Interception of precipitation by pole-stage Sitka spruce and lodgepole pine and mature Sitka spruce at Kielder Forest, Northumberland

Interception loss was measured indirectly for 3 years in adjacentunthinned 25-year-old stands of Sitka spruce and lodgepole pineand for 2 years in a 63-year-old selectively thinned stand ofSitka spruce. For each stand measurements were made of grossprecipitation, throughfall and stemflow. Interception loss wasderived by subtracting the sum of throughfall and stemflow (netprecipitation) from gross precipitation. For the years 1977–78, 1978–79 and 1979–80,interception losses in the pole-stage Sitka spruce were 32,28 and 27 per cent of gross precipitation respectively whilethose in the lodgepole pine were 33, 29 and 26 per cent. For1979–80 and 1980–81 interception losses in the matureSitka spruce were 44 and 53 per cent of gross precipitation.The average interception loss was 29 per cent for both pole-stagecrops and 49 per cent for mature Sitka spruce. The proportions of net precipitation reaching the ground asstemflow and throughfall were 0.18 and 0.82 respectively forthe pole-stage Sitka spruce, 0.14 and 0.86 for the pole-stagelodepole pine and 0.02 and 0.98 for the mature Sitka spruce.     

Comparisons of Production Costs and Genetic Benefits of Transplants and Rooted Cuttings of Picea sitchensis

A system has been developed by the British Forestry Commissionfor bulking-up plant numbers from scarce seedlots by rootedcuttings. Commercial-scale trials of the system are now underway.This paper describes a comparison of the costs of producingplanting stock by two methods; traditional nursery rearing oftransplants (1 + 1) and vegetative propagation of stock materialto produce cuttings (Cl + 1). Genetic gains are predicted andcompared for both systems, predictions being based on quantitativeestimates of genetic variables from progeny tests and on thecurrent progress of the breeding programme. The implicationsof the economic comparison for the future breeding programmefor Sitka spruce are discussed.     

Utilization of softwoods in Great Britain

The change in scale in wood processing in the UK over the past70 years is huge. From a position where sawmilling was on smallscale satisfying local market needs with native broadleaf species,it is now a huge industry supplying about 26 per cent of oursawn softwood demand; mainly from the exotic, Sitka spruce. Development has seen the industry reach levels of technologyequivalent to those in the Nordic countries and north America. Seventy years ago the only board manufacturing plants were producingplywood from imported tropical logs. Now the board industriesproduce chipboards, strand boards, MDF and cement bonded particleboardsfrom the home grownresource. Overall we produce some 56 percent of UK consumption of these products whilst in the growingMDF sector home production represents 78 per cent of demand. The wood pulp industry has developed over the past 15–20years from a position where it had almost ceased to exist tothe present situation of large volumes of newsprint, magazinepapers, packaging board and fluting being produced, largelyon four capital intensive sites. The sawmilling, board manufacturing and pulp and paper industriesare mutually dependent upon one another for their successfuloperation. Residue material from sawmills, for example, providesan important income source, whilst the market for small roundwoodprovides cash flow for forest owners prior to felling of thefinal sawlog crop.     

Autumn frost damage: clonal variation in Sitka spruce

Current-year needles of Sitka spruce (Picea sitchensis) can be injured by frost after hardening of stem and buds in the autumn, and in Scotland trees of southern provenances are most susceptible to damage. In October 1993 a frost of −5°C caused needle damage to clonal plants of Alaskan, Queen Charlotte Islands, and Washington provenances of Sitka spruce that had been selected for variation in the onset of root dormancy. Visual damage assessment revealed significant differences among clones in the severity of damage, and this damage was positively correlated with the lateness of root dormancy. Measurement of electrolyte leakage from shoot samples confirmed the observed differences between clones. The large clonal differences in frost hardiness found in this study demonstrate a potential for selecting frost tolerant trees from within southern provenances of Sitka spruce.     

The effect of whole-tree harvesting on the growth of second rotation Sitka spruce

Stem analysis has been used to examine the effects of two harvestingtechniques upon growth of second rotation Sitka spruce plantedin 1981 on a peaty gley site of low fertility in Kielder Forest,Northumberland. The effect of NPK fertilizer upon tree growthon conventionally harvested plots was also determined. Weedcompetition was reduced by hand weeding and the applicationof herbicides. Repeated measures analysis was used to identifythe time at which significant growth responses occurred. Whole-tree harvesting reduced mean tree volume from 1986 onwardswhile the addition of fertilizer to conventionally harvestedplots increased volume growth from 1990. By 1993, whole-treeharvesting had decreased mean tree volume by 32 per cent andthe addition of fertilizer to conventionally harvested plotshad increased mean tree volume by 13 per cent. Observed treatment effects are most likely due to the increasedremoval of nutrients during hole-tree harvesting. The releaseof nutrients from decomposing residues is expected to meet uptakerequirements for approximately 7–9 years following replanting.Effects of shelter and weed competition should also be consideredon sites where herbicides have not been used to control groundvegetation. Repeated measures analysis and the use of suitablegrowth functions provide powerful analytical tools to examinehistorical treatment effects derived from stem analysis.     

Annual and spatial variation in coning shown by the Forest Condition Monitoring programme data for Norway spruce, Sitka spruce and Scots pine in Britain

Conifer seed is a valuable forest resource; as well as beingreproductive material, it is an important foodstuff for manywoodland species. Information on cone and therefore seed productionof the main forest species are useful in the fields of bothforest management and forest ecology. Coning has been recordedsince 1989 in plots of Norway spruce, Sitka spruce and Scotspine across Britain as part of the Forestry Commission's ForestCondition Monitoring programme. An 11-year period of these recordswas analysed and a summary of annual cone production by speciesand coning synchrony is presented. Both Norway spruce and Sitkaspruce coned sporadically, with a 4-year period between mastcrops during which cone density was very low or cone productionabsent, whereas Scots pine produced a good cone crop in mostyears throughout Britain. Coning was synchronous within andbetween Norway and Sitka spruce across the whole of Britain(at distances >600 km) but coning within Scots pine was insynchrony only over distances of up to 200 km. Synchrony ofcone production was not evident between the spruce species andScots pine. These findings have implications when planning andinterpreting monitoring used to predict cone crops and in thedesign of forests for wildlife conservation.     

Production of a new generation of seeds through the use of somatic clones in controlled crosses of black spruce (Picea mariana)

To assess the potential to integrate somatic clones (SC) of desired characteristics in production of high genetic quality seed, controlled crosses between different SCs of black spruce (Picea mariana (Mill) B.S.P.) were used to assess their suitability for the production of viable pollen, cones, seeds and seedlings. These SC produced male and female strobili at an early stage. Pollen, cones and seeds produced were characterized (mass, size, germination); their characteristics were similar to those produced by trees in natural forests or seed orchards. A maternal effect was demonstrated for the cone size and seed mass. Although seeds had excellent germination rates, the somatic biparental crosses were divided into three distinct groups with different germination curves using the Weibull function. Seeds from controlled crosses between different SC enabled the production of high morpho-physiological quality seedlings in a forest nursery. Using black spruce as a model, we showed, for the first time, that SC can be used as seed producers. These encouraging results open new perspectives on the tangible integration of somatic embryogenesis (SE) in the chain of seed, vegetative propagation (cuttings and SE) and production of plants for high productivity plantations. Controlled crosses can be made between SC with the desired characteristics (fewer large branches, fewer nodes, good growth, high wood density, performance, improved yield, etc.), vegetative propagules produced and deployed to clonal tests. After elimination of the worst performing SC, clonal tests can be converted into seed orchards that produce a new generation of seeds of high genetic quality. This will allow the rapid introduction of new materials in elite breeding programs of forest species.     

Capercaillie habitat, diet and management in a Sitka spruce plantation in central Scotland

The ancestral habitat of capercaillie in most of its range isScots pine forest with an understorey of blaeberry. Keillourforest in Perthshire is dominated by Sitka spruce, has littleblaeberry, yet had a high density of capercaillie. Food andhabitat use by capercaillie were studied there from 1991 to1994. Seven cocks and two hens were caught, and marked withsmall radio transmitters. The habitats they occupied and foodremains in their droppings provided information on home range,habitat utilization and diet through the year. Sitka sprucewas the main food in autumn, winter and spring but was equalledby the fruiting heads of sedge in summer. Larch was the secondmost abundant item in spring and autumn diets. Sedge was plentifulon the wet restocks associated with the gleyed soils at Keillourand may provide a partial substitute for blaeberry in summer.Capercaillie showed a clear preference for the oldest blocksof trees, especially in winter. Sitka spruce, Norway spruceand Scots pine were used roughly in proportion to their availabilityin the birds' home range, but larch stands were used more thanexpected from availability. In summer, all birds used restocksto some extent. Management recommendations to encourage capercailliein commercial plantations largely comprising exotics are thatmature stands over 45 years and well-vegetated restocks shouldeach occupy at least 20 per cent of the forest, larch and blocksof mixed conifers each at least 15 per cent of the ground. Blaeberryshould be encouraged and, if possible, patches of windthrowinvolving living trees with the main root intact should be retained.     

Recent trends in nursery practice in New Zealand

The plantation resource in New Zealand is now 1.73 million hectares, of which 90% is Pinus radiataD. Don (radiata pine). The resource has been expanding at over 50,000 ha per year since 1992, although new planting is currently declining. In 1998, new planting and restocking of previously clear-felled areas was 81,100 ha. Initial stocking rates vary, but are typically in the range of 800–1000 plants per hectare, requiring around 80 million nursery plants to be raised per year.Sufficient open-pollinated seed is produced for New Zealand requirements. An increasing proportion of more expensive control-pollinated seed is being used to increase genetic gain. This has led to increased use of vegetative propagation by cuttings and tissue culture, providing more than 25% of current planting stock. These propagules, especially cuttings, often have better early performance compared with seedlings, perhaps because of their larger size. Clonal forestry options are also now being evaluated.Seedling quality specifications have been well defined for bare-root radiata pine, but not well quantified for more recent plant types such as vegetative propagules or container-grown plants. Both root system quality and physiological age can be important for vegetative propagules. These propagules, especially cuttings with a physiological age of less than 4 years, have performed as well as seedlings for growth, and have been better than seedlings for stem form and early stability. Container-growing of planting stock is being introduced with this more valuable genetic material, and issues of plant quality are being raised, as it is expensive to grow large stock in containers. More research should be done to determine what plant quality standards are required to ensure successful establishment with these stock types.     

Bark Stripping Damage by Red Deer in a Sitka Spruce Forest in Western Scotland: II. Wound Size and Position

Wounds to bark were measured within a few months of being inflictedby red deer in Glenbranter Forest, Argyll. About 8000 treeson 240 permanent plots were monitored; all the wounds occurringover a period of seven years were examined. Wound length varied little between forest stages, averaging12 cm. Wound breadth was greater on older trees, averaging 5cm in Sitka spruce and 6 cm in Norway spruce for the pole andhigh-canopy^* forest stages. A few wounds were large, maximumlengths being 95 and 80 cm in Sitka spruce and Norway sprucerespectively, but less than 20 per cent of the Sitka sprucewounds exceeded 100 cm² in surface area. Seasonal variationin size was modest; wounds were longest in spring (April–June). Often a single tree received two or more wounds during the 3-or6-month-long observation periods. For Sitka spruce there were89 instances of multiple wounding and 142 of single wounding,but these single wounds contributed only 37 per cent of thetotal of 383 wounds observed. The area of trunk wounded wasmore dependent on the size of the largest wound than on woundnumber, multiple wounds often being small. Trunks received most damage between 50 and 100 cm above ground,the lower and upper limits of wounding being 2 and 150 cm. Thepeaking in the incidence of damage with regard to height wasmost marked in pole-stage forest, whereas wounds were spreadmore evenly up the trunks on younger trees. Wound height waslittle affected by season, mean basal heights being 68, 70,74 and 67 cm in winter, spring, summer and autumn. Woundingon the trunk was not correlated with aspect.     

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.     

Susceptibility of Sitka spruce and grand fir trees to decay by Heterobasidion annosum

The susceptibility of Sitka spruce (Picea sitchensis) and grand fir (Abies grandis) to decay by Heterobasidion annosum was compared on a site with a previous history of serious disease. The incidence of decay 15–16 years after planting was 1.5% in grand fir, compared with 34.8% in Sitka spruce. These results are broadly similar to those reported from other trials. More information is required for older trees in Britain but the evidence so far available suggests that grand fir is more resistant to H. annosum than Sitka spruce. Planting grand fir on severely infested sites may therefore significantly reduce the serious losses that could be expected with Sitka spruce. In 14 out of 271 decayed Sitka spruce H. annosum was absent from the middle or base of the decay column but present at the top. Approximately 3% of infected spruce showed features suggesting some degree of resistance. Resin bleeding was observed at the base of 23.2% of the infected spruce, and the mean height of the decay column in these trees was significantly greater (0.96 m) than in those without this feature (0.66 m). The inoculum for infection was provided by stumps of the previous crop, and the genets of H. annosum that were present in some infected trees were also identified in stumps. The majority of infected trees contained only a single genet but three trees contained two genets. In this young crop individual genets were smaller than those found elsewhere; the largest extended to include six trees.     

The Effects of Clearfelling a Sitka Spruce Stand on the Water Balance of a Peaty Gley Soil at Kershope Forest, Cumbria

From 1981 to 1985 the water balance of four 2 ha plots of aploughed and drained Sitka spruce plantation was monitored.During 1983, three plots were clearfelled and a fourth was leftstanding as a control. A ground level raingauge over-collected during snow, but otherwisecollected 3 per cent more water than standard raingauges. Annualprecipitation (1259–1688 mm) averaged 1439 mm. The forest canopy intercepted 38 per cent and transpired 12per cent of gross precipitation. Fifty per cent of gross precipitationwas evaporated while the other 50 per cent left the site asrunoff. Throughfall and stemfiow fractions of net precipitationwere 0.87 and 0.13 respectively. After clearfelling, annual runoff increased to 68 per cent ofgross precipitation. After adjustment using the before and aftercomparison in the control plot, the decrease in annual evaporativeloss resulting from clearfelling was 290 mm.     

林木无性繁殖及其在遗传改良中的地位

本文对无性繁殖在林木遗传改良中的地位主及其主要优缺点作了评述。尤其对针叶树在混合无性繁殖条件下遗传结构的改变及欺 后果作了讨论，并提出无性繁殖中的问题和应采取的对策。     

Norway or Sitka Spruce?

The deep and wide continental range and climate occupied bythe European species Picea abies is contrasted with the long,narrow, and humid coastal strip which the American species Piceasitchensis inhabits. Norway is the more plastic spruce and cansuffer thinner soils and much more drought, but neither spruceis a shallow rooter where soils are good and deep. Of the two,the litter of Sitka is less harmful to the soil. To date thereis no evidence that height for height Norway is more stableunder high wind pressures, but the belief that it is less sensitiveto frost than Sitka is well established. Sitka is far superiorto Norway for planting at high altitudes and in exposed placesand on Molinia peatlands in Britain, which accounts for thevast preponderance of the American species used in the westand north of the British Isles. The present popularity of Norwayspruce with foresters and timber merchants is admitted, butthe point is made that in planting it where Sitka could growwell, only some 75 per cent, of the volume will be secured.Finally, the types of site which each spruce requires and alsowhich each cannot take are considered in detail. A plea is madefor mixtures in certain circumstances, and the belief expoundedthat only deeper and better cultivation of the hardpacked materialunder-lying thin soils will make it possible to extend considerablyour acreage of really stable crops of these high-volume producers.     

Norway spruce emblings as cutting donors for tree breeding and production

In the Nordic countries, Norway spruce (Picea abies) is a major species in tree breeding. In order to facilitate breeding work and availability of highly bred forest regeneration material, the time required for breeding and implementation of results should be shortened. This could be done by accelerating production of clonal material for field testing, and possibly for planting stock, by combining production of rooted cuttings with somatic embryogenesis (SE). This would allow efficient production of numerous plants of the same genotype, with equal age and propagation history between genotypes. In the present work, we studied the rooting potential of cuttings from Norway spruce emblings. Altogether 36 clones from 12 families representing elite breeding materials and ornamental forms were examined under different rooting conditions (container type and rooting media) in 2015 and 2016. Our results show that Norway spruce emblings are good donors for cuttings. Best combination (peat–vermiculite mixture and Plantek 81f containers) resulted in 91% rooting, variation among the tested clones of elite breeding materials being 55–100% per treatment. The rooting variation between families is acceptable for breeding purposes. High rooting (87–96%) of ornamental forms indicates propagation potential with the combination of SE and rooted cuttings.     

Multiplex real-time PCR detection of pathogen colonization in the bark and wood of Picea sitchensis clones differing in resistance to Heterobasidion annosum

A quantitative multiplex real-time polymerase chain reaction (PCR) procedure was developed to assess the extent of Heterobasidion annosum (Fr.) Bref. growth in Sitka spruce (Picea sitchensis (Bong.) Carr.) bark and wood and to determine correlations between lesion length and fungal colonization. Based on lesion length and real-time PCR, the responses of four 3-year-old Sitka spruce clones to inoculation with H. annosum were characterized as showing either resistance or susceptibility to the pathogen. In susceptible clones, the extent of bark colonization did not differ from the visible length of the bark lesion, whereas lesions were longer than the extent of fungal colonization in resistant clones. The resistant clones contained considerably less fungal DNA than the susceptible clones, relative to the amount of host DNA in both the bark and the wood, indicating less resistance and more host cell death in the susceptible clones following inoculation. In both resistant and susceptible clones, fungal colonization in the wood extended beyond the visible necrotic lesion in the bark, indicating that host defense responses are weaker in wood than in bark. The spread of the pathogen in both bark and wood was less in the resistant clones than in the susceptible clones, indicating that defenses in both bark and wood of the resistant clones were superior to those in the susceptible clones.     

Effect of Desiccation on Water Status and Forest Performance of Bare-rooted Sitka Spruce and Douglas Fir Transplants

Sitka spruce transplants which had been exposed to drying conditionswere assessed for shoot water potential (), shoot moisture content(MC), water saturation deficit (WSD) and root moisture content(RMC) before forest planting. Exposure for 1 hour 44 minuteshad no effect on subsequent survival or growth, but exposurefor 3 hours 18 minutes reduced survival to 68 per cent aftertwo years and significantly reduced height growth. The damagedplants were clearly distinguished at the time of planting by and RMC but not by MC or WSD. After a range of desiccation treatments, survival was high inSitka spruce unless RMC had fallen below 180 per cent but survivalwas reduced in Douglas fir with smaller reductions in RMC or. During the desiccation treatment, Douglas fir started withand maintained a higher RMC than Sitka spruce and reached lowlevels of less rapidly. The poor performance of desiccatedDouglas fir was therefore not the result of an inability toconserve water. After rewetting for one hour in the dark RMC was restored butnot , and there was no significant effect on survival or growthin either species. It may be possible to devise a method to establish when plantsare in poor condition by direct or indirect measurement of RMC,but high levels of RMC can be misleading if rewetting has occurred. Handling systems which involve brief periods of exposure aretolerable for Sitka spruce but not for Douglas fir, and specialmeasures are justified to ensure that the latter species isnever subjected to root desiccation during handling.     

Successive bulk propagation of juvenile plants from full-sib families of Norway spruce

The results of bulk propagation of Norway spruce for one year are presented. The number of cuttings produced per seedling ranged from 21 to 38 between different families, with a large within-family variation. No clear relationship between family field performance and production of cuttings could be seen. Established cuttings produced more propagules per plant than seedlings in the first propagation. Misting gave about 92% rooting, with no significant differences between different rooting media used. A bulk propagation programme is proposed with a potential production of about 1000–1500 plants per germinated seed within 3 years of sowing.     

Variation of Density and Growth Ring Width in Stems of Sitka and Norway Spruce

The variation with height and radial distance from the pithof basic density and ring width has been determined in stemsof 48-year-old Sitka and Norway spruce planted at two spacingsat Durris, Kincardineshire. The pattern of radial variationof density was broadly similar at all heights: high near thepith, falling to a minimum and then a gradual increase. Themean whole-stem densities were significantly different at thetwo spacings in Sitka but not in Norway spruce. Density at breastheight was inversely correlated with ring width, strongly inSitka but weakly in Norway spruce. The density/ ring width regressionequation for outer wood in Sitka spruce at age 48 differed fromthat at age 31. In Norway spruce a high correlation was foundbetween whole-stem density and the density of rings 16–25at breast height.