Sitka Spruce and Douglas fir Seedlings in the Nursery and in Cold Storage: Root Growth Potential, Carbohydrate Content, Dormancy, Frost Hardiness and Mitotic Index

Seedlings (transplants) of 2+1 Sitka spruce (Picea sitchensis(Bong.) Carr.) and 1 + 1 Douglas fir (Pseudotsuga menziesii(Mirb.) Franco) were grown in a nursery at the Bush Estate,Scotland. Batches were lifted and cold stored at 0.5°C inNovember, December and January. Changes in growth, shoot apicalmitotic index, root growth potential (RGP), carbohydrate content,bud dormancy and shoot frost hardiness were monitored throughoutthe winter by taking samples at intervals from the nursery andfrom cold storage. Frost hardening occurred during the later stages of bud development(as mitotic indices decreased); autumn hardening was arrestedwhen seedlings were put in cold store, and some dehardeningoccurred in cold storage, especially in spring. Bud dormancystarted, and was greatest, just after bud growth (mitotic activity)virtually ceased; chilling in cold store was almost as effectivein releasing dormancy as natural chilling. The concentrationof total nonstructural carbohydrates stayed more or less constantat 100–150mg g^–1 from September to April in thenursery; in cold storage carbohydrates were depleted at 0.4–0.6mgg^–1 d^–1 (corresponding to respiration at 0.03–0.05mgCO₂ g^–1 h^–1) until there was only 40–50mgg^–1. Root growth potentials in the nursery increased in December,once the buds ceased growth, became dormant and had receivedsome chilling. Sitka spruce was ‘storable’ in November,before RGPs increased, but they then failed to achieve maximalfrost hardiness or ROP. Winter RGPs were high in Sitka spruceand were increased or maintained in cold storage, whereas RGPswere low in Douglas fir and decreased immediately after storage(except when stored in January). By the end of April, the RGPof cold stored Sitka spruce was much higher than that of directlifted plants. ROP changes in the nursery and in cold storagewere not consistently related to changes in seedling carbohydratecontents, shoot frost hardiness or bud dormancy. In practical terms, it was concluded that (1) the optimum dateto start lifting bare- rooted conifer transplants in the autumnis when their shoot apical mitotic indices have decreased tonear zero, and their RGPs have risen sharply; (2) high RGPsmay depend as much on the morphology of the roots (e.g. numberof undamaged root apices) as on the physiology of the shoots(e.g. carbohydrate status, dormancy and frost hardiness); and(3) in spring, transplants kept in cold storage since November,December or January are more frost hardy, slightly more dormant,and (in May) have higher RGPs than transplants lifted from thenursery.     

The Interaction of Green Spruce Aphid and Fertilizer Applications on the Growth of Sitka Spruce

In an 11-year-old stand of Sitka spruce (Picea sitchensis [Bong.]Carr.) application of nitrogen fertilizers, at a rate of 10kgN ha^–1 month^–1, increased mean diameter incrementby 12 per cent, while the further addition of phosphorus, at5 kg ha^–1 month^–1, resulted in a 23 per cent increase.An attack by the green spruce aphid (Elatobium albietinum Walker)occurred during the period of fertilizer addition. The mostseverely affected trees showed a reduction in diameter growthof 50 to 56 per cent but the severity of the attack betweentrees was unrelated to the treatments applied. However, fertilizerapplication did hasten the recovery of diameter growth afterdefoliation.     

Treatment of Severely Checked Sitka Spruce Trees with Injected Nutrients

Matched pairs of nutrient deficient Sitka spruce (Picea sitchensis(Bong.) Carr.) of mean height 3.0 m on a drained acid infertiledeep peat were injected in early summer by infusion with anaqueous solution of 40, 20, 66 and 0.2 g l^–1 N, P, K,Mg respectively, pH 7.2 and high conductivity. Three growingseasons later there were no responses in injected trees in treeheight increment, foliage nutrient levels of N, P, K, Ca, needlecolour, needle weight or crown density. Foliage Mg levels wereraised significantly. The injection procedure caused severetissue damage around the Infusion point and 84 per cent of thetrees had stain in stem cross sections 50 cm above the treatmentlocation.     

Internal cycling of nitrogen, potassium and magnesium in young Sitka spruce

Potassium (K) and magnesium (Mg) are essential macro-nutrients, but little is known about how they are cycled within plants. Stable isotope studies have shown that the internal cycling of nitrogen (N) is independent of current nutrient supply in temperate tree species. This is ecologically significant because it allows trees to produce rapid shoot growth in spring independent of current soil N uptake. We used stable isotopes to quantify N, K and Mg in new shoots of Sitka spruce (Picea sitchensis (Bong.) Carr.) seedlings and to compare the relative contributions from current uptake and internal cycling. Two-year-old Sitka spruce seedlings were labeled with (15)N, (41)K and (26)Mg in an abundant or a limited supply for one growing season. The trees were repotted in the subsequent dormant season to prevent further root uptake of enriched isotopes and provided with an abundant or a limited supply of unlabeled nutrients until they were harvested in early summer of the following year. The supply was switched for half the trees in the second year to create four nutrient regimes. Enrichment of (15)N, (41)K and (26)Mg in current-year growth was attributed to internally cycled N, K and Mg uptake from the previous year. The internal cycling of N, K and Mg in new growth was significantly affected by the first-year nutrient treatments. The second-year nutrient supply affected the growth rates of the trees, but had no effect on the amounts of N, K or Mg contributed from internal cycling. Thus, internal cycling of K and Mg in Sitka spruce are, like that of N, independent of current nutrient supply.     

Effects of water and nutrient availability on physiological responses of woody species to elevated CO2

The growth responses to elevated CO₂ found in experiments arehighly variable and depend on other experimental parameterssuch as irrigation, fertilization, light regime, etc. As yet,the strength or even the sign of most interactions is all butimpossible to predict from first principles. Experiments inambient and CO₂-enriched ambient air (+250 p.p.m.) have beenconducted in specially adapted greenhouses (Solardomes) at LancasterUniversity for the past four seasons on Sitka spruce (Piceasitchensis (Bong.) Carr.), wild cherry (Prunus avium L.), beech(Fagus sylvatica L.) and pedunculate oak (Quercus robur L.).These experiments are reviewed together with other publishedstudies on interactive effects of elevated CO₂ and water andnutrient supply on physiological processes, in particular gasexchange, in tree species. It is often assumed that drought tolerance will increase inelevated CO₂ because of a suppression of stomatal conductanceand an increase in instantaneous water use efficiency. Thereis, however, some evidence that such effects could be more thanoffset in beech by CO₂-induced increases in leaf area. It istentatively suggested that in beech, drought tolerance couldalready have been reduced by the increase in atmospheric CO₂over the last century.     

A Comparison of Element Fluxes in Throughfall beneath Larch and Sitka Spruce at Two Contrasting Sites in the United Kingdom

Annual chemical fluxes for ten elements beneath larch and Sitkaspruce are presented for contrasting sites in N.E. Scotlandand mid-Wales. The Scottish site is relatively low altitudewith moderate rainfall and the Welsh site is relatively highaltitude with high rainfall; both sites have low air concentrationsof SO₂ and NO₂ The data show clear differences in throughfallelement fluxes between larch and Sitka spruce of similar ageand, for the same species, between the two sites. For sea-derivedions and Ca, the trees appear to respond differently to thecontrasting climatic and depositional environments at the twosites; this overrides any consistent differences between speciesfor these elements. Species related differences, consistentat both sites, are apparent for H ion, SO₄ and the major nutrients.Larch releases more K and P but retains more inorganic N thanSitka spruce. Beneath larch, the H ion flux is approximatelythree times and the SO₄ flux 1.5 times that beneath Sitka spruce,indicating that larch is more acidifying than spruce.     

The Influence of Shelter and Weeds on Early Growth of Sitka Spruce and Lodgepole Pine

An experiment in Helmsdale Forest (Highland Region, Scotland)examined the effects of shelter and weed competition on Sitkaspruce (Picea sitchensis (Bong.) Can.) and lodgepole pine (Pinuscontorta Douglas ex Loudon). Different levels of shelter fromwind were achieved by using netting and were measured usingtatter flags. Three treatments compared weed competition byremoving no vegetation, heather (Calluna vulgaris L.) only orall ground vegetation respectively. Results indicate a definiterelationship between material lost from tatter flags and treedry weight at five years. Even the smallest increase in shelterresulted in increased growth of Sitka spruce and the beneficialeffect of shelter became most apparent 4 to 5 years after planting.Tree dry weight was found to be correlated with root collardiameter and height but not fifth year height increment. Resultsfrom weeding treatments were unclear and differed between species.This was because bird damage interacted with weeding, the completelyweeded plots being most heavily damaged; and because the methodof hand weeding (pulling out the whole plant including roots)damaged fine tree roots. Bird damage was prevented by nettingbut in unnetted plots it was found impossible to separate birddamage from other factors although it was clearly more seriouson lodgepole pine.     

THE PLACE OF A SPECIES IN THE FOREST, WITH SPECIAL REFERENCE TO WESTERN NORTH AMERICAN SPECIES OF CONIFER USED IN BRITAIN

The nature of the differences between the climates of the QueenCharlotte Islands and of England and Wales are discussed briefly.The author then examines the site tolerance of the principalspecies within their own natural range, comparing particularlythe place of Sitka spruce (Picea sitcbensis Carr.) in the foreston Graham Island with its place around Terrace and describingthe Douglas fir forests of the drier eastern side of VancouverIsland and the place that Sitka spruce has in them. Factorsaffecting the growth of Douglas fir (Pseudotsuga taxifolia Brit.)are discussed. It is suggested that care is needed before itis assumed that a markedly dry summer period such as occursin much of the Douglas fir region entails a ‘dry’period as regards supply to the tree. Illustrations are givenfrom eastern North America of changes in type of site occupiedby a species with change in climatic or edaphic environment.Observation of the relative position of a species in the forestas climate changes makes it possible to suggest the place ofSitka spruce and Douglas fir in Great Britain.     

Growth of Young Sitka Spruce (Picea sitchensis (Bong.) Carr.) and the Effect of Simulated Browsing, Staking and Treeshelters

Sitka spruce (Picea sitchensis (Bong.) Carr.) 1 + 1 transplantswere grown at 1 x 1 m for 3 years with 100 per cent chemicalweed control on a very fertile site. Treatments were control,firm staking, staked with 15 cm diameter netting with simulatedbrowsing, staked with simulated browsing to 15 cm diameter crown,1.2 m treeshelter, 1.2 treeshelter with holes and no browsing.No leaders were browsed. Trees were assessed for annual heightgrowth, stem diameter at 0.5 m and 1.0 m, total above and belowground biomass, root:shoot ratio, root plate diameter, rootdepth and root volume. No 3-year heights were significantlydifferent but third-year increments were; the greatest finalheight was in the control at 200.7 cm. All other tree parametershad significant treatment differences demonstrating the needto select carefully the criteria of success in experiments.Treatments which restricted the horizontal development of thecanopy either physically or by simulated browsing seriouslyreduced stem diameter and root development. The controls hada root:shoot ratio of 0.418; treeshelter treatments had thesmallest root:shoot ratio of 0.238; staked trees were 0.379while staked browsed trees had the highest value at 0.447. Acceptanceof browsing or use of shelters or guards to protect trees frombrowsing may seriously reduce growth.     

CONIFEROUS LITTER AMENDMENTS AND THE GROWTH OF SITKA SPRUCE

The growth of semi-checked Sitka spruce (Picea sitcbensis Carr.)on heathland has been stimulated to different degrees by theannual application of litter of Scots pine (Pinus sylvestrisL.), Corsican pine (P. nigra var. calabrica Schneid), Lodgepolepine (P. contorta Dougl.), Japanese larch (Larix leptolepisGord.), and Sitka spruce, at rates corresponding to normal plantationconditions, following an initial heavier rate. Foliar analysissuggests that the response is at least partially attributableto the influence of the litters on the nitrogen nutrition ofthe spruce and differences between litters appear to be largelydetermined by their total nitrogen contents. In this respect,Japanese larch, with an annual needle fall generally greaterthan that of the pines and a higher nitrogen content, offersthe best promise as a nurse species for spruce.     

Decay in Norway Spruce Caused by Stereum sanguinolentum Alb. & Schw. ex Fr. Developing from Extraction Wounds

In two stands of Norway spruce (Picea abies (L.) Karst.), plantedin 1952 and 1929 in Yair Hill Forest and Glentress Forest, BordersRegion, two per cent of the trees examined in 1983 had extractiondamage on stems and superficial roots. Extraction wounds were4 and 8 years old respectively and ranged in size from 52 to1099 cm². Infection frequency of the damaged trees was 47 percent and 54 per cent respectively. Stereum sanguinolentum wasthe most common fungus isolated, accompanied by Trichodermaviride Fr; Chaetomium cochlioides Palliser and Heterobasidionannosum (Fr.) Bref. The frequency of isolation of S. sanguinolentumincreased progressively in samples taken from the outside ofstems inwards, whereas the other microorganisms present showedthe opposite pattern. In four trees, T. viride overgrew S. sanguinolentumin the the decay columns. Positive correlations were demonstratedbetween surface area of wounds and vertical extension of decay,tree volume and decay volume, and diameter of stem at breastheight (DBH) and decay volume; whereas a negative correlationoccurred between number of growth rings per 5 cm (measured inwardsfrom the outside of the bole) and radial penetration of decay.The results confirm the importance of S. sanguinolentum as awound pathogen.     

Movement of Injected Dyes in Gymnosperm Stems in Relation to Tracheid Alignment

The path of upward movement of acid fuchsin dye was traced inpole-size stems of Japanese larch (Larix leptolepis Murr.),European larch (Larix decidua Mill.), Lawson cypress (Chamaecyparislawsoniana (A. Murr. Parl.)), Sitka spruce (Picea sitchensis(Bong. Carr.)), Norway spruce (Picea abies (L.) Karst.), andScots pine (Pinus sylvestris L.). In all of these species amarked, preponderantly clockwise spiral pattern of dye ascentwas observed. In general the upward movement of the dye followedtracheid alignment, except at the sapwood-heartwood boundary.The characteristic patterns of dye movement indicated that spiralgrain was much commoner than was straight grain among the pole-sizegymnosperms investigated. Large differences in spiral grainwere found among species, among trees within species, in differentannual rings within trees, and at different stem heights. Patternsof dye uptake were influenced somewhat by the method of injection.Dye injections through tubes driven into the stem were foundmore suitable for determining tracheid arrangement than wereinjections through individual roots immersed in dye. Factorsinfluencing spiral grain development and applications of thedye injection technique to spiral grain determination are discussed.     

Fomes annosus Butt-Rot of Sitka Spruce IV. Observations on the Distribution of Cryptosporiopsis abietina (Petrak) in the Stems of Rotted Trees

Cryptosporiopsis abietina was isolated from the heartwood of12 out of 18 Sitka spruce suffering from butt rot caused byFomes annosus, but from none of eight healthy trees from thesame plantations. C. abietina was present in a distinct zoneabove the tissue colonised by F. annosus. It was present inboth sound wood, and in wood with stain or incipient decay. C. abietina inhibited the growth of F. annosus on malt agar,and to a lesser extent in autoclaved Sitka spruce heartwood.The possible influence of this potentially antagonistic funguson infection by F. annosus is briefly discussed.     

Nutrient Changes in Peaty Gley Soils after Clearfelling of Sitka Spruce Stands

The roots of second-rotation Sitka spruce (Picea sitchensis(Bong.) Carr.) planted on peaty gley sites are restricted tothe old litter (LFH) layer and are dependent on its decompositionfor availability of nutrients. A series of these sites of increasingage from felling were sampled to estimate changes in the nutrientcapital of the LFH horizon over time at Kielder Forest, Northumberland.Previous stand histories were reconstructed from stump data.Geographical, climatic, soil and mensurational data suggestedthat the use of a time series was justified. Nutrient capital in the LFH horizon generally declined overa 5 year period after clearfelling from approximately 997, 51and 83 kg ha^–1 to 676, 30 and 31 kg ha^–1 of N, Pand K, respectively. However, N concentration increased overa 5 year period from 11 mg g^–1 to 14 mg g^–1, P concentrationremained constant at about 0.6 mg g^–1, and K concentrationdecreased from 1.0 mg g^–1 to 0.7 mg g^–1. Nutrientconcentrations and contents of the LFH horizon were higher underthe brash (slash) swathes that resulted from the use of organizedfelling techniques than under clear strips devoid of brash. The patterned input of nutrient capital in brash as a resultof organized felling was also determined. Brash containing 219,20 and 71 kg ha^–1 of N, Pand K, respectively, was systematicallydistributed at a rate of 491 ha^–1 over 66 per cent ofthe site after harvesting. The needles and small branch fractionscontained 71 per cent of the N and 80 per cent of the P andK present in the brash.     

Effects of benomyl and captan on growth and mycorrhizal colonization of Sitka‐spruce (Picea sitchensis) and ash (Fraxinus excelsior) in Irish nursery soil

The effects of two fungicides (benomyl and captan ‐ at recommended doses and up to three soil drenches) on root development and mycorrhizal colonization of Sitka‐spruce (Picea sitchensis) and ash (Fraxinus excelsior) were examined after 20 weeks growth, under environmentally controlled conditions, in soil from an Irish tree nursery. Although four mycorrhizal types have been found on Sitka‐spruce at the nursery, only one ectomycorrhizal type (Piceirhiza horti‐inflata) was identified on the short roots in this study. An inoculant (Vaminoc: MicroBio Ltd, Hemel Hempstead, UK) was used to inoculate ash and 20‐week‐old seedlings had a higher arbuscular mycorrhizal (AM) colonization in comparison with uninoculated controls. Multiple applications (2–3) of benomyl reduced the length of root and shoot and shoot dry mass of Sitka‐spruce, whereas in ash, it only depressed root length. Benomyl decreased the numbers of ectomycorrhizas of Sitka‐spruce and arbuscular mycorrhizal colonization of Vaminoc‐inoculated ash. A single application of captan stimulated root length and ectomycorrhizal colonization of Sitka‐spruce and root dry mass in ash compared with uninoculated controls. Applications of captan reduced arbuscular mycorrhizal colonization of Vaminoc‐inoculated ash to levels near to those of uninoculated controls. Of the two fungicides used, benomyl had the most deleterious effect on root length and mycorrhizal colonization of Sitka‐spruce and ash.     

The Dependence of Volume Increment of Individual Trees on Dominance, Crown Dimensions, and Competition

A study of the volume increment of individual trees over onegrowing season in a 23-year-old stand of Sitka spruce (Piceasitchensis Carr.), indicated that narrow crowned trees weremore efficient producers of increment. Other factors being constant,trees of greater girth at breast height were found to be inherentlybetter producers. Trees of the upper canopy were generally moreefficient than those of the lower canopy under varying conditionsof competition. Shorter periods of growth were recorded in lowercanopy trees and with trees under conditions of greater competition.     

Some Methods of Cold Storage can Seriously Affect Root Growth Potential and Root Moisture Content and Subsequent Forest Performance of Sitka Spruce and Douglas Fir Transplants

Sitka spruce and Douglas fir transplants were kept under threecold storage regimes: (1) bare-root in a humidified cold store(H); (2) sealed in polythene bags in a humidified cold store(HP); (3) sealed in polythene bags in a direct cold store (D).Regimes H and D are routinely used in current practice. Plants of both species had significantly (P < 0.001) lowerroot moisture content (RMC) in treatment H within 4 weeks ofstorage; this difference was maintained throughout the periodof storage and potentially damaging levels of RMC were reachedwithin 8 weeks. Sitka spruce had significantly (P < 0.001)higher root growth potential (RGP) than Douglas fir throughoutthe storage period. Differences in RGP between storage treatmentswere not significant until 12 weeks after storage when treatmentH was poorer (P < 0.05) than treatments HP and D. The survival of plants from treatment H after 1 year in thefield was significantly poorer (P < 0.001) than the othertreatments in both species. Height increment was also less intreatment H than the other treatments (P < 0.001) after 1year. However, this difference disappeared in the second season.After 1 year there were no differences in root collar diameter(RCD) increment between storage treatments but Douglas fir showedgreater increment (P < 0.001) than Sitka spruce. Rapid assessment of RMC in slightly over 48 h makes this a potentiallyuseful test of planting stock quality during and after coldstorage.     

Growth and mortality in underplanted tree seedlings in response to variations in canopy closure of Norway spruce stands

Six broadleaved tree species and Picea abies (L.) Karst. wereplanted under spruce plantations of varying densities, in Sweden.Treatments included control (994 stems ha^–1), dense (538stems ha^–1), sparse (294 stems ha^–1) and gap (0stems ha^–1) overstory treatments. There was an increasein height and diameter growth from control to sparse overstorytreatment of all underplanted tree species except for ash (Fraxinusexcelsior L.) and Norway maple (Acer platanoides L.). Site conditionsmay have hampered the growth of these species, as well as wildcherry (Prunus avium L.). Both oak (Quercus robur L.) and sprucehad greater growth in the gap treatment, relative to the othertreatments. Insecticide application did not influence seedlinggrowth or survival. The performance of beech (Fagus sylvaticaL.), lime (Tilia cordata Mill.), spruce and oak was consistentwith shade tolerance ranking. Beech and lime had a very highsurvival rate, even under the densest canopy. The growth andmortality of ash, maple and wild cherry differed significantlyfrom what was expected. This experiment demonstrated significantvariation in interspecific growth and mortality between sevenplanted tree species in relation to canopy density. Correctsite and species selection is crucial when underplanting inshelterwood systems.     

Relationships between nutrient supply, nitrogen partitioning and growth in young Sitka spruce (Picea sitchensis)

Budget studies have shown that internal cycling may contribute a large proportion of the annual nutrient supply required to support new growth in trees. Use of budgets to quantify internal cycling only quantifies the net transfer of nutrients within the plant. Differential partitioning of remobilized nutrients and current nutrient uptake could lead to errors in the interpretation of results from these studies. We have quantified the dynamic relationships among tree growth, nutrient uptake and internal cycling by labeling the current uptake of N in trees that received contrasting amounts of nutrient. Two-year-old seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.) were grown in sand culture in a greenhouse for one year. The trees received nutrients in a balanced solution at either a high (high-RAR) or a low (low-RAR) relative addition rate throughout the experiment. Current N uptake was labeled with (15)N from April 13 to July 25. Thereafter, trees were re-potted in clean sand and unlabeled N applied until November 13. Overall growth was sustained for approximately 10 weeks before treatment effects were observed. Initially, no differences in the partition of growth or remobilized N occurred, although partition of current uptake favored the roots of plants in the low-RAR treatment. After 6 weeks, the partition of both growth and remobilized N altered in favor of roots of plants in the low-RAR treatment. Nutrient supply had no effect on the amount or rate of N remobilization. No evidence was found to suggest that N taken up in the current season and partitioned to preexisting shoots or roots is remobilized late in the season to support growth of new shoots. However, some trees in the high-RAR treatment exhibited a second flush of growth later in the season that was partially sustained by remobilization of (15)N from current shoots formed earlier in the season. Use of (15)N demonstrated differential partitioning of current uptake and remobilized N. The results highlight the limitations of simple budget studies for quantifying internal cycling.     

Effect of Late-season Top-dressings of N (and K) applied to Conifer Transplants in the Nursery on their Survival and Growth on British Forest Sites

At two English forest nurseries, transplants of five coniferspecies—Picea sitchensis, Picea abies, Tsuga heterophylla,Abies grandis, and Pinus contorta—were grown with fertilizersupplying N, P, K, and Mg in amounts intended to be adequatefor producing healthy green trees with nutrient concentrationsin the ‘sufficiency range’ as determined by earlierexperiments. ‘Luxury uptake’ of nitrogen was obtainedwith top-dressings of ‘Nitro-Chalk’ applied in thenursery during early September, when top growth had nearly ceased.Tests of the effect of this extra N on forest establishmentwere repeated in four successive years under a wide range ofsoil and climatic conditions, keeping the trees in a cold storeduring each winter and planting them on forest sites in England,Scotland, or Wales during the following spring. Except for Grandfir, nitrogen advanced bud-break of all species during the firstsummer after planting and had no deleterious influence on survival.It tended to increase growth of Sitka spruce during the seasonafter planting, but in later years the differences became smallin relation to tree size. The effects on other species weresmall, except for one considerable decrease in the growth responseof Grand fir at a single site. Frost damage of Sitka spruce of Washington origin was severeon a Welsh and a Scottish site where this frost-sensitive provenancewould not normally be grown. At the Welsh, but not the Scottishsite, the nitrogen treatment increased the damage. In the few experiments (confined to Picea sitchensis) whichtested late-season potassium in the nursery, K concentrationswere increased from deficiency to barely sufficiency level;growth in the forest was increased in two of the four experiments.The extra K had no effect on frost damage.