Table 1). Al hough bo h plo ypes exhibi ed a
simila sunshine du a ion, oo ing plo s had a highe hea load. Ve y s iking was he di e ence in ege a ion s uc u e and hos plan
pa ame e s. Roo ing plo s we e cha ac e ised by ea lie successional s ages compa ed o con ol plo s. They had sho e swa ds and a
highe co e o ba e g ound and he bs, bu a lowe co e o g asses, li e and mosses. All ou hos plan species we e mo e equen
and had a highe co e in oo ing han in con ol plo s. Mo eo e , in he hos plan s P. media and S. columba ia, abundance was highe
and plan s had mo e lea es. Addi ionally, plan s o S. columba ia had la ge ose es in oo ing plo s han in con ol plo s. By con as ,
sh ub co e and heigh as well as diame e o he P. media ose es did no di e be ween he wo plo ypes. The la ge di e ences in
en i onmen al condi ions a e also depic ed by he NMDS, which showed a clea sepa a ion o bo h plo ypes on he i s axis (Fig. 2).
3.2. Response o bu e ly species o wild boa oo ing
O e all, we de ec ed 68 la al webs o E. au inia and 44 o M. au elia in he 100 plo s. Mo e han ou i hs (81 %) o he E. au inia
webs we e ound on S. columba ia. The emaining webs we e loca ed on D. ullonum (10 %) and K. a ensis (9 %). All webs o M. au elia
we e obse ed on P. media. Bo h bu e ly species posi i ely esponded o he oo ing ac i i y o he wild boa . They had a much highe
equency and abundance in oo ing han in con ol plo s (Fig. 3). Euphyd yas au inia was p esen on 52 % o he oo ing plo s, bu
occu ed only on 8 % o he con ol plo s. On a e age (±SE), 1.3 ±0.2 la al webs we e ound pe oo ing plo o 4 m² size, which was
a 13 imes highe abundance han on con ol plo s (0.1 ±0.1). By con as , M. au elia e en occu ed only in oo ing plo s. The e i had
a equency o 42 % and a mean (±SE) abundance o 0.9 ±0.2 webs/4 m².
The abundance and biomass, espec i ely, o S. columba ia and P. media, he wo main hos plan species, we e he mos impo an
d i e o bu e ly equency and abundance (Fig. 4, Tables A3 and A4). F equency and abundance o E. au inia inc eased wi h he
abundance o S. columba ia ac oss all and oo ing plo s; hose o M. au elia inc eased wi h he biomass o P. media in he oo ing plo s.
Mo eo e , he abundance o he wo u he hos plan species, D. ullonum and Knau ia a ensis, os e ed he equency o E. au inia
ac oss all plo s. In E. au inia, ege a ion s uc u e addi ionally a ec ed he equency and abundance. Ac oss all plo s, co e o mosses
and ege a ion heigh (only abundance model) had nega i e e ec s. Mo eo e , co e o sh ubs os e ed E. au inia abundance in all and
oo ing plo s. O e all, he explana o y powe o all models was high (R²
m
=0.49–0.80, R²
c
=0.49–0.84).
4. Discussion
Long- e m abandonmen o semi-na u al g asslands is known o esul in li e accumula ion and enc oachmen o some
compe i i e g ass and moss species, which o e all esul s in species-poo plan and insec communi ies (Ellenbe g and Leuschne ,
2010; S ei be ge e al., 2017; Schüle e al., 2023; Fa mann, 2024). Howe e , successional speed a ies depending on he p oduc-
i i y o he soils. Al hough all ou s udied suba eas we e cha ac e ised by a low successional speed due o shallow soils and mos ly
sou h- acing slopes, which cause high hea load, he nega i e e ec s o abandonmen we e clea ly isible in he con ol plo s. They had
a high co e o li e , mosses and g asses, bu a e y low co e o he hos plan s o he wo bu e ly species (mean co e : always <
4 %).
Popula ion es ima es o wild boa using non-in asi e gene ic me hods in 2018 indica e a popula ion o app oxima ely 12 in-
di iduals pe 100 ha. (Klamm e al., 2020). Al hough wild boa densi y can be subjec o signi ican annual luc ua ions, a simila
popula ion densi y is assumed a he ime o hese s udies. As a esul , a p opo ion o 14–18 % o oo ed a eas wi hin he calca eous
g asslands was eco ded in ou s udy. Wild boa a e conside ed ecosys em enginee s ha can al e ecosys em p ocesses h ough
changing hei physical en i onmen (Jones e al., 1994; Simon and Goebel, 1999). By digging he soil while sea ching o ood, hey
can ese successional p ocesses leading o open swa ds ich in ba e g ound (T eibe , 1997; Sandom e al., 2013; Sims e al., 2014;
Fig. 2. NMDS o con ol (n=50) and oo ing plo s (n=50) based on en i onmen al pa ame e s.
G. Sche e e al.
Global Ecology and Conse a ion 58 (2025) e03451
7
Bu ascano e al., 2015; Ho cicko ´
a e al., 2019). As a esul , compe i i e plan species become supp essed and he es ablishmen o
less-compe i i e ones (e.g. pionee o annual species) and o e all plan species ichness a e a ou ed. In line wi h his, he oo ing plo s
we e cha ac e ised by sho , open swa ds ich in ba e g ound and a high co e o he bs. Mo eo e , he oo ing ac i i y o he wild boa
had s ongly a ou ed he es ablishmen and i ali y o all ou hos plan species. They had a much highe equency and co e in
oo ing han in con ol plo s. Abundance, ose e diame e and numbe o lea es, which we e only sampled in S. columba ia and
P. media, we e also highe (excep ose e diame e in P. media).
Fo bo h bu e ly species, he mos impo an pa ame e s de ining habi a quali y a e hos plan abundance and biomass (Eichel
and Fa mann, 2008; Bo ham e al., 2011; B unbje g e al., 2017). To a oid ood sho age among he g ega iously eeding ca e pilla s,
he adul emales p e e luxu ian hos plan s in mic ohabi a s o high hos plan abundance o o iposi ion (An hes e al., 2003a;
Eichel and Fa mann, 2008; Sche e and Fa mann, 2022). Ou s udy con i med he p ime impo ance o su icien ood o he ca -
e pilla s o bo h i illa y species. In E. au inia, he abundance o S. columba ia was he key d i e o occu ence and abundance (all and
oo ing plo s). In M. au elia, he same was ue o he biomass o P. media ( oo ing plo s). Rega ding all plo s, in e es ingly, he
equency o E. au inia was also a ou ed by he abundance o wo u he hos plan species, D. ullonum and K. a ensis. Bo h plan
species we e less widesp ead and mo e a ely used as a hos plan by E. au inia in he s udy a ea. A mos 10 % o he webs we e ound
on each o he wo hos plan species. These indings e eal a leas a ce ain deg ee o lexibili y in hos plan selec ion o E. au inia in
ou s udy a ea. Simila obse a ions ha e been made in o he pa s o i s dis ibu ion ange (An hes e al., 2003b; An hes and Nunne ,
2006; Sche e and Fa mann, 2022).
Bu e ly, g asshoppe and ep ile species ha e been epo ed o bene i om he wa m mic oclima ic condi ions c ea ed by wild
boa oo ing (de Schae zen e al., 2018; Cabon e al., 2022; Labadessa and Ancillo o, 2023). The bu e ly species s udied he e,
E. au inia and M. au elia, a e also known o equi e wa m mic ohabi a s o success ul de elopmen o he imma u e s ages (Eichel and
Fa mann, 2008; Pielech e al., 2017; Sche e and Fa mann, 2022). Fo ep oduc ion, hey mainly (E. au inia) o e en only (M. au elia)
used he oo ing plo s. They we e p esen in 52 % and 42 %, espec i ely, o he plo s. O e all, oo ing plo s we e cha ac e ised by a
high sunshine du a ion and hea load as well as a e y high co e o ba e g ound (mean: 42 %). Acco dingly, hey p o ided e y wa m
mic oclima ic condi ions du ing sunny days (S ou jesdijk, Ba kmann, 2014), which explains, besides he high abundance/biomass o
hos plan s, why hey we e so ele an o he wo bu e ly species. The de ec ed ege a ion s uc u e p e e ences also unde pin he
s ong dependence on ea lie successional s ages p o iding a wa m mic oclima e. The co e o mosses had a nega i e e ec on he
equency and abundance o E. au inia ac oss all plo s. Mo eo e , sho e swa ds (all plo s) and a highe co e o sh ubs (all and oo ing
plo s) a ou ed he abundance o E. au inia. In calca eous g asslands, a highe co e o mosses is ypical o alle and dense swa ds
exhibi ing a mois e and coole mic oclima e (Ellenbe g and Leuschne , 2010; S ou jesdijk, Ba kmann, 2014; S ei be ge e al., 2017).
In he s udied plo s, usually sh ubs had a low co e (mean: <19 %) and we e small (heigh <1 m) (own obse a ion). Ne e heless,
hey may a ou hea accumula ion on hei sou he n sides in he o he wise open swa ds (c . S ou jesdijk, Ba kmann, 2014) and could
also play an impo an ole in male ma e-loca ing beha iou s (Kon icka e al., 2023). By con as , wi hin he oo ing plo s, he co e o
li e had posi i e e ec s on he occu ence o E. au inia. Acco dingly, he ea lies successional s ages in he oo ing plo s seemed o be
a oided. He e, a leas some li e may p e en he soil om excessi e d ying up and hea accumula ion, and, hence, om hea s ess
o hos plan s and la ae du ing e y ho summe days (c . B ¨
au e al., 2013; Shi e al., 2022).
In conclusion, in calca eous g asslands cha ac e ized by long- e m abandoned, wild boa as soil dis u bing ecosys em enginee s
ese succession. They c ea ed ea ly se al s ages ich in ba e g ound, hence a wa m mic oclima e, sho e swa ds and he bs, bu wi h a
lowe co e o g asses, li e and mosses. The wo i illa y species used almos exclusi ely (E. au inia) o e en solely (M. au elia) wild
boa oo ings o ep oduc ion. O e all, occu ence and abundance o he bu e ly species we e bes explained by a (i) high hos plan
abundance/biomass and (ii) wa m mic oclima e. Consequen ly, ou s udy demons a ed ha wild boa play a i al ole as soil dis-
u bing ecosys em enginee s o he pe sis ence o wo a e bu e ly species in abandoned calca eous g asslands. Howe e , as depic ed
Fig. 3. F equency (a) and abundance (b) o la al webs o E. au inia and M. au elia in con ol (n=50) and oo ing plo s (n=50). Pai wise
compa isons we e conduc ed by GLMMs using suba ea as a andom ac o . Fo pe cen age da a ( equency) a binomial and o coun da a
(abundance) a Poisson e o s uc u e was used. ***P<0.001.
G. Sche e e al.
Global Ecology and Conse a ion 58 (2025) e03451
8
by Sch ¨
oe e al. (2024), sh ub enc oachmen inc eased d as ically du ing he las h ee decades. Thus, we appeal o u gen ac ion o
p omo e he legally p o ec ed calca eous g asslands and he eby he wo a e bu e ly species. Because ou s udy only co e s one yea ,
we p opose a long- e m moni o ing o all species included in his s udy. Moni o ing should include mic ohabi a assessmen s o
E. au inia and M. au elia as well as popula ion moni o ing o wild boa and hei oo ing beha iou . This is impo an o de i e pa e ns
and o moni o possible ipping poin s o he popula ions o he wo bu e lies in he cons an ly de e io a ing calca eous g asslands.
5. Implica ions o conse a ion
A e 30 yea s o abandonmen , he in ensi e oo ing ac i i y o he wild boa has been iden i ied as he key o he s ill s ong
popula ions o E. au inia and M. au elia in he calca eous g asslands o he Hainich Na ional Pa k. He bi o ous wild ungula es also
occu in high abundance in he s udy a ea. Among hem in pa icula ed dee supp ess he expansion o woody plan s by b owsing
and, hus, slows down succession (e.g. Tsch¨
ope e al., 2011; de Schae zen e al., 2018; P´
apay e al., 2020). Acco dingly, o p omo e
na u al dynamics and o keep an h opogenic in luence small in he na ional pa k, high densi ies o wild ungula es in he calca eous
g asslands should gene ally be p omo ed. Howe e , o e all, hey canno hal sh ub enc oachmen and hus he con inuous loss o
calca eous g asslands (P´
apay e al., 2020; Sch ¨
oe e al., 2024). Acco dingly, ac i e g assland managemen is also equi ed. The e o e,
Fig. 4. Es ima es (±95 % CI) o en i onmen al p edic o s o he equency (p esence/absence) and abundance o E. au inia and M. au elia in all plo s
( ull model: oo ing [n=50] and con ol plo s [n=50]) and oo ing plo s ( oo ing model, n=50), espec i ely. Con idence in e als o signi ican
p edic o s (P<0.05) do no c oss x =0. Fo u he de ails see Tables A3 and A4.
G. Sche e e al.
Global Ecology and Conse a ion 58 (2025) e03451
9
we ecommend ini ial exhaus i e sh ub emo al (Ponia owski e al., 2020). Howe e , some sca e ed sh ubs o small g oups o hem
should be p ese ed, since hey ac as impo an habi a s uc u es o many h ea ened species o g assland bi ds (Fa mann e al.,
2022), o which a e s ill some p esen in he s udy a ea (Handschuh and Klamm, 2022). Opposed o M. au elia, E. au inia is less ole an
o mowing and sheep g azing in calca eous g asslands (Ul ich, 2004; An hes and Nunne , 2006). Fo ha eason, we ad ise yea - ound,
la ge-scale g azing by ca le and ho ses wi h e y low s ocking a es o secu e he pe sis ence o p obably he la ges popula ion o
E. au inia in d y habi a s in Ge many in he long un.
E hics s a emen
No applicable: This manusc ip does no include human o animal esea ch.
Funding in o ma ion
This s udy was unded by he Hainich Na ional Pa k.
Decla a ion o Compe ing In e es
The au ho s decla e ha hey ha e no known compe ing inancial in e es s o pe sonal ela ionships ha could ha e appea ed o
in luence he wo k epo ed in his pape .
Acknowledgemen s
We a e g a e ul o Man ed G oßmann, o me head o he Hainich Na ional Pa k, o insigh s in o he his o y o he na ional pa k.
We a e pa icula ly hank ul o Alisa Klamm, Madlen Schellenbe g and And eas Henkel, Depa men o Na u e Conse a ion and
Resea ch, o hei help in coo dina ing he s udy and aluable commen s on a p e ious e sion o he manusc ip . Gwydion Sche e
was suppo ed by a PhD schola ship o he S udiens i ung des Deu schen Volkes. A las , we app ecia e he cons uc i e eedback
p o ided by wo anonymous e iewe s.
Appendix
Table A1
S a is ics o he binomial GLMMs (model a e aging): mesoclima e/ ege a ion s uc u e (a) and hos plan p edic o s (b) o he equency (p esence/
absence) o E. au inia in oo ing plo s (n=50). Ma ginal R² =R²
m
, condi ional R²=R²
c
. Mesoclima e/ ege a ion s uc u e model: R²
m
=R²
c
=0.57–0.71. Hos plan model: R²
m
=0.80–0.83, R²
c
=0.85–0.87. *P<0.05; n.s., no signi ican
Pa ame e Es ima e SE Z p
(a) Mesoclima e/ ege a ion s uc u e model  
In e cep –3.19 5.03 0.63 n.s.
Co e o li e 0.10 0.04 2.33 *
(b) Hos plan model  
In e cep –3.95 1.64 2.35 *
Abundance o S. columba ia 0.35 0.14 2.41 *
Table A2
P edic o a iables used in he binomial and Poisson GLMMs (model a e aging). The a iance in la ion ac o (VIF) o all included a iables was <10.
Fo u he in o ma ion see Sec ion 2.4
Pa ame e Binomial models Poisson models
E. au inia M. au elia E. au inia M. au elia
FM RM RM FM RM RM
Mesoclima e        
Sunshine du a ion x x x x x x
Hea load index x x x x x x
Vege a ion s uc u e        
Co e        
Ba e g ound x x x x x x
Mosses x x x x x x
Li e x x x x x x
G asses x x x x x x
(con inued on nex page)
G. Sche e e al.