Light quality and growth of Norway spruce (Picea abies (L.))

Seedling of Norway spruce (Picea abies L.) were grown under three different light qualities in fluid-roof growth chambers. Blue light with a high red/far-red ratio decreased shoot length as well as total plant dry weight compared to natural light. Yellow light with a low blue/red ratio did not significantly affect the plants. The effects of light quality were generally the same at 18, 24 and 28 °C day temperature. Plant growth was reduced at temperatures above 24 °C.     

Effects of aluminium and calcium on Picea abies seedlings

Newly‐germinated Norway spruce seedlings were grown for 15 weeks in pots of iron podzol soil that received additions three times a week of nutrient solution containing six levels of Al (0, 0.37, 0.74, 1.5, 3.0 or 6.0 mM) and two levels of Ca (0.09 or 0.46 mM). The Ca concentrations in shoots and roots decreased with increasing Al levels. Growth was suppressed at 0.74 mM Al in the nutrient solution, which gave 0.5 mM Al in saturated soil extracts at the end of the experiment.     

Influence of initial spacing and tree class on the basic density of Picea abies

The effects of initial spacing and tree class on the basic density of Norway spruce were evaluated in a stand on a fertile site in southwestern Sweden. The basic density at 0 and 4 m above ground level was significantly higher for trees planted with an initial spacing of 1.5 m than for trees planted with wider initial spacings. A decrease in initial square spacing from 2.5 m to 1.5 m had little effect, of small practical importance, on the basic density. The density at 0 and 4 m above ground was significantly higher for the suppressed trees than for the intermediate and dominant ones, and for the intermediate trees compared with the dominant trees. Differences in basic density appeared to be due mainly to differences in growth‐ring width. Basic density decreased outwards from the pith to the bark at 1.3 and 4 m above ground.     

Effects of early cleaning on young Picea abies stands

Young Norway spruce stands (Picea abies [L.] Karst) are typically cleaned of non-crop species on one or several occasions during young stand stage. In order to objectively evaluate the perceived benefits of early cleaning (EC), we studied the effects of EC on three study sites 2–2.5 years after receiving the treatment. Experiments were established as a randomised complete block design with a total of 40 blocks. Although height growth and mortality were not significantly affected, we found that EC substantially reduced canopy competition and, consequently, the mean diameter of released spruce grew 21–32% faster depending on the site. Furthermore, non-crop trees that were cleared during EC had fewer sprouts in two of the three sites and the sprouts were substantially smaller than the corresponding non-crop trees on control in all sites. EC can reduce the cost of pre-commercial thinning because EC reduced the estimated time needed for subsequent management by 18–49%. Thus, EC offers forest owners and managers an economically viable young stand management option.     

Effects of initial stand states on optimal thinning regime and rotation of Picea abies stands

Abstract

This study analysed the effects of young stand characteristics on optimal thinning regime and length of rotation periods for even-aged Norway spruce [Picea abies (L.) Karst.] stands. Stand development was based on a distance-independent, individual-tree growth model. The young stand data were collected from 12 well-stocked Norway spruce stands in southern Finland. Results showed that optimal thinning regimes and rotation period depend on site quality and initial stand characteristics. At the first thinning, optimal thinning type depended on initial density. Thinning from both ends of the diameter distribution turned out to be optimal for initially dense stands. At the second and subsequent thinnings, thinning from above was clearly superior. At a low interest rate, thinning from below was optimal for the first thinning regardless of stocking level. For the study data, optimal rotation periods varied from 61 to 92 years at 3% interest rate. The high variation in length of rotation period was due to the sensitivity of optimal length of rotation period to site qualities, initial stand structure and density.     

Effects of Partial Cutting and Scarification on Planted Picea abies at Mid-elevation Sites in South-east Norway

Mortality, injury and height growth of planted Picea abies (L.) Karst, were examined over a 6 yr period in eight stands at middle altitudes (430–620 m a.s.l.) in south-east Norway. There were four residual stand density treatments (shelterwoods of high, medium and low density, 25 × 25 m patch-cut) combined with three scarification treatments (unscarified, patch scarification, inverting) in a split-plot design. Mortality was very low during the experimental period, and did not differ significantly between the residual stand density treatments (mean = 11.1%). Both survival and plant height after 6 yrs were improved by inverting, while patch scarification was intermediate but not significantly different from the unscarified alternative. The patch-cutting resulted in the tallest plants, while only minor differences in height growth were found between the shelterwood treatments. The frequency of injured plants after 6 yrs was not significantly affected by the treatments (mean = 10.6%). The improved plant establishment at inverting is in agreement with previous studies on clear-cuts.     

Effects of initial spacing on the stem and branch properties and graded quality of Picea abies (L.) karst

The effects of spacing on the stem and branch properties of Norway spruce growing on a good soil in southwestern Sweden were evaluated. Butt logs from sample trees were test sawn, and the boards were machine‐stress graded and graded according to Swedish export rules. Branch diameter and bole diameter both responded positively to an increase in spacing. Quality, as reflected by stress and export grades, increased in response to a decrease in spacing.     

Effects of scarification and mulch on establishment and growth of six different clones of Picea abies

Abstract

The effects of mulch and scarification on the establishment and growth of six clones of Norway spruce [Picea abies (L.) Karst.] were examined in a study in southern Sweden. Mulch and scarification reduced the amount of competing vegetation and tended to improve soil moisture and soil temperature. Budbreak occurred earlier for cuttings planted in the scarification treatment in comparison with the control and mulching treatment. Scarification increased survival and the combination of scarification and mulch resulted in the best growth. Gas exchange and the number of new roots were higher in planting spots covered with mulch. Clonal differences regarding gas exchange and growth were significant. Clones with a poor height growth also had a low gas exchange and a small number of new roots. In contrast, the clone with the best height growth had high gas exchange and a large number of new roots. Clonal effects on growth were greater than site preparation effects.     

Pathogenicity of Thekopsora areolata from seed orchards in Finland on Prunus spp. and Picea abies

Pathogenicity of cherry‐spruce rust, Thekopsora areolata, was investigated by inoculations with aeciospores from seven Norway spruce, Picea abies, seed orchards that had suffered from successive severe rust epidemics in the 2000s in Finland. Detached leaves of Prunus spp. were inoculated in the laboratory using aeciospores from cones of various ages. In the greenhouse, live Prunus padus plants were inoculated, and possible autoecism of the rust was tested by inoculations of Picea abies seedlings. Thirty‐five spore sources from the seed orchards formed uredinia on Prunus spp. in the laboratory 2 weeks after incubation, but no telia developed. In the greenhouse, uredinia developed on live P. padus, but no rust symptoms, cankers or sporulation were detected on Picea abies. Thus, no evidence of autoecism was observed among the T. areolata populations and therefore all populations, suggesting all those tested from the Finnish seed orchards were heteroecious.     

The effect of crown form and plagiotrophy on the growth of Picea abies f. pendula cuttings

Seven‐year old cuttings of pendula spruce were taller and had larger diameters than seedlings or cuttings of Norway spruce of normal crown type. Pendulous cuttings still had plagiotropic growth at age 7 years and the rate of change to orthotropic growth form was weaker than in cuttings with normal crown type. In pendulous cuttings the effect of the origin of ortet and clone on the crown symmetry was significant at age 5 years but not at age 7 years. The effect of clone on the growth form was evident at ages 5 and 7 years, but the effect of the origin of ortet was significant only in 7‐year‐old cuttings. There were no differences in plagiotrophy between clones from 4‐ and 7‐year‐old ortets. For pendulous cuttings the average height and diameter growth decreased in 5‐ and 6‐ year‐old cuttings with less pendulous crown form and with more plagiotropic growth form but this decrease had almost disappeared in 7‐year‐old cuttings.     

Long-term Growth Effects Following Forest Nitrogen Fertilization in Pinus sylvestris and Picea abies Stands in Sweden

Forest nitrogen (N) fertilization induces changes in the soil and soil microorganisms that could hypothetically affect the long-term productivity of the soil. The tree growth response following a normal (i.e. 150 kg N ha^?1) single shoot N fertilization has a duration of 7–10 yrs. The aim of this study was to investigate whether any residual effects on tree growth persist, which could be attributed to previous N fertilization. The study included six Pinus sylvestris L. and three Picea abies (L.) Karst. experimental sites, sampled for growth parameters 14–28 yrs after the last fertilization. Residual growth effects were on average small, and not statistically significant. Negative residual growth effects of varying duration could be discerned, especially at low-fertility P. sylvestris sites. However, there was an overall tendency for growth to increase in the long term after N fertilization. The main conclusion is that operational forest N fertilization with a normal N dose should not be regarded as a threat to long-term forest production.     

Root growth capacity and field performance of Pinus sylvestris and Picea abies seedlings

Correlations between root growth capacity (RGC), at the time of planting, and field performance were studied for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings. Before planting a gradient in seedling viability was generated through exposure to low root temperatures and different winter storage regimes. The hypothesis that high RGC values would improve field performance was to some extent verified for pine seedlings while no correlations could be registered for spruce. Reasons for these results are discussed.     

Influence of Shelterwood Density on Survival and Height Increment of Picea abies Advance Growth

Abstract

The increases in the arithmetic mean diameter at breast height (dbh) of the 100, 200, 300 and 400 largest stems ha^?1 by dbh associated with six different thinning regimens for periods up to 35 years were compared, by analyses of variance, to the corresponding stem fractions in unthinned stands using permanent sample plot data. In addition, the expected mean dbh of these stand fractions at future points in time was modelled, based on site and stand data obtained at the time of the first thinning. Thirty-five years after the first thinning, the thinning from below regimens resulted in actual increases (a measure affected by both the thinning intensity and the thinning method), compared with the unthinned stands, in the mean dbh for the 100, 200, 300 and 400 largest stems ha^?1 of 2.6–9.0 cm. The corresponding genuine increases (a measure principally affected solely by the thinning intensity) were 4–11 cm. The functions predicting the future dbh of these stand fractions yielded good fits.     

Effect of topography and geology on the site index of Picea abies in the West Carpathian,Poland

Abstract

The effects of topographic features and the soil parent rock on the site index of Norway spruce [Picea abies (L.) Karst.] were examined. Field data were collected on 347 plots located in the Polish West Carpathian. On these plots, the diameter at breast height and the height of trees were measured and the age of trees was determined. On 64 plots one dominant or codominant tree was felled for stem analysis. In addition, topographic features of each site were measured, including elevation above sea level, aspect and slope. Stem analysis data were used in the development of a local site index system, which was used for calculating the site index for particular plots. In order to interpret site index as functions of elevation, aspect, slope, size of a mountain massif and soil parent rock, the multiple regression model was used, which explained 79.0% of the variation in Norway spruce site index. Elevation above sea level was the major factor responsible for variation in site index, and was negatively correlated (R ² _adj=0.610) with site index. Site index also depended on the soil parent rock. The stands growing on the tertiary Magura sandstones had considerably higher site indices than those located on the geological substratum composed of Istebna and Godula sandstones formed during the Cretaceous period. The site index of Norway spruce is also determined by the aspect, slope and height of mountain massif.     

Effect of timing of precommercial thinning on the consumption of working time in Picea abies stands in Finland

The effect of the timing of precommercial thinning on the productivity of work was examined in young Norway spruce [Picea abies (L.) Karst.] stands in southern Finland. The common problem of large variation between sample plots in time studies was avoided by introducing a new approach based on a combination of stand measurements, tree-ring analysis and existing work productivity functions. The results indicated that a 2 year delay in the precommercial thinning of a stand was enough to cause an increase of 10-42% in the consumption of working time at a mean height of 1.5-3.1 m. At a later thinning, at a mean height 4.1-7.2 m, the increase was 8-24%. The development of the stand up to the first commercial thinning was not significantly influenced by a 2 year delay in the late precommercial thinning.     

Induction of hairy and normal roots on Picea abies,Pinus sylvestris and Pinus cortorta by agrobacterium rhizogenes

Two‐ to three‐week‐old seedlings of Picea abies, Pinus sylvestris and Pinus contorta were inoculated with the supervirulent strain Agrobacterium rhizogenes R1600 2cm above the base of the hypocotyl; other treatments included inoculation with Agrobacterium tumefaciens strain A281 (pTVK291) or mock inoculation. Hairy or highly branched roots formed on 2–3% of seedlings of all 3 species that were infected by R1600 but on none of the other seedlings. Normal adventitious roots were also induced on 5–10% of Agrobacterium‐treated seedlings but none appeared on the other seedlings. Opine assays and growth rates of hairy and normal roots indicated that only roots with the hairy morphology were transformed.     

Effects of Demand-driven Fertilization on Nutrient Use,Root:Plant Ratio and Field Performance of Betula pendula and Picea abies

Norway spruce [Picea abies (L.) Karst.] and silver birch (Betula pendula Roth) seedlings were grown for one season under three different fertilization regimens in the forest nursery. During the first 50 days the seedlings were grown in a glasshouse, and thereafter outdoors until the beginning of September. Finally, the plants were exposed to 16 h nights in the glasshouse throughout September. When the seedlings were supplied with fertilizers at a rate adjusted to expected plant demand (R_O), less than half as much of each nutrient was applied as in a conventional regimen (R_C), in which equal amounts were supplied per unit time during the growth season, yet the plants still looked healthy. Utilization of N increased by almost 50% in spruce when supply was adjusted to plant demand. In the third treatment (R_L), nutrients were supplied as in the R_O treatment, but at a growth-limiting rate. These plants were loaded with nutrients at the end of the season and had higher root:plant ratios, i.e. root weight in relation to total plant weight, compared with the other treatments. The nutrient status of the plants was not growth limiting at the end of the growing season in any of the treatments. The plants given the different treatments differed in size at planting out, but they had similar heights after 3 yrs in the field. This indicates that the root:plant ratio may be important for growth performance, provided that nutrient status is not at a growth-limiting level. This study suggests that the use of fertilizers can be considerably reduced in Swedish forest nurseries.     

Basic density,longitudinal shrinkage and tracheid length of juvenile wood of Picea abies (L.) Karst

Variation in the growth ring width, basic density, longitudinal shrinkage and tracheid length was investigated in the juvenile wood of Norway spruce samples taken from different heights in the stem. Annual height increments were cut from the ten youngest shoots from trees of three different heights. By this method the properties of an individual growth ring could be analysed without taking samples from each ring. Sixteen tree tops of an average stem height of 8, 15 and 25 m were analysed. Basic density was low in the first shoot, highest in the second or third one and decreased gradually thereafter. Longitudinal shrinkage was highest close to the pith and decreased to about 0.2% in the outer rings. Tracheids were only ca. 1 mm long close to the pith and their length increased sharply towards the tenth shoot. The properties of juvenile wood varied with the height in the stem. Longitudinal shrinkage around the pith seemed to increase with increasing height and basic density was highest at 25 m stem height. The applicability of the method for the calculation of basic density and tracheid length in individual growth rings close to the pith is discussed.     

Variation in sapwood thickness of Picea abies in Estonia depending on the tree age

Variation of sapwood thickness in terms of a linear measurement and a growth ring count with reference to the age was studied in dominant and suppressed Norway spruce trees. In the trees of both dominance classes the sapwood thickness increased in absolute terms, while its relative portion decreased with the age of the trees growing. Great differences were found in sapwood thickness between dominant and suppressed trees in linear measurements but not in the number of sapwood rings or the rate of the heartwood formation. The number of sapwood growth rings reached 40 in old trees. The index of vigour differed considerably in dominant and suppressed trees.     

Influence of a long-term storage in anaerobic conditions on Norway spruce (Picea abies,L. Karst.) physical and mechanical wood properties

Timber storage is a key aspect of storm damage management. After huge storms, sprinkling storage is usually the most used conservation process but anaerobic storage in sealed silos appears as good alternative to preserve wood quality over long periods. This paper investigates the impact of long-term (57 months) storage of Norway spruce logs in anaerobic atmosphere on wood properties. Tests were performed on clear wood specimens and on lumbers to determine the modulus of elasticity (E), the static bending strength (σ_f) and the dynamic bending strength (K). Storage effects on impregnability and colour variation were also studied. Results show no effect of storage on E, σ_f and K. The naturally poor impregnability of Norway spruce is not improved by the anaerobic conditions, compared to traditional wet storage. Triangle tests reveal no discernible colour variation between logs that underwent anaerobic storage and the control sample. As a conclusion, despite a mould (Gliocladium solani) frequently observed on logs surface after the storage, the process offers ideal conservation conditions. While overall cost remains the main drawback for using anaerobic storage at large scale, the process can be recommended for high value logs, especially since it has few environmental impacts.