IMPACTS OF DROUGHT ON GROWTH AND REGENERATION OF CONIFERS ON THE CANADIAN PRAIRIES

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1 :::!1 m () o "'0 -< 46 "\.,.~'. ) IMPACTS OF DROUGHT ON GROWTH AND REGENERATION OF CONIFERS ON THE CANADIAN PRAIRIES E.H. (Ted) Hogg Canadian Foest Sevice, Natual Resouces Canada, Steet, Edmonton AB T6H 3S5 and A.G. Schwaz Canadian Cicumpola Institute, Univesity of Albeta Edmonton AB T6G 2V2 ABSTRACT In the Canadian paiie povinces, the natual distibution of conifes is geneally esticted to moist aeas in the noth and at high elevation, whee annual pecipitation exceeds potential evapotanspiation. Pedictions of a wame and die futue climate pose concems fo the poductivity and egeneation of all tees in this egion, especially on the paiies, whee conifes ae absent except in plantations and sheltebelts. We conducted tee-ing analysis at thee plantations on the paiies of southen Saskatchewan to examine the impact of climatic vaiability on conife gowth in this dought-pone egion. Radial gowth of yea old white spuce (Picea glauca (Moench) Voss), jack pine (Pinus banksiana Lamb.) and othe conifes was seveely educed duing majo dought yeas in 1980, 1984 and 1988, but gowth had fully ecoveed duing the fist 1-3 yeas following each dought These esults indicate that conifes ae capable of withstanding sevee dought, at least once they have attained a cetain size. Howeve, pevious studies suggest that climatic conditions on the paiies ae too dy to pemit natual egeneation of conifes fom seed, and histoic ecods indicate a low success ate in establishing conife plantations in these dought-pone egions. Thus, although conifes epesent an excellent oppotunity fo affoestation and agofoesty on the Canadian paiies, innovative appoaches to plantation establishment would be necessay to avoid dought-induced motality of seedlings du~ng the fist few yeas afte planting. Keywods: plantation, dendochonology, tee-ing, dought, conife, spuce, pine INTRODUCTION In the westen Canadian inteio, seveal species of conifeous tees shae a simila southen limit of natual distibution that is govened, eithe diectly o indiectly, by moistue (Zoltai 1975; Hogg 1994; see also Figue 1). In this egion, boeal and codillean foests ae geneally esticted to Climatically moist aeas whee mean annual pecipitation is moe than sufficient to satisfy plant wate use on a well-vegetated landscape, leading to significant wate unoff intc steams and ives duing most yeas. Howeve, in the die, southen potions of the Canadian paiie povinces, natual foests ae eithe absent (paiies) o esticted to stunted patches of deciduous tees (aspen pakland). I these aeas, dought poses challenges to the atificial establishment and maintenance of plantations and sheltebelts The natual ange of tembling aspen (Populus temujoides Michx.) and othe poplas extends futhe south into d) aeas whee conifes ae natually absent; howeve, popla foests on the Canadian paiies and paklands ae pone to sevee cown die back following peiods of dought (Zoltai et a!. 1991; Hogg and Hudle 1995; Hogg et al. 2002) 0 afte loweing of wate levels along ives (Tyee et al. 1994). Conifes have been extensively planted as sheltebelts and plantations fo vaious puposes acoss the Canadia paiies (Johnson 1953; Jameson 1956; Johnson and Lesko 1977). These conifes include native species such a! white spuce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana Lamb.) that have been tansplanted fa outside thei natual ange, as well as intoduced conifes such as the Euopean Scots pine (Pinus sy/vestis L.) ani Coloado spuce (Picaa pungens Engelm.). The pesistance of these planted conifes, even in non-iigated aeas c dy paiie, demonstates that they ae highly toleant of dought

2 In a pevious s~udy, ~ogg and Schwa.: (1997) concluded!hat conifes ae natually absent fom the Canadian paiies because the climate IS too dy to pemit natual egeneation fom seed. This conclusion was based on the esults of suveys showing that seedlings aely occu aound matue planted conifes on abandoned paiie fams in southen saskatchewan. In contast, seedlings wee abundant aound conifes planted in compaable habitats on fams situated in cleaed aeas of boeal foest. Given that natual egeneation is the main facto peventing conifes fom colonizing the Canadian paiies, thee appeas to be no eason why conife species could not be good candidates fo lage-scale agofoesty and affoestation pojects in this dy egion, povided that they can be successfully established afte planting.. '., I! I The objective of the pesent study was to examine the impact of paiie dought on the gowth of conifes in peviously established plantations on the Canadian paiies. Conditions duing the 1980s wee especially dy in this egion, and 1988 was one of. the most sevee dought yeas since the "dust bowl D peiod of the 1930s (Tenbeth et al. 1988; Heington et al. 1997). This povided an ideal oppotunity to detemine the ability of planted conifes to Withstand, and ecove fom peiods of exteme dought that might also seve as an analog fo the futue, if conditions in this egion become die unde human-induced climate change (Hogg and Hudle 1995). In this peliminay investigation, we conducted tee-ing analysis at thee conife plantations in southen Saskatchewan to examine past gowth esponses to changes in moistue ove the peiod , including impacts of majo dought yeas such as METHODS The thee conife plantations selected fo this study wee located on the plains of southen Saskatchewan, Canada, whee conifes ae natually absent (Figue 1). This egion is heavily cultivated, and the native tee cove is esticted mainly to stunted goves of tembling aspen. I i Southen ange limits of othe boeal conifes Study sites (conife plantations) - White spuce: Natual ange!iii Absent (except whee planted)... Jack pine Lodgepole pine Black spuce Tamaack i f Figue 1. Map showing the location of thee paiie conife plantations whee tee-ing analysis was conducted, in elation to the natual distibution of the five majo species of boeal conifes In the Canadian paiie povinces of Albeta, Saskatchewan and Manitoba (fom Zoltai 1975). The Motlach plantation ( 'N, 'W) is situated on the paiies west of Moose Jaw, Saskatchewan, and COnsists of an 800 x 300 m block planting (25 ha) on sandy soils whee a total of about 47,000 conifes and 17,000 deciduous tees wee planted between 1945 and 1961 (G. Howe, PFRA Sheltebelt Cente, pes. comm. 1993). When Sampling was conducted fo this study (ealy Septembe 1993), thee was little evidence of past conife motality. Incement coes wee collected fom ten tees of each of the following fou conife species: white spuce, jack pine, COloado spuce and Scots pine.

3 48 The Dundun plantation (51 50'N, 'W) is situated on the bundun militay base (Depatment of Nationa Defence) south of Saskatoon, Saskat~hewan. It occupies a total aea of appoximately 5 ha on sandy sails, whee about 37,000 jack pine, 5,000 Sc~t~ pl~e, and 300 whit? spuce wee planted in 13 blocks between 1916 and 1929 as pat of an expeimental foesty Initiative by the Canadian fedeal govenment. Subsequent suveys in 1948 showed oveall suvival ates of 6-8% fo the pine, and only 1 % fo the white spuce (Johnson 1953). In late August 1993 incement coes wee collected in this plantation fom ten jack pine and ten Scots pine. The Keppel plantation (52 27'N, 'W) is located in the aspen pakland zone notheast of Bigga, Saskatchewan. It occupies a total aea of 120 ha, whee a total of about 350,000 conifes wee planted on sandy loam to clay loam soils between 1934 and The plantings oiginally consisted of 60 blocks of equal size (about 2 hal, including 42 blocks of white spuce and 6 blocks each of jack pine, lodgepole pine, and Scots pine; howeve, subsequent suveys showed that nealy all of the pine had died pio to 1948 (Johnson 1953). Of the blocks planted with white spuce, most showed low suvival but the 9 blocks that wee planted in 1934 had an oveall suvival ate of about 27%. In July 1994, incement coes wee collected fom ten white spuce in this plantation. Fo the tees sampled at the thee plantations (as indicated above), incement coes wee collected fom two sides of each stem at sampling heights anging fom 30 to 130 cm. Coes wee placed in labelled staws and died (50 C) pio to mounting in gooved boads using a slow-dying hide glue. Afte the glue had died, coes wee polished using a palm sande with pogessively fine sandpape, and ing widths wee measued with an ocula micomete unde a dissecting micoscope. The ing width measuements wee used to estimate annual values of basal aea incemenl (BAI, in cm 2 pe yea) fo each tee (Hogg and Schwaz 1999), which seves to educe the tend fo deceasing ing widths ove time that typically occus as tees gow in cicumfeence (Kolb and McComick 1993). Fo eact plantation, aveage values of BAI wee calculated annually fo the ten tees of each species sampled. Annual valuee of elative go~h wee then detemined as a pecentage of the 30-yea mean (peiod ) fo each of the species sampled in each of the thee plantations. The impact of dought on yea-to-yea vaiation in conife gowth was assessed though linea coelation analysis 0 elative gowth (dependent vaiable) vesus annual values of a Climate Moistue Index (CMI) developed by Hog! (1997). The CMI is based on tlie quantity P minus PET, whee P is the annual pecipitation and PET is the annua potential evapotanspiation (i.e., expected loss of wate vapo loss fom a well-vegetated landscape when soi moistue is not limiting) using a simplified fom of the Penman-Monteith equation. Negative values of the CMI denote the dy climatic conditions that typically occu in the aspen pakland o paiie gasslands, wheeas positive value: indicate the moiste climatic conditions that ae nomally associated with boeal and codillean foest in westen Canada (Hogg 1994). Monthly values of mean daily maximum and minimum tempeatue, and monthly pecipitation wee obtained fo Envionment Canada, fo climate stations adjacent to each plantation. The stations used wee Moose Jaw and Chapli (aveage of both stations fo the Motlach plantation), Dundum (Dundum plantation) and Bigga (Keppel plantation: Values of PET wee calculated monthly fo each plantation fom the estimated vapo pessue deficit, which was i tum estimated fom the aveage daily maximum and minimum tempeatue fo each month (Hogg 1997). Pecipitatio and moistue conditions late in a calenda yea (Septembe-Decembe) wee assumed to have a negligible effect 0 the ing width fo that yea because adial gowth of conifes is nomally completed by late summe (Belyea et al. 195' Fase 1956). Thus values of annual pecipitation and the CMI wee calculated fo vaious12-month peiods endin in mid summe to ealy fall. RESULTS AND DISCUSSION The chaacteistics of tees sampled at the thee plantations is shown in Table 1. Pattens of elative gowth base on tee-ing analysis wee geneally simila among the thee plantations, and among the conife species sampled; the Motlach and Dundum plantations (Figue 2). In coelation analyses of gowth vesus the CMI-, the stonge oveall elationships wee obtained using a "tee wate yea" beginning on 1 August of the pevious yea and endi on 31 July of the cuent yea.

4 ,! 49., Plantation (when planted) Motlach ( ) Dundun ( ) Keppel White spuce Diamete at beast height (1.3 m) Table 1 Chaacteistics of tees sampled in thee conife plantations Mean Height Mean DBW Spcecies (m) (cm) White spuce Jack pine Coloado spuce Scots pine Jack pine Scots pine Ealiest ing (yea ange) t 1 If g ~ il e s n 11 in,). in In In 1; 19 Fo the 30-peiod of analysis ( ), the coelations between elative gowth and the CMI wee statistically significant (P<0.05) fo each of the species at the thee plantations, with the exception of jack pine at the Motlach plantation (P<0.10) which had the lowest coelation coefficient ( = 0.35). In contast jack pine at the Dundun plantation had the geatest coelation coefficient ( = 0.76). Coelation coefficients fo the othe species (white spuce, Coloado spuce and Scots pine) anged fom 0.59 to 0.68 (Figue 2).. Figue 2. Changes in elative gowth of conifes at thee plantations, based on tee-ing analysis. Relative gowth fo each yea :5 300 Motlach plantation ~ WItHe spuce (po.68) D Coloado spuce (=O.62) IS, Jack pine (-O.35) CD 4 Scots pine (-O.59)! ~ 100 CIl ~ O+---:-:-:------'7.f.~--j.Wet -~ (,) -40 ~O D~ :5 300 ~ Dundum plantation E 200 td CD ~ 100 CIl ~ O+---:-:-:------:-:±~--j.Wet ~ (,) -40 ~O~~-~~-~~~~_4D~ i 300 td 200 CD ~ 100 ~ o+-~~:_:_:_~~--~~--+ Wet -~ (,) -40 ~O D~ Yea is the B.veage incement in stem coss-sectional aea (c! pe tee pe yea), expessed as a pecentage of that ecoded ove ~e penod Also shown ae annual values of the Climate Moistue Index (CMI, fo 12-month peiod ending on 31 July ~ th~ cuent yea). Coelation coefficients () ae given fothe elationships between elative gowth and the CMI, fo each conife :pec/es sampled at each plantation. ~flues D~ the emi show that the 12-month peiod ending 31 July 1988 was the diest ecoded ove the 30-yea peiod analysis. This yea was especially dy at Motlach, when total pecipitation was only 196 mm and a CMI of -51 was ecoded. Othe dought yeas included 1961, 1964, 1977, 1980 and Gowth was educed in each of these

5 dought yeas, especially in the most sevee dought yea of 1988 (Figue 2). Howeve, gowth showed a ecovey in all species afte each dought. Gowth ecovey appeaed to be most apid in the white and Colc spuce (often within one yea), wheeas the jack and Scots pine often equied 2 o 3 yeas to ecove. The apid gowth ecovey of these conifes following these paiie doughts is emakable, because these event much moe sevee than the species would nomally encounte in thei native habitats in the Canadian boeal f (white spuce and jack pine), subalpine foests in the Rocky Mountains (white spuce and Coloado spuce), C tempeate and boeal foests of Euasia (Scots pine). The esults futhe suggest that conifes have excellent pate fo agofoesty applications on the paiies and paklands of westen Canada, povided that efoestation pac can be successfully modified to minimize dought losses of seedlings duing fist few yeas afte planting. Alth otation lengths ae geneally geate fo conifes than fo high-yielding cultivas of hybid popla, the isk of Ie due to cown die back following dought may be less. Futhe investigations ae waanted to detemine the feas of lage-scale planting of conifes on the Canadian paiies, fom both ecological and socioeconomic pespec (Johnston et al. 2000). Such investigations would stongly benefit fom the ich legacy of conife plantations that established thoughout the last centuy acoss the Canadian paiies and paklands, many of which have bee documented in the achives of fedeal and povincial land management agencies. 50 ACKNO~EDGEMENTS This study was funded unde the Canada-Saskatchewan Patneship Ageement in Foesty, with additional SUI fom Geen Plan within the Depatment of Natual Resouces Canada. We thank Godon Howe of the Paiie I Rehabilitation Administation (PFRA) in Indian Head, Saskatchewan, fo poviding advice and assistance in loc conife plantations. Thanks ae also extended to officials with the Depatment of National Defense am Govenment of Saskatchewan fo pemission to conduct the sampling of these plantations. Ring width measuen wee made by Tisha Hook, Canadian Foest Sevice. David Pice and Deek Siddes povided helpful commen the manuscipt. We also acknowledge the helpful advice and encouagement of Stephen C. Zoltai duing the stages of this wok. LITERATURE CITED. Belyea, R.M.,. Fase, D.A and Rose, AH Seasonal gowth of some tees in Ontaio. Foesty Chonicl Fase, D.A Ecological studies of foest tees at Chalk Rive, Ontaio, Canada II. Ecological conditiom adial incement. Ecology 37: Heington, R., Johnson, B. and Hunte, F Responding to global climate change in the paiies. Volume the Canada County Study: Climate Impacts and Adaptation. Envionment Canada. 75 pp. Hogg, E.H Climate and the southen limit of the westen Canadian boeal foest. Canadian Jounal of F Reseach 24: Hogg, E.H Tempoal scaling of moistue and the foest-gassland bounday in westen Canada. Agicu and Foest Meteoology 84: Hogg, E.H. and Hudle, P.A The aspen pakland in westen Canada: A dy-climate analogue fo the f boeal foest? Wate, Ai, and Soil Pollution 82: Hogg, E.H. and Schwaz, AG Regeneation of planted conifes acoss climatic moistue gadients 0 Canadian paiies: implications fo distibution and climate change. Jounal of. Biogeogaphy 24: Hogg, E.H. and Schwaz, AG Tee-ing analysis of declining aspen stands in west-cental Saskatche Canadian Foest Sevice, Nothen Foesty Cente, Infomation Repot NOR-X pp. Hogg, E.H., Bandt, J.P. and Kochtubajda, B Gowth and dieback of aspen foests in nothwesten Aft Canada, in elation to climate and insects. Canadian Jounal of Foest Reseach (in pint).

6 J 1 51 id t 10. I e ~ 'st l 1e! ial [ t :S l ~h! :S i ity 1 es ie eu ot, m ng' ne nts on Ily,,' Jameson, J.S. 1.9?~. Planting. of conifes in the Spuce Woods Foest Reseve, Manitoba, Foest Reseach DIVISion Technical Note No. 28. Foesty Banch, Depatment of Nothen Affais and Natual Resouces, Ottawa. 29 pp. Johnson, H.J Refoestation in foest eseves of Saskatchewan, 1916 to Canada Depatment of Resouces and Development, Foesty Banch, Foest Reseach Division, Winnipeg MB, (unpublished epot, Nothen Foesty Cente, Canadian Foest Sevice, Edmonton AB). Johnson, J.D. and G.l. Lesko Recomme:ndations fo species selection and management in the amenity plantations of south em Saskatchewan. Canadian Foesty Sevice, Nothen Foest Reseach Cente, Infomation Repot NOR-X pp Johnston, M., Kulsheshtha, S. and Baumgatne, A Agofoesty in the paiie landscape: oppotunities fo climate change mitigation though cabon sequestation. Paiie Foum 25: Kolb, T.E.and McComick, l.h Etiology of suga maple decline in fou Pennsylvania stands. Can.J. Fo. Res. 2.3: , ' Tenbeth, K.E., Banstato, G.W. and Akin, P.A Oigins of the 1988 Noth Ameican dought. Science 242: Tyee, M.T., Kolb, K.J., Rood, S.B. and Patino, S Vulneability to dought-induced cavitation of ipaian cottonwoods in Albeta: a possible facto in the decline of the ecosystem? Tee Physiology 14: Zoltai, S.C Southen limit of conifeous tees on the Canadian paiies. Canadian Foesty Sevice, Nothen, Foest Reseach Cente, Edmonton, Albeta. Infomation Repot NOR-X-128. :'Z9'tai, S.C., Singh, T. and Apps, M.J Aspen in a changing climate. Pp In: S. Navatil and P.B. 1/ Chapman (eds.) Aspen management fo the 21 st centuy. Poceedings of a Symposium, Novembe 1990, Foesty Canada, Nothen Foesty Cente, Edmonton, AB. 27: 3 of est.'

7 Tempoate ty: Adaptiv~ and Mitigative nm A Changing Physical and S cio-ec@domic Climat~ Poceedings of the Seventh Biennial Confeence on Agofoesty in Noth Ameica and Sixth Annual Confeence of the Plains and Paiie Foesty Association William Schoede andjohn Kot, Editos