Evaluation of Precommercial Thinning of Lodgepole Pine from Long-term Research Installations in Alberta. J. D. Stewart and J. C.

Transcription

1 CANADIAN FOREST SERVICE CANADIAN WOOD FIBRE CENTRE Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert J. D. Stewrt nd J. C. Slvil INFORMATION REPORT FI-X Cndin Wood Fibre Centre Working together to optimize wood fibre vlue creting forest sector solutions with

2 The Cndin Wood Fibre Centre brings together forest sector reserchers to develop solutions for the Cndin forest sector s wood fibre relted industries in n environmentlly responsible mnner. Its mission is to crete innovtive knowledge to expnd the economic opportunities for the forest sector to benefit from Cndin wood fibre. The Cndin Wood Fibre Centre opertes within the CFS, but under the umbrell of FPInnovtions Bord of Directors. FPInnovtions is the world s lrgest privte, not-for-profit forest reserch institute. With over 500 employees spred cross Cnd, FPInnovtions unites the individul strengths of ech of these interntionlly recognized forest reserch nd development institutes into single, greter force. For more informtion, visit FPInnovtions.c. Additionl informtion on Cndin Wood Fibre Centre reserch is vilble online t cwfc.nrcn.gc.c. To downlod or order dditionl copies of this publiction, visit the Web site Cndin Forest Service Publictions t cfs.nrcn.gc.c/publictions. Informtion contined in this publiction or product my be reproduced, in prt or in whole, nd by ny mens, for personl or public non-commercil purposes, without chrge or further permission, unless otherwise specified. You re sked to: - exercise due diligence in ensuring the ccurcy of the mterils reproduced; - indicte the complete title of the mterils reproduced, nd the nme of the uthor orgniztion; nd - indicte tht the reproduction is copy of n officil work tht is published by Nturl Resources Cnd (NRCn) nd tht the reproduction hs not been produced in ffilition with, or with the endorsement of, NRCn. Commercil reproduction nd distribution is prohibited except with written permission from NRCn. For more informtion, contct NRCn t copyright.droitduteur@nrcn-rncn.gc.c.

3 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert J. D. Stewrt 1 nd J. C. Slvil Informtion Report FI-X-16 Nturl Resources Cnd Cndin Forest Service Cndin Wood Fibre Centre 017 1, Cndin Wood Fibre Centre, Cndin Forest Service, 50 1 Street, Edmonton, AB T6H S5

4 Her Mjesty the Queen in Right of Cnd, 017 Nturl Resources Cnd Cndin Forest Service ern Forestry Centre 50 1 Street Edmonton, AB T6H S5 Ctlogue No.: Fo18-1/16E-PDF ISBN ISSN For n electronic version of this report, visit the Cndin Forest Service publictions website t publictions TTY : (Teletype for the hering-impired) Cover photos: Lodgepole pine thinning tril ner McKy, Albert. Top left: eril photo of treted stnd; bottom left: oblique view of cnopy in thinned plot; bottom center: bird s eye view of thinned plot; right: ground-level view of thinned plot. Cover photos: Brent Joss nd Jred Slvil, Cndin Wood Fibre Centre, Edmonton, AB. Disclimer: The exclusion of certin mnufctured products does not necessrily imply dispprovl nor does the mention of other products necessrily imply endorsement by Nturl Resources Cnd. ii Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

5 Stewrt, J.D.; Slvil, J.C Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert. Nt. Resour. Cn., Cn. For. Serv., Cn. Wood Fibre Cent., Edmonton, AB. Inf. Rep. FI-X-16. Abstrct As the forestry lndbse shrinks nd demnd for wood increses, improving productivity of commercil forest stnds becomes more importnt. Becuse of its commercil vlue nd common occurrence, lodgepole pine is cndidte for productivity improvement. Regenerting lodgepole pine forests re often chrcterized by very high density nd slow growth, limiting their vlue. Therefore, vriety of precommercil thinning tretments hve been tried t longterm instlltions, which provide vluble dt to evlute projections from existing growth nd yield models. In this report, we evlute the stnd growth nd yield from different thinning tretments in long-term silviculture instlltions in the Upper Foothills (Gregg Burn nd Teepee Pole Creek) nd er Foothills (McKy) subregions of Albert. The McKy instlltion ws estblished in 195 with the objective of determining whether precommercil thinning of lodgepole pine could improve merchntble volume nd qulity t young ge, nd in turn shorten rottion nd increse nnul llowble cuts. The Gregg Burn nd Teepee Pole Creek instlltions were estblished in the 1960s to ssess the response of tree nd stnd growth to different juvenile spcing tretments, with densities rnging from 500 to stems per hectre. Tree growth nd survivl in these instlltions re mesured periodiclly to evlute the effect of different intensities of thinning on the growth nd yield of the lodgepole pine crop trees. To provide decdl updte to previous mesurements nd evlution, published in 006, we exmined totl nd merchntble volumes in these instlltions using the most recent dt (011 01). Our nlysis found tht thinning is unlikely to increse yields; however, if thinning is crried out for other resons, judicious choice of thinning regime cn void yield loss. Thinning to stems per hectre ppers to be optiml, mximizing the positive effect on tree growth without mjor losses in volume. Informtion Report FI-X-16 iii

6 Résumé Comme les territoires forestiers diminuent et que l demnde en bois ugmente, l ccroissement de l productivité des peuplements commerciux devient crucil. En rison de s vleur commercile et de s présence commune, le pin tordu ltifolié est un bon cndidt pour ccroître l productivité. L régénértion des forêts de pins tordus ltifoliés est souvent crctérisée pr une très forte densité et un fible tux de croissnce, ce qui pour conséquence d en limiter l vleur. C est pourquoi une vriété de coupes d éclircie précommerciles été testée dns des instlltions à long terme, ce qui procure d excellentes données pour évluer les projections des modèles de croissnce et de production ctuels. Dns ce rpport, nous évluons l croissnce et l production d un peuplement, à l suite de l utilistion des différentes sortes de coupes d éclircie pour des instlltions à long terme de sylviculture situées dns les sous-régions du Upper Foothills (Gregg Burn et Teepee Pole Creek) et du er Foothills (Mcky) de l Albert. L instlltion Mcky été mise en plce en 195 dns le but de déterminer si les coupes d éclircie précommerciles du pin tordu ltifolié pouvient ugmenter le volume et l qulité mrchnde, à un jeune âge, ce qui, en retour, permettrit de rccourcir l période de rottion et d ugmenter l quntité de coupes nnuellement possibles. Les instlltions Gregg Burn et Teepee Pole Creek furent étblies dns les nnées 1960 fin d évluer l réponse des rbres et l croissnce du peuplement à des coupes d éclircie hâtives, vec des densités vrint de 500 à tiges pr hectre. L croissnce et l survie des rbres sont mesurées périodiquement fin d évluer l effet des différentes intensités des coupes d éclircie sur l croissnce et l production des rbres exploitbles de l espèce du pin tordu ltifolié. Pour mener une mise à jour décennle ux mesures et ux évlutions précédentes, publiées en 006, nous vons exminé le volume totl et le volume mrchnd de ces instlltions, à l ide des plus récentes données (011 à 01). Notre nlyse déterminé que les coupes d éclircie ne sont ps susceptibles d ugmenter l production; cependnt, si l coupe d éclircie est effectuée pour d utres risons, un choix judicieux de système d éclircie peut éviter une perte de production. Une coupe d éclircie qui vise à conserver de 000 à 000 tiges pr hectre semble optimle, mximisnt insi l effet positif sur l croissnce des rbres, sns cuser de perte mjeure de volume. iv Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

7 Contents Introduction... 1 Methods... Description... Experimentl Design nd Lyout... Mesurements... Sttisticl Anlysis... 5 Results... 6 Stnd Development... 6 Stnd... 6 Mortlity... 6 Spcing Fctor Stnd Index Tree-Level Properties... 1 Tree Dimeter... 1 Tree Height... 1 Height Dimeter Rtio... 1 Live Crown Rtio Piece Size Stnd-Level Properties... Qudrtic Men Dimeter... Top Height... Stnd Yield... Bsl Are... Totl Volume... Merchntble Volume... Men Annul Increment of Totl Volume... Men Annul Increment of Merchntble Volume... Discussion... 7 Stnd Development fter Tretments... 8 Is There n Optiml Stnd?... 9 Informtion Report FI-X-16 v

8 Effects of Precommercil Thinning on Non-yield Chrcteristics... 0 Johnstone s Generl Principles Revisited... 1 Conclusions... Acknowledgments... Literture Cited... Appendix Tbles of lest squre mens... 5 Figures 1. Loction of the four study sites.... Stnd density t ltest mesurement for four lodgepole pine precommercil thinning trils Reltive nnul mortlity rte since estblishment for four lodgepole pine precommercil thinning trils Spcing fctor t ltest mesurement for four lodgepole pine precommercil thinning trils Stnd density index t ltest mesurement for four lodgepole pine precommercil thinning trils Dimeter t brest height t ltest mesurement for four lodgepole pine precommercil thinning trils Height t ltest mesurement for four lodgepole pine precommercil thinning trils Height dimeter rtio t ltest mesurement for four lodgepole pine precommercil thinning trils Live crown rtio t ltest mesurement for four lodgepole pine precommercil thinning trils Piece size of merchntble trees (1/7 stndrd) t ltest mesurement for four lodgepole pine precommercil thinning trils Qudrtic men dimeter t ltest mesurement for four lodgepole pine precommercil thinning trils Top height t ltest mesurement for four lodgepole pine precommercil thinning trils Bsl re t ltest mesurement for four lodgepole pine precommercil thinning trils Totl volume t ltest mesurement for four lodgepole pine precommercil thinning trils Merchntble volume (1/7 stndrd) t ltest mesurement for four lodgepole pine precommercil thinning trils... 9 vi Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

9 16. Merchntble volume (15/10 stndrd) t ltest mesurement for four lodgepole pine precommercil thinning trils Men nnul increment for totl volume for four lodgepole pine precommercil thinning trils Men nnul increment for merchntble volume (1/7 merchntbility stndrd) for four lodgepole pine precommercil thinning trils Men nnul increment for merchntble volume (15/10 merchntbility stndrd) for four lodgepole pine precommercil thinning trils... 6 Tbles 1. Stnd tretment nd site description for the four study sites.... Dtes mesurements were tken t the study sites.... Results of nlysis of vrince of the effect of site nd density tretments on stnd density t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on mortlity rte t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on spcing fctor t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on stnd density index t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on tree dimeter t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on tree height t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on height dimeter rtio t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on live crown rtio t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on piece size t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on qudrtic men dimeter t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on top height t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on bsl re t the ltest mesurement in four lodgepole pine precommercil thinning trils... 7 Informtion Report FI-X-16 vii

10 15. Results of nlysis of vrince of the effect of site nd density tretments on totl stnd volume t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on merchntble volume (1/7 stndrd) t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on merchntble volume (15/10 stndrd) t the ltest mesurement in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on men nnul increment of totl stnd volume over time in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on men nnul increment of merchntble volume (1/7 stndrd) over time in four lodgepole pine precommercil thinning trils Results of nlysis of vrince of the effect of site nd density tretments on men nnul increment of merchntble volume (15/10 stndrd) over time in four lodgepole pine precommercil thinning trils... 7 viii Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

11 Introduction Development of the forest industry in Cnd fces two constrints: shrinking lnd bse nd incresing demnd for mny nturl resources including wood products, energy, nd minerls. These constrints men tht n incresing demnd for forest fibre products will hve to be met from development in smller re. Climte chnge is incresing forest disturbnce from fire nd insects, especilly mountin pine beetle (Dendroctonus ponderose Hopk.), which ggrvtes this sitution. It is chllenging for Cndin producers to be competitive in the globl commodity mrket for wood fibre products, becuse of reltively low growth rtes of tree stnds s well s high trnsporttion nd lbour costs. One strtegy for ddressing these chllenges is more intensive mngement of forests to increse productivity nd to improve the qulity nd vlue of the wood. Lodgepole pine (Pinus contort L.) is cndidte for intensive mngement becuse of its brod ecologicl mplitude (Lotn nd Critchfield 1990), common occurrence, nd high commercil vlue (Kennedy 1985; Koch 1996). In ddition, post-fire regenertion often results in slow-growing stnds of lodgepole pine with very high densities (Smithers 1961). Although there my be size differentition in mny of these stnds, self-thinning often does not occur to n pprecible degree nd the resulting stnds would not meet current forest mngement objectives (Goudie 1980). Such excessive densities reduce verge stnd dimeter, height, nd merchntble volume while incresing mortlity, length of rottions, nd hrvesting costs. As result, much of the lndbse of lodgepole pine is growing t well below its site-productivity potentil. Erly mngement of stnd density through precommercil thinning hs been shown to mitigte mny of the negtive effects of excessive density in nturl lodgepole pine stnds (Johnstone 1985; Johnstone nd Cole 1988; Johnstone nd vn Thienen 011b). Therefore, nturl lodgepole pine stnds re good cndidtes for stnd density mngement to improve timber production. Forest mngement in Cndin lodgepole pine forests is bsed on projections from models such s Tree nd Stnd Simultor (TASS, Mitchell 1969), Growth nd Yield Projection System (GYPSY, Hung et l. 001), nd Mixedwood Growth Model (MGM, Boklo et l. 01). Vlidtion of these models, specificlly to forecst yield of density-mnged lodgepole pine, hs been limited. It is essentil to review ctul cse studies of stnd development in response to site conditions nd stnd mnipultions from long-term field instlltions s check on the function of the models. A network of long-term lodgepole pine instlltions in Albert, with rnge of precommercil thinning prescriptions differing in timing nd intensity, is vilble for this purpose. Severl erlier reports re vilble for these instlltions (Smithers 1957; Johnstone 1981, b; Johnstone 198; Yng 1986, 1991; Stewrt et l. 006). In this report, our objectives re (1) to provide n introduction to the long-term instlltions nd their ssocited dtsets for potentil use in growth nd yield models, () to test principles of thinning response reported in the literture, nd () to evlute responses to precommercil thinning tht support or chllenge conventionl wisdom on erly stnd-density mngement of lodgepole pine. In this report, only growth nd yield effects will be evluted. The effect of thinning on products nd their mrket vlues, s well s on wood qulity, will be ddressed elsewhere.

12 Methods Description Precommercil thinning tretments hve been estblished in nine field instlltions in west-centrl Albert. All stnds regenerted nturlly following wildfire. The Gregg Burn (two sites begun in 196 [Gregg6] nd 198 [Gregg8]) nd Teepee Pole Creek sites re locted in the Upper Foothills ecologicl subregion, nd the McKy site in the er Foothills subregion (Beckinghm et l. 1996). Plnt community types were lodgepole pine blck spruce/lbrdor te/fether moss for the Gregg6 low-productivity site, Gregg8 low-productivity site, Gregg8 medium-productivity site, nd McKy tril sites; lodgepole pine/lbrdor te/fether moss for the Gregg6 medium-productivity site, Gregg8 medium-productivity site, nd Gregg8 high-productivity tril sites; nd lodgepole pine/ green lder/fether moss for the Gregg6 highproductivity nd Teepee Pole Creek tril sites. Other site chrcteristics re summrized in Tble 1. Geogrphic loctions re shown in Figure 1. Further informtion on nd results for stnd development over time re found in Tble 1 nd Stewrt et l. (006). Tble 1. Stnd tretment nd site description for the four study sites Nme Estblishment (yer) Age (yers) Tretments density (stems/h) Nutrient regime Moisture regime Teepee Pole McKy Gregg Gregg Control stnds. Flt: medium : medium poor medium rich Poor : very poor poor ium: poor : medium poor medium rich : poor ium: poor medium : medium Flt: mesic : submesic subhygric Mesic : submesic ium: mesic : mesic to subhygric : mesic ium: mesic : mesic Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

13 Figure 1. Loction of the four study sites. Experimentl Design nd Lyout The McKy tril ws estblished in 195, t stnd ge yers, with three rndomized complete blocks of similr productivity. Ech block consisted of six tretment plots: n unthinned control nd five thinned plots. Thinning tretment prescriptions were 1 680, 986 (replicted twice), nd 8 stems per hectre. The fifth tretment regime involved second thinning; however, this tretment is not included in this nlysis. Spcing ws done by hnd, with spcing grid set up s guideline. An effort ws mde to retin the most vigorous trees rther thn to rigidly dhere to the spcing prescriptions. An unreplicted tretment of 77 stems per hectre ws lso estblished djcent to one of the complete blocks. The Gregg Burn 196 tril ws estblished in 196, t stnd ge seven yers, in three sites of differing productivity (low, medium, nd high), bsed on pre-fire stnd chrcteristics. Two semi-rndomized complete blocks were estblished on ech site. Ech block contined five tretment plots, which were sized to contin exctly 100 trees on uniform squre grid. Spcing ws done by hnd in , following string grid templte, with residul trees locted no frther thn 6 cm from grid intersections. The tretments were 00, 00, 800, 1 600, nd 00 stems per cre, or pproximtely 500, 1 000, 000, 000, nd stems per hectre. The Teepee Pole Creek experiment hs the sme experimentl design nd estblishment procedures s the erlier Gregg Burn 196 tril: semirndomized complete-block design, with two replicte blocks of tretment plots in ech site. In this cse, the sites were of similr productivity but differed in slope spect: flt, north, nd south spect slopes. The south spect site ws dropped Informtion Report FI-X-16

14 from nlysis becuse of lyout problems nd lter dmge to the site. Spcing ws done by hnd in summer 1967 t the stnd ge of 5 yers. An extension to the Gregg6 tril ws estblished in 198, lso in the Gregg Burn. The experimentl design ws identicl to tht of the Gregg6 tril, except tht the 00 stems per cre tretment ws replced by 1 00 stems per cre tretment, nd the 00 stems per cre tretment ws dropped, so tht the resulting thinning levels were pproximtely 1 000, 000, 000, nd 000 stems per hectre. The high- nd low-productivity sites were locted on different sites from those of the Gregg6 tril; however, the medium sites for both trils were co-locted. Tble. Dtes mesurements were tken t the study sites Teepee Pole Greg6 Greg8 McKy Creek Only the medium-productivity site ws mesured. Mesurements The following dt were collected fter the growing seson during ech yer of mensurtion: dimeter t brest height (DBH; 1. m from the estimted point of germintion), height to the tllest live portion of the crown (Ht), height from the ground level to the bse of the continuous live crown (HLC; i.e., the lowest contiguous whorl with t lest three brnches), nd crown socil clss (dominnt, co-dominnt, intermedite, nd suppressed). Tree condition nd pthology were lso noted. Mesurements were tken on the following dtes (Tble ): Gregg6 were tken in 196, 1966, 1971, 1976, 1981, 1986, 1991, 1996, 001, 006, nd 011. Gregg8 were tken in 198, 1989, 1996, 00, 009, nd 01 (medium-productivity site only). McKy were tken in 195, 1960, 1969, 1979, 1989, 1996, 00, 008, nd 01. Teepee Pole Creek were tken in 1967, 197, 1977, 198, 1987, 199, 1996, 00, 009, nd 01 (medium-productivity site only). Becuse of the lrge size of the McKy tril, heights were mesured only for smple of the trees in ech plot, nd height ws estimted for ll other trees. Dt from the 1996 mesurements t Teepee Pole Creek hve been excluded becuse of suspected errors nd lck of informtion bout qulity control during the collection of dt. Crop trees tgged t estblishment were included in the dtset for this nlysis, long with ingress trees tht were considered to interct with the crop trees (i.e., those tht ttined 90% of the height of the shortest unbroken crop tree). When tree heights hd not been mesured, they were estimted from provincil height dimeter equtions, using coefficients estimted for individul tretments in ech tril for lodgepole pine nd coefficients estimted for the er Foothills subregion for other species (Hung 1999). Before compiltion for nlysis, the dt were screened for obvious errors (e.g., decresing height or dimeter mesurements) nd, when possible, such errors were corrected. Totl nd merchntble volumes were clculted for ech tree t ech mesurement time, using equtions developed for lodgepole pine in Albert (Hung 199). Totl volume ws clculted s totl residul live-stem volume inside brk (1.5 cm top dimeter nd 0 cm stump height). Merchntble volumes were clculted ccording to two utiliztion stndrds commonly used in Albert: Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

15 1/7 nd 15/10. In these stndrds, the first number refers to the dimeter in centimeters outside the brk t stump height (0 cm) nd the second number refers to the dimeter in centimeters inside the brk t the top, with minimum merchntble length of. m (Hung et l. 001). Piece size ws clculted s the merchntble volume (1/7 stndrd) per tree. Dt for surviving trees were ggregted by plot nd tretment nd were converted to per-hectre bsis. We clculted the reltive rte of mortlity s the lmbd prmeter from the exponentil decy function for the number of live trees per hectre over time. Top height (TopHt) ws clculted s the men height of the 100 lrgest dimeter trees per hectre, prorted to the ctul plot size, with the minimum number of three trees used to clculte top height in the smllest plots. Qudrtic men dimeter ws clculted s follows: [1] Dq = 100 BAsum πntrees where Dq = qudrtic men dimeter, BAsum = the sum of bsl re of ll trees in the plot, nd Ntrees = the number of trees in the plot. Competition within the density tretments ws clculted in two wys, s spcing fctor (SF, Wilson 196) nd stnd density index (SDI, Reineke 19), s follows: stems [] SF = 100/( TopHt) h where SF = spcing fctor nd TopHt = top height, nd stems Dq [] SDI = ( ) 1.6 h 5 where SDI = stnd density index (stndrdized to Dq of 5 cm) nd Dq = qudrtic men dimeter. Sttisticl Anlysis Stnd conditions chnged over time; representing the density tretments by the trget stnd density when they were estblished fils to tke into ccount the dynmic nture of the treted plots. Although the initil stnd density is controlled to prticulr level, subsequent stnd development is subject to number of other fctors tht ffect growth nd mortlity. Therefore, the trjectories of post-thinning stnds my differ lthough they strt t the sme density. Becuse stnd is dynmic system, there is no one mesure (such s initil density) tht dequtely cptures the conditions of the stnd during the entire course of its development. A given stnd density hs different implictions, depending on the ge of the stnd nd the size of the trees. Therefore, we grouped initil tretments into density tretment ctegories to emphsize tht initil conditions re n pproximtion of the tretment conditions nd tht tretments my converge during stnd development. Results re presented s density clss tretments A through G, corresponding to the estblishment densities s follows: A (9 stems/h), B (77 nd 988 stems/h), C (1 977 stems/h), D ( 965 nd 986 stems/h), E ( 95 stems/h), F (7 907 stems/h), G ( stems/h unthinned). Results of prticulr tretment in different trils re not directly comprble becuse they were estblished nd mesured t different times nd different ges. We chose not to project dt to common rottion ge using existing growth nd yield models. Therefore, no forml sttisticl comprisons mong trils were mde in this nlysis, nd sttisticl nlysis ws crried out on ech of the four trils seprtely. Sttisticl nlysis of differences between tretments used only the ltest mensurtion dt from ech site. We used the squre trnsformtion of tree height nd the log10 trnsformtion of piece size, live crown rtio, nd height dimeter rtio in the nlysis to meet ssumptions of normlity nd homoscedsticity. Other vribles did not require trnsformtion. The significnce of site nd tretment fctors ws tested using nlysis of vrince (ANOVA, Proc GLM [SAS Institute]). The ANOVA models used were liner combintion of the min fctors nd their interctions, s follows: Vr ~ S + B(S) + D + S D + B D(S) + S B D(S) + ε (for the Gregg Burn nd Teepee Pole Creek sites) Vr ~ B + D + B D + ε (for the McKy site) where Vr represents the dependent vrible being tested, S is site, B is block, D is the density clss tretment, nd ε is the error. Informtion Report FI-X-16 5

16 The Type III sums of squres were used becuse of uneven cell sizes in the nlysis. For the Gregg Burn nd Teepee Pole Creek trils, site effects were tested ginst the block(site) term, nd the density effect nd site density interction were tested ginst density site block(site) term. For the McKy tril, the density effect ws tested ginst density block term. The Tukey Krmer test (lso known s Tukey s honestly significnt difference [HSD] test; Tukey 199) ws used to test for differences mong tretments. Results In this report, we evlute the stnd growth nd yield from different thinning tretments in longterm silviculture instlltions in the Upper Foothills (Gregg Burn nd Teepee Pole Creek) nd er Foothills (McKy) subregions of Albert. The McKy instlltion ws estblished to determine whether precommercil thinning of lodgepole pine could improve merchntble volume nd qulity t young ge, nd in turn shorten rottion nd increse nnul llowble cuts. In the Gregg Burn nd Teepee Pole Creek instlltions we ssess the response of tree nd stnd growth to different juvenile spcing tretments, with densities rnging from 500 to stems per hectre. Tree nd stnd outcomes in these instlltions re mesured periodiclly to evlute the effect of thinning level on the growth nd yield of the lodgepole pine crop trees. To provide decdl updte to previous mesurements nd evlution, we exmined totl nd merchntble volumes t these sites using the most recent dt (011 01). Results re presented in Figures 16. Tree-level properties re presented s notched box-nd-whisker plots to show the distribution of the dt (Figures 6 to 10). Dot-plots of stnd-level vribles represent the plot mens of the tretment for ech block (Figures to 5, 11 to 16). Stnd Development Stnd In ll trils, the ltest stnd densities were, s expected, relted to the initil density (Figure, Tbles nd A1). However, stnd densities hve converged over time, s result of mortlity of the originl trees. Stnd densities still spn rnge from more thn stems per hectre in the Gregg6 low-productivity site to between 00 nd 50 stems per hectre in the A tretments of the Gregg6 nd Teepee Pole Creek trils, but only to 6 in the McKy A tretment. Stnd density t the lst mesurement of the Gregg6 tril ws ffected by the interction of the thinning tretment nd site conditions; lthough stnd density ws decresed with the intensity of the thinning tretment, the differences mong tretments were lest in the high site nd greter in the medium nd low sites, suggesting tht selfthinning ws greter in the high site. There were no significnt interctions between site nd density tretment in the Gregg8 nd Teepee Pole Creek trils (Figure, Tbles nd A1). Therefore, the self-thinning trjectories for ech tretment were pproximtely the sme cross the different sites. Stnd density in the low site of the Gregg8 tril ws slightly, but significntly, higher thn in the medium nd high sites. differences in stnd density were not significnt in the Teepee Pole Creek tril. Mortlity Men reltive mortlity rtes over the course of the tril mesurement period did not differ mong sites, except in the Gregg6 tril, where the rtes were higher in the high-productivity site thn in 6 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

17 Gregg6 Gregg6 Gregg Stnd density (stems/h) Gregg8 Gregg8 b Gregg8 McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G A B C D E F G clss Figure. Stnd density t ltest mesurement for four lodgepole pine precommercil thinning trils. See text for explntion of tretment design. Tretment plot mens under the sme horizontl line re not significntly different t the 0.05 probbility level, bsed on the Tukey Krmer tests. Where the results re too complex to indicte significnt differences with lines, lower-cse letters re used; those tretments tht shre the sme letter re not significntly different from ech other t the 0.05 probbility level. clss is described in the Stnd Development nd Tree-level Properties sections of the pper. Informtion Report FI-X-16 7

18 Tble. Results of nlysis of vrince of the effect of site nd density tretments on stnd density t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 density 8 Type III sum of squres Men squres F vlue Pr > F Gregg8 density Teepee Pole density McKy Block DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. Tble. Results of nlysis of vrince of the effect of site nd density tretments on mortlity rte t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 density 8 Type III sum of squres Men squres F vlue Pr > F Gregg8 density Teepee Pole density McKy Block DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. 8 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

19 Gregg6 Gregg6 b Gregg6 b Mortlity rte (lmbd, %/yer) Gregg8 Gregg8 Gregg8 McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G A B C D E F G clss Figure. Reltive nnul mortlity rte since estblishment for four lodgepole pine precommercil thinning trils. See cption for Figure for explntion of tretment design. Informtion Report FI-X-16 9

20 the medium- nd low-productivity sites (Figure, Tbles nd A). In ll sites, there is significnt effect of density tretment on reltive mortlity rte, lthough the mortlity rtes differed little between djcent density tretments within tril. Mortlity ws in the rnge of % per yer in the highest density tretments, nd less thn 1% per yer in the lowest density tretments. Although mensurtion dt in the pst three cycles hve included recording of tree condition, the cuses of mortlity re not cler. There is no indiction tht density hs n effect on insect nd disese occurrence; in fct, there is evidence of some level of ttck in 100% of trees in most plots, nd in t lest 85% of the trees even in the helthiest stnds. Spcing Fctor Since the spcing fctor (SF) is closely relted to stnd density, s well s to height, the results mirror those of stnd density to some degree (Figure, Tbles 5 nd A). In the Gregg8 tril, SF ws higher in the low-productivity site, rnging up to lmost 0.5, thn in the medium- or high-productivity sites. The medium- nd highproductivity sites hd similr rnge of SF (from bout 0.1 to 0.5; Figure ). There ws no significnt difference mong sites in the other trils. Spcing fctor decresed with incresing density tretment. Although SF differed mong density tretments t estblishment (not shown), fter severl decdes of growth nd mortlity SF vlues hve become similr mong some of the djcent density tretments. However, the SF vlues in the lowest-density tretments still differ from those in ll other tretments in lmost ll cses. The lowest vlues of SF were in the McKy tril, where they rnged from bout 0.17 in the most open (A) tretment to less thn 0.10 in the unthinned control (G tretment) plots. Stnd Index Stnd density index (SDI) shows pttern of differences similr to tht of SF, lthough the vlues of SDI increse, rther thn decrese, with incresing density tretment (Figure 5, Tbles 6 nd A). The vlues rnged from less thn 00 to more thn 1 00 stems per hectre. The low-productivity site in the Gregg8 tril hd significntly lower SDI vlues thn the medium- nd high-productivity Tble 5. Results of nlysis of vrince of the effect of site nd density tretments on spcing fctor t the ltest mesurement in four lodgepole pine precommercil thinning trils Type III sum of Men squres Tril Source DF squres F vlue Pr > F Gregg6 density Gregg8 density Teepee Pole density McKy Block DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. 10 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

21 Gregg6 Gregg6 Gregg Gregg8 Gregg8 b Gregg8 0.5 Spcing fctor McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G clss A B C D E F G Figure. Spcing fctor t ltest mesurement for four lodgepole pine precommercil thinning trils. See cption for Figure for explntion of tretment design. Informtion Report FI-X-16 11

22 Gregg6 Gregg6 Gregg Gregg8 Gregg8 b Gregg8 Stnd density index McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G A B C D E F G clss Figure 5. Stnd density index t ltest mesurement for four lodgepole pine precommercil thinning trils. See cption for Figure for explntion of tretment design. 1 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

23 Tble 6. Results of nlysis of vrince of the effect of site nd density tretments on stnd density index t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 density 8 Type III sum of squres Men squres F vlue Pr > F Gregg8 density Teepee Pole density McKy Block DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. sites, otherwise, the rnge of SDI vlues cross the density tretments ws not significntly different between the sites within tril. The rnge of SDI vlues cross the rnge of density tretments within site ws nrrower in the McKy nd Gregg8 trils (15 57) compred with the Gregg6 nd Teepee Pole Creek trils ( ). As with the other stnd-development vribles exmined, there were often no significnt differences in SDI between djcent density tretments with site. Tree-Level Properties Tree Dimeter Precommercil thinning hd consistent significnt effect on DBH (Figure 6, Tbles 7 nd A5). In generl, DBH decresed with incresing stnd density nd incresed with site productivity. Slope spect hd no effect on DBH in the Teepee Pole Creek tril. The rnge in DBH in the Gregg8 tril ws less thn in ny of the other trils, for similr density tretments (bout cm in Gregg8 vs 10 cm in other trils). Tree Height In the Mcky tril, tree height incresed with the severity of the thinning tretments (Figure 7, Tbles 8 nd A6). Although height differences mong tretments were not s gret s in the McKy site, heights in the Gregg6 nd Teepee Pole Creek trils lso incresed with the severity of the thinning tretments, except for the most severe thinning where it decresed. Mximum heights occurred in the B nd C tretments. There were no significnt differences in height mong thinning tretments in the Gregg8 tril. Height responded to site productivity, being lower in the low-productivity sites thn in the medium- or high-productivity sites in the Gregg Burn trils, lthough it ws unffected by site differences in the Teepee Pole Creek tril. Heights rnged from 10 m to 0 m or more in the trils, except for the Gregg8 low-productivity site, where heights were less thn 10 m. Height Dimeter Rtio Tree slenderness, or height dimeter rtio (HDR), consistently incresed with incresing density tretment in ll trils nd sites, s dimeter Informtion Report FI-X-16 1

24 c b Gregg6 Gregg6 Gregg Gregg8 b Gregg8 Gregg8 Dimeter t BH (cm) McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G clss A B C D E F G Figure 6. Dimeter t brest height (BH) t ltest mesurement for four lodgepole pine precommercil thinning trils. Note tht where notches overlp the mens re not significntly different. Horizontl brs tht overlp more thn one tretment indicte tht these tretments re not significntly different from ech other t the 0.05 probbility level, bsed on the Tukey-Krmer tests. 1 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

25 Tble 7. Results of nlysis of vrince of the effect of site nd density tretments on tree dimeter t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 Gregg8 Teepee Pole McKy density block density(site) density block density(site) density block density(site) Block Block density Type III sum of squres Men squres F vlue Pr > F DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue Tble 8. Results of nlysis of vrince of the effect of site nd density tretments on tree height t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 density block density(site) 8 1 Type III sum of squres Men squres F vlue Pr > F Gregg8 density block density(site) < Teepee Pole density block density(site) McKy Block Block density DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. Informtion Report FI-X-16 15

26 5 c b Gregg6 Gregg6 Gregg6 b b c d b b c d b b c d Gregg8 b c Gregg8 Gregg8 5 Height (m) McKy Teepee Pole Flt Teepee Pole c d b c d b d c b d c b A B C D E F G A B C D E F G clss A B C D E F G Figure 7. Height t ltest mesurement for four lodgepole pine precommercil thinning trils. See cption for Figure 6 for explntion of tretment design. 16 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

27 responded more strongly thn height to chnges in stnd density (Figure 8, Tbles 9 nd A7). Trees with more growing spce in the more open density tretments (A, B, nd C) hd HDR vlues minly between 0.5 nd 1.0, while those with more competition in the high density tretments (D, E, F, nd G) hd HDR vlues of bout 1.0 nd bove. Significnt site effects were seen only in the Gregg8 tril, where there were smll but significnt increses in HDR from the low- to medium- to highproductivity sites. Live Crown Rtio Live crown rtio (LCR) generlly decresed with incresing density, nd with incresing site productivity, in the Gregg Burn nd Teepee Pole Creek trils (Figure 9, Tbles 10 nd A8). Live crown rtios did not differ with slope spect in the Teepee Pole Creek tril. Live crown rtios were lowest in the McKy tril (minly between 0. nd 0.) nd were little ffected by density tretments. Elsewhere, LCR vlues rnged from 0. to 0.6 or 0.7. In Gregg8, there ws significnt interction between the density tretment nd site. In the low-productivity site, the vlue of LCR in the C tretment did not differ from tht in the B tretment, wheres the C tretment vlue ws the sme s tht for the D tretment in the high-productivity site, nd ws intermedite between, nd significntly different from, both B nd D tretments in the mediumproductivity site. Piece Size Piece size (i.e., merchntble volume per tree t the 1/7 stndrd) decresed significntly with incresing density in the Gregg6, McKy, nd Teepee Pole Creek trils (Figure 10, Tbles 11 nd A9). tretment hd no significnt effect on piece size in the Gregg8 tril, probbly due to the smll size of the trees this erly in stnd development, resulting in little merchntble volume in ny of the tretments. In the D, E, nd F density tretments, representing initil stnd densities from bout 000 to stems per hectre, piece size did not differ in ny of the trils. Significnt differences in piece size were seen only mong the A, B, nd C tretments, representing initil densities from bout 500 to 000 stems per hectre. Tble 9. Results of nlysis of vrince of the effect of site nd density tretments on height dimeter rtio t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 Gregg8 Teepee Pole McKy density block density(site) density block density(site) density block density(site) Block Block density Type III sum of squres Men squres F vlue Pr > F DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue Informtion Report FI-X-16 17

28 Gregg6 Gregg6 b Gregg6 b Gregg8 b Gregg8 c Gregg8 Height dimeter rtio McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G A B C D E F G clss Figure 8. Height dimeter rtio t ltest mesurement for four lodgepole pine precommercil thinning trils. See cption for Figure 6 for explntion of tretment design. 18 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

29 1.0 Gregg6 Gregg6 Gregg Gregg8 Gregg8 b Gregg8 1.0 Live crown rtio McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G A B C D E F G clss Figure 9. Live crown rtio t ltest mesurement for four lodgepole pine precommercil thinning trils. See cption for Figure 6 for explntion of tretment design. Informtion Report FI-X-16 19

30 Tble 10. Results of nlysis of vrince of the effect of site nd density tretments on live crown rtio t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 Gregg8 density block density(site) density block density(site) Type III sum of squres Men squres F vlue Pr > F Teepee Pole density block density(site) McKy Block Block density DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. Tble 11. Results of nlysis of vrince of the effect of site nd density tretments on piece size t the ltest mesurement in four lodgepole pine precommercil thinning trils Tril Source DF Gregg6 Gregg8 Teepee Pole McKy density block density(site) density block density(site) density block density(site) Block Block density Type III sum of squres Men squres F vlue Pr > F DF = degrees of freedom; Pr > F = the probbility of getting by chnce n F-vlue greter thn the estimted vlue. 0 Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert

31 Gregg6 Gregg6 c Gregg6 b Gregg8 Gregg8 Gregg8 Piece size (m /tree) McKy Teepee Pole Flt Teepee Pole A B C D E F G A B C D E F G A B C D E F G clss Figure 10. Piece size of merchntble trees (1/7 stndrd) t ltest mesurement for four lodgepole pine precommercil thinning trils. See cption for Figure 6 for explntion of tretment design. Informtion Report FI-X-16 1

32 Stnd-Level Properties The results reported in this section re closely relted to the dimeter nd height vribles reported bove, nd re included becuse they re commonly used in growth nd yield nlysis. Note tht the height nd dimeter vribles reported bove were mens of ll trees in the tretment, wheres these vribles re the mens of plot-level vlues, verged cross two or three blocks. Qudrtic Men Dimeter As with DBH, qudrtic men dimeter ws sensitive to site productivity nd density tretment (Figure 11, Tbles 1 nd A10). The vlues of the rithmetic mens nd the qudrtic mens differed little in these stnds. Top Height Top height ws clculted from subsmple of the trees with the lrgest dimeter in ech plot. The number of trees included ws determined by plot size, nd therefore the smple size ws very smll (nd the estimte less precise) in the smllest re plots (Figure 1, Tbles 1 nd A11). As expected, top height reflected site productivity, lthough not slope spect, nd ws not significntly different mong density tretments. Most top heights were from 1 m to m, except for the Gregg8 lowproductivity site, where top heights in ll tretments were bout 10 m or less. Stnd Yield Bsl Are Bsl re (BA) more strongly reflected the effect of stnd density thn of tree size, incresing with incresing density tretments (Figure 1, Tbles 1 nd A1). However, men BA reflects the smll tree size in the low-productivity site of the Gregg8 tril, where the BA in ll plots is low (7 m /h) compred with other sites where the lowest vlues re bout 1 m /h nd the highest bout 5 m / h. Bsl re in other trils rnged s high s 0 50 m /h, nd, in the cse of the Gregg6 highproductivity site, exceeded 50 m /h. Totl Volume Stnd totl volume ws very similr to bsl re but lso reflected differences in height (Figure 1, Tbles 15 nd A1). Totl volume rnged from 100 to 00 or 00 m /h in the Gregg6 nd Teepee Pole Creek trils, but did not exceed 50 m /h in the Gregg8 tril. Totl volume ws higher in the McKy tril, which lso hd the highest totl volume for the A nd C tretments (00 nd m /h, respectively). Totl volume incresed with incresing density tretment, s did BA, but there ws some inconsistency mong blocks, nd there ws no significnt difference mong the density tretments in the McKy tril. Merchntble Volume The higher-productivity sites in the Gregg6, Teepee Pole Creek, nd McKy trils produced t best between 00 nd 00 m /h of merchntble volume t the 1/7 stndrd (Figure 15, Tbles 16 nd A1). The lower-productivity sites in Gregg6 nd ll of Gregg8 produced less thn hlf tht volume. Slope spect hd no significnt influence on merchntble volume. The interction between site nd density in the Gregg6 tril resulted from n increse in merchntble volume with stnd density tretment in the fster-growing high-productivity site, wheres, in the medium- nd low-productivity sites, the trees hd not yet grown lrge enough to crete much merchntble volume in the higher-density tretments (E nd F). Merchntble volume t the 15/10 stndrd showed the sme effects nd ptterns of significnce s merchntble volume t the 1/7 stndrd, but the declines in volume t higher densities, in stnds where the trees were still smll, ws excerbted by the lrger threshold of the merchntbility stndrd (Figure 16, Tbles 17 nd A15). The top vlues of volume were still m /h, but the lowest vlues were t or ner zero in some cses. Evlution of Precommercil Thinning of Lodgepole Pine from Long-term Reserch Instlltions in Albert