Effect of Stem Inclination on Compression Wood Formation

Effect Of Stem Inclination On Compression Wood Formation-Free PDF

  • Date:27 Oct 2020
  • Views:1
  • Downloads:0
  • Pages:38
  • Size:391.53 KB

Share Pdf : Effect Of Stem Inclination On Compression Wood Formation

Download and Preview : Effect Of Stem Inclination On Compression Wood Formation

Report CopyRight/DMCA Form For : Effect Of Stem Inclination On Compression Wood Formation


24 Lachenbruch B Droppelmann F Balocchi C Peredo M and Perez E 20xx Stem form and. 25 compression wood formation in young Pinus radiata trees Canadian Journal of Forest Research. 26 x xxxx xxxx,28 Abstract, 29 The crooked stems of some individuals of radiata pine Pinus radiata D Don can hinder volume. 30 recovery and wood quality To infer causes of crookedness and to learn how angle affects. 31 compression wood CW formation we studied 4 1 year old trees in southern Chile Eight. 32 initially straight and 8 initially crooked trees were tethered to 15 or 30 or were left untethered. 33 for 131 days 48 trees total There were no significant differences between straight and crooked. 34 trees in the extent of CW in pre treatment wood or in the relationship between stem angle and. 35 CW extent Crooked trees however righted themselves more quickly than did straight trees at. 36 angles 15 which supports the overcompensation hypothesis for the development of crooked. 37 stems Stem angle had a complex effect on CW extent In 2 3 year old wood there was no. 38 meaningful effect of angle on CW extent One year old wood produced less CW at stem angles. 39 10 than 10 but above or below that threshold there was no meaningful effect of angle on. 40 CW extent The inter tree differences in CW extent as well as the correlation of leader CW. 41 extent with bole CW in the best individuals suggests that CW assays could be used for early. 42 screening for wood quality,44 Introduction, 45 In some cases plantations of radiata pine Pinus radiata D Don have individuals with. 46 markedly poor stem form with kinks and crooks within one year s growth as well as sweep. 47 spanning several years growth Such stem form will hinder both volume recovery and value. 48 Recovery is hindered primarily by the log s form It is assumed that wood quality will also be. 49 hindered by the elevated incidence of compression wood CW in crooked logs and or by the. 50 embedded CW within straight logs if the crooked saplings eventually improve their stem form. 51 Compression wood decreases log value because of its negative effects on lumber appearance. 52 longitudinal shrinkage and warp du Toit 1963 Harris 1977 Cown et al 1996 Donaldson and. 53 Turner 2001 Compression wood also makes poor pulp because of the increased lignin content. 54 lower yield shorter tracheids and inferior strength properties of the resulting paper Watson and. 55 Dadswell 1957 This study focuses on CW in young straight stemmed and crooked stemmed P. 56 radiata trees We investigated whether the straight vs crooked trees differ in their incidence of. 57 CW and or in the angles needed to turn on CW production We also used the data to question a. 58 biomechanical explanation for stem crookedness and to infer genetic variation in the CW. 59 response, 60 Extent of CW in straight vs crooked trees Following the assumption that CW will form. 61 where stems are inclined beyond their equilibrium position of near vertical reviewed in Wilson. 62 and Archer 1977 1979 it is reasonable to assume that vertical trees with straight stems will. 63 have no CW and that vertical trees with crooked stems will probably have CW Many studies. 64 however show that straight trees do indeed contain some CW e g Zobel and Haught 1962. 65 Barger and Ffolliott 1976 Donaldson et al 2004 or that there is no positive correlation between. 66 CW percentage and stem straightness Shelbourne and Stonecypher 1971 As summarized by. 67 Timell 1986 p 711 many straight vertical stems have attained this favorable growth form. 68 because they had been able to counteract earlier displacements by forming compression wood. 69 He continues by stating that few coniferous trees are completely devoid of compression wood. 70 Donaldson et al 2004 compared one leaning and one straight tree of P radiata They reported. 71 that 28 of the growth rings examined in the straight tree had CW 1 had severe CW 27 had. 72 mild CW compared to 38 of the growth rings in the leaning tree 20 had severe CW 18. 73 had mild CW Breast height stumps of vertical P palustris and P taeda trees had an average of. 74 10 CW Pillow and Luxford 1937 Merchantable logs of vertical 17 52 year old P taeda trees. 75 averaged 6 CW Zobel and Haught 1962 The outer 2 5 cm of sapwood of vertical P. 76 ponderosa trees had CW in 7 of the young trees n 64 and 13 of the old growth trees. 77 n 100 Barger and Ffolliott 1976 Thus we would expect to find some level of CW in the. 78 boles of the straight trees as well as the crooked trees. 79 Effect of angle on extent of CW The extent of inclination necessary to stimulate CW. 80 development in P radiata is unknown Our understanding of where CW will form is surprisingly. 81 incomplete in spite of sophisticated research on its formation e g Archer and Wilson 1973. 82 Sinnott 1952 and a century of investigation on its incidence reviewed in Pillow and Luxford. 83 1937 Westing 1965 1968 Wilson and Archer 1979 Timell 1986 Timell 1986 stated that. 84 CW development in conifers may show any of the following patterns have very little. 85 relationship with inclination angle increase continuously with increasing inclination increase to. 86 an asymptote or peak at an intermediate stem angle and then decline However some of the. 87 variability in reported patterns may result from studying different genotypes e g Zobel and. 88 Haught 1962 Burdon 1975 or different ranges of angles tissue ages e g Barger and Ffolliott. 89 1976 Spicer et al 2000 or heights e g Low 1964 Burdon 1975 Archer and Wilson s 1973. 90 simulations of where CW would be expected in a growing tree show some of the computational. 91 and data collection difficulties in predicting the location of CW and the duration of its. 92 production, 93 Over some range of angles there is usually a positive effect of inclination on CW incidence. 94 reviewed in Westing 1965 Timell 1986 although there is often large tree to tree variation. 95 Burdon s study of clones of P radiata 1975 however reported no significant relationship. 96 between the average degree of tree lean at four sites and the average CW rating at those four. 97 sites Barger and Ffolliott 1976 showed a weak correlation r 0 22 between stem angle and. 98 CW amount in old growth P ponderosa at the top of the first merchantable log Zobel and. 99 Haught 1962 conducted a thorough census of CW within the stems of 15 P taeda trees in. 100 which they examined cross sections every 61 cm 2 feet up the stem They found broad overlap. 101 in the amount of CW in trees in the three inclination classes straight trees n 5 had 3 8 CW. 102 intermediate trees n 5 had 5 14 CW and crooked trees n 4 had 12 19 CW Our. 103 prediction for the current study was that there would be a weak positive effect of inclination on. 104 CW incidence, 105 Evidence for overcompensation as a cause of crookedness There has been much.
106 research into the causes of stem deformation crookedness in P radiata in old pasture sites and. 107 in response to high and low supplies of mineral nutrients Downes and Turvey 1990 1993. 108 Turvey et al 1992 1993 Downes et al 1994 The results have shown that nutrition is often. 109 related to stem lignification and or slenderness relative to foliar mass both of which could. 110 potentially contribute to the stem crookedness On nutritionally good sites stem crookedness in. 111 P radiata has been related to previous land use Carlyle et al 1989 Birk et al 1993 wind. 112 environment Burdon 1975 Turvey et al 1993 understory competition Peri et al 2002 and. 113 other unidentified site factors Burdon 1975 Jayawickrama and Balocchi 1993 Stem. 114 crookedness in this species has a strong genetic component Pederick et al 1984 Jayawickrama. 115 and Balocchi 1993 Downes and Turvey 1993 Jayawickrama et al 1997 The knowledge that a. 116 cause is genetic however does not reveal the actual physiological or structural mechanism by. 117 which trees differ in stem crookedness Compared to crooked trees for example the straight. 118 trees could have a more vertically aligned apical bud they could have stiffer stems through. 119 stoutness Downes et al 1994 or material properties and or they could react differently to small. 120 changes in the apex s orientation, 121 In this research we tested only the latter mechanism related to the reaction to inclination. 122 and termed overcompensation In overcompensation the apex of a crooked leader may grow. 123 toward a vertical orientation relatively quickly whereas the lower part of the leader adjusts its. 124 orientation toward vertical more slowly through the production of CW The CW is position. 125 appropriate for the lower part of the leader but if it occurs too quickly or too slowly relative to. 126 tip growth it will push the former apex no longer at the apex because of continued growth. 127 away from vertical The former apex then produces compression wood to adjust toward vertical. 128 and so on Harris 1977 Timell 1986 p 763 771 Downes et al 1994 Gartner and Johnson. 130 Tree to tree differences in response to inclination For the purposes of genetic. 131 improvement it would be useful learn whether some individuals consistently have less CW than. 132 others and whether assessment of CW in the leaders can be used to identify the least or most. 133 CW prone clones Burdon 1975 showed that P radiata genotypes differ in their propensity to. 134 form CW He also showed that genotypes differed in CW amount in different sites presumably. 135 because of differing site conditions, 136 In the current research we studied young P radiata trees in a 4 year old plantation in. 137 southern Chile comparing initially straight and initially crooked trees that we then inclined in. 138 several treatments By following stem angle and then studying the wood formed before and. 139 throughout treatments we were able to test the following hypotheses 1 trees with straight stems. 140 have less CW than trees with crooked stems 2 the amount of CW in samples from either. 141 straight or crooked trees is positively correlated with the sample s stem inclination and 3. 142 straight trees produce more CW at a given angle of stem inclination than do crooked trees We. 143 also used the results to speculate on whether stem crookedness is caused by overcompensation. 144 and to ask whether CW extent can be used as an early screening tool for P radiata wood quality. 146 Materials and Methods, 147 Site and plant material Pinus radiata trees were sampled from the San Alejandro farm 39. 148 45 16 S 72 54 14 W 100 m elevation a 4 year old operational plantation located 30 km. 149 east of Valdivia Chile The soil is recent volcanic ash over metamorphic material Pichoy. 150 weather station 20 km away receives about 2377 mm of precipitation annually The Royal. 151 Netherlands Meteorological Institute, 152 http climexp knmi nl getprcpall cgi someone somewhere 85767 4 VALDIVIA PICHOY. 153 The plantation had previously supported at least one rotation of P radiata trees Trees were half. 154 sibs derived from the same seed trees but with various pollen genotypes and were planted as 1. 155 year old seedlings in 2002, 156 Implementation of treatments Two observers walked between rows of trees searching.
157 for extremes of stem form that were vertical and either very straight or very crooked Straight. 158 trees had main stems that were within 3 of vertical and that appeared straight both within. 159 interwhorls the space between major branch whorls and in the mutual alignment of subsequent. 160 interwhorls Crooked trees had main stems with marked sinuosity and or several occurrences of. 161 marked sweep The form of the current year s leader growth was not considered because leaders. 162 on straight trees are not always straight, 163 After 24 straight and 24 crooked trees had been found we divided them haphazardly into. 164 three treatments for each stem form n 8 for each treatment and stem form combination no. 165 tether 15 tether and 30 tether Fig 1 Treatments were installed on 11 Jan 2006 Ordinal. 166 Date 11 abbreviated here as JD 11 at which time trees were part way through their fifth year of. 167 growth For trees in the 15 and 30 tether treatments we attached a tether just below the final. 168 branch whorl of the previous growing season The tether was made of heavy gauge wire that was. 169 looped around the stem and attached near ground level to a stake within the loop the wire was. 170 covered with hose Tethered trees were pulled tightly in the direction of the prevailing wind so. 171 that the stem segment in the 20 cm long zone immediately below the tether was either 15 or 30. 172 from vertical Tethered trees were free to move within the constraints of this one wire The. 173 morphologically identical zone was identified in trees that were not tethered. 174 The center of the 20 cm long zone was marked with white corrector fluid designed for use. 175 on paper which was durable and very visible on wet bark The zone was designated as position. 176 a b and d in each of the trees that were in the no tether 15 and 30 treatments respectively. 177 n 8 straight trees and 8 crooked trees per treatment Fig 1 On the 15 trees we also marked. 178 the position at which the stem was at 7 5 position c Fig 1 and on the 30 trees we marked the. 179 positions at which the stem was at 15 and at 7 5 positions e and f respectively Fig 1 All. 180 stems were also marked at breast height 1 3 m, 181 Angle measurements Angles were measured at all positions a b c d e and f six times. prediction for the current study was that there would be a weak positive effect of inclination on CW incidence Evidence for overcompensation as a cause of crookedness There has been much research into the causes of stem deformation crookedness in P radiata in old pasture sites and

Related Books