Evlution of Willow Propgtion Methods FHWA Cnyonville 5 Project Dvid Steinfeld November 2007 Summry: Willows tht were plnted s rooted cuttings becme estblished t much greter rte thn those from live stkes (90% vs. 12%). Live stkes cut in the dormnt period (November or Jnury) hd greter vibility thn those cut in erly October (68% vs 12%). Future bioengineering projects should consider the vibility, estblishment potentil, nd production costs of the plnt mterils when developing strtegy for estblishing willows on construction site. Bckground: During the Winter of 2003, recently constructed fillslope on the Cnyonville 5 Highwy (rod section 30+400 to 30+800; commonly referred to s the Scheffer Fill) developed shllow slope filures due to high moisture conditions. To increse slope stbility, the FHWA implemented bioengineering project tht included pinning the slope t pproximtely 1-meter centers with live willow stkes nd instlling willow brush lyers where shllow slumps hd occurred (see Rodside Revegettion Mnul Chpter 10.2.2 Collecting Wild Cuttings nd 10.3.3 Instlling Cuttings for bckground on this type of plnt mteril). Construction crews were scheduled to instll willow wddles nd live stkes between November 1 nd November 30, 2004. To meet this timeline, willow plnt mteril ws hrvested during October 2004. Given tht the willows were still physiologiclly ctive during this period, there were reservtions tht the cuttings would not successfully root. In ddition, the fillslopes re hot nd dry (south fcing spect) from My through September, further limiting plnt estblishment. Knowing these limittions we proceeded under severl ssumptions: first, storing willow mteril in wter fter cutting would increse willow rooting nd plnt estblishment; second, live willow stkes would dd slope stbility whether or not they rooted. From October 5 through October 28, 2004, 3,450 willow stkes nd 190 willow bundles were collected on the Tiller Rnger District by locl contrctor, district employees nd Stone Nursery employees. Cuttings were plced in shllow prt of the South Umpqu River for soking. During the third week of October storm rised the wter level of the South Umpqu River three feet, floting the willow stkes nd bundles downriver. A few dys lter, the bundles were retrieved from the river nd plced in lrge stcks bove the flood zone. They were not put bck in wter becuse of the obvious concern tht they would flot downriver gin. There were no logisticl lterntives for storing in wter. The wether hd lso chnged nd hd become overcst during this period, reducing the potentil tht the willows would dry out. Hd the sun come out during this period, the only prt of the lrge pile tht would hve potentilly dried out ws the top lyer of willows. There ws discussion whether these cuttings would root becuse they were not in wter but the project engineer decided to stick the cuttings under the premise tht even if they didn t root, they would still increse slope stbility. Since the FHWA uses willows in other bioengineering projects for slope stbility, this project creted n opportunity to test the effectiveness of severl methods of instlling willow plnt mteril in controlled study. A simple study ws estblished on this site with the objectives of determining if there were ny differences in willow estblishment 1
nd growth between five different willow tretments 1) willows cut in erly October nd instlled in lte November, 2) willows cut in erly November, plced in wter nd instlled in lte November; 3) willows cut in erly November, stcked under moist, shded conditions, instlled in lte November; 4) willows cut in Februry nd immeditely instlled nd 5) rooted cuttings grown in nursery nd plnted in Februry. The species used in this tril ws Scouler s willow (Slix scoulerin). Methods Tretments Study Design Oct cut, sok, lte Nov stick. 100 four-foot long live stkes were cut on October 6, 2004 nd plced immeditely in the South Umpqu River. On October 25, the stkes were pulled from the river nd plced in lrge pile of stkes nd stored there until they were instlled on November 30, 2004. The collection site ws Scott s Mill (1200 foot elevtion). The willow stnds where the stkes were collected still hd most of their leves ttched indicting the plnt mteril ws not dormnt. Nov cut, no sok, lte Nov stick. 100 four-foot long live stkes were collected on November 3, 2004 from the Pickett Butte Rod (3000 foot elevtion). The willows hd lost most of their leves indicting tht they were dormnt. The stkes were stcked in pile under shded cnopy ner Tiller RS. On November 30, 2004, the live stkes were instlled in the fillslope. Nov cut, sok, lte Nov stick. 100 four-foot long live stkes were collected on November 3, 2004. The willows were from the sme collection s the no-sok tretment mteril. 100 stkes were plced in smll pond ner Tiller RS. On November 30, 2004, the live stkes were instlled in the fillslope. Jn cut, no sok, Feb stick. Willow stkes were hrvested from the Pickett Butte Rod (sme source s Nov collections) on Jnury 24, 2005 nd stored in pile under shded cnopy ner Tiller RS. Willows were instlled on Februry 14, 2005. The willows collected t this time hd lost their leves. Feb rooted cutting plnt. 80 rooted cuttings were strted t J. Herbert Stone Nursery from willow cuttings tken from site ner the project. They were grown in long tubes - 3 inch dimeter PVC pipe by 18 inches long with vexr tubing to hold the medi together. Rooted cuttings verged 5 mm cliper nd 24 inch top. Rooted cuttings were plnted so tht 4 to 6 inches of the stem were buried below the surfce of the soil. Vexr tubing ws slit longitudinlly with n excto-knife becuse of the concern tht the mesh it ws too fine nd would not brek down in the soil. The tril consisted of 8 replictions (or blocks) locted rndomly cross the Scheffer Fill. The five tretments were rndomly ssigned row position within ech block (Figure 3). Ech tretment within block consisted of 10 willows. A totl of 80 willows were instlled for ech tretment (8 blocks x 10 cutting or rooted cuttings per block). Willows were instlled 2 feet prt within row nd 3 feet between tretment rows. Instlltion For the November tretments, live stkes were instlled using homemde stinger. This equipment consisted of rebr welded to the bucket of n excvtor to crete 2-2.5 foot deep by 2 dimeter hole. Willows were inserted in the hole nd the bck of the bucket ws used to push the stke to the bottom of the hole. For the Februry instlled tretments, holes were ugured (stinger ws not vilble or prcticl t this time). 2
All willows were instlled perpendiculr to the slope grdient. Soil round ech willow ws lightly tmped with tile shovel to obtin good soil contct. After instlltion, the tops of the stkes stuck pproximtely 1.5 to 2 feet bove the ground line. These were trimmed with chin sw (which left clen cut) so tht the finl height of ll stkes ws pproximtely 6 inches bove the soil surfce. The wether during instlltion on ll dtes ws overcst nd cool in the morning nd cler nd cool in the fternoon. Plot Cre All blocks were weeded severl times during the spring nd summer to reduce the effects of weed competition on willow survivl. Dt Collection Dt ws collected My 23, 2005 nd September 9, 2005. On My 23, ny stke or seedling with the presence of new leves ws considered to be vible nd hd initited roots. Any stke or rooted cutting with the presence of live leves on September 9, 2005 ws considered estblished. Results nd Discussion Vibility. The qulity of the live stke mteril to produce roots under low stress (or idel growing environment) I refer in this report s live stke vibility. Much like the concept of live seed, live stke vibility is independent of the site nd reflects the potentil of the plnt mteril to grow when plced in n idel growing environment. Since the wether t the Cnyonville site during spring 2005 ws lmost perfect for estblishing roots on cuttings nd new roots on rooted cuttings (there were few dys without rin nd tempertures were mild), dt tken t the end of this period reflect the vibility of the plnt mterils. 3
Figure 1: Plnt mteril vibility dt collected My 23, 2005 100 90 d 80 percent vible 70 60 50 40 b,b 30 20 10 c 0 Oct cut, sok, Nov instll Nov cut, no sok, Nov instll Nov cut, sok, Nov instll Jn cut, no sok, Feb instll Feb rooted cutting plnt Tretments not shring the sme lph chrcter re significntly different t p<0.05 The vibility of willows s determined by the My 23 evlution (Figure 1) ws excellent for the rooted cutting tretment, while fir for cuttings tken in November nd Februry nd poor for collections mde in October. Compring the vibility of cutting tretments, it ppers tht willows cut in October were less vible thn mteril cut during the dormnt period. Cuttings mde in Jnury hd the best vibility of ll cutting tretments. The premise tht soked willow stkes perform better thn non-soked stkes when collected in the fll ws not supported in this tril. The timing of the soking could hve plyed role in this. If these sme tretments hd been done erlier in the fll or in the lte winter or erly spring, positive result might hve been observed. Chris Hog (NRCS) hs reserch results showing tht soking willow cuttings in the spring increses estblishment 1. He sys tht there is good evidence tht soking swells the root primordil, decresing the time fter willows re instlled for roots to emerge from the brk. Estblishment. The fct tht willows were vible when they were instlled, doesn t necessrily men they will survive nd become estblished on ll sites. After mild, moist spring on the Cnyonville site, the wether turned hot nd dry for three months. While mny live stkes ppered to hve developed roots (s indicted by lef growth in lte My), the live stkes hd not estblished well enough to withstnd the hot dry conditions of this site (Figures 2 nd 3). Only plnted rooted cuttings becme estblished t 90 percent survivl rte. Surprisingly, there were no significnt differences between the survivl rtes ny of the live stke tretments, which indictes the predominnce of site climte over timing of cutting. 1 emil from Hog October 2004 4
Figure 2: Plnt Estblishment Dt collected September 5, 2005 100 90 80 b 70 % Survivl 60 50 40 30 20 10 0 Oct cut, sok, Nov instll Nov cut, no sok, Nov instll Nov cut, sok, Nov instll Jn cut, no sok, Feb instll Feb rooted cutting plnt Tretments not shring the sme lph chrcter re significntly different t p<0.05 Considering the hrshness of the site, it is not surprising tht the estblishment of willows from cuttings ws low. Mny of the helthy, Dougls-fir, mdrone, nd some ponderos pine seedlings, grown in one-gllon continers nd plnted on the sme site in lte winter perished in the first yer fter plnting. Wht is unexpected is tht rooted cuttings pf willow survived t higher rtes thn mny of the other species plnted on this site. The results of this study support the premise tht on hrsh sites, rooted cuttings hve n dvntge over live willow stkes becuse their root systems re lredy estblished nd redy to grow. Immeditely fter plnting, roots elongte from the bottom of the root plug nd ccess moisture in the lower soil horizons. Live willow stkes, on the other hnd, must first initite roots from the stem. The bundnce of root initition nd growth depends on the vibility of the plnt mteril. 5
Figure 3. Photo of Block 5 tken on September 9, 2005. Plnted willow rooted cuttings (D) hd 100% estblishment; both November cutting tretments (A nd B) hd 10% estblishment nd October nd Jnury cutting tretments (C nd E) hd no estblishment. Rooted cuttings (D) hd heights rnging from 2 to 4 feet. E D A B C Mngement Considertions. These findings show tht plnted rooted cuttings hd greter chnce for estblishment thn live stkes on hrsh site in southwestern Oregon. Bioengineering projects don t often cll for rooted cuttings in lieu of cuttings becuse obtining cuttings is often considered n esier or cheper venue thn propgting nd plnting rooted cuttings. In ddition, the results of live cutting projects re often cceptble, even when estblishment rtes re low. Consider this: if 10 percent of the live stkes in this project estblished into willow plnts, s the results from this tril indicte, there should be round 350 estblished plnts ( wlk through the Scheffer Fill shows tht these estimtes re pretty close). While this estblishment rte is low, the number of plnts for the site might still be cceptble for meeting project objectives. On less stressful yer, the estblishment rte t this site might hve pproched 50 to 60%, which would hve trnslted into 1700 to 2000 estblished plnts on this site. This would hve been very well-stocked re. Future bioengineering projects should ddress: 1) the desired spcing between estblished willow plnts (density) one yer fter sticking or plnting, 2) the predicted rooting vibility of the collected mteril, 3) the sites potentil for willow estblishment nd 4) the cost of obtining the plnt mteril. Bsed on these fctors simple eqution would predict the mount of cuttings or rooted cuttings to plnt on ny given site: # cuttings or rooted cuttings to plnt = desired plnt density x (100/predicted % vibility) x (100/predicted % survivl) 6
desired plnt density = number of estblished plnts per re one yer fter instlling per re (cre, hectre etc) predicted % vibility = percent of cuttings or rooted cuttings tht will initite roots when plnted in low-stress environment. Much like germintion testing, which is done in growth chmber, cuttings cn be plced in low stress environment (e.g. greenhouse, growth chmbers) to determine the percent of mteril tht will root t weekly intervls. The vibility of rooting mteril is ffected by the dte when the mteril is cut, ge of stem mteril, willow species, ppernce or disese, soking, hndling, storge etc. predicted % survivl = percent of vible plnt mteril tht will survive on construction site. This is ffected by site fctors such s evpo-trnspirtion rtes (spect, slope, rinfll, precipittion, wind), plnt competition, soil wter holding cpcity (texture,% rock frgments, bulk density, % orgnic mtter). On the Cnyonville site, for exmple, the project objectives might hve clled for desired plnt density of 400 estblished plnts per cre fter one yer from live stkes cut nd instlled in November. From Figure 1, 68 percent of the cuttings were vible in the spring nd 12% of this mount survived the summer (from Nov cut, no sok, Nov stick in Figure 2). This equls to n overll survivl rte for the site of 18% (12 x 100/68). Using the bove eqution to meet the objective of 400 live plnts per cre - # cuttings to stick = 400 x (100/68) x (100/18) = 3460 cuttings And for estblishing rooted cuttings t 100 percent vibility nd 90 percent survivl rte - # rooted cuttings to plnt = 400 x (100/100) x (100/90) = 444 rooted cuttings The costs of obtining nd plnting 444 rooted cuttings cn then be compred to collecting nd sticking 3460 cuttings. For this project the estimted cost (2004 rtes) for plnted seedling is roughly $6 ($3.50 for growing 2, $.50 for trnsporttion, $2.00 for plnting) nd the estimted cost for n instlled stke is $2.50 ($1.50 for collection 3 nd $1.00 for plnting). At these rtes, obtining 400 estblished plnts per cre from cuttings would cost $8,650 nd from rooted cuttings $2664. Plnt estblishment from cuttings on site with more moisture nd less stress could be less expensive thn plnted rooted cuttings, especilly if cuttings hve high vibility nd re esily obtined. Future work to develop high vible cuttings t resonble costs might come from estblished cutting or stooling beds. 2007 Site Review. A review of the study site ws mde in erly November 2007. Severl of the blocks hd undergone surfce sliding in Spring 2006 however, ll of the rooted cuttings tht were plnted were still live. Growth rtes depended on the block some blocks hd rooted cuttings exceeding 6 feet in height (see Figure 4). 2 Costs for rooted cutting production could be lowered significntly if smller continer ws used. 3 This project hd higher collection costs becuse of the lck of ccessible willows. Costs for rooted cutting production could be lowered significntly if smller continer ws used. 7
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