An 854-year tree-ring chronology of Scots pine for south-west Finland

S udia Qua e na ia, ol. 31, no. 1 (2014): 61–68. DOI: 10.2478/squa-2014-0006 AN 854-YEAR TREE-RING CHRO NOL OGY OF SCOTS PINE FOR SOUTH-WEST FIN LAND Samuli Helama1, Ja i Holopainen2, Mau i Timonen3, Ka i Mielikäinen4 1 Finn ish Fo es Re sea ch In s i u e, No h e n Uni , P.O. Box 16, 96301 Ro aniemi, Fin land, e-mail: [email p o ec ed] 2 De pa men o Geosciences and Ge og a phy, P.O. Box 64, 00041 Uni e si y o Hel sinki, Fin land, e-mail: ja i.a.holopainen@hel sinki. i 3 Finn ish Fo es Re sea ch In s i u e, No h e n Uni , P.O. Box 16, 96301 Ro aniemi, Fin land, e-mail: [email p o ec ed] 4 Finn ish Fo es Re sea ch In s i u e, Sou h e n Uni , Van aa, P.O. Box 18, 01301 Fin land, e-mail: [email p o ec ed] Ab s ac A nea -mil len nial ee- ing ch o nol ogy (AD 1147–2000) is p e sen ed o sou h-wes Fin land and an a lyzed us ing dend oclima ic me h ods. This is a com pos i e ch o nol ogy com p is ing sam ples bo h om s and ing pine ees (Pinus syl es is L.) and sub ossil unks as e co e ed om he lake sed i men s, wi h a o al sam ple size o 189 ee- ing sam - ple se ies. The se ies we e dend och onologically c oss-da ed o ex ac cal en da yea s o po ay a i abil i y in ee- ing wid hs on in e -an nual and lon ge scales. Al hough he s ud ied ch o nol ogy co e la es s a is i cally sig ni i can ly wi h o he long ee- ing wid h ch o nol o gies om Fin land o e hei com mon pe iod (AD 1520–1993), he sou h-wes ch o nol ogy did no ex hibi sim i la ly s ong mid-sum me em pe a u e o sp ing/ea ly-sum me p e cip i a ion sig nals in com pa i son o pub lished ch o nol o gies. On he o he hand, he sou h-wes ch o nol ogy showed high es co e la ions o he No h A lan ic Os cil la ion in di ces in win e /sp ing mon hs, his as so ci a ion ol low ing a dend oclima ic ea u e com mon o pine ch o nol o gies o e he e gion and ad ja cen a eas. Paleoclima ic com pa i son showed ha ee- ings had a ied sim i la ly o cen al Eu o pean sp ing em pe a u es. I is pos u la ed ha he col lec ed and da ed ee- ing ma e ial could be s ud ied o wood su ace e lec ance (blue chan nel ligh in en si y) and s a ble iso opes, which bo h ha e e - cen ly shown o co e la e no ably well wi h sum me em pe a u es. Key wo ds: dend och onology, No h A lan ic Os cil la ion, paleoclima e, Pinus syl es is, sub ossil wood. Manu sc ip e cei ed 29 Oc obe 2013, ac cep ed 20 May 2014 IN TRO DUC TION T ee ings p o ide la e Qua e na y paleoen i onmen al e co ds (B adley, 1999; Walke , 2005). Mil len nia-long ee- ing ch o nol o gies ha e e cen ly been con s uc ed in Fenno- scan dia whe e hei de el op men is an on go ing ac i i y (Linde holm e al., 2010). These e co ds con sis o com pos - i e ch o nol o gies whe e he li ing- ee se ies a e com bined wi h ee- ing se ies om sub ossil unks o pine, usu ally p e se ed in subae ial con di ions o sed i men a y a chi es o small lakes o bogs (Ba holin and Ka lén, 1983; E onen e al., 1999, 2002; G udd e al., 2000, 2002; Linde holm and Gunna son, 2005). Ma jo i y o hese ch o nol o gies o ig i na e om e gions nea he im be line. Con s uc ion o long ch o - nol o gies is how e e pos si ble also o mo e sou h e n e gions, ei he sim i la ly us ing na u ally p e se ed wood o by u i liz - ing sam ples om his o i cal build ings (Ba holin, 1987; Läänelaid and Ecks ein, 2003; Kop owski e al., 2012). The alue o hese e co ds o paleoen i onmen al s ud ies has been p o en as he ee- ing ch o nol o gies ha e p o ided in - o ma ion o pas cli ma e a i abil i y om in e -an nual o mil - len nial scales and o a i ous spa ial do mains (G udd e al., 2002; Helama e al., 2002, 2009a, 2009b, 2009c, 2010; Helama and Lindholm, 2003; Linde holm and Gunna son, 2005; Goui and e al., 2008). He e we dem on s a e he de el op men and cha ac e is - ics o a nea -mil len nial ee- ing ch o nol ogy o Sco s pine o a si e in sou h bo eal o es zone in sou h-wes Fin land. This is a e gion whe e no such long ee- ing e co d has been a ail able be o e he de el op men o his ch o nol ogy and whe e no sub ossil wood e co e ed om lake sed i men s ha e p e i ously been used o con s uc ion o ee- ing ch o - nol o gies. P e i ously, he mos e cen pa o he ch o nol ogy has been used o dend oclima ic e sea ch and com pa ed wi h in s u men ally ob se ed cli ma e e co ds om he same e gion (Holopainen e al., 2006). Sim i la ly, he ch o nol ogy was com pa ed wi h la ge-scale cli ma e in di ces (No h A lan - ic Os cil la ion NAO; Hu ell, 1995; Hu ell e al., 2001). These s ud ies ound ou he sen si i i y o he ch o nol ogy o con di ions in win e (Helama and Timonen, 2004) and sp ing B ough o you by | Me la Finnish Fo es Resea ch Ins i u e Au hen ica ed Download Da e | 12/15/16 11:44 AM (Holopainen e al., 2006) cli ma e. How e e , he co e la ion o sp ing em pe a u e a i abil i y ap pea ed em po ally un s a - ble (Holopainen e al., 2006). Mo e o e , he ch o nol ogy was co e la ed wi h se e al o he ee- ing ch o nol o gies o Sco s pine om ad ja cen a eas o e eal ha hei spa ial co ela- i i y likely e lec s he pas luc u a ions in he NAO (Lääne- laid e al., 2012). Ou ob jec i e he e is o de ail he ch o nol ogy con s uc - ion by dem on s a ing i s em po al cha ac e is ics in sam ple size and ch o nol ogy con i dence, in ad di ion o he ee- ing wid h a i a ions. Mo e o e , he dend oclima ic co e la ions a e de i ed us ing lo cal cli ma e da a and he NAO in di ces. This p o ce du e ol lows ou p e i ous anal y ses o la e Ho lo - cene ee- ing ch o nol o gies om Fin land (Helama e al., 2005) hus en abling com pa i sons o hese ch o nol o gies and cha ac e iz ing he p op e ies o he sou h-wes Finn ish ch o - nol ogy as paleoen i onmen al e co d. Ad di ional com pa i - son is made o he sub ossil pa o he ch o nol ogy by com- pa ing he ee- ing a i a ions in he s udy e gion wi h he em pe a u e a i abil i y as e con s uc ed o cen al Eu ope us ing doc u men a y da a (P is e and B ádzil, 1999) o e he 16 h cen u y. MA TE RIAL AND METH ODS Ou ee- ing ma e ial o ig i na es om Lake Kai ajä i and Lake Vähä-Melku injä i (60°40' N, 23°35' E) si u a ed in sou h-wes Fin land (Fig. 1). The si e is lo ca ed in he sou h bo eal zone (Ah i e al., 1968). This ee- ing da ase o Sco s pine (Pinus syl es is L.) com p ise 189 se ies. Li ing ee samples we e co ed a he m ees g ow ing a he sho e us ing in c e men bo e a b eas heigh . Sub ossil sam ples we e e - co e ed om lake sed i men s. Disks we e cu by saw a e li ing he unks o he su ace and sam pled unks we e e - u ned in o he lake. Se ies o ee- ing wid hs we e p o duced by mea su ing he ing-wid hs un de a ligh -mi c o scope o he nea es 0.01 mm. The sam ple se ies we e da ed us ing ee- ing c oss-da ing, a ou ine o dend och onology, whe e he em po al a i abil i y o con spic u ously wide and na ow ings a e ex am ined and each ing can be da ed o ex ac cal en da yea s (F i s, 1976). C oss-da ing was ob ained us ing nu me - i cal p o ce du es (Hol- mes, 1983; Van Deusen, 1990), in ad - di ion o i sual com pa i son o he plo ed mea su e men se ies on he com pu e sc een. The da ing p o cess ini i a es om he c oss-da ing o se ies om li ing ees. The sub ossil se ies a e c oss-da ed agains each o he and he sub ossil ch o nol - ogy is c oss- da ed agains he ob ained ch o nol ogy o li ing ees. The i nal ch o nol ogy com p ises 47 sam ple se ies om li ing pines and 142 sub ossil se ies. Mean leng h o he se - ies was 143 yea s. The ch o nol ogy co e ed he pe iod AD 1147–2000. Fol low ing p e i ous ee- ing s ud ies in ad ja cen a eas (Helama e al., 2005, 2013), he dou ble-de ending o he ee- ing se ies was ca ied ou . To do so, in di id ual ee- ing se ies we e ans o med in o in dexed se ies in he p o cess called ee- ing s an da d iza ion (F i s, 1976; Cook, 1985; Helama e al., 2004). This was done o e mo e he age-size e la ed end in a dial g ow h us ing he mod i ied neg a i e ex - po nen ial cu e, lin ea e g es sion line o line h ough he se - ies mean (F i s e al., 1969). In di ces we e de i ed om he mod eled cu e by di i sion. Sec ond, a spline unc ion (Cook and Pe e s, 1981) was i ed o he se ies o hese in di ces and a new se ies o ee- ing in di ces we e ex ac ed om his cu e as a ios. The i gid i y o he spline was de e mined o be wo- hi ds o he leng h o each in di id ual ime se ies (50 % e quency e sponse cu -o ). Thi d, he sec ond se o in di - ces was p e-whi ened us ing Box and Jenkins (1970) me h ods o au o eg essi e and mo ing a e age ime se ies mod el ing (Cook, 1985). The a io nale us ing his h ee-s ep p o cess lies as ol lows. The i s de ending is ex pec ed o e mo e he long- e m g ow h end om he ee- ing mea su e men se - ies and o s a bi lize hei a i ance. The sec ond de ending is ex pec ed o e mo e g ow h a i a ion e la ed o dis u bance caused by o es dy nam ics wi h ad di ional a i ance s a bi li za - ion (F i s, 1976; Cook e al., 1990a; Helama e al., 2004). P e-whi en ing ans o ms au oco ela ed se ies in o se i ally in de pend en ob se a ions (Cook, 1985; Monse ud, 1986). Ex p essed pop u la ion sig nal (EPS) was used as in di ca ion o ch o nol ogy e li abil i y. The EPS p o ides an ex p es sion o com mon a i abil i y among he a ail able ee- ing se ies h ough ime. The p e-de e mined limi o EPS > 0.85 can be used as a ea son able al bei ob jec i e alue o an ac cep able le el o ch o nol ogy con i dence (Wigley e al., 1984). 62 S. HELAMA e al. Fig. 1.Lo ca ion o he s udy si e in sou h-wes Fin land (SW) and e gions om which he o he long ch o nol o gies o ig i na e in no h - e n Lapl and (NL), Pääjä i (PJ), No h Ka elia (NK) and sou h-eas Fin land (SE). B ough o you by | Me la Finnish Fo es Resea ch Ins i u e Au hen ica ed Download Da e | 12/15/16 11:44 AM T ee- ing ch o nol o gies we e p o duced by a e ag ing he an - nual al ues o in di ces us ing a bi-weigh o bus mean (Cook, 1985; Cook e al., 1990b). In o de o ad jus he ch o nol ogy a i ance o sam ple size, each an nual alue was scaled by an e ec i e num be o in de pend en sam ples a ail able in each yea as dem on s a ed by Osbo n e al. (1997). The long- e m and pe iod a i a ions in he ch o nol ogy we e il lus a ed by ap ply ing a smoo h ing spline unc ion (Cook and Pe e s, 1981) o he an nual ch o nol ogy al ues. He e a e , he p e- whi ened in di ces we e used in he anal y ses, i no o h e wise men ioned. Lo cal cli ma ic da a was adop ed as mean mon hly em - pe a u es and p e cip i a ion sums as es i ma ed (Fig. 2) om he cli ma e e co ds made by he Finn ish Me e o o log i cal In - s i u e (Ojansuu and Hen onen, 1983). Mo e o e , he mon hly in di ces o he No h A lan ic Os cil la ion (NAO; Hu ell, 1995) we e used o com pa i sons. The a i a ions de - sc ibed by he NAO in di ces a e cha ac e ized by he os cil la - ion o a mo sphe ic masses p o duc ing la ge-scale changes in he mean wind speed and di ec ion o e he No h A lan ic, whe e he pos i i e (neg a i e) NAO phases com monly oc cu wi h s eng h ened (a en u a ed) wes e lies and hus milde and mois e (coole and d ie ) win e s and sp ing ime con di - ions on lo cal scale (U o and Be nd sson, 2002; Helama and Holopainen, 2012). Pea son co e la ion co e i cien s we e com pu ed be ween hese cli ma ic e co ds and he ee- ing ch o nol ogy. Co e la ions we e cal cu la ed o e he pe iod 1909–1993. The pa ic u la pe iod was com mon o ou p e i - ous anal y ses (Helama e al., 2005) hus mak ing he dend o- cli ma ic co e i cien s be ween ha and his s udy com pa a ble wi h each o he . RE SULTS T ee- ing p op e ies On a e age, he mod e n and sub ossil pine se ies con - ained 109 and 154 ings wi h mean a dii (sum o mea su ed ARWs) o 164 and 150 mm, e spec i ely, hese al ues ans - la ing in o ab so lu e g ow h a es o 1.50 and 0.97 mm/yea . These ig u es in di ca e ha he co ed pines had g own as e han he an cien pines e co e ed om he lake sed i men . The old es li ing pine was mo e han 233 yea s old. I s i s ing a b eas heigh had g own in 1768. In com pa i son, he bi o log i - cally old es sub ossil pine con ained 309 ings. Ch o nol ogy con i dence Sam ple size luc u a es h ough ime wi h high es num be o ep li ca ion du ing he 18 h cen u y (Fig. 3). Pe i ods o low sam ple ep li ca ion oc cu du ing he las hal o he 19 h cen - u y and be o e 17 h cen u y. Co e la ion among ee- ing se - ies a e aged 0.275 and 0.272, e spec i ely, as cal cu la ed om de ended and u he p e-whi ened in di ces. Us ing hese al ues and he EPS-s a is ic, he ch o nol o gies build us - ing de ended and u he p e-whi ened in di ces showed he EPS-s a is ic o e he p e-de e mined le el o 0.85 con in u - ously since 1264. T ee- ing luc u a ions Ch o nol o gies il lus a ed ee- ing g ow h a i a ions on in e -an nual o lon ge scales (Fig. 4). The mos anom a lous AN 854-YEAR TREE-RING CHRO NOL OGY OF SCOTS PINE 63 Fig. 2.Omb o he mic di a g am o long- e m mean mon hly em - pe a u es (T) and mon hly p e cip i a ion sums (P) in he lo cal i y o e he dend oclima ic s udy pe iod (1910–1993). Fig. 3.T ee- ing ch o nol ogy o sou h-wes Fin land. Each sam - ple o he ch o nol ogy, ep e sen ed by a ho i zon al ba , is shown in i s po si ion co e spond ing o he dend och onological c oss-da ing (a). Rep li ca ion o he sam ples as a unc ion o ime (b). The ex - p essed pop u la ion sig nal (EPS) and i s em po al a i a ions el a i e o he p e-de e mined le el o 0.85 (ho i zon al dashed line) (c). B ough o you by | Me la Finnish Fo es Resea ch Ins i u e Au hen ica ed Download Da e | 12/15/16 11:44 AM pos i i e in di ces we e ound in 1384, 1434, 1341 and 1406. No sim i la ly pos i i e in di ces oc cu ed in he cou se o he 20 h cen u y. The eye-ca chingly anom a lous neg a i e g ow h in di ces we e ound in 1328, 1369, 1377, 1608 and 1823. Du - ing he 20 h cen u y, he yea s 1917, 1940 and 1969 un de - wen sim i la ly neg a i e in di ces. No a ble pe i ods o amelio- a ed g ow h oc cu ed in he 1380s, 1540s and 1750s. Co e - spond ing pe iod o de e i o a ed g ow h we e e i den in he 1460s, 1530s, 1770s. This shows ha he pe iod om 1530s o 1540s ex pe i enced a ma ked change in he g ow h om low o high in dex al ues. Dend oclima ic co e la ions T ee- ings we e ound o co e la e s a is i cally sig ni i - can ly wi h se e al mon hly cli ma ic a i ables as ol lows. Pos i i e co e la ions we e ound o em pe a u es in Feb u - a y and Ma ch (Fig. 5a). Cal cu la ing he co e la ion be ween he ee- ing ch o nol ogy and he Feb u a y–Ma ch em pe a - u e se ies showed a co e la ion co e i cien o 0.338 (p<0.01). This in di ca es ha he ee- ing g ow h was ben e i ed om mild win e con di ions p io o he ac ual s a o he g ow ing sea son. Mo e o e , he ee- ing ch o nol ogy co e la ed pos i - i ely wi h p e cip i a ion in Ma ch and June (Fig. 5b). Since he lo cal Ma ch mean em pe a u e yp i cally e mains be low ze o (Fig. 2), he co ela i i y o Ma ch p e cip i a ion likely dem - on s a es he pos i i e e ec s om in c eased snow all on hese pines. NAO-co e la ions S a is i cally sig ni i can co e la ions o he NAO in di ces we e ound o win e and sp ing mon hs p e ced ing he g ow ing sea son in De cem be , Feb u a y, Ma ch and May (Fig. 5c). High es co e la ion be ween he NAO in di ces and ee- ings was ound o a mul i-mon hly sea son (De cem be h ough May) com bin ing he win e and sp ing mon hs. This co e la ion showed a co e i cien o 0.483 (p<0.01). This mul i-mon hly NAO in dex ec og nized i m link ages wi h he lo cal em pe a u e and p e cip i a ion e co ds wi h s a is i cally sig ni i can co e la ion co e i cien s o 0.628 (p<0.01) and 0.295 (p<0.01), e spec i ely. These as so ci a ions dem on - s a e he NAO-d i en e ec s on he lo cal win e (De cem be h ough May) cli ma e a i abil i y whe e he wes e ly winds, as in di ca ed by he pos i i e NAO in dex, a i e in o he e gion wi h wa me and mo e hu mid ai masses. 64 S. HELAMA e al. Fig. 4.T ee- ing ch o nol o gies based on de ended (a) and u he p e-whi ened (b) in di ces. Long- e m a i a ions o he ch o nol o gies a e high ligh ed us ing hei smoo hed e sions (c). The smoo hed ch o nol o gies a e shown since hei EPS-s a is ic ex ceed he 0.85 le el (Fig. 3c). Fig. 5.Dend oclima ic co e la ions com pu ed be ween he mon hly cli ma e a i ables and ee- ings (AD 1910–1993). Col - umns show he co e la ion co e i cien s o em pe a u e (a) and p e - cip i a ion (b) a i ables as well as he in di ces o he No h A lan ic Os cil la ion (NAO) (c) o he p e i ous (small le e s) and con cu en yea (cap i al le e s). S a is i cally sig ni i can e la ion ships a e in di - ca ed as black (0.01 le el) and g ay (0.05 le el) his o g ams. B ough o you by | Me la Finnish Fo es Resea ch Ins i u e Au hen ica ed Download Da e | 12/15/16 11:44 AM DIS CUS SION We ha e dem on s a ed he main cha ac e is ics o he nea -mil len nial ee- ing ch o nol ogy om sou h-wes Fin - land. Com pa i son be ween his ch o nol ogy wi h o he long Finn ish ee- ing ch o nol o gies o Sco s pine show ha he ee- ing a i a ions o he s ud ied ch o nol ogy co e la e bes wi h he ch o nol ogy om sou h-eas Fin land (Fig. 6), ha is, wi h i s geo g aph i cally clos es e co d. Mo e o e , he co e la - ions de c ease sys em a i cally as he dis ance be ween he ch o nol o gies in c eases. This de cline oc cu s in ac co d wi h he p e i ous iews on spa ial ee- ing co ela i i y in Fenno- scan dia (Schweing ube , 1988; Helama e al., 2005) and likely e sul s, in pa , om de c eas ing sim i la i y be ween he cli ma e a i abil i y wi h in c eas ing dis ance. E en a s on ge ac o be hind he de cline is likely o o ig i na e om dis sim i - la i y o ee- ing g ow h e sponse o cli ma e in di e en eco - log i cal po si ions om sou h e n bo eal o es s o he no h e n im be line. Com pa i son o hese dend oclima ic e la ion - ships is p e sen ed below. Cold sea son and hyd oclima e sig nals Ou e sul s con i med he p e i ous ind ings ha hese ee- ings co e la e no ably wi h he cli ma ic a i ables in win e and sp ing sea sons (Helama and Timonen, 2004; Holopainen e al., 2006) and ha he ee- ing a i abil i y ol - lows he pos i i e and neg a i e NAO phases a leas o e he in s u men al pe iod (Helama and Timonen, 2004; Läänelaid e al., 2012). The NAO is an a mo sphe ic os cil la ion o syn - op ic scale o e he No h A lan ic sec o whe e he wes e - lies b ing wa me and mois e ai -masses on o s udy e gion (U o and Be nd sson, 2002; Helama and Holopainen, 2012). This con di ion is dem on s a ed by he pos i i e NAO in dex. In i s op po si e phase, he wes e lies a e a en u a ed wi h p e - dom i nance o coole and d ie con di ions o e he no h-wes Eu ope (Hu ell, 1995; Hu ell e al., 2001). In his s udy, he a mo sphe ic phe nom e non was in di ca ed by ma k edly pos i - i e co e la ions be ween he NAO in dex and he lo cal em - pe a u e and p e cip i a ion a i abil i y du ing he win e and sp ing sea sons. Com pa i son o he NAO-co e la ions in sou h-wes Fin land wi h p e i ously es ab lished NAO-co e - la ions (Helama e al., 2005) shows ha he win e (De cem - be ) NAO in dex co e la es wi h pine g ow h o e ex ended a eas (Fig. 7a). Sim i la co ela i i y o Sco s pine ee- ings o win e NAO in dex has been ob se ed o e mul i ple si es in Fin land, Es o nia, Go land, and no h-wes Rus sia (Lindholm e al., 2001). Mo e o e , i has been ound ha he p o longed pe i ods o pos i i e NAO phase come wi h in c eased co e la - ion be ween he ee- ing ch o nol o gies o e he same e gion h ough he pas mil len nia (Helama e al., 2005; Läänelaid e al., 2012). I is e i den ha he ee- ing g ow h is gen e ally ben e i - ed om he mild and mois win e /sp ing con di ions h ough Fin land and ad ja cen a eas as in ac e i denced by s a is i - cally sig ni i can co e la ions o em pe a u e (Feb u a y h ough Ma ch; Fig. 5a) and p e cip i a ion (Ma ch; Fig. 5b) a i ables o cold sea son. The mos ob i ous paleoen i on- men al change as in di ca ed by he ch o nol ogy oc cu ed as he mid-1500s e en , when he an oma lously low in di ces in he 1530s we e ol lowed by he high in dex al ues in he 1540s. O no e, P is e and B ádzil (1999) de ailed he em pe a u e and p e cip i a ion a i a ion in cen al Eu ope us ing doc u men - a y da a. They u he e con s uc ed cli ma e a i abil i y o e he 16 h cen u y us ing de cad al es i ma es o pas em pe a u e and p e cip i a ion. We com pa ed hei e con s uc ions o decadally a e aged ee- ing in di ces om sou h-wes Fin - land and ob ained high es co e la ion wi h co e i cien o 0.751 (p<0.05) ea son ably o a sp ing em pe a u e as so ci a - ion (Fig. 8). Mo e o e , he em pe a u e e con s uc ion (P is e and B ádzil, 1999) ex hib i ed a pos i i e change o - wa ds he 1540s, com pa a ble o in di ca ions by he s ud ied ee- ing ch o nol ogy. These ind ings im plied a a he sim i la sp ing em pe a u e changes in cen al and no h e n Eu ope, a leas on de cad al scale, du ing he 16 h cen u y. In a p e i - ous anal y sis, he SW Finn ish ee- ings we e seen o co e la e pos i i ely wi h e con s uc ed and in s u men ally e co ded sp ing em pe a u e a i a ions in he same e gion since 1750s (Holopainen e al. 2006). The s eng h o he co ela i i y was howe e empo ally uns able. Simila ly, he co espon- AN 854-YEAR TREE-RING CHRO NOL OGY OF SCOTS PINE 65 Fig. 6.Co e la ions be ween he ee- ing ch o nol ogy o his s udy and he o he long Finn ish ee- ing ch o nol o gies (Helama e al., 2005) o ig i na ing om no h e n Lapl and (NL), Pääjä i e gion (PJ), No h Ka elia (NK), and sou h-eas Fin land (SE) (see also Fig. 1). Co e la ions we e cal cu la ed o e he com mon pe iod (AD 1520–1993). All co e la ions a e s a is i cally sig ni i can (p<0.01). Fig. 7.Com pa i son o he Finn ish mil len nial ee- ing ch o nol o - gies us ing hei dend oclima ic co e la ions (Helama e al., 2005) o No h A lan ic Os cil la ion (NAO) in dex in De cem be p e ced ing he g ow ing sea son (a), p e cip i a ion in June (b), em pe a u e in July (c), and hei ee- ing in di ces in AD 1601 (d). Ch o nol o gies o ig i - na e om no h e n Lapl and (NL), Pääjä i e gion (PJ), No h Ka elia (NK), sou h-eas Fin land (SE) and his s udy (SW) (see also Fig. 1). B ough o you by | Me la Finnish Fo es Resea ch Ins i u e Au hen ica ed Download Da e | 12/15/16 11:44 AM dence be ween he wo eco ds he e (Fig. 8) is somewha mu ed du ing he las decades o he 16 h cen u y. P e i ously, he mil len nial ee- ing ch o nol ogy o Sco s pine om sou h-eas Fin land was used as a p oxy e co d o e con s uc ing he paleoclima ic a i a ions in pas sp ing– sum me (May h ough June) p e cip i a ion (Helama and Lin- dholm, 2003; Helama e al., 2009b). Sim i la ly, he ee- ings co e la ed s a is i cally sig ni i can ly wi h June p e cip i a ion in sou h-wes e n Fin land (Fig. 5b). How e e , he dend ocli - ma ic sig nal o sum me p e cip i a ion was no a bly lowe in sou h-wes Fin land, in com pa i son o he s eng h o his sig - nal in ee- ing g ow h in sou h-eas Fin land (Fig. 7b). In e - es ingly, his dend oclima ic e la ion ships was ound as ma k edly pos i i e only o he si es in sou h bo eal o es s, in sou h-wes and sou h-eas Fin land, in com pa i son o he mo e no h e n si es in Finland whe e he co ela ion appea- ed nega i e (Fig. 7b). Sum me em pe a u e sig nals In Fennoscandia, he lon ges ee- ing ch o nol o gies ha e been com monly buil o no h e n im be line e gions whe e he u i li za ion o subea ial wood (Si én, 1961; Ba - holin and Ka lén, 1983; Ba holin, 1987) as well as he e - co e y o sub ossil pine unks as p e se ed wi hin lake sed i - men s (i.e., mega ossils) s a ed se e al de cades ago (E o- nen, 1979). These ch o nol o gies ha e o en imes been used as p oxy e co ds o e con s uc ing he paleoclima ic em pe a - u e a i a ions h ough pas mil len nia (G udd e al., 2002; Helama e al., 2002, 2009a, 2009c, 2010; Linde holm and Gunna son, 2005; Goui and e al., 2008). Na u ally, hei paleoclima ic alue de pends on hei s ong dend oclima ic sig nal o sum me em pe a u es. Also he sou h-wes ch o nol - ogy e la es pos i i ely wi h mid-sum me (July) em pe a u es (Fig. 5a) bu he s eng h o his co e la ion is dwa ed by he high as so ci a ion be ween mid-sum me em pe a u es in he ee- ing ch o nol o gies om mo e no h e n a eas (Fig. 7c). Ye an o he sui able way o s udy ing his paleoclima ic sig - nal in Finn ish ee- ing ch o nol o gies is he com pa i son o ee- ing in di ces o he ch o nol o gies in AD 1601 (Helama e al., 2005; Helama e al., 2009a). This yea is known as one o he mos ob i ous sig na u e yea s in he no h e n ee- ing ch o nol o gies (B i a e al., 1998) ol low ing he sum me ime cool ing o e he No h e n Hemi sphe e due o he e up ion o Huaynapu ina ol cano (Pe u) ha had oc cu ed in he p e i - ous yea (de Sil a and Zielinski, 1998). As a e sul o his cool ing, he im be line ee- ings dem on s a ed mos se e e e duc ion in hei g ow h, as in di ca ed by hei e y low ee- ing in dex, in AD 1601 (Fig. 7d). A sim i la , al bei a en - u a ed, g ow h e ac ion was ob se ed in mo e sou h e n ch o - nol o gies, wi h a pa e n o g ad u ally weake e sponse o- wa ds he sou h, wi h he high es ee- ing in dex in AD 1601 in he sou h-wes Finn ish ch o nol ogy (Fig. 7d). I is ob i ous ha he s ud ied ch o nol ogy pos sesses a neg li gi ble sum me em pe a u e sig nal in i s ee- ings, in com pa i son o ch o nol - o gies om mo e no he n a eas. Al hough he sum me em pe a u e sig nal in he sou h- wes Finn ish ch o nol ogy o ee- ing wid hs ap pea ed mean - ing less, he col lec ed ee- ing ma e ial could p o ide an im - p o ed paleoclima ic em pe a u e p oxy a chi e o anal y ses o he su ace e lec ance o he la e wood po ion o each an - nual ing o de e mine he min i mum blue chan nel ligh in en - si y (BI). P e i ous s ud ies ha e shown ha he BI p o ides a highly skilled su o ga e o la e wood den si y o high-la i ude pine ee- ings (McCa oll e al., 2002; Camp bell e al., 2007; Wil son e al., 2011). The BI was e cen ly (Helama e al., 2013) shown o p o ide a use ul p oxy o pas em pe a - u e a i a ions also sou h o he im be line, as he BI ch o nol - ogy o li ing pines ex plain ing mo e han 40 pe cen o he sum me em pe a u e a i ance in No h Ka elia (de no ed as NK in Fig. 1) in eas e n Fin land. Al e na i ely, he col lec ed ee- ing ma e ial could be used as ma e ial o dend o-iso o - pic anal y ses. S a ble ca bon iso opes (d13C) as ex ac ed om Sco s pine ee- ings ha e p e i ously shown o p o ide a ea - son able p oxy o em pe a u es in No h Ka elia whe e he d13C ch o nol ogy ex plained 30–40 pe cen o he sum me em pe a u e a i ance (Hilas uo i e al., 2009). An a lyz ing hese p op e ies om Sco s pine ee- ings in sou h-wes Fin - land o BI and d13C ch o nol o gies o e he pe i ods o in s u - men al cli ma e ob se a ions (Holopainen, 2006) will de ail hei ex ac paleoclima ic alue. An o he in e es ing op po u - ni y would use bo h he BI and d13C da a as mul i ple p ox ies o com mon em pe a u e sig nal, as an in c eased ange o in - di ca o s is likely o e sul in mo e o bus paleoclima e e con - s uc ion. CON CLU SIONS T ee- ing ch o nol ogy om sou h-wes Fin land p o ides an in e es ing pos si bil i y o s udy he paleoen i onmen al a i a ions o e he pas eigh cen u ies. Al hough he dend o- cli ma ic co e la ions be ween his ch o nol ogy and lo cal cli - ma e a i ables did no in di ca e s aigh o wa d op po u ni ies o ee- ing based em pe a u e o p e cip i a ion e con s uc - ions, he ch o nol ogy showed i s po en ial o e co d ing he NAO sig nals o win e and sp ing sea sons. Mo e o e , he ma k edly high co e la ion be ween he ee- ing ch o nol ogy and e con s uc ed cen al Eu o pean em pe a u es du ing he 16 h cen u y was dem on s a ed. This com pa i son showed ha he pas a i a ions in he ee- ing wid h we e syn ch o - nous wi h la ge-scale em pe a u e luc u a ions also du ing he p e-in s u men al pe iod. As a u u e p os pec , he ee- ing da ed ma e ial may be used o mo e elab o a ed p ox ies 66 S. HELAMA e al. Fig. 8.De cad al com pa i son o he sou h-wes Finn ish ee- ing in dex and he es i ma ed cen al Eu o pean em pe a u e a i a ions as anom a lies o m he e e ence pe iod 1901–1960 (P is e and B ádzil, 1999). B ough o you by | Me la Finnish Fo es Resea ch Ins i u e Au hen ica ed Download Da e | 12/15/16 11:44 AM o sum me em pe a u e ia p o duc ion o wood p op e y and/o dend o-iso o pic ch o nol o gies. Ac knowl edge men s We hank he e e ee com men s by wo anon y mous e iew e s. This s udy was also sup po ed by he Acad emy o Fin land (#251441) and he oun da ion o Koneen Sää iö. REF ER ENCES Ah i, T., Häme -Ah i, L., Jalas, J., 1968. Veg e a ion zones and hei sec ions in no h wes e n Eu ope. Annales Bo anici Fennici 3, 169–211. Ba holin, T. 1987. Dend och onology in Swe den. Annales Aca- demiae Scien ia um Fennicae 145, 79–88. Ba holin, T.S., Ka lén, W., 1983. Dend och onology in Lapl and (Dend ok onologi i Lapl and). Dend ok onologiska Sällskape 5, 3–16 (in Swed ish). Box, G.E.P., Jenkins, G.M., 1970. Time se ies anal y sis: o e cas ing and con ol. Holden-Day, San F an cisco. B adley, R.S., 1999. Paleoclima ology: e con s uc ing cli ma es o he Qua e na y. Ac a demic P ess, Lon don. 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