View metadata,citationandsimilarpapersatcore.ac.uk This article isThis article by protected copyright. All rightsreserved. 10.1111/1365 to lead may which d process, proofreading and pagination typesetting, copyediting, the been not through has but review peer full undergone and publication for accepted been has article This 4 3 2 and Technology,Norway 1 Hansen LeMathilde Moullec past Annual r Editor :TommasoJucker type Article :Research Article MATHILDE: MISS ID (Orcid 0000 MOULLEC LE

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ing g - 2745.13036 rowth ofa 1* , Agata Buchwal

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widespread 2,3 , Ren rsity ofrsity Alaska USA Anchorage, ,

- é Adam Poland University, Mickiewicz level plantbiomass

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brought toyouby CORE This article isThis article by protected copyright. All rightsreserved. fluctuationsto track inpast plantproduction vascular of high suggestthat ringresults growth measurements dominating performedshrub this can on beused becomingsignal clearwhen particularly accounting forplant, site andhabitat hete ground biomass, temperature wasthemain summer driverof growth, with this ring ecological S 3. of above usinglinearmixedseries polaris 2. shrub (78Svalbard groundunique reflects primaryactually production above allocation trade most rapidly warming biome. Yet,high toolsDendrochronological are increasingly used instead,particularlyintheArctic understanding 1. Longtime Summary *

. Corresponding author: [email protected]

Acceptedpolaris Annual ring Using Article Salix polaris

shrubs five across ineach sites oftwo habitats - a balanced designa balanced ground

(r (r and = 0.56) vascular plantcommunitythe as =0.70).a whole(r Asforabove

 - series ofprimaryseries are rarely production available, restricting our N), - of andecosystem vegetation dynamics climate change. under growth waspositively correlated with above based monitoringbased time - offs, andwhether

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to established established - growth of ground biomass of both production local weather local records and 13years - arctic tundra. arctic

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This article isThis article by protected copyright. All rightsreserved. Fauria greening’a phenomenon knownas‘arctic 2014) fastertemperatures rising are anywherethan else on andfoodproductivity islow websareoften bottom ecosystemthe formPrimary foundation producers the of Eltonianpyramid, the fuelling higher tr Introduction production.vegetation willow;polar permanentKeywords: dendrochronology; whereplaces annual new opportunitiesfor community irregularly growing community for the above application to such understanding 4.

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2012) Dendrochronological tools are toolsDendrochronological are increasingly used on

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in themost world’s warming rapidly biome

of both plots; plots; p (Elmendorf

showed that showed that ring growth indeed confirm the focalshrubthe lant populationlant andcommunity dynamics - up controlled up controlled E arth

et al. et that . Intheterrestrialwhere Arctic, primary .

(Larsen

shrub shrub

2012; Epstein

reflects betweenreflects

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rc et al.et tic shrubs toenhance our

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2014; Nordli

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a robust proxy a robust proxy ophic levelsof . y Fundamental

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This article isThis article by protected copyright. All rightsreserved. shrubstundra developments which al. carbongrowth relationships, arealsotools increasinglyonarctic shrubs used for purposes understanding suchas cli years, toimprovefive toten readings to al. et estimating standdevelopment rates sequestration orcarbon usedendrochronologyregularly assess netprimary to for the purpose production the through measurement ofring product knowledge this gapretrospectively, if provento aproxyrepresent forabove growth,measures secondary such of as tree remotethe Field ecosystem changerequireslong climate change impacts inthisrealm. However 2016) primary in productivity some areas 2009) as well

Accepted Article 2014; Myers

- 2014; Dye , which stresses further the importance of amechanistic andpredictive understanding of . based monitoring time Recent observations and field remoteindicateacontrasting also tre sensing The field of dendrochronology consists of reconstructing woody plant growth,The fieldwoodyplant ofdendrochronology consistsofreconstructing typically ivity. on carbon andnutrient cycling A in situ rctic biome rctic

(Wilmking -

et al. et Smith

measures ofwoody plots, biomass inpermanent forest overcome associated difficulties the

2016; &Frank Klesse, Etzold 2016)

et al. (Ims

et al. et

- precision 2015a) cycle series arestillextremelyseries for primary rare

& Fuglei 2005; Wal& Fuglei Vander 2014) &Stien

2012; Myers - term, high - widths trees andshrubs.Forestry growth, both in studies

, dynamics, processes evengeomorphological or . followedThese applications recent methodological known as the “browning of known asthe“browning Arctic” the of pri (Stenseth - - quality across andcontinuousdata trophic levels. - mary productivity ring ring havegrowth chronologies, potential the fill to Smith , identifyi

et al. et

et al. et

2002; Post

ng mechanisms vegetation and behind

2015b)

with high . Suchstudies compare tree (Metsaranta & Lieffers 2009; Babst measures . Duringthelast fewdecades,

et al. et irregularity ofringgrowth in

producers, particularly in 2009; Wookey . Dendrochronological often . Accordingly, (Phoenix (Phoenix & Bjerke - ground plant

sampled every sampled every

of e.g. nd (Owczarek

of declining

- mate et al. et ring ring annual annual -

ring ring

et

This article isThis article by protected copyright. All rightsreserved. Ropars isju growing season herbivores trade individual,aswellbetween asacross landscape,the substantial heterogeneity (and ringgrowth ingrowth associated irregularities) withinand situ growthactuallyreflectsabovering complement restrictions of sensing remote precise information, theat indivi available Walker 2016 no effective may of validity the limit ( sufficiently cloud production Weijers al. Normalized Difference Index Vegetation shrub (NDVI) to Vickers measures annualoverall vegetation of product developmentthe sensing has ofremote products alternative beenan route throughwhich Karlsen

Accepted Article 2010

biomassmonitoring is rare. - offs inresourceallocation between e.g.stem production, growth,leaf

A key challenge for ecological forA keychallenge ecological inferencefrom shrub the dendrochronology is arctic et al.et

; et al. et al.

et et al. Forbes, Macia

or reproductive structures, especially in high harsh maps with sufficiently high mapswith sufficiently spatial resolution arerelativelyrecent techniques

. Here, dendrochronological provide. Here,dendrochronological potentiallytools much more 2017)

2018) 2016; Karlsen

2018) - free images plant the growingmajor during season remains achallenge . Indifferentof parts and landscape, biotic the conditions abiotic introduce . st afew weekslong . Moreover, However, especially at highHowever, especiallyat latitudes, remotely vegetation sensed

to their signalsexist separate sofar s

- NDVImeasurements Fauria Fauria & Zetterberg2010

et al.et

soilmoisture levels and

2018) - ground plantbiomass vascular . (Skarpe (Skarpe & Vander Wal 2002;Milner Some studies using using Somethese tools, studies dual, or species community level . It . It remains unknown,however, ivity can be obtained ivity canbe as estimationsof vascular ; Blok et 2011;Macias; Bloket al. due to agreatvarietydue to face of factors.Plants

extensive expansion

(Fang, Yu&Qi2015; - latitude environments the where ,

likely likely because bryophyte andlichen cover (Pettorelli and plant productivity,plant have growth to whatextent shrub , whichcould defence against defence against - , andobtain

Fauria et al.

related related e.g. fine et al.et traits

long Raynolds & Raynolds & -

scaled and 2005;

2016; et al. et

- ( term Babst ing

2012;

since in

et

This article isThis article by protected copyright. All rightsreserved. monitoring location forhigh archipelago of Svalbard, characterise al. production growthsecondary between stemannual mass standardi year per usetypically retrospectivemeasures ofshootprimary ( growth CampioliChapin 2002; a So or with branches,versus accordingphenological totheir growth stage woody plants geneticmaketheir individualaddition, shrubs may to differently environmental conditions respond according to & Newsham2012) 2013) which include starklydifferential levels of,herbivory in variation plant arctic patternsgrowth and allocation rctic shrubs,rctic i.e

Accepted Articleme studies 2012; Van Wal der 2014;Karlsen &Stien , interspecificcompetition Recent studiesRecent have lagged responses ) and to secondary relates growth,whichit the canbemeasured asbasal stem diameters, above

and a annual annual

have investigated can even - ground primary growth . between primary (apical

strong effectstrong direct of summer temperatures , onan basis, annual - , soil , soil movement damage andfrost up or phenotypic up or phenotypic plasticity shr

ub ring prioritise et al. et Van der Wal and Stien (2014)Van derWal andStien (i.e. carry (i.e.

s shown - ed by its length

arctic biomassmeasurements todemonstrate that summer 2013; PuntieriMagnin, &Villalba 2014;Berne growth

trade (Dormann, Walder Van &Woodin2004) growth

- high over effects, &VanSkarpe Wal der 2002;Wu - offs in (Myers remain

( inter including in ) and secondary ) and vestment

or ringgrowth. - growth

- annual plant variability biomassin arctic s et al. Smith

(Albert to bestudied new

2018)

differentially a allocation within allocation et al. et (Bokhorst

(Babst, &Parlow2010; Esper Speed et al.et

(Armbruster, Rae & Edwards2007)

green biomass used the only continuous andlong used theonlycontinuous

. Thesame appearsto pattern

(radial) 2015a; Weijers

Nonetheless, Nonetheless, 2011; Housset and

(Gauthier (Sloan, Fletcher(Sloan, & Phoenix 2016) i.e.

et al.et

is therefore length andnumber growth mong plant parts, e.g. roots mong parts,e.g.roots plant

) 2 above , 008; Crawford 2008)

and et al.

t

( he

et al.et , pathogen load Bret et al.et

- below

far from clear ground

r relation 2011; Elmendorf

et al. et -

Harte, & Shaver

2017) 2016) -

et al. et ground

2015) structures ofstructures ship

of shoots . .

On the Arctic Arctic

2015)

- .

(Tojo (Tojo . ,

term

They

et al. et . In .

et et

This article isThis article by protected copyright. All rightsreserved. ( Semmeldalen, herbivore the community comprises wildand the non habitat by habitat1). Ridge wasdominated dwarfshrubs bythe 2005)Jónsdóttir primary productivity 1998 Svalbard, areawasinSemmeldalenThe study ( areaStudy Methods ofproduction thespecies itselfandthe plantcom vascular growth ring shrub representsanadequate for proxy variation annual inabove polaris series Here, wetakeunique the opportunity ofcombining existing biomass the plant monitoring time shown tobeprim polaris At biomass production. another inSvalbard,location ring functionalplant typesand species, a temperature abovewas indeed driving AcceptedRangifer tar Article (Van der Wal(Van der 2014) &Stien (Van Walder 2014) & Stien

shrubs sampled same inthe allows This permanent ustotest plots. whether retrospective Wahlenb.

were S. polaris

a ndus platyrhynchus

a long . We ontwofocused types:dry widespreadhabitat ridge and moist (Fig. heath , acommon mostbiomass dwarf with ofits shrub below arily driven year’s current arily bythe summer temperature ,

the the wood rush for northernlocation sucha - term above - ), with adoublingpopulation size studythroughout the period . T ground plant biomass set ground plant monitoring

with the establishedmethodology fordendrochronolog

nd strong without carry Luzula confusa his wide U his wide 77 - ground vascular plantground vascular acrossbiomass production habitats, ° 90 ’

N,

- 15 shaped inlandhas valley arelatively (bioclimatic zoneC °

20 and Dryas octopeta ’

E the grass the , 100 m, 100 central a.s.l.), Spitsbergen,

- munity asawhole. widths thepolar of willow - over effects from previous year’s the Alopecurus boreal - l herding Svalbard herding Svalbard reindeer : a

middle

- and (Buchwal up wasestablished in - ground, was also ground, wasalso S .

-

ground biomass polaris a rctic rctic tundra

et et al. is , Salix Salix high

. In and heath and heath

2013) y on , . - S .

This article isThis article by protected copyright. All rightsreserved. Accepted collara root (i.e.theoldest part ofthe shrub) ground structure of liveSvalbard’s vascular plant smalland represent avery proportion 1d). Overall, oftheplant 5 (Fig. nomorethan of parts information represents a potential knownoldest (A. individual old was 120years meanwith a age ofaround40years plant Wal fooddigestibility make resource andespeci animportant forherbivores, it desert widespread S. polaris Article speciesStudy 192mmaverage mmmax: (min: 92 265mm in1998, in2012). 4.7°C (min: recorded at Svalbard (Anderson grasslike the habitats pinkabundant (Lee

et al. et et al.et ( http://svalbardflora.no/ S. polaris by pulling outmoss gain to access to the belowextensive

has

2000; Bjørkvoll

2015) et al.

shrub speciesshrub found relevant forrelevant arctic vegetationstudying andecosystem The above dynamics. - 8.9°C in1

Dupontia fisheri a circumpolar distribution -

footed goose

, rock ptarmigan, rock ( 2012)

(i.e. S. polaris airport key

. branch tips,leavesandreproductive structures) grow toaheight of2 9 From 1985 to 2014 (i.e. our study period), From period), annual 2014(i.e. our study the temperature 1985 to 88,

species forspecies reconstructing long

et al.

max: ( (78°25 N,30 km 15°46E,study fromthe area) Anser brachyrhynchus

can extendseveral decimetres intothe ground composed andis of biomass , , Rønning 1996;Nakatsubo

the the rush across 2009) - Lagopus mutahyperborea 1.7°C t in 2006)and . The species has been . Thespecieshas tolivereported for many decades,

is Svalbard, inhabitats rangingSvalbard, from meadow arctic topolar ( Eriophorum scheuzeri above the moss layer http://www.flora.dempstercountry.org/ (Buchwal from which

Buchwal, obs.).Therefore, pers.

, Madsen et al.et he annual -

develop term, large 2013; 2016) Owczarek &Opała

et al. ) and ) and

et al. et

(Bardgett

and the forb

2010)

precipitation sum on was - a network ofbranches and ground offorageparts species geese. Theincreasingly

2017) - scale primary productivity . Its . Its abundanceand high

et al. et

notably disruptswet notably ally reindeer

was onaverage Bistorta vivipara

20 S. polaris )

07) and is - . 6% of The (Van der (Van der - the mostthe ground

. The below - - 5 cm

- This article isThis article by protected copyright. All rightsreserved. Accepted August2015, completeIn early Shrub 2013. dominated and dry community scale, biomassalarger including oni.e. fourother habitats: grass wet moss,moist vascularcomprising plantspecies, all inthe twofocalhabitats combined; iii)total and polaris performance therein from squares small to the represent the well permanent not plots whilst impacting plant shootspecific mass estimates, through obtained destructivesampling siteat each suc at cm (2 habitats biomass of did Articlefollowed overtime. distributedacross were landsc the Sites August the 1998 early in years oftheIn each focal two habitats, i.e. andheath,ridge above Biom designStudy both windandinsectpollination dominate. The reproductive system (i.e. beasexual cloning rhizomes) with can through orsexual habitats such asmeadow Generally, rootsroots. those consist of ro acore ; 10 quadrats persite) 13yearsS1). inall (Fig. ; 10quadrats Shoot were densities multiplied with site

not exclud ass sampling

sampling

biomass two separately inthe focalhabitats, × S. polaris S.

5 sites)b

e

herbivory and processing

Luzula .

In the study, current measures ofabove weusedthree and ofall that plantspecies othervascular wasestimated forthose 10sites y counting shootsspecies ofall insmall permanent quadrats ( s

- (see (see and snowbed Salix - Van der Wal (2014) andStien 2009 and2013.Ineachhabitat, five replicate S. polaris tun (i.e. ambophily, Rønning1996;Dormann &Skarpe 2002) dra sampled 2002,and until s

muchmore complex orfine

shrubs both(i.e., above ot with

and co

several lateral thinner roots, but inmoist

mbined; ii) total communitymbined; ii) biomass, ape an ofca. within area 4.4 km - ground

for further for further Abovedetail). Dupontia -

and below biomass wassampled - rooted rooted individuals seemto

marsh until sampled - ground biomass: i) d -

ground structures) sites were 25

cm - h distance ground in × . - 2

25 and - S. This article isThis article by protected copyright. All rightsreserved. the closetothe located developed clearly ( Additionally, we boundaries radius,each manually wemeasured ring each within werandomlyquarter aradius, drew Eachprepared. cross Ring Chronology building Appendix I. 2010) toavoidbiasofe.g.largerringbranches juvenile parts growth in rootcollarthe individualper shrub microtomsledge sectioning for serial rootdistinguishable collar, branches and plant and roots, withfairlystraight sections appropriat in shrubs total, suitable fordendrochronological appearance,analysis, i.e.ofhealthy with clearly sampling Ofallclones. of sampled indi (Fig.S1).sites Sampled individuals byaminimumwere separated of5m distance toavoid excavatedwere carefully from soilinclosevicinity the heathto all and ridge biomass sampling Acceptedi.e. Article eccentricity ofour cross

wedging rings - widths . The detailed laboratory pr. Thedetailed ) startingfrom the

of shrubwere ondigital each measured from images captured thethin ; and e visually inspect

ring (Gärtner, Lucchinetti &Schweingruber Lucchinetti 2014)(Gärtner, ,

two sections fromtwo sections pith Buchwal 2014) : (Kolishchuk 1990; Myers - two tothree section ofaparticular partof shrub the was di

and . Thisstep assessed the number of - sections moderatesections was outermost ring ed thecross entire eparation of the

sections

allow . We stopped

the branches.the viduals, we selected viduals, weselected three shrubs per site,i.e. - ed widths (i.e.

from us to us to for correct

to -

Smith

the the

the mainthe and root excluding injured

ring 15

the remainingthe (usually highly , webelieve - pith in - The section for irregular,

20 the the

- et al. et width

sectioning was sectioning shortest

ImageJ 1.48

2015b, Fig.S1d)

an thick measur age effect (see below).age effect (see

that ourthat

to cut distance betweenadjacent ring

(Büntgen &Schweingruber thin /or side /or roots

xylem parts ements vided fourinto quartersand - section (Schindelin five to six five tosix cross

spread alongspread shrub the four partially missing

at at the . We - radi s

; (Fig. S2)(Fig. is described in

one section

i wedg innermost used

reading

et al. et sections n

Because

ing a GLS = 30 - . Along sections

2015) ) rings s of

rings from - 1 ’s ’s .

e

This article isThis article by protected copyright. All rightsreserved. Accepted awayfurther from pitharing the is formed, has area greater covered the tobe xylem, bythe so with higher ring 2016) cross of all 2016) growth variation by caused Tree Chronology standardi three levels of cross move with linear mixed mean shrubs’ curveswithin a growth site, to obtain site to obtain a foranmean curve 3) individual and shrub; cross growth Article asinglewithin conduct 1990) established entirelymissingrarely, formingconditions, shrubs,Arctic andinparticular Cross ring - - widths ring d , . We investigated first the effect ofageonraw ring - to allowmultilevel dating

pac back and forth between these betweenback andforth these ed

standardisation aims biological toremove

kage ‘dplR’ e.g. ageand/or three -

ring growth sections capture

cross - levels of cross widths atayoungage(Fig.S (Fritts 1976;Cook&Kairiukstis Helama 1990; - effects models,effects below see d - irregular, wedgi irregular, aligned bycambial age ( - dating detailed are AppendixI in section individual growth s (Bunn 2008) ation (Buchwal chronologies, we serial adopted the sectioning method

geometry cross

;

2) - - dating S. polaris dating cross

et et al. . A variety of . Avariety methods toaccount forage exists . Th ng three levels - : 1) : 1) dating (Buchwal 2014; Myers (Buchwal 2014;

rings that rings absentpart ofthecan be in or, shrub more 2013) e cambial curve showed age juvenile atypical effect, of specimen the well , cross are known theirgrowthharsh torestrict under ) . To i.e. between all . Given these challenges 3 - a). patternwascaused by This dating

biological age of cross ensure theensure highest quality ofcross trends

and Fig.S2 between - specific mean (obtained curves growth - -

five six to widthsmean plotting by curves growth dating allmissing todetect rings from growthtime (Buras &Wilmking(Buras 2014,Fig. - Smith ) the fourthe in R

et al. et .

- cross dating individual between

version 3.3.2 et al. et

and toensure 2004; Sullivan radial measurementsradial - sections ofsections

2015b) - series thatseries are geometry (Kolishch . We - (R CoreTeam driven mean - correctly dating, we one shrub, one shrub,

et al. et , i.e. , i.e. the uk . The

S2

) .

This article isThis article by protected copyright. All rightsreserved. structure andnested ofthestudydesign(seebelow Fig. S1). models used However, notethat finalthis chronology growth curves dendrochronologystandard below) statistics (see maximum were particularthis year i.e. (2015), the outermostwasexcludedfrom ring, theanalysesgrowth since the secondary of methodsstandardisation le simplyhereafter growth’,‘ring called S Fig. age effects wh were eliminated, 20 increment S age (Fig. area basal increments against series cambial weobserved aslightbut with age, constant increase & Wilmking 2014) transforming ring 1990;BiondiKairiukstis Qeadan & 2008) that, in

Accepted Article- year mean curves growth also also evitably, widthsbecome ring and thinner thus may with seemingly age decrease , Descriptive statistics, commonlyDescriptive in used -

which windows

truncated truncated suffito ensurea series number of number 3 b). Therefore,finalstandardisation the step to deriv enabl using

- cut widthmeasures tobasalareaincrements ( , using mean the curve growth constructed foreachcross had in ed - with ‘chron’ the function in Rpackage‘dplR’using arithmetic means. chronolog off. Combined, standardisation those approaches ensured that allpossible all other

e the curve regional standardisation method

not always us toaccount dependencyfor spatial and randomdue to the variation

an overall an overall ( a at at habitatthe study or arealevel d ing to

analys ich ich resulted dimensionlessin turn ina Ring ies

mean completed similar S1). results (Table over cient numbercient ofcross es

(

S. polaris the periodthe i.e. . Wefor this accounted 3 related toabove c). at at timethe ofsampling

We dendrochronology, dendrochronology, , wecombined shrubs all individual

chronology chronology 1985 additionally

consisted of consisted -

2014 (Appendix I). - sections foreach resulting year, in )

obtained from mixed linear -

ground biomass andclimate The year ofsampleThe year collection for

) ran our analyses with our ran analyses other (Briffa Melvin & 2008)

geometric

(Biondi & (Biondi Qeadan 20 the study area. We studyarea. the of thetruncated growth ring detrending

(Fig. 1e) (Fig. - Width (RWI; Index - constraint by section. Plotting T . o calculate

G basal area rowth curves rowth curves ’

computed mean (Cook & - 08; Buras 08; Buras effects

) with a with a ,

we This article isThis article by protected copyright. All rightsreserved. standard errors measurements violate would assumptions of all were not overmonitored exactly the sameUsingordinary linear period). models onall based (for instance togive correctthird, the toeachobservation weight partition the within forthenon account designa nested ( al. variance in the modelboth square residuals, measures were distributions with onlya few growth(seeabove)Standardised ring ringEstimating and growth above Statistics Wigley,(EPS, Briffa1984;Cook Jones & & numberinfinitive of cross constructed between section cor ‘detrendeR’,package Campelo, García time

Accepted Article relation between individual 2015) - series al growthal curves We linear ran growth of curves allshrubs (r .

This modelling approach is

were computedwiththe mean ,

this applthis . Instead, Cnaan, Laird &SlasorCnaan, Laird 1997

S. polaris - -

independency of replicates within independency ofreplicateswithin a nested second, tocorrectly level; and - mixed models effects the using ‘lmer’ function ies

within within using linear linear using mixed between

here to sampling to here oftotal biomasshabitats, across since the - sections,

chronology represents hypotheticalchronology a on based an large values (Fig. S values (Fig. large growth curves individual -

- variatio ground biomass

with function

and above recommended bar.bt - González 2012)& Nabais

the the shrub (r n ). Additionally - effects m effects in s so , measurements Kairiukstis 1990) Kairiukstis

( Grafen &Hails 2002, ‘rwi.stats the different ecologicallevelssampled S1); (Fig. r - bar.tot called called - 4 ground bar.wt ). To

s )

, when analysing when analysing replicated da when theunbalanced samplingis design odels, we we odels, the the ) Expressed PopulationSignal , ’ (R ’ (R ‘dplR’)package obtain obtain normal distribution

and themean inter biomass hadsimilar(right , mean correlation cross between

we - independence root transformed for analysis.

evaluat .

include . We reported

Zuur et al.2009 Zuur et ed (R package ‘lme4’,(R package Bates d

how closely the a random intercept ,

- resulting resulting in too small series correlation

and ‘RwlInfo’ t he ta collected in ta and -

skewed) skewed) mean statistic statistic ) six habitats ; first, to first, constant -

(R

et et This article isThis article by protected copyright. All rightsreserved. Acceptedtemperature total(°C) and precipitation for sum data werethis station obtained from (mm) ofthe north site,atstudy airport( Svalbard The closest weather climateEstimating scale. Pearson’s correlations ( trans & Weisberg 2011) from obtained 1000bootstrap iterations the with ‘Boot’ function the within Rpackage‘car’ obtained function in R package‘lme4’). with as Article structurerandom described intercept above. to obtain annual estimates habitat. per fixed included Factors as excluded effects were from the coefficient yearly extracted estimat growth and structure as random effect period, study the estimate habiwas nested within growth(for ring structure ( formed scale

sociated Trends over timeTrends over were

mean from theselinear mixed i.e. biomass variation invariation mean composed replicatedunits) andindividual between shrub ofyear ring ring 95 %confidence interval

estimations both in total andbyhabitat (using deltamethod)(using the foreaseof interpretationofeffect size. However, . Trendcoefficients biomass onthe andannual reported estimatesback were effects onringgrowth growth (1985

station withlong time tat. We linearmixed used r ) and - series series (variance partitioning reported) ) or plot) or (for biomass t fitted withlinearmodels,fitted confidence and95% intervalswere - In further analyses below)In further (see weusedthetime tests tests were always calculated and reported square on the for - - effects models.effects 2014 es. By a similar way, we added the es. Byasimilarway,we the added

the area study - term andprecipitationdata temperature islocated 30km ) and ) and s, obtained from

78°25 N, 15°46E) , From thesemodels, we mean

we

- only

effects

, weincludedasa year fixed factor estimations biomass production biomass production (1998

included models intwotypes ofanalysis

1000 bootstrap 1000 . Second, estimate to ring annual ) nested within which) nested site, turn in , at the the , at meancoast. Daily

the interceptthe hierarchical the and

reported interaction iterations

- mean estimates 2009, 2013) - series estimatesseries

year

(‘bootMer

and × - root root .

habitat F over over irst, to irst, to the the (Fox ’ - This article isThis article by protected copyright. All rightsreserved. months (June,August, June July, to investigate preliminarily, for temperature and precipitation, whichcombinationofsummer based apriori biologicalwithout support including numerous one can,by select several predictors chance, or statistically significant as covering climate months forall oftheyear variables andeven years.However, including prior random structure described above. effect proposedall habitat with precipitation wasincluded. theaddition, interaction year’s the between previous ringgrowth andsummer and temperature variables listed above main drivingshrub climaticvariables ringgrowth. Thefullmodelweather containedthesix temperatures <1°Cand defined snowfall (mm) and rainfall [‘rain onset timefirst autumn in below stayed (and 0°C for of as (Julian) winter the daywhen a10 on variables:weather day);endof onset ofday); (Julian winter (Julian winter snowfall (mm); rain institute Norwegian Meteorological

Accepted Article- snow (mm); summertemperat

of oppositewasused. spring) the winter Forthe period(i.e. we from November toApril), procedure Pearson’s Pearson’s correlation commonly is climate in used The mod the the predictors predictors previous presented predictors el selection was performedlinear using selection mixedel (using thefunction from ‘dcc’ Rpackage the ‘treeclim’, Biondi Zang& 2015) and in TableS2). Thehierarchical designstudy wasaccounted forinthe ≥

1°C, respectively previous year’s previous

To test forTo test habitat possible effects we proposed aninteraction of - ure ure ( July (Peres

( http://eklima.met.no , July  - C); and summerC); and (mm). precipitation We onset definedthe day forwardmoving below0°C windowaveraged for the

- - on Neto 1999) ring growthring - (Hansen August, June - snow’, log(mm)] falling astheprecipitation at

(i.e. upto ≥

10 days); for (and endofwinter 10 days); the therefore

et al.et . Thus, to detect possible carry possible to detect

three

). We considered thefollowing ). Weconsidered six - -

July 2013) ring growthring relationship analy

we only adopted this we onlyadoptedthis - ways interactions, seesummaryways interactions, of - - August) bestAugust) captured ring effects models to identify the modelseffects toidentify .

- over ef hypothesis fects. s is , I n -

This article isThis article by protected copyright. All rightsreserved. Accepted inve usingmodel wereobtained restrictedmaximum Residual distributionswere likelihood. proposed (see above).correlation testing,hypotheses BurnhamAnderson 2002) & basedranking parsimonyofthe onthe cor principle Article0.70:1.59] mm/year, mm in ( year max:1987, with 6.4°Cin2007,Fig.2) significantly a increasing of0.06 rate [0.03:0.08] °Cper temperature S (Fig. model selection month combinations for precipitation sumwere significantly correlated togrowth,andinthe ring referred to as‘summer explained best temperature’) growth (Fig. S stigated for normality andhomoscedasticity. t

1998, max: didnot 122.7mmand 1998, changesignificantly overtime in2013) [ (0.13 = 4.27, The function from ‘dredge’ (Barton Rpackage‘MuMIn’ the formodel 2013)wasused

interaction 5 P ).

(below) < 0.001). Thesummer< 0.001). precipitation sum48.7mmwas onaverage 14.4 (min: For the fullperiod 1985 5 and s ). For this t

were considered tobe = 0.26, therefore A

we therefore decided we therefore decided to sameuse the month summer combination asfor ll

predictors’ pairwise correlations .

This rankingapproachu

P

period, mean the was5.2°C summer temperature (min: 3.6°Cin

= 0.80).

is not to subject

- 2014, June

biologically meaningful

issues of issues rected S. polaris - July tili s

e Akaike Information Criteron - s multiple testing like August mean (hereafter temperature

maximum likelihood were

ring growthring .Noneof summer the relatively . Estimates top from the low in

( , as opposed to r < 0.5 Pe a rson’s rson’s

(AICc, - ) and all ) and This article isThis article by protected copyright. All rightsreserved. [0.04:0.69], betweentrends habitats, growthinheathand the ring r thistrendwasyet, found positive habitat only for (Tab heath habitat ( wasnosignificantdifferenceand there inannual ring pattern growth between and heath ridge therefore likewise small [0.035:0.053]mm,mean (0.045 % confidence [95 interval] 1.5 between and 4.1mmin diameter(bark excluded). comparison above with highly Thus,thechronologyhigh (EPS=0.90). wasconsidered for applicable reliable (r (r shrubs withinvariability shruban individual (r unprodrelatively with variation, years). haveyoungerplantshabitat tended to twomeasurementswhich the becompared same could forthe study takenmeasurements were in1998 Semmeldalen, central Robust and Ring growthintime space Results

Acceptedbar.tot Article

= 0.22), despite Expressed but thisthe Population Signal forperiod 1985 the

Both growthandvegetation ring biomass time In line S. polaris

t bar.bt

= 1.55, d.f =55, t

= 0.21). Meancorrelation= 0.21). individualgrowth between wa curves = 2.29, with thesmall ofthespecies, stature 1998 and 2007 uctive years. Descriptive chronology statisticsrevealedlimited growth annual

ring ring d.f Spitsbergen, growth were curves constructed1985 fortheperiod -

ground biomassmeasures. = 25, P

= 0.1

P

standing out as highlyproductivestanding outas yearsand 1999and2008as

< 0.05 3) - 2009 resulted and 2013,this inanoverlap of13 Svalbard . Over the period1985 . Overthe (25 ± 7years,(25 ± mean , bar.wt Fig .

= 0.65), butrather highgrowth= 0.65), variability between (Fig. 2).Because above S6 ) , indicating shareddrivers of growth , indicating annual

S.

- polaris Annual mean ring raw idge series demonstratedseries highinter

- ±

2014 growth ring increasedtime; over co

sd) than than sd) the le

- had very small root

fluctuated over fluctuated 1 ) . Despite difference. Despite this in area - ground biomass

heath habitat ±8 heath (30 (Fig 2). The(Fig 2). ridge - 2014 - s relatively low widths werewidths time ( in - collars, collars, - years for years , 2014 was r

- 1), Table annual = 0.42 .

This article isThis article by protected copyright. All rightsreserved. rema significant dueoutlying toan point (year 2013,Fig. whilstfor 3h), ridge habitatthis relation polaris by patterns habitat, the asthevariable driverof overall significantlymeasures positively were related to summer suggesting temperature, this climate variationgrowth reflects inabove S measurementsWhen combining fromandheath,ringgrowth ridge and Ring growthversusabove timeover mean above biomass 1).Total inridgehabitat increasedovertime(Table six Over all habitats monitored, the ofproduction vascular was composed of includingalso monitoring 2013(nobiomass took place 1998 period habitat 1998 g/m meanThe estimated annual above Above .

Acceptedpolaris Article 2

ined strong 3e). strong (Fig. was ined The opposite casethe for the relationship ringbetween growth (Table 1), andlargerinheaththanridgehabitat 1), (Table ( to 201 - ground biomassintime

increased over time 1,Fig. (Table About half of the total vascular plantAbout halfof total vascular the above above

(Table 1). 1). (Table were positively correlated 3, the overall tendency for3, theoverall tendency positivetrend a - - ground vascular plantground vascular biomass37.0 [29.9:45.1 was 2009 ( - ground biomass andsummer temperaturefor heathhabitat was nolonger S. polaris r

= 0.61 [0.05

plants differed thesetwohabitats between ( strength relationships ofthese Therelationship dropped. between - ground biomass p

(Table 1).Like for and space S. polaris :0.88], - - ground this biomass in ground biomass production of

(r =0.56[0.01:0.85]),(r demonstrating variation that inring t

= S6 growth 2,Figs.3aand3b). (Table When inspecting 2.41 ). Ridge andheathbiomass). Ridge co roduction S. polaris , d.f - ground biomass and inheath ridgehabitat

= 1 t

was = 3.58, d.f=22, in 2010 0

,

biomas high P non

< 0.05), < 0.05), - - arctic arctic shrub 3cand4).Both (Figs. - ] g/m significant; 20 s, S. polaris

t 12 the annual biomass annual the

= but notsignificantly when 2 , Fig. - and 5.45,

P above

< 0.01,Fig. - showed no clear trend showed noclear S6

fluctuated the during was

yet, inridge biomass d.f =24, - ). ground biomass of

17. 9 [10.7:27.3 P S6

< 0.001). ). From S. ]

This article isThis article by protected copyright. All rightsreserved. summers.compared incold to words, other In S7a Additionally, summer the temperature effect interacted withlastyear’s ring growth(Table 2,Fig. withassociated ringgrowth, allmodels beingselectedin with growth effectsClimate onring [0.21:0.90]). removing polaris combined forall =0.67[0.19:0.89]), then six (r and ground biomass ofthetotal vascular plant withthat community, first for andheathridge habitat growthandabove ring moving tohigherlevelsof thehierarchical sampling the design, relationships between the at site level,random (i.e. variation inintercept) plot and plant respectively. level, Although measurements of random Table3), variabilityin greatest effects, ringgrowthandabove weakened (Figs.4fand4i). 4 and summer temperature, which weakenedforridgebutremained strong (Figs. for and heath 4d Accepted Articleg). Thus,habitat ). In w ). In Indeed, whenIndeed, partitioning the variance across differentnested ecological scales (i.e. Model selection retainedModel summeras temperature the for emergingWhen different heterogeneity accounting these levels,andthus across ring ring growth reflect S. polaris arm summers

S. polaris - specific correlations ringand between growth biomass

from biomass the ofallhabitats, the correlation remained strong (r = 0.68 - ground biomass clear. are , growth , ed vascularplantbiomassincreasingly well (Fig.

was fou

w as nd at the the nd at smallest spatialsampling i.e.at scale, individual

les s influenced previousyears’ growth bythe ring S. polaris after ayearof low ringgrowth,positive the effect Interestingly,

at at habitatthe level habitats habitats combined (r = 0.70[0.25:0.90]),

biomass considerable variability wasstill

main weathervariable (positively) Δ when replacing when replacing AICc <2

- was ground biomass of

( small Table Table 4 S. polaris ). Evenwhen S. polaris (Table 3 S3 ).

were S. polaris

). above

S. -

This article isThis article by protected copyright. All rightsreserved. Acceptedmeasures plants within (i.e. four each radii within cross five tosix duetomeasurementvariation error. However, withthelevelofreplication high ofring growth within plots s variablehighly atthesmallest spatial i.e. sampling among scale, individual sampling plants or Wal2014; Vander 2014,Table 3) &Stien existsatthat differentspatiotemporal s aboveversus summer temperature ground biomass oflocalpatterns above growth ofthewidespread withthat, sufficient replication scalesacross successful spatial and stepwise cross thealso vascu Articleretrospective ringgrowth represents above in situ By Discussion: growth was growth. of summer temperature was constructing

plant

Multilevel samplingMultilevel enabled successive partition over years usto plant out traitvariation

The top ranked The topranked

less pronounced in ridge pronouncedless in than biomass production - ites, respectively.ites, These were levels samplingand the units thus included also ground biomass, strong ascould expectedunder energyallocation be trade lar plantcommunitylar whole(Figs. asa 2and4). fluctuations of shrub , and noevidence wasfoundfor i opposing - chronolog ground primary production.Accordingly, b model also suggested model also that and more highly S , we were able to reveal ies and combining withlong those existing .

polaris pronounced abundant abundant cales cales

were bycontrolled - . Shrub ring ground production focalshrub ofnotthe but only (Messier, McGill(Messier, & LechowiczGalván 2010; heath habitat

than polar willow

the the

when the previous yearwhen the previous alargering had positive effect of growth andabove on an bases, annual

(Table 2,Fig. S the samethe i.e. climate driver,

. By doingthis,wedemonstrated polaris nvestment insecondarygrowth - oth sections pe

ring can adequ previous year’sprevious S7b - ground biomass

growth andabove - ) how well term time . r shrub) r shrub) and high

ately capture - dating, ring - series ofseries ring ring - offs.

were et al. et -

This article isThis article by protected copyright. All rightsreserved. vascularpast plantbiomass oftundra ecosystems, tetragona pubescens Betula low found correlations positive between NDVI Furthermore,measurements only. studies shrub new shootsinthree species, although basedonasingle year Anadon proxy ofprimary throughout production the Although biomassannual productionof plantcommunity totalvascular (r=0.70 the [0.25:0.90]). reveal aremarkably high correlation ringbetween growtho multiple a patchy topography withdifferent biotic habitat) capturedwithin Accounting for measurements growth and above al. differences inplantcover the in high Arctic small.to be Bycontrast, duevariability to densitiesofshoot

Accepted Article 2007) Arctic: Arctic: While our results confirm results While our asapromising toreconstruct dendrochronology tool f -

Rosell sources ofvariation strengthen . Consequently, likely the this increased when variance withinasite correlating ring

insufficiently researched, current suggests evidence that from Canada Northwest Salix Salix lanata w

et al. multilevel spatial as several metres sampled awayfrom plots the - from SwedenNorthern S. polaris ground biomass

(2014)

to a considerable extentto a from RussianArctic the

within ‘biomass effect plots’, weexpect the ofmeasurement errors reported

variation

(Weijers of

a positive correlation growtha positive betweenring andbiomass of S. polaris s the and abiotic and abiotic (Babst utili - micro (i.e. site, plotorindividual nestedwithin nested based plant productivity plant based

et al. typically occuralreadytypically withinm

alpine and ecological s ing ,

- micro since ashrub sampled dendrochronological for et al.et (Forbes

habitat conditions habitat conditions 2018) constructing a ring growth fromconstructing aring curve small remotely vegetation sensed characteristics

2010) - A

. insight and inference,andallowedinsight and usto and macro

rctic biome.instance,in the Alps, For

et al. f a single shrub species f asingleshrubspecies and the ; and

201 for biomas Salix pulchra - ring and single location 0 habitat variation .

will be aslarge great, , Macias and ring growthacrossthe Acknowledging

growthmay be a well s measurements. s measurements. - etre Fauria production

and s (Armbruster

Cassiope ari et al.

such of sing from ine

2012 maps - scale

) et

;

This article isThis article by protected copyright. All rightsreserved. 2009)Van derWal&Hessen ofproduction plants tundravascular in general polaris al.2018; et al arctic findings across and alpine shrubs above summer temperature woody plants during their cope with live plant linear mixed tetragona 0.22) waslower threshold us enabled to a chronology develop reliable with verification irregularities, missing on study al. irregularlyand highly growing inaharsh shrubs environmentarctic ischallenging .

Accepted Article 2012; Buchwal 2014) 2013;

growth curves - ground biomass

In this harshIn this environment for growth, woodyplants ring ring growth onSvalbard

from cross from S. polaris Van Wal der 2014;Myers &Stien

of (r Weijers bar.tot during during - 0.85 effect (Crawford Wilmking 2008; a persistent

than = 0.32, (Wigley

- s a stepwise in another Svalbard location, 14 on average

sections,

et al. (r models atthe individual plant lowlevel, the correlation betw

– in an bar

that and . Weijers . bt

2018) se Buchwal

et al. et s Svalbardother specieswith amore growth regular suchas pattern = 0.21) = 0.21) stands outasmain ofboth the driver arch arch in S. polaris

while 11%werecompletely missing. Despite .

cross this stressful environment Van derWal (2014) andStien

. 1984)

(Owczarek 2016) (Owczarek & Opała Sun exposure has also been has been Sun exposure also suggested to influencepotentially for et al. also

- et al.

dating missing rings

. Themeanwithin

below

2012) reflects (Forbes

(2013)

et al.et

procedure (i.e. withinandbetween shrubs - . - Smith ground In accordancethe with

the numerousdisturbances

(Wiegolaski

2012)

et al. et estimated that a , whichincluded detection their and n

et al. et

EPS ring growth.ring

. 2010; Elmendorf

-

-

2015a; Weijers located at located at distributionalthe margin of

value and between , and that

we found et al. et

found a negative foundrelationship anegative

in theirdendrochronological above the above the commonly accepted % of the rings were partially % oftheringswere vascular vascular plant

1981; Muraoka This is This is in linewith previous

variance partitioning oft of theabove net o -

ne weather variable ne weather plant et al. et

et al.

that

these commonthese

correlation 2012;

2017; the shrubs the community’s

een individual et al. (Wilmking Buchwal Ackerman , Fig.S2 - ground

2008; (r have to have to bar.tot –

et et C. ), he

et et = S. This article isThis article by protected copyright. All rightsreserved. Acceptedtemperature effects only indirect toadecrease this in Junesea iceextentinstead Likewise, beduetoincreased could defoliation from herbivo Greenland continentalgrowth in Western for of increasing summer temperatures, in resulted a prominentin habitat’s above reduction heath ourgrowth in withpossible study, the exceptionthat extremely summer rainy in2013 t than that soilmoistureproposed andsoil havestructure influence alarger on Svalbard, (Forchhammer 2017;Gamm on adeviation from aforementioned the Article of growth. surprisingly, adriver shrub tightly connected for to the physiological required processes ringgrowth, and theref shrub the influences the fl thatcambial leads formation activity tothe ring growth.More temperature ofannual specifically, tissuefavourable temperature and the presence of xylogenesis, trigger i.e. auxinhormones the process photosynthetic beagoodindexofphotonfluxcould density cloudcoverandsummerbetween in temperature ours emperature More surprisingly, recent surprisingly, More dendrochronology studies fromandSvalbardreportGreenland (Sundberg, Uggla & Tuominen 2000; Uggla&Tuominen2000; Wilmking(Sundberg, with ashigh twice precipitation levels Forchhammer (2017) ux ofwhich orshort auxins, in cold summers all likelydoes not reach of parts . W ater availability availability precipitationater through did tonot appear influence (Muraoka

et al. et

reported anoverall decline in ly through correlation

et al.

20 Gamm 17; Opała

2008) clear andclear positivesummer responses temperature

et al. et

. Nonetheless,inadditiontocarbohydrates, necessary forcarbohydrate production in the Betula nana . latterWhile the implicates summer study - Owczarek as inland our site,

(2017) ry and increasingry and moisture limitation. tudy area, suggesting that temperature

with extent, seaice reported the effects

observed atemporal decline in ring

-

and ground biomass. et al. et al. et B. nana Salix glaucaSalix

2018) 2012) Opała

. In aco . Airtemperature isthus ring S. polaris S. polaris - Owczarek . They suggested . Theysuggested this growth but related related growth but Furthermore, in spiteFurthermore, in a stal site in ring growth

ore, not ore, et al. S . polaris

(2018)

This article isThis article by protected copyright. All rightsreserved. interaction, herbivore above (i.e. Blume primary ramification (lengtharchitecture) and growth and see secondary (but toestablishneeded which belowtundra function oftempera al. maywoody structures in result a growth Prokushkin & 2006;Mokany, Raison Iv mostly Wood of far shrubs’ unfavourable oflikelihood storage usingavailable resources(i.e. growth) from last year’s are whenconditions ring ringwasless (positively)Accordingly, weshowthat growth influenced by previous the years’ were

our study species is species our study Accepted Article 2015) (Bret

below growth duringwarm compared summers, summers. cold anincreased to indicates This weak on Svalbard, becauseweak onSvalbard, possibly ofcarry - y tissues - ground

located below S Werry importantly contribut below - econdary growthbiomassecondary in of shrubs production . Harte

A - ground ccording to ccording our results, - .

) ground biomass fromabove -

et al. et

. Therefore, ground

ha et al. ve )

ture inform onthe

2018

much C:N higher ratio than lea 2002; Iversen - were ground andarerepresented

growth situated . studyA recent by ). mechanisms below control

this Starting Starting to fillupthis knowledge ga robust e

–

to the storagelarge ofcarbon below can make the can makethe link to more

the “hidden the part of iceberg” the n

annual greenbiomassannual forhighertrophic available level underestimation of an

et al. below nual nual - ground ersen

2015) vegetation production - - ground ground measurements,ground Berner ,

et al. even .

However, asubstantial proportion of the biomass

by -

carbon storage maycarbon et al.et over effectsover (i.e. previous growth). year’s

2015) ves, branches strong strong - carbon storage storage carbon ground growthdynamics includingboth

(2018) and

. T extensively studied extensively

is often is often . p herefore especially especially in High the

Considering ositive rootositive are

p, ou roughly estimatedroughly large

time –

nested into ground 1). the (Fig.

but clearly, further studies has received littleattention so overlooked. E r work on secondary growth r workonsecondary , - in

series s vary greatly annually greatly asa vary hrubs’ below

tundra - to

only above - are are shoot ratio Wang topics soils too often specially - Arctic, are

(Iversen - et al. et like ground - ground - ( scale

> 4, plant s

2016;

(i.e.

et are are -

This article isThis article by protected copyright. All rightsreserved. Accepted Arctic to compensate oflocal forthe lack climate orvegetation productivity time remote datatypesincommunitycomplement other cycling, production considerable potential to use above al. et for nutrition andotherherbivores at reindeer a larger scale.Inlinewiththatexpectation, oursystem,do expect measurements weof densityeffect onreindeer (truncated to reindeer the abundancetime Articlecorresponding toapproximately 6animals/km Thus,and between years. whenincluding numbers annual reindeer thebrowsingimpactlocation, onthesampled constitut biomass production inthe followingsummer dwarfshrub, possible this with carry Wal miss

ing. et al. et

(2017) - ground biomass estimatesAccordingly, fromoursamplingthere sites. isnotonly

Given that Given that In conclusion, while shrub dendrochronology is In conclusion, shrubdendrochronologyis while increasingly usedacross thecircumpolar places climate where

and es aroundhalfof total the

2000; Bjørkvoll , to but also

energy flowhigh energy through found reindeerb that S .

polaris

inform ecosystemquestions ecological ascarbon such and nutrient S.

et al.

polaris formsmajorcomponent ofof diet Svalbardreindeer the a or vegetation or vegetation S. polaris

2009) odymass inautumn was positively related annual to total above

ring growth( ring - over effects.over was Simulated grazing shown toreduceleaf - , it , it could bethat well herbivory influences ring growthin

arctic foodarctic webs ring growthasaproxy ring for large - - ground series 1994 series data not are available - S. dynamic but are also studies particularly

(Skarpe &Van Wal(Skarpe der 2002) 2 shrub polaris , in ourmodel for testing climate, in effects

vascular plantcommunityvascular biomassstudy atour Table S4 Table

is expected to be to is expected highlystochastic, in space

- annual plane represent the of growth to 2014) . Ring growth proxies may. Ringgrowthproxies therefore

). C , evidencewe foundstrong for no a onversely, bottomonversely, in this up .

(Lee -

scale biomass et et al. . Although

2015) - series, ,

useful (Van der S. polaris

this this Albon in

This article isThis article by protected copyright. All rightsreserved. Accepted the collected data; MLM, LSandABconducted the work; MLM laboratory MLM, BBHandRvdW Author contributions: Anchorage. paper Ma advice (1072/MOB/2013/0). and funding scheme 223257), (project This project was Acknowledgment Article large missing as well rings,as acrosssampling landscape, replication the thereby accounting forthe of dendrochronology using shrub requiresof climate clearly (change) rigoroussearch wedging or where time retrospective studiesofcommunity dynamics climate under particularly change, in studyareas productivity. plant This opportunitiesopens new for ecosystem demonsstudy tth the Arcticthe , and habitat ews, L. Veylit and ews, L.Veylit B. Peeters ; TK J . -

effery. M. areseries available for highertrophic levels

Kåsi andD variation variation trates trates Field Grant(project 246054) supported supported

in situ

We and AudunStien Grøtanfor profoundlyVidar thank

characterising high Welker for . M.

conceived conceived the id

that by the Researchby the Council ofNorway

Alvsvåg for annual enabling FRIPRO (project 276080)FRIPRO (project for ring growth curves canring growthcurves indeed fruitful discussions fruitful discussions and draft comments onearly eas the the - arctic landscapes. a , aswell as fundingthe scheme and methodology; designed MLM, RvdW help in the labo research stayatresearch ofAlaska University the .

However, detecting ecologicalsignals

ratory; Ø.H.ratory; Opedal,K.L.

, KLIMAFORSK -

based monitoring and based through through reliably its ofExcellence Centres

MOBILITY PLUSMOBILITY

and

track past vascular

valuable statisticalvaluable (project 244647), 244647), (project BBH

analysed analysed

and LS s

of the

This article isThis article by protected copyright. All rightsreserved. Accepted Article http://datadryad.org/resource/doi:10.5061/dryad.d7p3b40 Dryad inthe Data deposited repository: Data accessibility: data; the MLM

wrote

the manuscript , withthe help ofallco

- authors.

( Le Moullec

e t al., 2018)t al.,

Accepted isThis article by protected copyright. All rightsreserved. article as doi: 10.1111/1365 d to lead may which types process, copyediting, proofreading and the pagination through been not has but review peer full undergone and publication for accepted been has article This Article - 2745.13036

ifferences between this version and the Version of Record. Please cite this this cite Please Record. of Version the and version this between ifferences etting, etting, 1998 1985 ring S. polaris S. S. biomass

polaris - width - - 2013 2014 This article isThis article by protected copyright. All rightsreserved. tobackfitted c Ring Me t habitats six of biomass plant for and combined, and separately Ridge) and (Heath habitats focal two the for studied; period 1. Table FiguresTables &

oefficients (Trend) and their associated 95% confidence intervals (from 1000 bootstrap iterations) were calculated with linea with calculated were iterations) bootstrap 1000 (from intervals confidence 95% associated their and (Trend) oefficients

Accepted Article an estimates of estimates an - it Idx RI cretd for corrected (RWI) Index Width

Mean estimates Mean estimates Mean

Summary of mean ring growth and plant biomass estimates [and 95 % confidence intervals] and their trends over the time the over trends their and intervals] confidence % 95 [and estimates biomass plant and growth ring mean of Summary (g.m (RWI/year) (g.m Trend Trend (mm) - - transformed mean 2 /year) - 2 )

S. polaris S.

ring growth are based on (raw) ring (raw) on based are growth ring 21.3 [10.3 21.3 0.0 [0.03:0.05 0.04 0. - 3 1 [ 1 estimate time

[0.0 Heath - 0.8

2 : :35. :0.0 1.0

g and age ] 6 4

] ] ]

- series. series. geometry

<0.01 <0.01 0.0 1

0.6 [5.6 4.7 5

[ [0.0 Ridge - [0. fet. eotd siae wr square were estimates Reported effects. 0.01

3 4:0.06 :1. :26. - widths (in mm), whilst trends in trends whilst mm), (in widths :0.02]

2 6 ]

] ]

a

Both heath andridge heath Both 0.02 [0.01:0.03]*0.02 17. 0.0 0.4 [ 0.4 9 [10.7:27.3 9 5

[0.0 - 0.3

4:0.05 :1. 1 ]

] ]

S. polaris S.

- ot back root 17.1 [11.2:24.7] 17.1 0.2 [ 0.2 All habitats

ring growth are based on based are growth ring - 0.3:1.0] - -

-

transformed. Trend Trend transformed.

r models r ogether. All vascular All vascular 1998 biomass plants plants - 2013 This article isThis article by protected copyright. All rightsreserved. when* Stillincreasing trend consideringthesame time asthebiomass 1998 scale measurements a 1988

Accepted Article - 2014 Mean estimates Mean (g.m

(g.m Trend - 2 /year) - 2 )

36.8 [26.7 36.8

0.4 [ 0.4 - 1.2:1.7

:49. ] 4

]

2

4.0 [15.7:33.9 4.0 0. 9

[0.

2:1.6 ]

]

30. 0.7 1

[19. [ - 0.

4:1.7 3:43.5 ]

- ] 2013

3 7.0 [29.9:45.1 7.0 0. 8

[ - 0.6

: 2.1 ]

]

This article isThis article by protected copyright. All rightsreserved. 10.1111/1365 to lead may which d process, proofreading and pagination typesetting, copyediting, the been not through has but review peer full undergone and publication for accepted been has article This feecs ewe ti vrin n te eso o Rcr. lae ie hs ril a doi: as article this cite Please Record. of Version the and version this Accepted between ifferences Article - 2745.13036

This article isThis article by protected copyright. All rightsreserved. Accepted Summer temperature × RWI Habitat (ridge) RWI ArticleHabitat (ridge) (°C) Summer temperature as reference) (heath Intercept Parameter ringgrowth)ison square years’ the 1985 period maximum ( statistics test and iterations) bootstrap 2. Table t - 1

- aaee estimates Parameter likelihood) from model selection, of selection, model from likelihood) - 2

1. h rsos vral RI ad h epaaoy aibe RWt variable explanatory the (and RWI variable response The 014. × t -

1 RWI

t -

1

β - - [0.15:1.20] 0.67 [ 0.16 0. - β 0.08 [ 0.08 0.17 [ 0.52

- 23 [0.13:0.3 23 with

root scale.

- [ t 0.07:0.39 - - - 1.07:0.02] 0.18:0.01] 0.33 and their associated 95% confidence interval (from 1000 1000 (from interval confidence 95% associated their : - P 0.03

3]

values) of the top ranked model (using restricted (using model ranked top the of values)

] S. polaris S.

]

1.26 4.52 - t - - 2.59

1.88 1.82 2.32

Ring

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This article isThis article by protected copyright. All rightsreserved. Accepted Landsat confounds wetness Increased (2016) D.A. Walker, & M.K. Raynolds, Bret M.C., Forchhammer, E., Post, reversing trends and events extreme browning: Arctic (2016) J.W. Bjerke, & G.K. Phoenix, (2005) N.C. Stenseth, & C.J. Tucker, J.M., Gaillard, A., Mysterud, J.O., Vik, N., Pettorelli, Peres tree the in years pointer extreme and Dendrochronology (2016) M. ArticleOpała, & P. Owczarek, A., Nawrot, P., Owczarek, Opała - - eo P (99 Hw ay ttsia ts ae o mn? h polm f conducting of problem The many? too are test statistical many How (1999) P. Neto, Owczarek, M., Pirożnikow, E., Owczare E., Pirożnikow, M., Owczarek, species ( species plant vascular two of growth the on factors abiotic of influence The (2018) K. Migała, 2012. 1898 series, temperature Airport Svalbard extended the Spitsbergen: on variability and climate change. B., greening. arctic T satellite the Using multiple ecological inferences revisited. Norway). 1951 (AD record 43, high small in change climate contemporary to 232. rends

. . . Aastrup, P. (2009) Ecological dynamics across the Arctic associated with recent with associated Arctic the across dynamics Ecological (2009) P. Aastrup, . . . 384

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- in Ecology andEvolution 402. Saxifraga oppositifolia Saxifraga Geochronometria,

Global ChangeBiology, Science, - – derived NDVI to assess ecological responses to environmental change.environmental to responses ecological assess to NDVIderived

Migała, K., Malik, I. & Korabiewski, B. (2014) Flood (2014) B. Korabiewski, & I. Malik, K., Migała, 01 o plr ilw rm otwsen ptbre (Svalbard, Spitsbergen southwestern from willow polar of 2011)

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1355

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Mari k, P., Szymański, W., Luks, B., Kępski, D., . . . . . D., Kępski, B., Luks, W., Szymański, P., k, 22,

- 510.

2960 ne Ecology ProgressSeries, -

arctic basins (Svalbard, Norway). (Svalbard, basins arctic

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This article isThis article by protected copyright. All rightsreserved. Accepted (2016) T.N. Hollingsworth, & S.M.P. Cahoon, A.H., Brownlee, R.R., Pattison, P.F., Sullivan, Otter A., Mysterud, N.C., Stenseth, alpine of response The (2013) A. Mysterud, & A.J. Hester, G., Austrheim, J.D.M., Speed, leaf and root in synchrony Contrasting (2016) G.K. Phoenix, & B.J. Fletcher, V.L., Sloan, growing of length and browsing simulated of Effects (2002) R. Wal, der Van & Article C. Skarpe, an ecosystem: ImageJ The (2015) K.W. Eliceiri, & M.C. Hiner, C.T., Rueden, J., Schindelin, Rønning, O.I.(1996) Angers P., Ropars, collars ve collars root in stronger is growth of sensitivity climate stories: different parts, Different (2017) Letters, r Slope North Alaska central the in trends spruce in Alaska. in spruce interior tree of Effect effectsEcological ofclimate fluctuations. andAntarctic, Research, Alpine long to shrubs 248. sub multiple across phenology Antarctic,Arctic, andAlpine Research, shrub, arctic deciduous a in flowering and characteristics leaf on season 82, for platform open

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- 085004. Blondin, S., Gagnon, M., Myers M., Gagnon, S., Blondin,

The ofSvalbard flora - ig ernig ehd on method detrending ring - term browsing varies with elevation and herbivore density. density. herbivore and elevation with varies browsing term biomedical image analysis. image biomedical

Environmental ResearchEnvironmental Letters, e, . Hrel JW, hn K. Chan, J.W., Hurrell, G., sen, -

arctic plant communities. plant arctic 45, . Norsk Polarinstitutt,Oslo,Norway.

584 Global ChangeBiology,

34, - 593. Science,

282 paet rwh rns f lc ad white and black of trends growth apparent go, 1985 egion,

- Molecular Reproduction and Development, and Reproduction Molecular Smith, I.H., Levesque, E. & Boudreau, S. Boudreau, & E. Levesque, I.H., Smith, - 286.

297,

1292 – 2011.

Journal of Ecology, of Journal 11, - 1296.

23, 114007. niomna Research Environmental - . Lm, . (2002) M. Lima, & S.

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This article isThis article by protected copyright. All rightsreserved. Lo R., Broekman, P., Eidesen, Bronken I., Alsos, Greve S., Weijers, D., Blok, A., Buchwal, S., Weijers, Heijma P., Wang, Vi High (2014) A. Stien, & R. Wal, der Van (2000) S.D. Albon, & R. Langvatn, C., Dormann, S., Lieshout, van N., Madan, R., Wal, der Van w food terrestrial and aquatic Analogous (2009) D.O. Hessen, & R. Wal, der Van environments. polar in moulds Snow (2012) K.K. Newsham, & M. Tojo, gradients. auxin and growth Cambial (2000) H. Tuominen, & C. Uggla, B., Sundberg,

Accepted B.B. Hansen, & R. Aanes, H., Tømmervik, S., Karlsen, S., Solbø, K.A., Høgda, H., ckers, Article 395 169 Formation Wood of Biology Molecular polar desert.polar increased by tracked warming with temperature. relationship its and ecosystems tundra in allocation biomass plant Belowground (2016) max NDVI forSvalbard. dataset AVHRR year 30 a from insights arctic: high the in greening in Changes (2016) between reindeer. for quality forage Trading and Systematics, climate. harsh a of force structuring the arctic: - - 402. 188. -

year variability in plant biomass. Oecologia, BIOS Scientific Publishers, Oxford, UK. ns, M.M.P.D., Mommer, L., van Ruijven, J., Maximov, T.C. & Berendse, F. F. Berendse, & T.C. Maximov, J., Ruijven, van L., Mommer, M.M.P.D., ns, Global ChangeBiology,

11, Environmental Research Letters,

231 123, -

240. 108

Environmental Research Letters, quantity? Plant phenology and patch choice by Svalbard Svalbard by choice patch and phenology Plant quantity? -

115. ofe, J. Loffler, asoe tetragona Cassiope

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23, (eds R.A. Savidg R.A. (eds

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Ecology, Ebrig B (07 Hg aci summer arctic High (2017) B. Elberling, & - 5020. Perspectives in Plant Ecology, Evolution Ecology, Plant in Perspectives

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055003. 3414 e, J.R. Barnett & R. Napier), pp. Napier), R. & Barnett J.R. e, -

3427. 11,

onen, M.J. & Rozema, J. J. Rozema, & M.J. onen,

105004.

- term investigation of investigation term ugl Ecology, Fungal

ebs in the high the in ebs Cell and Cell

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This article isThis article by protected copyright. All rightsreserved. Accepted proxy of calibration numerical the for package R an treeclim: (2015) F. Biondi, & C. Zang, Time (2015) W. Zhao, & B. Tang, K., Huang, T., Zhou, S., Liang, X., Zhao, D., Wu, . . . J.H.C., Cornelissen, K.A., Bråthen, F., Baptist, R.D., Bardgett, R., Aerts, P.A., Wookey, C. Völlm, . . . W., Hahne, F., Babst, T., Kyncl, R., Bogaert, Van M., Hallinger, M., Wilmking, series, time correlated of value average the On (1984) P.D. Jones, Article& K.R. Briffa, T.M., Wigley, p Primary (1981) G. Doyle, & J. Svoboda, L.C., Bliss, F.E., Wiegolaski, & J. Löffler, R., Pape, S., Weijers, o al sme tmeaue laig o orsodne f hu got patterns. growth shrub of correspondence to leading temperatures summer early to Botany, multi under and gradient temperature latitudinal in divergence No (2012) 3531. c climate to responses vegetation global of Change Biology, change. environmental to ecosystems alpine and arctic of responses the in role thei understanding processes: cascade and feedbacks Ecosystem (2009) G.R. Shaver, Dendrochronologia, in rings outer missing Continuously (2012) meteorology, applied hydrometeorology. and dendroclimatology in applications with pp. 187 analysis comparative a ecosystems: Tundra ResearchEnvironmental Letters,

-

225. 110,

653 Cambridge University Press, Cambridge, Press, Cambridge University UK.

- 15, 665.

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- Smith, I.H. (2018) Contrasting shrub species respond species shrub Contrasting (2018) I.H. Smith,

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woody plants at their distributional margins. distributional their at plants woody

hange. (eds L.C. Bliss, O.W. Heal & J.J. Moore), J.J. & Heal O.W. Bliss, L.C. (eds pritne f rwh epne ln a along response growth of persistence : -

year experimental warming. experimental year lbl hne Biology, Change Global

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This article isThis article by protected copyright. All rightsreserved. AcceptedFig. monthlysummer temperature and Fig Fig Fig. Fig. S2 Fig. S1. including reindeer abundance. Table S Table Table S ArticleTable S1. Appendix I. Additional supporting i Supporting i (2009) G.M. Smith, & A.A. Saveliev, N.J., Walker, E.N., Ieno, A.F., Zuur, . . S5 S4 S3 S 6 S . . . . . and extensions ecology in R with climate relationships.

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