Landsat archive holdings for Finland: opportunities for forest monitoring

1 SILVA FENNICA Sil a Fennica ol. 52 no. 3 a icle id 9986 Ca ego y: esea ch no e h ps://doi.o g/10.14214/s .9986 h p://www.sil a ennica. i Licenced CC BY-SA 4.0 ISSN-L 0037-5330 | ISSN 2242-4075 (Online) The Finnish Socie y o Fo es Science Ninni Saa inen1,2, Joanne C. Whi e1,3, Michael A. Wulde  3, Annika Kangas 4, Saka i Tuominen 5, Ville Kanka e1, Ma kus Holopainen1, Juha Hyyppä 6 and Mikko Vas a an a 2 Landsa a chi e holdings o Finland: oppo uni ies o o es moni o ing Saa inen N., Whi e J.C., Wulde M.A., Kangas A., Tuominen S., Kanka e V., Holopainen M., Hyyppä J., Vas a an a M. (2018). Landsa a chi e holdings o Finland: oppo uni ies o o es moni o ing. Sil a Fennica ol. 52 no. 3 a icle id 9986. 11 p. h ps://doi.o g/10.14214/s .9986 Highligh s • The 45-yea Landsa a chi e con ained 30 076 images o Finland by Decembe 31, 2017. • 16.3% o hese we e acqui ed wi hin ±30 days o Augus 1 (no he n hemisphe e summe ), ha e <70% cloud co e , and a 30 m spa ial esolu ion. • Using ime se ies analyses, hese da a p o ide unique in o ma ion ha complemen s o he da ase s a ailable o o es moni o ing and assessmen in Finland. Abs ac The e is g owing in e es in he use o Landsa da a o enable o es moni o ing o e la ge a eas. F ee and open da a access combined wi h high pe o mance compu ing ha e enabled new app oaches o Landsa da a analysis ha use he bes obse a ion o any gi en pixel o gene a e an annual, cloud- ee, gap- ee, su ace e lec ance image composi e. Finland has a long his o y o inco po a ing Landsa da a in o i s Na ional Fo es In en o y o p oduce o es in o ma ion in he o m o hema ic maps and small a ea s a is ics on a a ie y o o es a ibu es. He ein we explo e he spa ial and empo al cha ac e is ics o he Landsa a chi e in he con ex o o es moni o ing in Finland. The Uni ed S a es Geological Su ey Landsa a chi e holds a o al o 30 076 images (1972–2017) o 66 scenes (each 185 km by 185 km in size) ep esen ing he e es ial a ea o Finland, o which 93.6% we e acqui ed since 1984 wi h a spa ial esolu ion o 30 m. App oxima ely 16.3% o he a chi ed images ha e desi ed composi ing cha ac e is ics (acqui ed wi hin Augus 1 ±30 days, <70% cloud co e , 30 m spa ial esolu ion). Da a om he Landsa a chi e can aug- men o es moni o ing e o s in Finland, p o ide new in o ma ion o science and applica ions, and enable e ospec i e, sys ema ic analyses o cha ac e ize he de elopmen o Finnish o es s o e he pas h ee decades. The capaci y o moni o ends based upon his mul i-decadal eco d wi h he addi ion o new measu emen s is o bene i o mul isou ce in en o ies and o e s na ion- ally comp ehensi e spa ially-explici da ase s o a wide ange o s akeholde s and applica ions. Keywo ds Landsa ime se ies; sa elli e; na ional o es in en o y Add esses 1 Depa men o Fo es Sciences, Uni e si y o Helsinki, P.O. Box 27, FI-00014 Uni e si y o Helsinki, Finland; 2 School o Fo es Sciences, Uni e si y o Eas e n Finland, P.O. Box 111, FI-80101 Joensuu, Finland; 3 Canadian Fo es Se ice, (Paci ic Fo es y Cen e ), Na u al Resou ces Canada, 506 Wes Bu nside Road, Vic o ia, BC, V8Z 1M5, Canada; 4 Na u al Resou ces Ins i u e Finland (Luke), Bioeconomy and en i onmen , Yliopis oka u 6, FI-80100 Joensuu, Finland; 5 Na u al Resou ces Ins i u e Finland (Luke), Bioeconomy and en i onmen , 2 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… La oka anonkaa i 9, FI-00790 Helsinki, Finland; 6 Depa men o Remo e Sensing and Pho og am- me y, Finnish Geospa ial Resea ch Ins i u e, Na ional Land Su ey o Finland, Geodee in inne 2, FI-02431 Masala, Finland E-mail [email p o ec ed] Recei ed 28 Ma ch 2018 Re ised 12 June 2018 Accep ed 13 June 2018 1 In oduc ion The Landsa p og am has been acqui ing da a o he Ea h’s su ace since 1972, and since 1982 he da a has been acqui ed a a spa ial esolu ion o 30 m. The Landsa p og am hi he o u ilized h ee 30-m senso s: Landsa Thema ic Mappe (TM; Landsa s 4 and 5), Enhanced Thema ic Mappe Plus (ETM+; Landsa 7), and Ope a ional Land Image (OLI; Landsa 8). Da a om he Mul i-Spec al Scanne (MSS) senso is a ailable wi h a 60 m spa ial esolu ion. In 2008, all newly acqui ed and a chi ed Landsa images in he Uni ed S a es Geological Su ey (USGS) a chi e we e made eely and openly a ailable (Woodcock e al. 2008), ad ancing he accessibili y o all coun ies o use Landsa da a o gene a e in o ma ion ele an o science, policy, and epo ing needs (Wulde e al. 2012). The spec al and spa ial p ope ies o Landsa make i pa icula ly use ul o o es moni o ing (Cohen and Gowa d 2005) and he ad en o ime se ies analyses has u he s eng h- ened his capaci y (Bansko a e al. 2014). The spa ial and empo al na u e o he Landsa a chi e is no uni o m globally, and no all acqui ed da a is ound wi hin he cen al a chi e. Th ough he Landsa Global A chi e Consolida ion ini ia i e, he USGS and In e na ional Coope a o s ha e combined o ensu e all p e iously acqui ed da a, downloaded and s o ed egionally, a e added o he cen al a chi e (Wulde e al. 2016). The gene a ion o image composi es wi h Landsa ime se ies (LTS) has become inc eas- ingly common (Hansen and Lo eland 2012). Composi ing app oaches use a ule-based app oach o selec om a ailable obse a ion o any gi en pixel, gene ally de e mined om wi hin a desi ed empo al window o add ess seasonali y and o mee speci ied in o ma ion needs (G i i hs e al. 2013; Whi e e al. 2014). These bes -a ailable-pixel (BAP) composi es o e come issues esul ing om clouds, haze, and ela ed shadows, which can o he wise p e en assembly o an annually ep esen a i e co e age o image y. Mo eo e , a equen LTS da a allows o he gene a ion o p oxy pixel alues in yea s when he e is no bes obse a ion o a gi en pixel (i.e. illing da a gaps; He mosilla e al. 2015). The esul is a cloud- ee, gap- ee, wall- o-wall, annual su ace e lec ance BAP composi e. Consecu i ely, a s ack o hese annual BAP composi es, ep esen ing se e al decades, may be used o ime se ies analyses (Zhu 2017), suppo ing he cha ac e iza ion o o es dis u bance and eco e y o e as a eas (Sen e al. 2017; Whi e e al. 2017). In e na ional o es moni o ing p og ams and ag eemen s ela ed o clima e change equi e na ional-le el in o ma ion abou o es esou ces. The Finnish Na ional Fo es In en o y (NFI) has been p o iding in o ma ion on Finland’s o es s since he 1920s (Tomppo e al. 2010; Kangas e al. 2018). The NFI is based on s a is ical sampling o ield measu emen s including cha ac e is ics ela ed o o es heal h and biodi e si y, along wi h adi ional o es in en o y a ibu es. In o ma- ion p o ided by he NFI is used as he basis o na ional and egional-le el s a egic o es -planning scena ios o imbe p ocu emen , ha es s, and sil icul u al ea men s, as well as o es ima ing o es ca bon budge s and assessing he sus ainabili y o o es managemen . Based on he need o ob ain eliable o es esou ce in o ma ion o a eas smalle han would be achie able wi h NFI ield da a only, he de elopmen o mul isou ce-NFI (MS-NFI) s a ed in 1989. In he MS-NFI, Landsa da a (also Sen inel and SPOT image y) a e used oge he wi h digi al maps and measu emen s om NFI ield plo s o p oducing wall- o-wall hema ic maps o o es a ibu es and municipal-le el o es s a is ics. Al hough es ima es o he MS-NFI and NFI (based 3 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… on ield plo s only) a e simila a he egional le el, he p edic ion e o a he le el o indi idual pixel is gene ally ela i ely high (Tomppo e al. 2014; Tuominen e al. 2017). As he me hods used o gene a e he MS-NFI a e unde con inuous de elopmen (Tomppo e al. 2008) and he a ibu es ha e no been p edic ed using consis en app oach, he compa abili y be ween hema ic maps a pixel o s and le el om di e en MS-NFIs can be challenging. De ailed spa ial and empo al analyses o he Landsa a chi e o speci ic applica ions a e uncommon, pa icula ly o a eas ou side No h Ame ica (Whi e and Wulde 2013). Mo eo e , he capaci y o he Landsa a chi e o e ospec i ely suppo he de elopmen o a his o ic eco d o o es change and analyses in he con ex o o es moni o ing in o ma ion needs in no he n Eu opean bo eal o es s has he e o o e no been documen ed. To be e unde s and he de elopmen and impac s o na u al dis u bances and managemen ac i i ies on Finnish o es s h ough ime, spa ially-explici o es change in o ma ion is equi ed. The Landsa p og am p o ides a aluable long- e m eco d o science and applica ions. Howe e , he comp ehensi eness o he Landsa a chi e o Finland has no ye been documen ed and he po en ial o LTS o spa ially-explici o es moni o ing in Finland emains o be de e mined. The e o e, he aim o his s udy was o in es iga e he spa ial and empo al ex ensi eness o he USGS Landsa a chi e o he suppo o long- e m o es moni o ing in Finland. 2 Da a and me hods Me ada a o all images acqui ed since he beginning o he Landsa p og am in 1972 un il Decembe 31, 2017 and held in he USGS Landsa a chi e we e downloaded. Me ada a we e p o ided sepa a ely o Landsa s 1–3 (MSS), Landsa s 4–5 (MSS and TM), Landsa 7 (ETM+), and Landsa 8 (OLI). All Landsa me ada a o Landsa 4–5 TM, Landsa 7 ETM+, Landsa 8 OLI and P e-Collec ion me ada a o Landsa 1–5 MSS a e a ailable a h ps://landsa .usgs.go / landsa -bulk-me ada a-se ice. In his analysis, we included he unique scene iden i ica ion numbe , senso , acquisi ion da e, Wo ldwide Re e ence Sys em (WRS) pa h and ow, as well as pe cen cloud co e age om he me ada a. The WRS is he e e ence sys em used o pa i ion he Ea h in o Landsa scenes, each wi h dimensions o 185 km × 185 km; Landsa s 1–3 used WRS-1 whe eas Landsa 4 and subsequen Landsa sa elli es ha e used WRS-2. The numbe o images acqui ed is analogous o he numbe o obse a ions o each scene. Landsa image y acqui ed wi hin ±30 days o Augus 1 (no he n hemisphe e summe ; Julian da e 213) has been conside ed sui able o BAP composi ing and o es moni o ing (G i i hs e al. 2013; Whi e and Wulde 2013; Whi e e al. 2014; He mosilla e al. 2015). Based upon simila seasonali y and expec a ion o peak pho osyn hesis mid-summe , he empo al dis ibu ion o images was analyzed wi hin his ime window o cha ac e ize he po en ial o he Landsa a chi e holdings o o es moni o ing pu poses. Fu he mo e, MSS e a images we e excluded om hese analyses because o he cu en challenges in inco po a ing he di e en spa ial and spec al p ope ies o hese da a in o ime se ies analyses (P lugmache e al. 2012; B aa en e al. 2015). Thus, we ha e only included he images acqui ed om 1984 onwa ds o o es moni o ing pu poses. Addi ionally, a h eshold o cloud co e was se o 70% based on p e ious s udies (G i i hs e al. 2013; Whi e and Wulde 2013). The 70% maximum cloud co e is selec ed o ensu e some minimum le el o clea pixels and su icien g ound isibili y o aid in geome ic ec i ica ion p ocedu es (Whi e e al. 2014). Ou analyses also inco po a ed he egional a iabili y o he Landsa a chi e sui able o BAP composi ing and o es moni o ing (i.e. a composi ing window o Augus 1 ±30 days and cloud co e <70%), by cha ac e izing a chi e holdings o he 13 Public Se ice Uni s o he Finnish Fo es Cen e. 4 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… We calcula ed he a e age numbe o images pe scene and pe yea cu en ly in he a chi e (as o Decembe 31, 2017) mee ing he BAP composi ing c i e ia. These numbe s we e hen summed in he o e lapping a eas be ween scenes, o demons a e he heo e ical impac on obse a ion yield esul ing om Landsa scene o e lap. To demons a e he ealized po en ial o he a chi e o image composi ing, we c ea ed annual BAP composi es o a 5.3 Mha a ea ( ep esen ing 11 unique WRS-2 pa h/ ows) in sou he n Finland o 1984–2017 ollowing he app oach desc ibed in Whi e e al. (2014) and He mosilla e al. (2016). We hen calcula ed he o al numbe o obse a ions (i.e. he numbe o yea s wi h clea pixels used in he composi es). As a esul , we demons a e he heo e ical impac o Landsa scene o e lap on he gene a ion o BAP image composi es in Finland. 3 Resul s As o Decembe 31, 2017, he e we e a o al o 30 076 images in he Landsa da a a chi e o Finland. Mos o he images we e acqui ed wi h he TM (42.8%) and ETM+ (31.8%) senso s (combined 74.6%), ollowed by OLI (19.1%) and MSS (6.4%) (Fig. 1). The dis ibu ion o a ailable da a h ough ime is no consis en : he numbe o images is limi ed p io o 1984 and o 1991–1993, and 1995–1997. Mo e han wo- hi ds (68.5%) o he a chi ed images we e acqui ed a e he launch o Landsa -7 ETM+, enabled by a sys ema ic long- e m acquisi ion plan (A idson e al. 2001). Image acquisi ions inc eased ma kedly wi h he launch o Landsa 8 (OLI) in Feb ua y 2013; a e only 5 yea s o ope a ion, OLI da a ep esen 20% o he a chi ed holdings o Finland. Mo eo e , he annual a e a which OLI has acc ued da a in he a chi e since 2013 is mo e han double ha o TM and ETM+ (Fig. 1). Fig.1. To al numbe o a chi ed Landsa images acqui ed o Finland, by yea and senso . MSS = Mul i-Spec al Scan- ne , TM = Thema ic Mappe , ETM+ = Enhanced Thema ic Mappe Plus, and OLI = Ope a ional Land Image . 5 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… Fig. 2. Pe cen age o all a chi ed Landsa images acqui ed o Finland and hei acquisi ion day o yea (A) as well as numbe o a chi ed Landsa images acqui ed o Finland wi hin ±30 days om he a ge day o yea (Augus 1) and wi h cloud co e < 70%, by yea and senso (B). MSS = Mul i-Spec al Scanne , TM = The- ma ic Mappe , ETM+ = Enhanced Thema ic Mappe Plus, and OLI = Ope a ional Land Image .. 6 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… The o al numbe o a chi ed Landsa images o Finland acqui ed wi hin ±30 days o Augus 1 (Julian da e 213) was 8901, o which 8121 images (o 27.0% o he o al a chi e holdings) we e acqui ed wi h a senso o he han MSS (Fig. 2A). Fo he BAP composi ing scena io (i.e. Augus 1 ±30 days wi h <70% cloud co e ) he e we e 4897 images om TM, ETM+, and OLI, ep esen ing 16.3% o he o al a chi e holdings (Fig. 2B). All he Public Se ice Uni s o he Finnish Fo es Cen e, wi h excep ion o Lapland, ha e a minimum o 76 images pe Landsa scene acqui ed since 1984 mee ing he BAP composi ing c i e ia, co esponding 72.3% o he land a ea o Finland (Fig. 3). The Sou hwes Finland and Åland egions ha e he g ea es numbe o a chi ed Landsa images pe scene (>100). The mean numbe o a chi ed images pe yea was g ea e in o e lap a eas be ween adjacen scenes (Fig. 4A). Inc eased obse a ional densi y in o e lap a eas u he enables BAP composi - ing app oaches, as hese a eas will ha e mo e po en ial obse a ions o BAP composi ing. This po en ial o inc ease obse a ions is ealized when composi es a e gene a ed, as shown in Fig. 4B ep esen ing annual BAP composi es gene a ed o 1984–2017. O e lap a eas ha e mo e images pe yea and mo e yea s wi h obse a ions in he inal BAP composi es. Fig. 3. To al numbe o images (1984–2017) o WRS-2 Landsa scenes co - e ing Finland ha we e acqui ed wi hin ±30 days om he a ge day o yea (Augus 1) and <70% cloud co e , by Public Se ice Uni s o he Finnish Fo es Cen e. 7 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… 4 Discussion LTS o e a unique oppo uni y o long- e m o es moni o ing. Al hough he a chi e holdings o Finland a e no as ex ensi e as o No h Ame ica (Wulde e al. 2016), hey do p o ide possibili- ies o inc easing knowledge abou de elopmen o Finnish o es s bo h spa ially and empo ally. The NFI has p o ided s a is ics abou Finnish o es s since he 1920s, and MS-NFI om he ea ly 1990s. Howe e , he hema ic maps be ween di e en MS-NFIs a e no compa able hus, di ec change de ec ion using hem is challenging. U iliza ion o LTS could he e o e enhance spa ially- explici and e ospec i e analyses o explo a ions o changes in land use (i.e. o es ed a ea) o suppo g eenhouse gas epo ing, o example. Howe e , i de ailed in o ma ion abou he amoun o emo ed wood is o in e es , da a om ield measu emen s would be equi ed. The 1980s and 1990s ep esen ed a pe iod o ins abili y in he Landsa p og am, wi h Landsa da a p iced o cos eco e y by NOAA, and p og amma ic con ol o Landsa s 4 and 5 (and de elopmen o Landsa 6) ans e ed om he Uni ed S a es go e nmen (NOAA) o he p i a e sec o (EOSAT) om 1985 un il 2001. Simul aneously, cos s o Landsa da a inc eased d ama ically and demand ell. The Landsa a chi e holdings su e ed mos signi ican ly du ing his ime. In he absence o a long- e m acquisi ion plan, and aced wi h subs an ial da a downlink cos s, acquisi ions became inc easingly US-cen ic and we e demand-d i en (Gowa d e al. 2017). Al hough In e na ional Coope a o s con inued o downlink da a, hey we e also applying he same Fig. 4. Mean numbe o images (1984–2017) pe yea o WRS-2 Landsa scenes co e ing Finland ha we e acqui ed wi hin ±30 days om he a ge day o yea (Augus 1) and wi h <70% cloud co e (A). Realized num- be o obse a ions (i.e. numbe o yea s wi h clea pixels o composi ing) om bes -a ailable pixel (BAP) composi es (1984–2017) o a sample a ea in sou he n Finland (B). 8 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… cos - eco e y model as EOSAT, wi h a simila da a p icing s uc u e. Faced wi h signi ican unding sho alls om he US Go e nmen , EOSAT ceased p ocessing Landsa da a by he end o 1992 and did no esume p ocessing un il 1994. The MS-NFI was i s in oduced du ing he eigh h NFI (ca ied ou be ween 1986 and 1994). Concu en ly, he co e age o he Landsa a chi e in Finland is e y limi ed, pa icula ly o 1991–1997 (excep o 1994). Despi e spa ial gaps in a chi e holdings, o e lap be ween adjacen scenes ensu es adequa e spa ial and empo al co e age o enable BAP composi ing (G i i hs e al. 2013; Whi e e al. 2014). Fu he mo e, app oaches o change de ec ion, among o he s (He mosilla e al. 2016; Zhu 2017), enable a spa ially-explici his o ic eco d o o es change o be cons uc ed om he LTS, which can enhance he cha ac e iza ion o he de elopmen o Finnish o es s o e ime. Consequen ly, es ima es o ha es ed o bu ned a eas can be iden i ied as well as when land use class om o es has changed. In addi ion o he cap u e and documen a ion o o es dis u bances, LTS su ace e lec ance alues ha e demons a ed u ili y o moni o ing and quan i ica ion o ege a ion eco e y ollowing i e and ha es (Whi e e al. 2017). As assessmen s o o es eco e y using ield plo s a e ypically spa ially and empo ally cons ained (Ba els e al. 2016), he capaci y o assess bo h dis u bance and eco e y o e la ge a eas wi h LTS da a can augmen plo -based analyses wi h bo h empo ally and spa ially exhaus i e in o ma ion on eco e y. The “always on” s a us o OLI has esul ed in an inc ease in he numbe and seasonal dis- ibu ion o images o Finland. This inc eased da a collec ion o e s enhanced possibili ies o he u u e o o es moni o ing (i.e. om annual o wi hin yea BAPs). Mo eo e , he ela i ely sho u na ound ime be ween acquisi ion and a ailabili y o he images in he Landsa a chi e as analysis eady da a enables he de elopmen o nea - eal ime applica ions (Zhu and Woodcock 2014). Howe e , he s eng h o LTS is long- e m o es moni o ing wi h he unique ime ame o obse a ions. In combina ion wi h Sen inel-2 sa elli es, acqui ing da a wi h simila cha ac e is ics o OLI da a and a e being made openly and eely a ailable (Li and Roy 2017), composi ing algo i hms can become mo e obus , bu essing he complemen a y ole o op ical sa elli e image y o expand suppo Finnish o es moni o ing ac i i ies. Due o spa ial and spec al complemen a i y be ween Landsa and Sen inel-2 (D usch e al. 2012), and gi en p og ess owa ds c oss-calib a ion o hese da a (Zhang e al. 2018), Landsa a chi al image y can p o ide a baseline agains which ends de i ed om Sen inel-2 obse a ions can be compa ed (Wulde e al. 2015, 2018). Mo eo e , syn- e gies be ween Landsa and Sen inel-2 p o ide oppo uni ies o sho e e isi imes and imp o e he likelihood o cloud- ee obse a ions o suppo composi ing app oaches (Li and Roy 2017). 5 Conclusions Global co e age o Landsa da a has luc ua ed o e ime due o logis ical and p og amma ic ac- o s. The USGS Landsa a chi e holdings o Finland ep esen mo e han h ee-decades o da a acqui ed since 1984 wi h a 30 m spa ial esolu ion. These a chi e holdings a e su icien ly dense o suppo he de elopmen o annual image composi es ha can consecu i ely be used o long- e m o es moni o ing. Re ospec i ely, hese da a p o ide a use ul sou ce o baseline in o ma ion o o es moni o ing in he con ex o clima e change, and mo eo e , could suppo a b oad sui e o in o ma ion needs and scien i ic applica ions, such as spa ially-explici in es iga ions o changes in o es connec i i y and composi ion o e ime, and a ia ion in egional ends in o es eco - e y. These da a complemen he dense ne wo k o NFI ield plo s and p o ide new in o ma ion o o es moni o ing a egional and na ional le els. 9 Sil a Fennica ol. 52 no. 3 a icle id 9986 · Saa inen e al. · Landsa a chi e holdings o Finland: oppo uni ies… Acknowledgemen s This esea ch was unde aken wi h suppo om he Academy o Finland h ough he Cen e o Excellence in Lase Scanning Resea ch (p ojec numbe 272195) and he ‘Ea h Obse a ion o In o m Canada’s Clima e Change Agenda (EO3C)’ p ojec join ly unded by he Canadian Space Agency (CSA), Go e nmen Rela ed Ini ia i es (GRI) p og am, and he Canadian Fo es Se ice (CFS) o Na u al Resou ces Canada. T. 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