Competition Within Stands of Picea sitchensis and Pinus contorta

Competition was analysed in plots of Picea sitchensis and Pinuscontorta grown in 50 x 50 hexagonal arrays at 14 cm spacingto ages 7 and 5 years, respectively. Relative growth rates in height (RHGR) became positively relatedto tree heights during the year before harvest. Frequency distributionsof tree heights became negatively kurtotic with tendencies towardsleft-skew ness. By the time of harvest, dead trees were evenlydispersed over the plots. Trees with many taller neighbourshad lower RHGRs than trees with few taller neighbours, and theRHGRs of intermediate-sized trees were correlated with their‘competitive status’. Competition was confined mostlyto first-order neighbours. Large trees depressed the RHGRs ofsmaller neighbours and not vice versa; a simple test for this‘one-sided’ competition is described. Neighboursdid not need to greatly overtop a tree to depress its RHGR,they needed only to be at least as tall. Systematic trends inRHGR across the plots, attributed to site heterogeneity, decreasedwith time, and accounted for only about 10 per cent of the variationin RHGR at harvest. Competitive status accounted for 25 and38 per cent of the variation in RHGR in the Picea sitchensisand Pinus contorta plots, respectively. Picea sitchensis, Pinus contorta, competition, monoculture, self-thinning, relative growth rate, growth model     

Shoot Extension in Picea sitchensis II. Analysis of Weather Influences on Daily Growth Rate

The influence of mean temperature and total solar radiationon the daily increment of shoots of 12-year-old Picea sitchensisis described. Serial auto and cross-correlation analysis isused to show that variation in shoot increment is correlatedwith variations in weather occurring over several previous hours.The relationships between daily increments for the leading andtopmost five whorl shoots and the two controlling variablesof temperature and solar radiation are described for the firsthalf of the growing season by auto-regressive models fittedby time-series methods as described by Box and Jenkins. Thesedynamic system models showed that there was a delay of one dayand two days respectively in the influence of temperature andsolar radiation on shoot increment and that after these delaysthe response continued for more than a single day. The maximumfinal response (or steady state gain) of a typical topmost shootto temperature and solar radiation change was found to be 0.091mm d^–1(°C)^–1 and 0.027 mm d^–1 (MJ m^–2)^–1.For the normal range of these variables experienced this indicatesthat shoot extension was five times more sensitive to changesin temperature than to those in solar radiation. Picea sitchensis, Sitka spruce, shoot growth, weather influences, ARMA model, time-series analysis, Box-Jenkins method     

Effects of Environmental Change on Wood Production and Wood Structure in Picea sitchensis Seedlings

Changes in environment that would be expected to reduce substrateavailability, decrease the rate of xylem increment, tracheiddiameter and wall thickness, in seedlings of Picea sitchensis.But after reaching a minimum about 10 days to 3 weeks afterenvironmental change, xylem increment, tracheid wall thickness,and in some instances tracheid diameter, increase again up toabout 4 to 6 weeks after transfer. This recovery parallels arecovery in net assimilation rate, and is associated with anincrease in photosynthetic efficiency. Although the light intensity and temperature treatments imposedwere more drastic than those that would normally be expectedin the field, they had remarkably little net effect on tracheiddimensions. On the other hand change in photoperiod producedgreater changes in tracheid dimensions, photoperiodic effectsbeing superimposed on effects of change in substrate availability.It is suggested that adaptation to reduced substrate will bufferthe plant against climatic fluctuations during the growing season,while the photoperiodic response will ensure preparation forwinter dormancy. It is concluded that the major seasonal changes in tracheiddimensions are unlikely to be caused by variation in substrateavailability. Changes in light intensity and temperature haveminor effects on wood production and structure through effectson substrate availability, but the major seasonal trends aremore likely to be associated with changes in growth regulationproduction.     

Annual Variations in Competition Symmetry in Even-aged Sitka Spruce

Understanding of the temporal development of competition symmetry,size hierarchy and the role of episodically supplied resourcesin forest stands is limited. Because of intrinsic differencesin the symmetry of competition for light and below-ground resources,it is hypothesized that the overall expression of competitionvaries as a consequence of variations in water availability.Historical growth and precipitation data from an unthinned standof Sitka spruce (Picea sitchensis(Bong.) Carr.) in Denmark areanalysed with respect to the effects of precipitation on competitionsymmetry. The shape and linearity of the size-increment relationshipare analysed, and the temporal development of diameter distributionand size hierarchy is modelled. The test value of lack of linearfit through the origin for the diameter/increment relationshipplotted against precipitation in the growth period forms a triangularenvelope, indicating a more curvilinear relationship for yearswith high water availability. This indicates that dominant treesapparently benefit more from increased precipitation than suppressedtrees—which is also shown in the analysis of the temporaldevelopment of the diameter distribution—and as a consequencethe size hierarchy increases. Finally, it is proposed that temporaland spatial variations in the availability of water and otherbelow-ground resources may have similar effects on competitionsymmetry. Copyright 2001 Annals of Botany Company Competition symmetry, size hierarchy, precipitation, temporal development, Picea sitchensis     

Shoot Apical Meristems of Picea sitchensis Seedlings Accelerate in Growth Following Bud-set

First-year seedlings of Picea sitchensis were induced to setbuds by transferring them from long days (17 h) to short days(10 h at 20 °C, 12 h night at 12 °C). After 20 shortdays, the seedlings stopped growing in height, the shoot apicaldomes began enlarging and the transverse growth rates of theshoot apical dome tissues increased. For about 25 days thereafterprimordia were produced faster within the developing buds thanat the apices of seedlings which had been kept in long daysto prevent bud-set. Accelerated primordia production after bud-setenables the largest possible buds to be formed during the frost-freeperiod before winter. Picea sitchensis, apical meristem, bud-set     

The Structure and Composition of Bead-like Projections on Sitka Spruce Callus Cells Formed during Grafting and in Culture

Projections at the cell wall surface in callus formed at thegraft interface and in vitro in Picea sitchensis (Bong.) Carrhave been examined using light and electron microscopy. Thesestructures range in size from 1 to 5 µm in diameter, andconsist of a homogeneous matrix enclosing one or more fibrillar/vesicularcores. Histochemical and cytochemical studies have shown thatthe homogeneous matrix is made up of a mixture of pectins, carbohydrate,protein and fatty acids, while the fibrillar/vesicular componentis mainly carbohydrate and pectins. The possible functions ofthese structures are discussed on the bases of their composition.Copyright1993, 1999 Academic Press Picea sitchensis, callus, cell-wall projections, histochemistry, cytochemistry     

Studies of Growth and Flowering in Picea sitchensis (Bong.) Carr. 2. Initiation and Development of Male, Female and Vegetative Buds

Vegetative shoots from the base of the crown, and from partsof the tree likely to form male or female buds, were collectedfrom 40–years–old trees of Picea sitchensis (Bong.)Carr. throughout the 1973–4 annual growth cycle. The morphologyand growth rates of the terminal buds on these shoots were assessed. Bud scale primordia were formed most quickly in the female position,at an intermediate rate in the male position and most slowlyin the basal vegetative position during April, May and June.In July and early August the apical meristems swelled to formdomes and continued to grow at the same relative rates in themale, female and basal vegetative positions. Reproductive budswere first morphologically distinct in late August and sporangiaappeared in October. Dormancy, defined by the pause in apicalvolume increase, extended from mid-October to mid–March.Young strobili grew much faster than basal vegetative shootsof the same age between mid–March and bud burst in lateApril. Throughout the growth cycle, external changes in budsize reflected changes in size of the apical meristem, youngstrobihis or young vegetative shoot inside the bud. It is proposed that the rate of growth of an apical meristemmay be causally related to the type of bud which subsequentlydevelops from it. Sitka spruce, Picea sitchensis, bud development, morphology, growth of apical dome, flowering     

Effects of Light Intensity on Tracheid Dimensions in Picea sitchensis

In seedlings of Picea sitchensis grown in constant conditions,or within older trees in the field, light intensity had no neteffect on the wall thickness of tracheids produced at the samepoint in time. This appears to be due to a balanced regulatorysystem, effects of light intensity on rate of accumulation ofwall volume per leaf being offset by differences in rate ofxylem increment, and differences in wall material per tracheidbeing nullified in their effects on wall thickness by effectson tracheid diameter. Mean tracheid wall thickness across the growth ring increasedwith light intensity, due to increase in proportion of late-woodassociated with the longer duration of cambial activity at higherlight intensity, duration of wall thickening increasing duringthe season. Duration of wall thickening did not vary with lightintensity. The rate of increase in wall volume was limited by light intensity(and hence possibly by substrate availability) at all lightintensities in the field, but in seedlings in controlled conditionsthe rate of wall production was no greater at 20 000 lx thanat 6700 lx.     

Graft Formation in Sitka Spruce: A Scanning Electron Microscope Study

Low-temperature and conventional scanning electron microscopyhave been used to examine the callus formed at the graft interfacein Picea sitchensis (Bong.) Carr. Callus cells are producedby both cambium and ray parenchyma dedifferentiation and redifferentiationin scion and stock. Adhesion between the cells derived fromscion and rootstock is thought to be my means of pectinaceousbeads at the surface of the callus cells, preceding a more generalfusion of cell walls. The cambia of the two graft componentsare prevented from growing towards each other by the presenceof callus. Instead, the differentiation of new cambium withinthe callus, in the vicinity of the cambia exposed at the preparedsurfaces of the scion and rootstock, links them to form a continuouscambial layer around the combined stem. Callus, cambium, differentiation, grafting, Picea sitchensis     

Analysis of Shoot Apical Growth of Picea sitchensis Seedlings

During the first 100 days after sowing (March-June) the followingchanges took place at the terminal shoot apices of Picea sitchensisseedlings: plastochrones (T) decreased from over 24 h to 4 h;apical domes enlarged from less than 0·20 mm to 0·45mm diameter (D); the ‘projected’ area of tissuesproduced by the apical domes (i.e. viewed from above) increasedin amount from less than 0·012 to 0·024 mm² day^-1;about 15 per cent of this tissue was re-invested in the apicaldomes, the rest was used to produce primordia; and the volume-doublingtimes of the apical dome tissues decreased from over 150 h to50 h. After 100 days there was no further re-investment in theapical domes, but the domes did not decrease abruptly in size.Less tissue was produced per day, but the primordia were smallerso that the rate of primordia formation did not fall precipitously.Plastochrone ratios were inversely related to D, but the relationshipbetween T and D depended on whether T was decreasing or increasing.Progenies which were known to be fast growing tended to build-uptheir apical domes rapidly (i.e. have large ‘re-investmentratios’) and to be capable of producing small primordia.These attributes can evidently be evaluated on seedlings andcould help to lessen the cost of tree breeding progeny-testprogrammes. meristem, Picea sitchensis, Sitka spruce, growth, shoot apex     

Effects of Waterlogging on Water Relations of Actively-growing and Dormant Sitka Spruce Seedlings

Two-year-old Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings,either actively growing or dormant, were waterlogged in a growthroom at 15 °C. Shoot and root growth, transpiration andleaf water potential were observed. In actively-growing plants shoot extension continued after waterlogging,though at a reduced rate, and shoots of dormant plants brokebud and extended during the waterlogging period. Root growthwas suppressed by waterlogging in both types of plant. The 22day waterlogging treatment eventually killed the actively-growingplants but plants which were dormant at the time of waterloggingwere more tolerant. Changes in plant water relations after waterloggingwere entirely different depending on the condition of the plantswhen the soil was flooded. Dormant plants showed a gradual reductionin transpiration and increased water stress over the waterloggingperiod; after the soil was drained leaf water potential increasedto equal the value of control plants which had been maintainedin a freely drained condition, but transpiration did not increaseuntil root growth began. Actively-growing plants exhibited amore complex behaviour, characterized by a very rapid reductionin transpiration after waterlogging, accompanied by a briefperiod of water stress, followed by a period of increasing transpirationrate in the absence of water stress. Finally a second reductionin transpiration occurred and water stress increased as theseedlings died. The importance of the stage of activity of theroot system to the response of plants to waterlogging is discussed. Picea sitchensis (Bong.) Carr., Sitka spruce, waterlogging, water relations, dormancy, transpiration, water potential     

Studies of Growth and Flowering in Picea sitchensis (Bong.) Carr. 1. Effects of Growth Regulator Applications to Mature Scions on Seedling Rootstocks

Effects of growth regulator applications on the flowering of5-years-grafted mature scions of Picea sitchensis (Bong.) Carr.were assessed. Growth regulators were applied to the bud surfacein droplets of ethanol during July, August and September ina polythene house or glasshouse. A mixture of gibberellins A₄and A₇ applied alone, and in combination with gibberellins A₃and A₅, significantly increased numbers by up to seven timesfor male and by up to eight times for female strobili, gibberellinA, gave relatively the strongest response, and gibberellin A₄was inactive. Phosphon D and abscisic acid each reversed thepromotion of flowering by gibberellins, whilst kinetin and N,N-diphenylureahad no effect. The number of female strobili was negativelycorrelated with vegetative shoot length in the year after treatment. Under field conditions hormones were applied in July and Augustunder flaps of bark on the branches of 10-years-grafted maturescions. Gibberellin applications caused a 5-fold increase inflowering and N⁶-benzyladenine further increased the response.Naphth-lyl-acetic acid reduced female and increased male flowering.Bark removal near the base of the branch further enhanced hormone-inducedstrobilus production. The usefulness of these findings for thebreeding of Picea sitchensis is discussed.     

The Influence of Pine on the Form of Sitka Spruce Fine Roots

The form of fine roots of Sitka spruce (Picea sitchensis Bong.Carr.) when grown in immediate proximity to roots of Scots pine(Pinus sylvestris L.) and when grown separately was comparedusing split-root systems. When spruce roots were intimatelymixed with pine roots the mean length of individual spruce lateralswas significantly greater, while the length: weight ratio andnumber of root tips: weight ratio were smaller than when grownalone. A similar alteration in growth strategy was achievedby direct addition of mineral nitrogen. Key words: Fine root form, pine-spruce interactions     

The Effect of Cold Storage on Subsequent Growth of One-year-old Seedlings of Picea sitchensis

One-year-old seedlings of Picea sitchensis showed a significantdecrease in survival and a decline in vigour in a 5-week growthperiod with periods of cold storage. The effects of cold storagewere most clearly evident in the reduction of main shoot needleweight which would be reflected in the loss of photosyntheticcapacity.     

Daylength Effects on Growth, Tracheid Development, and Photosynthesis in Seedlings of Picea sitchensis and Pinus sylvestris

Effects of change in daylength on tracheid expansion and tracheidwall thickening are considered in relation to shoot and rootgrowth, assimilation rate, and starch content, in seedlingsof Picea sitchensis and Pinus sylvestris grown in controlledenviroments. Rates of wall thickening decreased in the first tracheids tobegin wall thickening after decrease in daylength. A sharp decreasein starch-grain size at the same time supports previous suggestionsthat wall thickness is related to available substrate; however,rates of assimilation were found to be far greater in shortdays than in long, suggesting that a surplus of carbohydratemay be produced in long days. It is pointed out that if availablesubstrate does limit wall thickening it is likely to determineto al accumulation of wall material; wall material per tracheidwould follow logistically from this depending on the numberof tracheids around the xylem, and wall thickness would dependalso on the radial tracheid diameter. Unexpectedly, rate of shoot growth accelerated after transferto short days before its final cessation with terminal-bud formation.Root growth declined in short days, but later increased againafter terminal bud formation. Rate of root growth did not appearto be associated with tracheid development in the shoot.     

祁连山东部青海云杉死亡和存活个体径向生长对气候变化的响应差异

研究建立了祁连山东部青海云杉(Picea crassifolia)存活个体与死亡个体的树轮宽度年表和断面生长增量(BAI)序列,对青海云杉存活个体与死亡个体的径向生长特征及其对气候要素的响应关系进行了比较,尝试厘清青海云杉径向生长与气候要素之间的响应机制。结果表明:青海云杉死亡个体的径向生长速率明显低于存活个体(P ＜ 0.001),尤其是在20世纪80年代快速升温后,这一差距进一步加大,青海云杉死亡率也大幅增加。在1951-1986年期间,青海云杉径向生长主要受生长季前(上一年9月到当年2月)干湿状况的影响;而在1987-2020年期间,青海云杉径向生长则更多受生长季(当年6-8月)干湿状况的影响。并且与活树相比,死树对区域干湿状况表现出更高的敏感性,对气温的负响应也更强。随着气候变暖加剧,高温及其带来的干旱胁迫已成为区域内限制青海云杉径向生长的主要气候因素,青海云杉的死亡率可能会继续升高。     

Inoculation and field testing of Sitka spruce and Douglas fir with ectomycorrhizal fungi in the United Kingdom

Picea sitchensis and Pseudotsuga menziesii seedlings were grown in containers, inoculated with ectomycorrhizal fungi, and planted in British forestry sites. Root samples taken during the year after planting were assessed for mycorrhiza formation. Survival and shoot height were assessed at the end of each year. Observations were made each autumn on the occurrence of sporophores of ectomycorrhizal fungi. Pot experiments were used to assess the colonization potential of soils from the experimental locations. Assessment of mycorrhiza formation by the inoculant fungi both before planting and the following year showed much variation among the fungi used. Similar variation was found among field sites. Inoculation with Laccaria isolates was most successful. Height measurements are reported for the first 2 years after planting, at which time there were few significant effects on growth of Picea sitchensis or Pseudotsuga menziesii seedlings. Experimental assessment of colonization potential was of little value in this work for predicting events in the forest.     

The Effect of Explant Type on the Establishment of Sitka Spruce [Picea sitchensis (Bong.) Carr.] in Culture

Five different types of shoot tip explant from three-year-oldand 13-year-old Sitka spruce trees were established on a rangeof media and shoot growth was recorded. While Schenk and Hildebrandtmedium gave the greatest shoot elongation, Webb and Street mediumproduced the healthiest-looking shoots. Poorest growth was recordedfor the explants cultured without the crown or any vasculartissues from the previous year's growth. [¹⁴C]sucrose tracerstudies indicated that poor uptake was not responsible for thereduced growth and it was suggested that damage due to inadequatewater uptake may be responsible. Results demonstrated that peelingthe protective scales from resting buds and trimming the shoottissues below the crown to a wedge shape and excluding the barkwas a reliable method of explant preparation for establishingmature and juvenile Sitka spruce in culture. Picea sitchensis, Sitka spruce, mature, juvenile, crown, [¹⁴C]sucrose, micropropagation     

Adaptations to Environmental Change in Picea sitchensis Seedling-changes in Photosynthesis, Growth and Substrate Availability

Effects of a change in night temperature with or without reductionin the duration of photosyntheticallyuseful light were studiedon assimilation and growth of Picea sitchensis seedlings. An increase in night temperature resulted in a rapid, but temporary,increase in photosynthesis while lowering the night temperaturedecreased photosynthetic rate. For the lowest night temperaturetreatments, reduction in light quantity resulted in increasedphotosynthetic efficiency while for the highest night temperaturetreatment, reduction in light quantity apparently checked thefinal decline in photosynthetic rate noted above. These changestended to minimize treatment effects on absolute growth andnet assimilation rates. The results are discussed in relationto the hypothesis or photosynthetic control by substrate level. Short-term redistribution of ¹⁴C labelled assimilate was examinedin control plants and those in the most and least adverse environments.In the most unfavourable environment, total ^l4C transport andincorporation into turnover materials increased while labellingof reserves and new growth decreased. Paradoxically, labellingpatterns for plants in the most favourable environment weresimilar although total ¹⁴C transport was much reduced. It issuggested that this indicates a substrate excess resulting fromoverloading of transport and utilization systems. Growth pattern was markedly affected in the case of developingbranch initials and established branches only. The possibilitythat the observed changes represent adaptive responses is discussed.     

Water Relations of Sitka Spruce Seedlings After Root Damage

Sitka spruce[Picea sitchensis(Bong.) Carr] seedlings were subjectedto varying degrees of root damage in a growth room, rangingfrom careful transplanting to exposure of the root system toair for up to 3 h. After replanting, transpiration (E), leafwater potential (₁) and growth of the shoot and root were measuredand observations made on plant survival. Some plants in the root exposure treatments died 20–85days after planting. In plants which eventually died, E wasdepressed directly after treatment, but ₁ showed a variableresponse. In some plants ₁ decreased from —8·0x 10⁵ to —30 x 10⁵ Pa after only 10 days but in othersthere was little change in ₁ for 50 days. In spite of the maintenanceof a high water potential in some of the latter plants for longperiods, no root or shoot growth occurred. In plants which lived, the root damage reduced root and shootgrowth relative to untreated controls, and most treatments stronglydepressed E but had little or no effect on ₁. The changes of E and ₁ in treated plants suggest that the suppressionof E was often independent of ₁ although water stress eventuallydeveloped in some of the severely treated plants. Sitka spruce, Picea sitchensis (Bong.)Carr, water relations, root damage, transpiration, leaf water potential