FIA-FSP Project Y Effects of intensive fertilization on timber and non-timber resources. Executive Summary April 2006

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1 FIA-FSP Project Y21 Effects of intensive fertiliztion on timber nd non-timber resources Executive Summry April 2 Project Purpose nd Mngement Implictions Without strtegic intervention, ge clss imblnces in the timber inventory nd ctstrophic mortlity losses from the mountin pine beetle (Dendroctonus ponderose Hopk.) will likely result in significnt mid-term timber supply shortflls in severl interior forest mngement units. Incresing the productivity nd ccelerting the development of young, mnged forests is primry objective of severl timber supply mitigtion strtegies being developed for interior Timber Supply Ares nd Tree Frm Licences. Fertiliztion is the most proven silviculturl tretment for incresing hrvest volume nd ccelerting the operbility of estblished stnds. A single fertilizer ppliction typiclly produces only temporry increse in tree nd stnd growth. However, fertiliztion reserch in other forest regions hs indicted tht sustined growth responses, nd lrge reductions in rottion length, re chievble by repetedly fertilizing young conifer stnds. To wht extent cn intensive fertiliztion potentilly mitigte mid-term timber supply shortflls in the B.C. interior? Wht re the potentil long-term ecologicl consequences of dding lrge quntities of nutrients to interior forests? This reserch project ws initited to provide forest plnners nd prctitioners with relible nswers to these importnt questions. Project Strt Dte This long-term reserch project ws initited in 1992 with funding provided by the Cnd-British Columbi Forest Resource Development Agreement (FRDA II). Subsequent funding ws provided by Forest Renewl BC nd Forestry Innovtion Investment Ltd. Three-yer continued project funding by FIA-FSP begn in 24/25 (Y511). Methodology Overview Loction, Site nd Stnd Descriptions The distribution of instlltions by species, stnd origin, nd BEC subzone is shown in Tble 1. Detiled stnd nd site descriptions of individul field instlltions re provided in Brockley nd Simpson (24). Tretment Description At ech site, six tretments re replicted three times for totl of 1, re-bsed tretment plots. The six tretments re: 1. (i.e., not fertilized)

2 2 2. NB fertilize every yers with (kg/h): 2N, B 3. NSB fertilize every yers with (kg/h): 2N, 5S, B 4. Complete fertilize every yers with (kg/h): 2N, P, K, 5S, 25Mg, B 5. ON 1 yerly fertiliztion to mintin folir N concentrtion t 1.3% nd other nutrients in blnce with folir N. ON 2 yerly fertiliztion to mintin folir N concentrtion t 1.% nd other nutrients in blnce with folir N All of the fertiliztion regimes include boron (B) to sfegurd ginst the possibility of B deficiencies induced by repeted N dditions. Tretments 3 nd 4 re included to test for incrementl growth responses ttributble to sulphur (S) nd other dded nutrients. Previous studies hve clerly demonstrted B nd S deficiencies in interior forests (Brockley 199, 2, 23, 24). The ON 1 nd ON 2 tretments re ptterned fter Scots pine nd Norwy spruce optimum nutrition experiments in Sweden (Tmm 1991; Tmm et l. 1999), nd typiclly receive 5- kg N/h nd -2 kg N/h, respectively, ech spring. Other nutrients (P, K, Mg, S, B, Cu, Fe) re dded periodiclly to provide n pproprite nutrient blnce nd to minimize growth limittions cused by secondry deficiencies. Tble 1. Distribution of mximum productivity instlltions by species, stnd origin nd BEC subzone Instll. Stnd BEC Yer. No. Loction Species Origin Subzone Estb. estb. 1 Sheridn Creek Pl N SBSdw Kenneth Creek Pl P SBSwk Crow Creek Sx P SBSmc McKendrick Pss Pl P ESSFmc Lodi Lke Sx P SBSwk Tutu Creek Pl P SBSmk Crter Lke Pl N MSxv Hnd Lke Sx P SBSmk Plot Estblishment Ech instlltion consists of 1 rectngulr,.14-h tretment plots. Ech tretment plot consists of n inner, squre.5-h ssessment plot surrounded by treted buffer. The ssessment plot is offset t one end of the tretment plot to reserve n enlrged buffer re for future destructive smpling. Three sides of the ssessment plot re surrounded by.4-m buffer; the buffer on the fourth side is 15.1 m wide. Ech tretment plot contins pproximtely crop trees, equivlent to stnd density of 1 stems per hectre t 3-m squre spcing. Growth nlyses for ech plot re bsed on periodic mesurement of 4 permnently tgged trees within the inner ssessment plot. Surplus trees within the ssessment plot nd buffer were selected nd removed t the time of plot estblishment. Conifer nd brodlef ingress is periodiclly removed from tretment plots.

3 3 At ech study site, tretment plots were systemticlly locted so tht within- nd between-plot conditions (e.g., stnd density, tree height, tree dbh, soil chrcteristics, nd minor vegettion) were s uniform s possible. A minimum distnce of 5 m seprtes the outer boundries of djcent tretment plots. A minimum distnce of 2 m seprtes the outer tretment plot boundries from mjor disturbnces (e.g., rods or lrge stnd openings). Folir Smpling nd Anlysis Replicted smples of current yer s folige re collected from control, ON 1 nd ON 2 tretment plots ech fll (lte September to lte October). For ll other tretments (i.e., NB, NSB, nd Complete), folige is collected in the fll prior to ech fertilizer ppliction nd fter the 1 st nd th growing sesons following fertiliztion. Folige is collected from representtive helthy dominnt or codominnt trees evenly distributed within ech ssessment plot. Smples re collected from the lower portion of the top 1/3 of the live crown, consistent with stndrdized folir smpling guidelines (Brockley 21). Whenever possible, the sme trees re smpled ech yer. Individul folige smples re frozen following field collection, nd then dried in forced-ir oven t 7 o C for 2 hours before nlysis. One composite smple, consisting of equl mounts of folige from ech of the trees per tretment plot, is prepred for chemicl nlysis. Dried composite smples re ground in n electric coffee grinder nd sent to the Ministry of Forests nd Rnge nlyticl lbortory for chemicl nlysis. Fertiliztion At ech study site, ll NB, NSB, nd Complete tretment plots were fertilized in the spring following instlltion estblishment nd re re-fertilized every yers. In My 25, the NB, NSB nd Complete tretment plots in one instlltion (Sheridn Creek) ws fertilized for the third time (12 th yer). The NB tretment is customized combintion of ure (4--; N-P-K) nd grnulr borte (15% B) blended to deliver 2 kg N/h (2N) nd kg B/h (B). Ure, mmonium sulphte ( ; N-P-K-S), nd grnulr borte re combined to deliver 2N, 5S, nd B in the NSB tretment. In the Complete tretment, ure is the mjor source of N. A smll mount of N (24% of the totl) is dded s monommonium phosphte (11-52-; N-P-K), which lso serves s the P source. Potssium is delivered s potssium chloride (--; N-P-K) nd sulphte potsh mgnesi ( ; N-P-K- S-Mg). The ltter fertilizer is lso the source of S nd Mg. As in the NB nd NSB tretments, B is dded s grnulr borte. The individul sources re combined to deliver 2N, P, K, 5S, 25Mg nd B. Yerly fertilizer prescriptions for ON 1 nd ON 2 tretments re developed following folir smpling nd nutrient nlysis ech fll. Individul nutrients re included in customized blends in mounts nd frequencies tht re required to mintin individul folir nutrient levels, nd nutrient rtios (e.g., N/P, N/K, N/S, N/Mg) within suitble rnges s indicted in published forest nutrition literture. Customized fertilizer blends re pplied to the ON 1 nd ON 2 tretment plots ech spring, soon fter snowmelt. Ure is the primry N source for ON 1 nd ON 2 fertiliztion t ll study sites. Additionl sources of N re monommonium phosphte nd mmonium nitrte (34--; N-P-K). Phosphorus is lwys dded s monommonium

4 4 phosphte. Sulphte potsh mgnesi is used extensively s source of K, S, nd Mg. Potssium chloride, mmonium sulphte nd ProMg 3 (3% Mg) is used to supply dditionl K, S, nd Mg, respectively. Boron is supplied s grnulr borte. The ON 1 nd ON 2 fertilizer prescriptions for spring 25 fertiliztion were developed from folir nlyticl results from the fll 24 folir smpling. The ON 1 nd ON 2 plots t ll eight study loctions were fertilized My -19, 25. Fertilizer prescriptions re shown in Tble 2. Tble 2. ON 1 nd ON 2 fertilizer regimes pplied in 25 by study loction. Tretment Study Loction ON 1 ON 2 Sheridn Creek 5N, 5P, 5K, 5S, 25Mg N, 5P, 5K, 5S, 25Mg Kenneth Creek 5N, 5P, 5K, 5S, 25Mg N, 5P, 5K, 5S, 25Mg Crow Creek 75NN, 5S N, 5S McKendrick Pss 5N, 5P, 5K, 5S, 25Mg N, 5P, 5K, 5S, 25Mg Lodi Lke 75N, 5S N, 5S Tutu Creek 5N, 5P, 5K, 5S, 25Mg N, 5P, 5K, 5S, 25Mg Crter Lke 5N, 5P, 5K, 5S, 25Mg N, 5P, 5K, 5S, 25Mg Hnd Lke N, 5S 15N, 5S N = nitrogen; P = phosphorus; K = potssium; S = sulphur; B = boron; Cu = copper; Fe = iron. Vlues preceding the nutrients indicte the mount of nutrient pplied in kilogrms per hectre. Mesurement At ech instlltion, the dimeter t brest height (dbh), totl height, nd height to live crown of ll 4 tgged trees within ech mesurement plot ws mesured t the time of estblishment. Remesurements re scheduled for 3-yer intervls therefter. Stndrd codes re used to describe the condition nd form of ech tgged tree t ech remesurement. Beginning in 23, the crown width (i.e., the verticlly projected mximum horizontl distnce between opposite crown mrgins) of ech tgged tree is lso mesured nd recorded. Dimeter mesurements re tken with steel dimeter tpe t permnently mrked point pproximtely 1.3 m bove ground level. Heights re mesured with telescoping height pole or with n electronic mesuring device (Forestor Vertex hypsometer). Height to live crown is mesured with telescoping height pole, nd crown width is mesured in two directions (t right ngles) with steel mesuring tpe.

5 5 A totl of four mximum productivity instlltions were remesured in the fll of 24. A 12-yer mesurement ws completed t Sheridn Creek. Three other instlltions (McKendrick Pss, Lodi Lke, nd Tutu Creek) received 9-yer mesurements. Lef Are Index The development of effective stnd lef re index (LAI) is being monitored t ech mximum productivity instlltion, with mesurements timed to coincide with 3-yer growth mesurements. In ddition, yerly LAI mesurements re being conducted t three field loctions in order to monitor yer-to-yer chnges in LAI. Field mesurements re mde in lte spring immeditely prior to bud flush following the previous fll s growth mesurement. The mesurement of LAI following folige bscission in the fll nd before bud flush in the spring ensures reltively stble environment tht will fcilitte yer-to-yer comprison of LAI development in mximum productivity instlltions. Lef re index is mesured with Li-Cor LAI-2 plnt cnopy nlyzer (Li-Cor 1991). Within ech tretment plot, mesurements re obtined t height of - cm bove the ground t the nine permnently mrked points used to fcilitte fertilizer ppliction. Two redings re obtined t ech point, one fcing northwest nd the other fcing northest before nd fter solr noon, respectively. Sensors re equipped with -degree view cp. Simultneously, bove cnopy light mesurements re collected in n open re djcent to the study site where the light sensor hs n unobstructed view of the sky. In spring 25, lef re mesurements were undertken t McKendrick Pss, Lodi Lke, nd Tutu Creek to coincide with the 9-yer remesurement completed in the fll of 24. Lef re mesurements were lso undertken t Sheridn Creek (12-yer), Hnd Lke, Crter Lke, nd Kenneth Creek. White Pine Weevil The white pine weevil (Pissodes strobi Peck.) is the most serious nd economiclly importnt ntive insect of spruce regenertion in Cnd. Dmge inflicted by the weevil to terminl leders in young white spruce plnttions my result in severe growth losses nd stem defects. Lrge-scle fertilizer opertions in interior spruce forests re currently discourged due to observed incresed incidence of weevil dmge in fertilized Sitk spruce plnttions in costl B.C. To dte, there hve been no forml studies of the reltionship between fertiliztion nd susceptibility to ttck. In collbortion with Dr. R. Alfro nd L. vnakker (Cndin Forest Service), study ws initited in 21/2 to document the effects of vrious rtes nd frequencies of fertiliztion on weevil ttck nd tree defence mechnisms t three spruce mximum productivity instlltions. The three spruce sites re locted cross wide rnge of climtic conditions within the SBS biogeoclimtic zone (i.e., SBSmc, SBSmk, SBSwk). These climte differences hve mjor influence on white pine weevil popultion dynmics. In 21, retrospective surveys were conducted t ll three sites to determine weevil ttck rtes nd severity since tril estblishment. The sites were re-surveyed in 22 nd 23 to ssess current dmge. In ddition, field smpling nd lbortory nlyses were undertken to determine the effects of different fertiliztion regimes on 1)

6 tree constitutive nd trumtic resin cnl defences, 2) nutritive qulity of leder brk, nd 3) chemicl profile of voltiles from stem smples. Detiled smpling methodology is provided in vnakker et l. (24, 25b). Soil Biot As well s incresing bove-ground productivity, forest fertiliztion my lso ffect below-ground biologicl components of forest ecosystems. A single fertilizer ppliction generlly hs only smll nd temporry effect on below-ground resources. However, lrge nd persistent chnges in soil microbil popultions nd fine root development, nd in the ctivity, diversity nd structure of mycorrhizl nd mesofun communities, hve been reported from long-term fertiliztion nd N deposition studies in Europen forests. Although the long-term functionl implictions of these chnges re poorly understood, they my potentilly ffect processes such s nutrient cycling, nutrient uptke, nd drought tolernce in intensively fertilized stnds. In collbortion with Dr. S. Berch (B.C. Ministry of Forests nd Rnge, Reserch Brnch), fully replicted study ws undertken in 22/3 to document the effects of 9 yers of nnul nutrient dditions on fine root length, mycorrhizl coloniztion, soil microbil ctivity nd diversity, nd mesofun bundnce nd community structure t one lodgepole pine mximum productivity study site in centrl British Columbi (Sheridn Creek). In mid-september 22, smples were collected from 3 replicte instlltions of the tril: unfertilized control, ON 1, nd ON 2. For soil mesofun nd soil microbil community, seprte forest floor nd upper minerl soil (-3 cm) smples were rndomly collected from ech plot using 4.5-cm internl dimeter-coring device. For ectomycorrhizs nd fine roots, ten xx cm combined forest floor nd minerl soil smples were rndomly collected. Detiled smpling nd nlyticl methodology is provided in Berch et l. (2). A similr study ws undertken t spruce mximum productivity site (Crow Creek) in the fll of 24. To dte, much lrger growth responses hve been mesured in spruce thn in pine instlltions (Brockley nd Simpson 24), nd it is importnt to determine whether soil biot nd fine rooting differences lso exist between these two species. As with the previous study, field smpling in 24 coincided with the completion of the th growing seson following instlltion estblishment. The smpling methodology ws virtully identicl to tht described for the erlier study (Berch et l. 2). Litterfll Aboveground litter production is mjor flux of orgnic mtter nd nutrients to forest soils. Understnding how litter quntity nd nutrient concentrtions respond to fertiliztion is essentil for studies of relted ecosystem chrcteristics nd processes, including nutrient use efficiency, litter decomposition, nd forest floor ccumultion. Previous studies of litter quntity nd chemicl composition in reltion to fertiliztion of conifers hve shown rnge of responses, reflecting between-species differences, tretment conditions (rte, composition nd number of fertilizer pplictions), nd differences in methods or mesurement techniques. In collbortion with Dr. P. Snborn (University of Northern British Columbi), study ws initited in 1995 to exmine different spects of nutrient cycling in lodgepole

7 7 pine mximum productivity study site in centrl British Columbi (Kenneth Creek). The objective ws to exmine the rtes of boveground litterfll nd its chemicl composition in selected tretments, nd to consider the implictions of these responses for ecosystem functioning. Detiled smpling methodology is provided in Snborn nd Brockley (2). Soil Chemistry nd Forest Floor Mss Soil studies from other long-term fertiliztion studies hve shown tht mny physicl nd chemicl soil properties my be significntly ltered by repeted nutrient dditions. The rte nd mgnitude of these chnges, nd their long-term effects on ecosystem helth nd sustinbility, re lrgely unknown. In collbortion with Dr. P. Snborn (University of Northern British Columbi), detiled soil smpling ws undertken t one lodgepole pine mximum productivity instlltion (Kenneth Creek) in the spring of 25, immeditely before nnul fertilizer ppliction. The smpling coincided with the 12-yer remesurement of this instlltion (completed in fll 25). Results will be compred to previous soil smpling completed yers erlier t this site. Using strtified rndom smpling, eight forest floor smples were collected in ech of four equl-sized subplots within ech of the 1 tretment plots. The forest floor smples were quntittively collected with 2 x 2 cm smpling templte. All forest floor smples were ir-dried nd weighed following collection. Live roots corser thn.5 cm dimeter nd live moss nd herbceous vegettion were removed from ech smple prior to weighing. After drying nd weighing, the eight forest floor smples were combined into single composite for ech subplot, for totl of 72 composite forest floor smples (4 composites per tretment plot x 1 tretment plots). A representtive subsmple of ech composite smple ws submitted to the Ministry of Forests nlyticl chemistry lbortory. Minerl soil ws smpled for -2 cm depth t ech of the 32 forest floor smpling points within ech tretment plot. Soil smples from of the four subplots were combined into one composite smple, for totl of 72 composite minerl soil smples (4 composites per tretment plot x 1 tretment plots). Minerl soil composite smples were ir-dried nd sieved (2 mm), nd representtive subsmple of ech ws submitted to the Ministry of Forests nd Rnge nlyticl chemistry lbortory. Project Scope nd Regionl Applicbility Reserch ctivities re being undertken t eight re-bsed mximum productivity instlltions (5 Pl, 3 Sx) in the centrl nd north-centrl BC interior within three mjor biogeoclimtic zones (SBS, ESSF, MS). Results re pplicble to forest mngement opertions throughout the interior of British Columbi. Summrized Results Folir Nutrition Folir N levels in ON 1 nd ON 2 tretment plots responded positively following the initil fertilizer ppliction, nd hve remined higher thn control N levels since tht time. In most cses, the different rtes of yerly N dditions hve creted distinct

8 seprtion in folir N levels between control, ON 1 nd ON 2 tretments t most sites (Figure 1). Although there hve been yer-to-yer fluctutions, the trget folir N levels for ON 1 nd ON 2 tretments (1.3% nd 1.%, respectively) hve been pproximted t most sites. Periodic inclusion of P, K, S, nd B in ON 1 nd ON 2 fertilizer regimes hs generlly mintined folir concentrtions of these nutrients t, or bove, pre-tretment levels. Consequently, fvourble blnces between N nd these dded mcro- nd micronutrients hve been mintined t most lodgepole pine nd spruce study sites (Figures 2-). However, folir N/P, N/K, nd N/S rtios in ON 1 nd ON 2 tretments hve sometimes risen bove trget thresholds t Kenneth Creek (Figure 2). Similr trends re evident in ON 2 tretments t Tutu Creek (Figure ). Folir N/K nd N/S thresholds hve, t times, lso been slightly exceeded in ON 2 tretments t McKendrick Pss (Figure 4). Despite the inclusion of smll mounts of Mg in fertilizer prescriptions, folir N/Mg rtios in ON 1 nd ON 2 tretments t severl lodgepole nd spruce study sites incresed shrply shortly fter tril estblishment (Figures 2-). Reltively lrge quntities of Mgcontining fertilizers were subsequently dded to ll mximum productivity instlltions. These Mg dditions hve generlly succeeded in incresing folir Mg nd restoring fvourble folir N/Mg blnce. Except for B, micronutrients hve not been routinely included in ON 1 nd ON 2 fertilizer prescriptions. Folir N/Cu nd N/Fe rtios in ON 1 nd ON 2 tretments currently exceed threshold vlues t ll of the study sites (Figures 2-). Smll mounts of Cu nd Fe (3 nd kg/h, respectively) were pplied to ON 1 nd ON 2 plots t Kenneth Creek nd Crow Creek in 21. In 24, ll instlltions received 5 kg Cu/h nd kg Fe/h. To dte, these supplementl micronutrient dditions hve hd little, or no, effect on folir nutrient levels. Strong orgnic bonding in the forest floor, nd the formtion of insoluble compounds in minerl soil, hs undoubtedly reduced vilbility of the dded Cu nd Fe to tree roots. Also, dt presented by Snborn nd Brockley (2) indicted tht understory vegettion my be more ble thn lodgepole pine to exploit vilble supplies of some micronutrients. With the possible exception of Kenneth Creek, elevted N/Cu nd N/Fe rtios do not pper to be ffecting tree growth. Deficiency thresholds for Cu nd Fe re poorly defined for conifers, nd lbortory recovery nd nlyticl detection of these nutrients is problemtic. At Kenneth Creek, Amponsh et l. (25) suggested tht high N inputs in the ON 2 tretment were potentilly creting nutrient imblnces. However, n pprent induced Cu deficiency is not consistent with n pprently reduced degree of retrnsloction of Cu in the ON 2 tretment reltive to the control (Snborn nd Brockley 2). A more sophisticted pproch to understnding Cu behviour t this site is needed, such s following its concentrtion, content nd rtios with other elements cross needle ge-clsses following supplementry Cu pplictions. Growth The growth dt from the three remesurements conducted in fll 25 re generlly consistent with trends reported by Brockley nd Simpson (24). Kenneth Creek The Kenneth Creek lodgepole pine instlltion continues to respond poorly to fertiliztion (Figure 9). None of the fertilizer tretments hve resulted in sttisticlly

9 9 significnt improvement in bsl re (BA) increment fter 12 yers. Although not sttisticlly significnt, the ON 2 tretment hs pprently hd smll negtive effect on BA increment, especilly during the 7- to 12-yer mesurement period (Figure 9). Fertiliztion hs lso filed to stimulte height development of lodgepole pine t Kenneth Creek fter 12 yers. Height increments were pprently inversely relted to fertiliztion intensity t Kenneth Creek, where 12-yer height increment ws 21% less in the ON 2 tretment thn in the control tretment (Figure 9b). The negtive impct of lrge nutrient dditions on tree height ws clerly evident fter 3 yers t this site, nd hs become more pronounced t ech subsequent remesurement. In bsolute terms, the reductions in height growth in the ON 2 tretment t Kenneth Creek totlled m over 12 yers. The negtive impcts of fertiliztion on tree growth in the ON 2 tretment plots t Kenneth Creek re likely ssocited with previously reported folir nutrient imblnce (Brockley nd Simpson 24; Amponsh et l. 25). Folir nutrient imblnce my be excerbted by the leching of mobile ctions in the sndy soil t Kenneth Creek. Folir nutrient imblnce hs been linked to reduced growth nd cute mortlity following lrge N dditions to red pine (Pinus resinos Ait.) in the northestern United Sttes (Minoch et l. 2; Buer et l. 24; Mgill et l. 24). Despite much higher folir N levels, hevily fertilized trees hd significntly lower photosynthetic cpcity thn control trees (Buer et l. 24). Becuse disproportionte mount of the surplus folir N ccumulted s free mino cids (minly rginine), little of the excess N ws used to produce photosyntheticlly ctive metbolites. A number of N-contining compounds (NCC), including mino cids, ccumulte in the folige of trees subjected to environmentl stress conditions such s folir nutrient imblnces (Rbe 199). Why energy is diverted to NCC synthesis t the expense of protein synthesis nd growth under stress conditions is not fully understood. However, Rbe nd Lovtt (194) reported tht mmoni ccumulted with incresing P deficiency in Citrus trees, nd tht rginine synthesis provided mechnism for detoxifying lef tissue of excess mmoni. Arginine ccumultion hs lso been reported during Mg, K, C, S, Fe, nd Zn deficiencies (Rbe 199). In rdit pine (Pinus rdit D. Don), folir nutrient imblnces following lrge N dditions resulted in highly incresed rginine levels in folige (Lmbert 19). Accumultion of mino cids cn lso be ffected by the form in which N is pplied, with NH 4 -N fertilizers cusing higher mino cid ccumultions thn NO 3 -N. Becuse most plnts do not regulte N uptke, repeted N pplictions of ure t Kenneth Creek my hve led to excess N uptke, ccumultion nd disruption of nbolic mechnisms. At Kenneth Creek, studies need to be undertken to quntify mino cid levels in the folige of repetedly fertilized trees nd to exmine reltionships between poor growth, nutrient imblnce, mino cids, nd mmoni toxicity. Interestingly, Lmbert (19) reported strong positive correltion between folir rginine concentrtion nd tree infection level of Dothistrom needle blight (Mycospherell pini Rost. in Munk). At Kenneth Creek, severe infection of lodgepole pine trees in the ON 2 tretment plots with Dothistrom ws observed during the 25 mesurement. Crter Lke The lodgepole pine stnd t Crter Lke continues to respond positively to fertiliztion, with the lrgest rdil responses being ssocited with the most intensive

10 fertiliztion tretment (ON 2 ) (Figure ). The BA increments to repeted pplictions (yer nd yer ) of NB, NSB, nd Complete fertilizer were 25-29% higher thn growth of unfertilized trees over 9 yers (Figure ). Nine-yer BA responses in ON 1 nd ON 2 tretments were 47% nd %, respectively. Although differences were not sttisticlly significnt, fertiliztion hs pprently resulted in modest height response t Crter Lke (Figure b). In bsolute terms, 9- yer height increments of fertilized trees were cm lrger thn unfertilized trees. Hnd Lke The spruce plnttion t Hnd Lke continues to respond positively to fertiliztion (Figure 11). The BA increments to single ppliction of NB, NSB, nd Complete fertilizer were 1-25% higher thn the growth of unfertilized trees over yers (Figure 11). The BA gins (reltive to control) in ON 1 nd ON 2 tretments t Hnd Lke were 2% nd 43%, respectively. These responses were considerbly smller thn previously reported for the two other spruce mximum productivity sites t Crow Creek nd Lodi Lke (Brockley nd Simpson 24). At Crow Creek, BA gins (reltive to control) in ON 1 nd ON 2 tretments were 141% nd 153%, respectively. At Lodi Lke, the corresponding -yer reltive responses were 72% nd 11%. Height responses t Hnd Lke were lso smller thn mesured t the two other spruce study sites. The height gins (reltive to control) in fertilized tretments rnged from % to 17%, nd none of the height responses were sttisticlly significnt (Figuree 11b). In bsolute terms, the smllest height gins were chieved in the NB nd NSB tretments, with totl gins of only 1 cm nd 17 cm, respectively. The -yer bsolute height gins were slightly lrger in the Complete, ON 1, nd ON 2 tretments (37-42 cm). Height responses t Crow Creek nd Lodi Lke were positively relted to fertiliztion intensity, with the lrgest gins mesured in the ON 2 tretments. Spruce trees in the NB, NSB, nd Complete tretments t Crow Creek chieved 71 to 2 cm more height increment thn unfertilized trees over yers, representing reltive increses of 4-4%. Absolute height gins were even lrger in the ON 1 nd ON 2 tretments, with height responses totlling 1.2 m (%). At Lodi Lke, fertiliztion clerly incresed the incidence nd severity of leder dmge from the white pine terminl weevil (vnakker et l. 24, 25b). Despite these injuries, height increments were 3% higher in ON 2 tretments thn in control tretments over yers. In bsolute terms, height increment gins in ON 2 plots totlled 77 cm more thn for unfertilized trees t Lodi Lke. Lef Are Index Lef re index (LAI) mesurements t six study sites in the spring of 25 indicte tht LAI is positively ffected by fertiliztion t most study sites (Figure 12). Differences in LAI between the NB, NSB, nd Complete tretments re generlly smll, with no consistent response pttern between the three tretments. The lrgest LAI s re generlly mesured in the ON 1 nd ON 2 tretment plots. Except for Kenneth Creek nd Crow Creek, the lrgest LAI ws lwys obtined in the ON 2 tretment plots. These results re generlly consistent with the mgnitude of growth responses t the different sites. The lrgest LAI responses re generlly ssocited with the lrgest tree BA responses. Incresed lef re hs been identified s the primry engine driving fertiliztion growth response (Fgerstrom nd Lohm 1977; Brix 193). The strong reltionship

11 11 between stnd BA nd LAI tht hs been observed in this study, nd the lrge increses in LAI following fertiliztion (especilly in the ON 1 nd ON 2 tretments) t most sites, re consistent with these findings. White Pine Weevil Finl reporting for the spruce weevil project ws completed in 25, with the publiction of FORREX LINK rticle (vnakker et l. 25) nd B.C. Ministry of Forests nd Rnge Extension Note (vnakker et l. 25b). The reder is referred to these publictions s well s previously published journl pper (vnakker et l. 24) for comprehensive results from this study. In summry, results from this study indicte tht fertiliztion of young spruce plnttions in the SBSwk nd SBSmk biogeoclimtic subzones will likely excerbte leder dmge by the white pine weevil. Enhnced leder length, dimeter nd brk thickness due to fertiliztion increse the resources vilble for weevil feeding nd oviposition. Fertiliztion lso results in dilution of the resin cnl system in the brk, which is considered to be the first line of defence ginst brk-invding insects (vnakker et l. 24). However, despite the incresed incidence of weevil dmge to fertilized trees, the height losses due to weevil ttck re not s gret s the height gins due to fertiliztion. Our results lso indicte tht lrge-scle fertiliztion of spruce plnttions in the SBSmc biogeoclimtic subzone probbly entils low risk of incresing dmge by the white pine weevil. The Crow Creek study sites ws likely too cold to sustin lrge weevil popultions. Soil Biot Finl reporting of the soil biot study undertken t lodgepole pine mximum productivity site in 23 ws completed in 25, with the submission of mnuscript to, nd its subsequent cceptnce by, the Cndin Journl of Forest Reserch (Berch et l. 2). In summry, we found tht the repeted fertiliztion of lodgepole pine with moderte rtes (ON 1 ) of N, in combintion with frequent ddition of other nutrients, generlly hd either no effect or smll positive effect on soil mesofun nd microbil popultions. However, we found depression of components of the mesofun nd microbil communities t higher N ppliction rtes (ON 2 ). Also, ectomycorrhizl coloniztion nd fine root biomss nd vigour were lso negtively ffected by intensive fertiliztion, nd shifts in ectomycorrhizl community structure were lso observed. The soil smpling t the interior spruce mximum productivity site (Crow Creek) ws completed in September 24. The chrcteriztion of the mycorrhizl community structure nd fine root biomss nd vigour hs been completed, but the dt hve not yet been fully nlyzed. However, the negtive effects on mycorrhizl coloniztion nd lodgepole pine fine root biomss nd vigour with incresing fertiliztion intensity tht were documented t Sheridn Creek re not redily pprent t the Crow Creek spruce study site. These results re consistent with the very fvourble 9-yer growth responses reported for ON 1 nd ON 2 tretments this site (Brockley nd Simpson 24). We pln to prepre mnuscript for journl publiction in 2/7.

12 12 Litterfll Finl reporting of this study ws completed in erly 2, with the submission of mnuscript to the Cndin Journl of Forest Reserch (Snborn nd Brockley 2). Averged over the 4-yer collection period, nnul lodgepole pine needle litterfll ws similr in the control nd conventionl fertiliztion tretments (5-117 kg h -1 yr -1 ), in contrst to 221 kg h -1 yr -1 in the ON 2 tretment. Pine needles comprised 5-9% of the litter mss, nd the verge mss of other litter components in the ON 2 tretment ws pproximtely twice tht of the : 45 vs. 19 kg h -1 yr -1. Deciduous leves from shrubs nd trees comprised the lrgest proportion of the other litter components. These tretment-relted differences in nnul inputs of pine needles nd other litter components were not sttisticlly significnt, but there were significnt yer-to-yer vritions in litterfll. Litterfll ws highly sesonl, with most occurring in the fll-winter period, of which the lte fll nd over-winter (October-My) period contributed pproximtely hlf of the nnul totl cross ll tretments. Understory production ppered to hve been prticulrly stimulted by the ON 1 nd ON 2 tretments, with herbs such s fireweed (Epilobium ngustifolium) reching heights of up to 1 m by mid-summer, nd red rspberry (Rubus ideus) dominting the shrub lyer. Although the shrub contribution to understory biomss showed significnt tretment effect, this ws offset by other components, resulting in no overll tretment effect on totl understory biomss. Unlike in Swedish optimum nutrition studies with Scots pine (Tmm et l. 1999), we did not observe lrge nd rpid increse in litterfll rtes in tretments with high nnul nutrient inputs, nor the 2- to 3-fold difference in litterfll between the optimum nutrition tretments nd controls. In other studies of conifer responses to fertiliztion, incresed litterfll ws relted to decresed needle longevity, nd the ltter ws detected t this site (Ampsonh et l. 25), with reductions by 23% in the ON 2 tretment reltive to the for observtions in 22, three yers fter termintion of litterfll mesurements. Although production of both needles nd other litter components ws highest in the ON 2 tretment, the lck of ny significnt tretment effect my prtilly reflect the high sptil vribility in litterfll tht should eventully decrese fter cnopy closure (Tmm et l. 1999). Concentrtions of N, S, K, nd B were significntly incresed in needle litter from fertilizer tretments including those elements in fertilizer prescriptions, while concentrtions of other elements (C, Zn) were reduced. Apprent retrnsloction of N, S, K, B, nd Cu were significntly reduced in the tretment with the highest rte of nutrient ddition reltive to the. Generl ptterns of elementl behviour were consistent with those observed in other conifer fertiliztion studies. However, these chnges ccompnied ctul decresed crop tree growth in the ON 2 tretment, which ws n exceptionl response to ppliction of this fertiliztion regime t five BC interior sites, suggesting tht locl site nd stnd conditions were involved, such s induced nutrient imblnces on corse-textured soil in moist climte. Conclusions nd Mngement Implictions

13 It s too erly to relibly predict the potentil impcts of intensive fertiliztion on hrvest yields nd/or rottion length of mnged interior spruce nd lodgepole pine forests in the B.C. interior. However, preliminry results indicte tht young interior spruce plnttions re pprently prticulrly well suited to high input silviculture. To dte, the lrgest spruce responses re ssocited with the most intensive fertiliztion tretments. In contrst, lodgepole pine hs generlly responded less fvourbly to lrge, nd frequent, N dditions. In fct, ON 2 tretments hve pprently cused folir nutrient imblnces, chnges in soil biot community structure nd fine root ttributes, nd growth disruptions t some lodgepole pine study sites. Further studies re needed t these sites to quntify mino cid levels in the folige of repetedly fertilized trees nd to exmine reltionships between poor growth, nutrient imblnce, mino cids, nd mmoni toxicity. The recent observtion t Kenneth Creek tht repeted fertiliztion my increse the susceptibility of lodgepole pine to Dothistrom infection poses some interesting questions regrding the possible link between biochemicl imblnces nd folir pthogens in lodgepole pine. Lmbert (19) reported strong positive correltion between folir N:S imblnce (i.e., S deficiency) in rdit pine nd tree infection level of Dothistrom needle blight. Given tht Dothistrom poses serious forest helth thret to young lodgepole pine stnds in the B.C. interior, nd tht S deficiencies in lodgepole pine re well documented (Brockley 2, 24), the possible link between N:S imblnce nd Dothistrom certinly wrrnts further study. Results from the white pine weevil study indicte tht the beneficil effects of fertiliztion on the growth of young interior spruce plnttions likely outweigh the negtive effects ssocited with incresed incidence nd severity of leder dmge from the white pine weevil. At Lodi Lke (SBSwk), the ON 2 tretment produced 22 m 3 /h more stnd volume thn the control tretment over yers, representing reltive increse of 2% (Brockley nd Simpson 24). Smll mounts of weevil dmge, combined with lrge rdil nd height responses following nutrient dditions t Crow Creek (Brockley nd Simpson 24), indicte tht spruce plnttions in the SBSmc my be prticulrly good cndidtes for opertionl fertiliztion. Additionl fertilizer trils nd weevil dmge surveys in the SBSmc re needed to confirm estimtes nd predictions of fvourble growth responses nd low weevil ctivity following fertiliztion of plnted spruce. Future studies re lso needed to evlute the possible negtive impcts of weevil dmge on lumber qulity nd vlue. The published results from our soil biot study (Berch et l. 2) suggest tht decresed mycorrhizl coloniztion nd reduced fine root mss nd vigour might be contributory fctors in impired folir nutrient blnce nd growth in high-n tretments t the Sheridn Creek lodgepole pine site. Interestingly, the negtive effects on mycorrhizl coloniztion nd lodgepole pine fine root biomss nd vigour with incresing fertiliztion intensity tht were documented t Sheridn Creek re not pprent t the Crow Creek spruce study site. These results re consistent with the very fvourble 9-yer growth responses reported for ON 1 nd ON 2 tretments this site (Brockley nd Simpson 24). Unfortuntely, it s not possible to relibly seprte the roles tht species nd site my ply in the different responses of the soil biot community structure nd fine root ttributes to nutrient dditions t Sheridn Creek nd Crow Creek. Further studies re needed to exmine this issue. 13

14 14 Contct Informtion Contrct Rob Brockley for dditionl informtion bout this project. Phone: (25) 2-47 Emil: More complete bckground to this study, including preliminry results, is contined in B.C. Ministry of Forests Technicl Report 1 (Brockley nd Simpson 24). The report cn be downloded t: Project informtion is lso vilble on the Reserch Brnch stnd mngement website t: Literture Cited Amponsh, I.G., P.G. Comeu, R.P. Brockley, nd V.J. Lieffers. 25. Effects of repeted fertiliztion on needle longevity, folir nutrition, effective lef re index, nd growth chrcteristics of lodgepole pine in interior British Columbi, Cnd. Cn. J. For. Res. 35: Buer, G.A., F.A. Bzzz, R. Minoch, S. Long, A. Mgill, J. Aber, nd G.M. Berntson. 24. Effects of chronic N dditions on tissue chemistry, photosynthetic cpcity, nd crbon sequestrtion potentil of red pine (Pinus resinos Ait.) stnd in the NE United Sttes. For. Ecol. Mnge. 19: Berch, S.M., R.P. Brockley, J. Bttigelli, S. Hgermn, nd B. Holl. 2. Impcts of repeted fertiliztion on components of the soil biot under young lodgepole pine stnd in the interior of British Columbi. Cn. J. For. Res. In press. Brix, H Effects of thinning nd nitrogen fertiliztion on growth of Dougls-fir: reltive contribution of folige quntity nd efficiency. Cn. J. For. Res. 13: Brockley, R.P Lodgepole pine nutrition nd fertiliztion: summry of B.C. Ministry of Forests reserch results. Cndin Forest Service nd B.C. Ministry of Forests, Victori. FRDA Report 2. Brockley, R.P. 2. Using folir vribles to predict the response of lodgepole pine to nitrogen nd sulphur fertiliztion. Cn. J. For. Res. 3: Brockley, R.P. 21. Folir smpling guidelines nd nutrient interprettive criteri for lodgepole pine. B.C. Min. For., Victori. Extension Note 52. Brockley, R.P. 23. Effects of nitrogen nd boron fertiliztion on folir boron nutrition nd growth in two different lodgepole pine ecosystems. Cn. J. For. Res. 33: Brockley, R.P. 24. Effects of different sources nd rtes of sulphur on the growth nd folir nutrition of nitrogen-fertilized lodgepole pine. Cn. J. for. Res. 34:

15 15 Brockley, R.P. nd D.G. Simpson. 24. Effects of intensive fertiliztion on the folir nutrition nd growth of young lodgepole pine nd spruce forests in the interior of British Columbi (E.P..13): estblishment report. B.C. Min. For., Victori, B.C. Tech. Rep. 1. Fgerstrom, T., nd U. Lohm Growth in Scots pine (Pinus silvestris L.). Mechnism of response to nitrogen. Oecologi 2: Lmbert, M.J. 19. Sulphur nd nitrogen nutrition nd their interctive effects on Dothistrom infection in Pinus rdit. Cn. J. For. Res. 1: Li-Cor, Inc LAI-2 plnt cnopy nlyzer, Instruction mnul. Li-Cor, Inc., Lincoln, Nebrsk. Mgill, A.H., J.D. Aber, W.S. Currie, K.J. Ndelhoffer, M.E. Mrtin, W.H. McDowell, J.M. Melillo, nd P. Steudler. 24. Ecosystem response to 15 yers of chronic nitrogen dditions t the Hrvrd Forest LTER, Msschusetts, USA. Ecol. Mnge. 19:7-2. Minoch, R.S., S. Long, A. Mgill, J.D. Aber, nd W.H. McDowell. 2. Folir free polymine nd inorgnic ion content in reltion to soil nd soil solution chemistry in two fertilized forest stnds t the Hrvrd Forest, Msschusetts. Plnt Soil 222: Rbe, E Stress physiology: the functionl significnce of the ccumultion of nitrogen-contining compounds. J. Hort. Sci. 5: Rbe, E. nd C.J. Lovtt De novo rginine biosynthesis in leves of phosphorusdeficient Citrus nd Poncirus species. Plnt. Physiol. 42: Snborn, P.T. nd R.P. Brockley. [2]. Litterfll in lodgepole pine fertiliztion experiment, Sub-Borel Spruce zone, centrl interior British Columbi. Cn. J. For. Res. (submitted). Tmm, C.O Nitrogen in Terrestril Ecosystems. Springer-Verlg, Berlin. Ecol. Stud. 1. Tmm, C.O., A. Aronsson, B. Popovic, nd J. Flower-Ellis Optimum nutrition nd nitrogen sturtion in Scots pine stnds. Studi Forestli Suecic No pp. vnakker, L., R.I. Alfro, nd R. Brockley. 24. Effects of fertiliztion on resin cnl defences nd incidence of Pissodes strobi ttck in interior spruce. Cn. J. For. Res. 34:55-2.

16 1 vnakker, L., R.I. Alfro, nd R. Brockley. 25. Fertiliztion effects on weevil dmge: not ll bd news. FORREX Forest Reserch Extension Prtnership, Kmloops. LINK (3):2-21. vnakker, L., R. Brockley, nd R. Alfro. 25b. Interctions between fertiliztion nd white pine weevil (Pinus strobi) ttck in young interior spruce plnttions. B.C. Ministry of Forests, Victori. Extension Note 75.

17 17 Folir N (%) ) Sheridn Creek b) Kenneth Creek Folir N (%) Folir N (%) 2.2 c) Crow Creek Folir N (%) d) McKendrick Pss Folir N (%) 2.2 e) Lodi Lke Folir N (%) 2.2 f) Tutu Creek Figure 1. Folir nitrogen concentrtion by instlltion, tretment nd yer. For ech instlltion, ech plotted point represents the men of three composite smples ( trees/composite).

18 1 Folir N(%) 2.2 g) Crter Lke Folir N (%) 2.2 h) Hnd Lke Figure 1 continued

19 19 Folir N/P rtio ) b) Folir N/K rtio Folir N/S rtio 2 1 c) Folir N/Mg rtio 35 d) Folir N/Cu rtio e) f) Folir N/Fe rtio Figure 2. Folir nutrient rtios t Kenneth Creek by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

20 2 Folir N/P rtio ) 3. b) Folir N/K rtio Fdolir N/S rtio 2 c) Folir N/Mg rtio 25 d) Folir N/Cu rtio 12 e) f) Folir N/Fe rtio Figure 3. Folir nutrient rtios t Crow Creek by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

21 21 Folir N/P rtio ) b) Folir N/K rtio Folir N/S rtio 2 1 c) Folir N/Mg rtio 35 d) Folir N/Cu rtio e) f) Folir N/Fe rtio Figure 4. Folir nutrient rtios t McKendrick Pss by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

22 22 Folir N/P rtio ) 3. b) Folir N/K rtio Folir N/S rtio 2 1 c) Folir N/Mg rtio 25 d) Folir N/Cu rtio e) 7 f) Folir N/Fe rtio Figure 5. Folir nutrient rtios t Lodi Lke by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

23 23 Folir N/P rtio ) b) Folir N/K rtio Folir N/S rtio 2 1 c) Folir N/Mg rtio 3 d) Folir N/Cu rtio e) f) Folir N/Fe rtio Figure. Folir nutrient rtios t Tutu Creek by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

24 24 Folir N/P rtio ) b) Folir N/K rtio Folir N/S rtio 2 1 c) Folir N/Mg rtio 3 d) Folir N/Cu rtio e) f) Folir N/Fe rtio Figure 7. Folir nutrient rtios t Crter Lke by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

25 25 Folir N/P rtio ) b) Folir N/K rtio Yersfter tril estblishment Folir N/S rtio 2 1 c) Folir N/Mg rtio 3 d) Folir N/Cu rtio 12 e) f) Folir N/Fe rtio Figure Folir nutrient rtios t Hnd Lke by tretment nd yer. Ech plotted point represents the men of three composite smples ( trees/composite). The dotted horizontl line represents the uper threshold trget vlue.

26 () 1- to -yer 7- to 12-yer BA increment (cm 2 /tree) % 13% 15% 5% -4% 4 NB NSB Complete Tretment (b) 1- to -yer 7- to 12-yer Height increment (m/tree) 4 2-3% -2% -4% -5% -21% b NB NSB Complete Tretment Figure 9. Men tree ) bsl re increment nd b) height increment by mesurement period nd tretment t Kenneth Creek. Numbers bove ech br indicte chnge reltive to the control tretment over ll response periods. Brs with different letters re signficntly different (p<.5).

27 27 15 () 1- to 3-yer 4- to -yer 7- to 9-yer BA increment (cm 2 /tree) % b 29% b 25% b 47% c % d 25 NB NSB Complete Tretment Height increment (m/tree) (b) 9% 1- to 3-yer 4- to -yer 7- to 9-yer 17% 1% 1% 17%.5. NB NSB Complete Tretment Figure. Men tree ) bsl re increment nd b) height increment by mesurement period nd tretment t Crter Lke. Numbers bove ech br indicte chnge reltive to the control tretment over ll response periods. Brs with different letters re signficntly different (p<.5).

28 () 1- to 3-yer 4- to -yer BA increment (cm 2 /tree) % b 22% b 25% bc 2% bc 43% c 25 NB NSB Complete Tretment Height increment (m/tree) (b) 7% % 1- to 3-yer 4- to -yer 1% 15% 17%.5. NB NSB Complete Tretment Figure 11. Men tree ) bsl re increment nd b) height increment by mesurement period nd tretment t Hnd Lke. Numbers bove ech br indicte chnge reltive to the control tretment over ll response periods. Brs with different letters re signficntly different (p<.5).

29 29 Lef re index (m 2 /m 2 ) 3..5 Sheridn Creek 22% 9% 12% 4% 73% Lef re index (m 2 /m 2 ) Kenneth Creek 15% 19% 1% 2% 7%. Con NB NSB Comp Tretment. Con NB NSB Comp Tretment Lef re index (m 2 /m 2 ) McKendrick Pss 5% 37% 52% 3% % Lef re index (m 2 /m 2 ) Lodi Lke 9% 59% 73% 113% 15%. Con NB NSB Comp. Con NB NSB Comp Tretment Tretment Figure 12. Effective lef re index by instlltion nd tretment. Numbers bove ech br indicte chnge reltive to the control tretment. Error brs represent stndrd error.

30 3 Lef re index (m 2 /m 2 ) Tutu Creek 3% 27% 27% 4% 74% Lef re index (m 2 /m 2 ).5 Crter Lke 5% 43% 9% 1% 141%. Con NB NSB Comp Tretment. Con NB NSB Comp Tretment Lef re index (m 2 /m 2 ) Hnd Lke 19% 13% 27% 45% 9%. Con NB NSB Comp Tretment Figure 12 cont'd

31 31