Modelling incidence of root rot in picea abies plantations in Southern Sweden

An empirical model is presented to forecast the incidence of root rot at stand level. In addition, the impact of different thinning programmes on the incidence of root rot is evaluated. The model is based on data from 152 permanent forest research plots of pure Picea abies in southern Sweden, within which the incidence of root rot at stump height in thinned trees has been recorded after each thinning since 1950. In total, about 20 000 stumps have been studied. According to simulations with the model, areas previously used as fields or for grazing are particularly susceptible to root rot, while old hardwood sites are less susceptible. Furthermore, simulations with the model imply that the earlier, the harder or more often a stand is thinned, the faster will be the development of root rot.     

挪威云杉种源及家系苗期生长适应性的聚类分析

通过对引进的挪威云杉种源和窄冠垂枝型挪威云杉家系进行不同地点苗期试验,选取生长期、当年高和存活率等3个指标进行苗期生长适应性评价,研究结果表明,部分窄冠垂枝型挪威云杉家系具有良好的生长适应性,大部分存活率相对比较低,挪威云杉种源苗期生长普遍不能适应。     

Environmental influences on juvenile shoot growth in Picea abies

Under certain environmental conditions, juvenile shoot growth characters might give early indications of adaptability and growth potential. Therefore, the reaction patterns of predetermined and free shoot growth were studied on Picea abies (L.) Karst, plants, which at different times during the growth period were treated by (1) application of nutrients, (2) defoliation, and (3) short days. Fertilization caused an increase in both predetermined and free growth, while defoliation and short day treatment caused a decrease in both forms of shoot growth and short days did not allow any free growth to occur. In the growth period following the treatments, fertilization caused more predetermined and less free growth to occur, while defoliation caused less predetermined and more free growth. Predetermined growth is explainable by the finite number of predetermined needle primordia. Free growth is initiated thereafter. It is influenced strongly by the environmental conditions and seems not to be influenced by the amount of preceding predetermined growth. Free growth enables young plants to utilize favourable growth conditions in summer for height growth precociously, which might increase their adaptability and competitive value. However, predetermined growth is the preferable mode of shoot growth because favourable conditions in successive growth periods induce more predetermined than free growth. Predetermined and free growth are well integrated forms of shoot growth giving no supporting evidence to the hypothesis that free and predetermined growth are inherited independently of each other. Rank changes in provenance development are probably not explainable by a loss in height growth when free growth occurs no more due to age, but by other causes.     

挪威云杉幼树韧皮部挥发性物质的测定

通过GC-MS测定挪威云杉幼树主干上部与下部韧皮主要挥发性物质的化学成分与含量，结果表明挪威云杉幼树的韧皮部挥发性物质的主要成分为α-蒎烯、茨烯、β-蒎烯、月桂烯、3-蒈烯、柠檬烯、β-水芹烯7种单萜化合物。α-蒎烯、β-蒎烯、月桂烯、3-蒈烯、β-水芹烯的含量在上部韧皮与下部韧皮有明显差异，其中上部韧皮部α-蒎烯、β-蒎烯和β-水芹烯的含量明显高于下部主干韧皮部,这为解释松树皮象的取食习性，打下了基础。     

Rejuvenation of juvenile growth characters in picea abies

Cuttings were made from six‐year‐old seedlings of Picea abies L. (Karst.) that had been studied in the Stockholm phytotron. The seedlings belonged to four full‐sib families, one being of French origin, one of North‐Swedish origin and two being hybrids between parents of North‐Swedish and French origin. Nine clones from each family were included. After the rooting phase, the cuttings were exposed to the same cultivation regimes as the seedling ortets. Characteristics of growth rhythm, percentage free growth and leader length were recorded during the 2nd to the 5th growth period (GP). Plagiotropic growth habit was recorded in the 3rd to the 5th growth period, and, characteristics of the rooting phase were studied. A juvenile behaviour very similar to that characterizing growth periods 2–3 of the seedlings was observed for growth rhythm characteristics and for free growth capacity during GP2 of the cuttings. The absolute value of the differences between each observation of the seedling ortets in GP6 and the means of the cuttings in GP2 produced a new variable that quantified the degree of rejuvenation. This new variable was meaningfully calculated only for growth rhythm and growth pattern variables. A gradual reversion of the growth rhythm occurred for the cuttings, which corresponded to the change with increasing age for the seedlings. The capacity for free growth, on the contrary, disappeared already in GP3 for the cuttings, except for the French family. A large variation in the rejuvenation ability between families was observed. Furthermore, the rejuvenation ability was negatively correlated with the ability to grow plagiotropically.     

Effects of growth regulators on germination of picea abies and Pinus sylvestris seeds

Nine seed lots each of Norway spruce (Picea abies L.), and Scots pine (Pinus sylvestris L.) were treated with combinations of the growth regulators: Indole‐3‐acetic acid, indole‐3‐butyric acid, etephone, kinetin, fusicoccin, and the gibberellins A₁ A₃ A_4/7, and A₉. GA₉ GA_4/7 and fusicoccin significantly promoted the germination of five Norway spruce, and three Scots pine, seed batches. Independent of species, the germinability of seeds treated with auxins, etephone, kinetin, GA₁ and GA₃ were unaffected or reduced. The rate of germination was stimulated for both species when treated with GA₉ or GA_4/7. The germination percentage for Scots pine seeds was enhanced by GA₉ but not by GA_4/7. Neither of the two GAs enhanced the germination percentage of Norway spruce seeds.     

A comparison between three different methods of measuring knot parameters in picea abies

Both foresters and sawmillers are interested in the knot structure of trees; in particular, position and number of knots, knot diameter, knot length and dead knot border. For research purposes, it is possible today to carry out non‐destructive measurements using computer tomography (CT) and image analysis. The aim of this study was to measure knot parameters on Norway spruce (Picea abies (L.) Karst.) using a non‐destructive method developed for Scots pine (Pinus sylvestris L.), and to compare the results of this method with the results of two different destructive methods. In order to do this, two Norway spruce stems were scanned by CT. Then five logs from one stem were cut into flitches 20 mm thick and the defects on the sawn surfaces were scanned manually. The other stem was cut just above every whorl and then each knot was split through its centre and the knot parameters were measured manually. The study showed that the CT method compares well with the destructive methods. It is a reasonably fast, non‐destructive method which measures position and diameter of knots and detects larger knots with acceptable accuracy. The study also showed that a large number of smaller knots were not found by the CT method and that the CT method measured knot length and dead knot border with low accuracy. This means that the CT method has to be adjusted to Norway spruce in order to improve its ability to measure knot length and dead knot border and to detect smaller knots.     

Vitality rating of picea abies by defoliation class and other vigour indicators

The study was made to assess the relationship between visually estimated defoliation class and a number of other variables depicting the vitality of Norway spruce (n=50). Variables characterizing crown size and condition were determined on the standing trees. Electrical impedance (an indication of the physiological status of a tree) was measured in the inner bark tissue of the living trees. Shoot growth and needle variables were determined from the detached sample branches. Negative correlations were found between defoliation class and the growth parameters (5‐year height, radial and volume growth of the trunk). Positive correlations were observed between the needle loss class and the abundance of branch damage, secondary shoots and impedance values. 18 variables (defoliation excluded) describing tree size and vitality were summarized in a factor analysis incorporating 5 factors. These were interpreted as 1) vitality, 2) foliage discoloration, 3) tree size, 4) needle number and 5) needle size factors. The tree‐specific score values for the first factor were interpreted as “vitality indices”;. The rank correlation between these score values and defoliation degree was 0.835. This result suggests that the defoliation class and vitality parameters contributing to the first factor give a consistent estimate of the tree condition.     

Development of a method for sorting picea abies pulp wood with respect to basic density

The basic density of pulp wood can be used to convert green volume to dry weight, and as an indicator of the fibre quality. Because the methods for measuring basic density are cumbersome, a practical, on‐line method for sorting Norway spruce pulp wood with respect to basic density was developed. The relationship between mean annual ring width and basic density was used to sort the pulp wood. Brief visual inspection could separate piles of logs with different mean annual ring widths from each other with an acceptable precision. The resulting classes had significantly different mean basic densities (380, 400 and 434 kg m^?3). Means of other properties, such as juvenile wood content, heartwood content, and dry matter content, also differed among classes.     

Pitch pockets in Picea abies: Variation in amount,number and size within trees and within a stand

The occurrence of pitch pockets in a stand of Picea abies [L.] Karst, was studied, focusing on variations in amount, number and size of pitch pockets within trees and between trees from the centre and the border part of a stand. Pitch pockets were more abundant in the border part, which had a lower site index and was also more exposed to the wind. The highest frequency of pitch pockets was noted for sawn faces near the pith of the tree from around the half tree height. The size of pitch pockets on sawn faces is described by two exponential functions. In both parts of the stand there was a similar increase of pitch pocket length with increasing distance from the pith, but generally trees in the border part had longer pitch pockets. In order to determine the relative amount of pitch pockets accurately at different distances from the pith and to explain the variation within and between trees, further analyses are necessary.     

Canopy density in stands of Picea abies and Pinus sylvestris after different thinning methods

Altogether 82 plots (261 estimations) of Picea abies (L.) Karst, and 193 plots (360 estimations) of Pinus sylvestris (L.) stands were estimated by a vertical tube. The “crown free projection”, CFP, of stands thinned in three methods with different thinning grades was measured: unthinned, heavily and very heavily thinned, heavily thinned delayed first thinning, extra heavily thinned and thinned from the top. Basal area (m²ha^?1) density (stems ha^?1) and diameter sum (m ha^?1) were plotted against CFP. Basal area was the best practical measure of stand in this study. Generally Scots pine stands have higher CFP and the curves are steeper than in Norway spruce stands. Depending on the grade of thinning, heavily and very heavily thinned spruce stands, delayed first thinning included, have CFP values of 10–15% and stands thinned from the top, 20–40%, compared with 30–80% and 30–60% respectively in pine stands. Extra heavily thinned stands have the highest CFP, 20–80% in spruce and 50–90% in pine stands. The CFP levels after thinning are too high in pine stands for avoidance of sucker and sprout production of aspen and birch. In dense Norway spruce stands thinned from the top or heavily and very heavily thinned, the CFP values are low enough (≤30%) to diminish the production of suckers.     

Earliness and growth performance in clones of picea abies selected for late frost resistance

Four late frost reistant trees in a young plantation of Picea abies were selected and compared with 15 non‐resistant ones after they had been propagated as cuttings. Two cutting trials were established, one in a nursery and one at the original selection site. Flushing, growth rate and total growth were assessed during four years. Frost resistant clones were found to be delayed in their flushing and growth development in early summer as compared to non‐resistant clones but the differences were not statistically significant. Large block variance and errors reduced the power of the statistical tests. Clone, site and year were found to be significant sources of variation in ANOVA, but neither interaction between clone and site nor clone and year were statistically significant. It is concluded that differences in growth rhythm parameters cannot be established between resistant and non‐resistant clones in this experiment, but the results are encouraging for the deployment of clones in forest plantations, provided the clones are tested and their performance remain stable over several propagation cycles.     

欧洲云杉扦插繁殖技术研究

为了快速有效地规模化扦插繁殖欧洲云杉,满足造林、绿化用苗的需要。采用全光照自动间歇喷雾装置,用河沙做基质。在林科院甘肃小陇山沙坝的实验基地做了ABT1、NAA、IBA、GGR不同激素,ABT1不同浓度和浸泡时间,5-10 cm、10-15 cm和〉15 cm三种不同插穗长度,5 a和23 a不同采穗母株年龄的嫩枝扦插试验及200 mg.kg^-1ABT1处理1 h的不同插穗类型（嫩枝带硬枝和嫩枝）的试验,用清水处理插穗做对照（CK）。试验数据采用spss12.0进行方差分析,结果表明：不同激素处理的插穗生根率差异显著。生根率大小顺序为：ABT〉GGR〉IBA〉NAA。而IBA处理的插穗生根数,根系总长和根系效果指数均大于其它处理,根系发达。ABT1不同浓度和浸泡时间处理的插穗生根率差异达极显著水平。以100.mg kg^-1和200 mg.kg^-1浸泡30 min和2 h生根率最好。50 mg.kg^-1浸泡1 h处理的插穗生根数、根系总长、根系效果指数大。嫩枝带硬枝和嫩枝生根率差异不显著,但生根数、根系总长和根系效果指数嫩枝带硬枝〉嫩枝。〉15 cm的插穗生根率和其它指标都高。采自23a生母株的插穗没有生根。     

Photosynthesis and root respiration of Pinus sylvestris and picea abies seedlings after different root freezing and storage temperatures

Photosynthetic performance and root respiration were measured for seedlings of Scots pine and Norway spruce under constant conditions in an open gas exchange system in the laboratory. Measurements were carried out after root exposure to ‐20, ‐5 and 0°C and subsequent longtime storage in darkness at +1 or +4°C. Stomatal conductance in relation to net photosynthetic rates was also investigated after the same treatment of seedlings. Root respiration was low for seedlings whose root system had been exposed to ‐20°C, Scots pine showing lower rates than Norway spruce. This was probably an indication of root damage. At least for one provenance of Scots pine, respiration rates were higher for seedlings stored at +1 than at +4°C. Photosynthetic performance was also lowest for seedlings whose roots had been exposed to +20°C compared to higher temperatures, the difference being more clear‐cut for Norway spruce than for Scots pine. Storage at +1 gave slightly higher photosynthetic rates than at +4°C. There was a close relation between stomatal conductance measured on individual needles and photosynthetic performance measured on the whole seedling.     

Correlation between pH and depth in the Mor Layer of a picea abies (L.) Karst. stand on till soils in Northern Sweden

The paper presents a method where the mor layer was sliced into 1 cm thick layers before measuring of pH_H2O and pH_CaCl2. A significant decrease of pH with increasing depth was found. Except for the two deepest layers, 2–3 and 3–4 cm, pH of all layers were significantly different (p<0.001). There was a significant positive correlation between pH in adjacent cm‐layers within the cores. pH_H2O in the middle layer, 1–2 cm, showed a significant correlation with all other cm‐layers. This may indicate that a vertical influencing factor or factors determine the pH pattern, even in spots with deviating pH values compared to the sample plot mean. Alteration of the organic material during decomposition, leaching of organic acids and cation uptake are discussed as probable factors leading to the observed pH gradient. The preferability of calculating a mean pH value from untransformed logarithmic pH values was also confirmed.     

Controlling and predicting the spread of heterobasidion annosum from infected stumps and trees of picea abies

Two Norway spruce stands with heavy infections of Heterobasidion annosum were clear‐cut in 1957 and 1959 in Sweden. The stumps were extracted, the soil sifted to remove most of the roots, and young Norway spruce were planted. After 25 and 28 years, H. annosum had infected 1 % and 2% of trees on plots where stumps had been removed and 17 % and 12% of the trees on control plots, respectively. Several of the H. annosum clones fruiting on old‐growth stumps were also detected in decayed, standing trees. The same fungal clone was found to be infecting adjacent trees from several old‐growth stumps. In addition to old stumps, stumps from recent thinnings and diseased living trees were traced as infection sources. Their relative importance in spreading disease was estimated. Disease risk predictions based on the distance of a tree from various infection sources correlated well with observed frequencies of rot.     

Distribution and yield of biomass from young Pinus sylvestris and Picea abies stands on drained and fertilized peatland

Above‐ground biomass has been measured on fertilized and control plots up to stand age 31 years. Each biomass fraction was estimated by two statistically coupled linear models with squared diameter at breast height as independent variable. All fractions except reproductive structures of pine and dead branches of spruce were estimated at high precision levels, R. between 0.93 and 0.99. The above‐ground biomass fractions per hectare could be precisely described by stem volume with bark. Application of the models for prognostic purposes is discussed. Annual above‐ground net biomass production in pine increased from 2.05 to 4.34 MT d.m./ha‐yr on control plots over 11 years, while plots given complete fertilizer mixture ranged from 6.75 to 9.09. Spruce stands with a nearly optimum water relationship and fertilizer programmes yielded from 9.50 to 11.86 MT d.m./ha‐yr. The combination of energy and timber production in highly productive peatland stands is discussed.     

Yield capacity of planted Picea abies in northern Sweden

Norway spruce (Picea abies (L.) Karst.) is the dominant species in the older forests of central northern Sweden. However, spruce has seldom been planted in the area, partly because existing tools for site classification have indicated a low yield capacity for the species. The aim of this study was to examine the yield capacity of spruce on the basis of existing plantations. In total, 91 operational and experimental plantations in the age interval 27–46 yrs were sampled. Stands were located between 62° and 65° N at altitudes 130–620 m a.s.l. Site index was estimated by height growth and site‐factor equations previously developed from old‐growth stand data. Height developments in the plantations indicate that site index for these stands is on average 4.6 m higher than predicted by site‐factor equations. The differences between the two methods are larger on poor sites than on rich sites. No systematic deviations of top height development from the site index curves could be detected on remeasured sample plots. Existing growth models were applied on measured stand data to predict future growth. Calculated mean annual increments were on average 20% lower when site index was predicted by site factors instead of height and age. The bias means that the yield capacity of planted spruce in northern Sweden has been underestimated by about 35%.     

Between- and within-site variation of density and bending properties of Picea abies structural timber from Norway

This study provides an analysis on the variability of structural timber of Norway spruce (Picea abies) grown in Norway. Density, modulus of elasticity (MOE) and bending strength were measured on 1188 boards from 205 trees, sampled from 14 sites throughout Southern Norway, Eastern Norway and Trøndelag. The area represents the procurement area for the majority of Norwegian sawmills. The variability of the timber properties was analysed in a linear mixed model where the random variance was divided into variance due to site, variance due to trees and within-tree variance. Models describing variance due to site based on site index, altitude and latitude were developed, and combined with data from the Norwegian National Forest Inventory to estimate mean values and variability of the timber properties. The results showed that major parts of the variance due to site are explained by altitude and site index, and for density also by latitude. Major parts of the variance due to site and the variance due to trees in bending strength and MOE were explained by density.     

Comparing predictability of board strength between computed tomography,discrete X-ray,and 3D scanning of Norway spruce logs

Strength graded boards of Norway spruce (Picea abies (L.) Karst.) are important products for many Scandinavian sawmills. If the bending strength of the produced boards can be predicted before sawing the logs, the raw material can be used more efficiently. In previous studies it is shown that the bending strength can be predicted to some extent using discrete X-ray scanning of logs. In this study, we have evaluated if it is possible to predict bending strength of Norway spruce boards with higher accuracy using computed tomography (CT) scanning of logs compared to a combination of discrete X-ray and 3D scanning. The method was to construct multivariate models of bending strength for three different board dimensions. Our results showed that CT scanning of logs produces better models of bending strength compared to a combination of discrete X-ray and 3D scanning. The main reason for this difference was the benefit of knowing the position of where the boards were cut from the logs and therefore detailed knot information could be used in the prediction models. Due to the small number of observations in this study, care should be taken when comparing the resulting prediction models to results from other studies.