Relationship between wood anatomy,tree-ring widths and wood density of Pinus sylvestris L. and climate at high latitudes in northern Sweden

In this study, wood anatomy, tree-ring width and wood density of Pinus sylvestris at the northern timberline in Fennoscandia were used to identify relationships among the parameters and to screen them for their climatic signals. Furthermore we investigated the influence of the juvenile wood section for all parameters developed. The measurements of wood anatomy were conducted with confocal laser scanning microscopy (CLSM) while the density profiles were produced using an Itrax MultiScanner. We developed chronologies of ring width, wood density and anatomy for a period between 1940 and 2010. Correlations between wood density and wood anatomy were strong in the latewood part. For some wood anatomy and density chronologies youth trends were found in the juvenile part. Wood density decreased from the pith up to the 9th ring and stabilized afterwards, while cell lumen diameter and lumen area increased simultaneously up to the 15th ring. All chronologies contained strong summer temperature signals. The wood anatomical variables provided additional information about seasonal precipitation which could not be found in wood density and tree-ring widths. Our study confirmed previous results stating that the parameter maximum density contains the strongest climate signal, that is, summer temperatures at the northern timberline. Nevertheless, the intra-annual data on tracheid dimensions showed good potential to supply seasonal climatic information and improve our understanding of climatic effects on tree growth and wood formation.     

Dry-matter Production by Pinus sylvestris L.

This paper contains the data for the gross weight and relativeproportions of canopy, bole, and roots in a series of twelveeven-aged forest stands. From these it is possible to describe the growth curves of treesof Pinus sylvestris in Britain under the observed conditionsand the production of dry matter per unit area of such standsof trees. The following general results are given: regressionsrelating weight to bole, height, and diameter; the relativegrowth of leaves, roots, and bole; annual increments of drymatter; relative growth-rates per unit leaf area or per unitdry weight per annum. Some comparative data are given for Pinus nigra (one plantation)which is more productive than Pinus sylvestris.     

Population-genetic variation in Scots pine Pinus sylvestris L. from the main forest regions of Ukraine

Using electrophoretic analysis of 22 isozyme loci controlling ten enzyme systems, we studied intrapopulation and interpopulation variation of Scots pine Pinus sylvestris L. in the main forest regions of Ukraine. In 15 of the populations examined, 76.5% of genes were polymorphic, and an average plant was shown to be heterozygous at 23.4% of the genes. The lowest and highest values of major polymorphism parameters were characteristic of respectively the relic populations of Ukrainian Carpathians and the populations from the steppe and forest-steppe zones. Nei's genetic distances between the populations varied from 0.006 to 0.031 (on average 0.016). Cluster analysis failed to show clear trends in the population distribution relative to their geographical position.     

Mineral Content of Plantations of Pinus sylvestris L.

Data are given of the percentage composition and total contentsof Na, K, Ca, Mg, P, and N in trees forming an age series ofplantations of Pinus sylvestris. From these data, calculationsare made of the total nutrient uptake by the trees, both annuallyand for the whole rotation, the removal of nutrients in thecrop, the immobilization of nutrients within the trees, andthe return of nutrients to the soil by litter fall and unharvestedmaterial from selective thinning and cropping. Comparisons aremade of the nutrient uptake by the trees and typical agriculturalcrops, and the results are considered in terms of the maintenanceof soil fertility.     

Glucomannan-synthase activity in differentiating cells of Pinus sylvestris L.

Particulate membrane preparations have been isolated from cambial cells, and from differentiating and differentiated xylem cells of the main stem of pine trees. These preparations synthesise a 14 glucomannan from guanosine 5-diphosphate-mannose. The polysaccharide and the synthase have been characterized and the K_m and V_max for the synthase determined as 85 M and 52.9 M·min^-1, respectively. The enzymic activity was inhibited by the addition of guanosine 5-diphosphate-D-glucose so that the presence of an epimerase on the particulate fraction in conjunction with the synthase probably allowed the heteropolymer to be formed with the optimal ratio of the concentrations of the nucleoside-diphosphate sugar donors. No evidence for a polyprenyl-phosphate derivative as an intermediate during the polymer synthesis was obtained. Part of the control mechanism for the deposition of the large amounts of the glucomannan during the secondary thickening of the tracheids of the vascular system is by an increase in the amount of synthase activity at the endomembrane system of the cells. This probably occurs by an increase in the amount of enzyme which is modulated by gene regulation during differentiation.Abbreviations GDP guanosine 5-diphosphate - GLC gasliquid chromatography     

The refilling of embolized xylem in Pinus sylvestris L.

Abstract. The hypothesis that ray parenchyma cells are actively involved in the refilling of embolized xylem of Pinus sylvestris L. was tested by killing the ray parenchyma and comparing rehydration of killed stems with that of control material. Killing of ray parenchyma was achieved using hot water or sodium azide. In most experiments, the available water for refilling was at negative water potential. Experiments were done on three kinds of plant material: small branch segments, potted seedlings and small potted trees. In all experiments, there was no indication that the azide-killed xylem was slower to refill than the control material and it was concluded that the parenchyma has no role in the refilling process, which therefore must be purely physical or physicochemical. Stems treated with hot water did not refill; we suggest that this may be caused by high temperatures decreasing the water permeability of the tracheid wall. The refilling of small branch segments may be explained by surface tension forces (capillary action), which inside the tracheid lumen may lower the water potential down to -9.7kPa; this may be enough to draw in water from the available water that in experiment one was at -2kPa. In the case of seedlings or saplings, capillary action cannot explain refilling, because the xylem water potentials were always lower than those estimated from tracheid radii. Condensation of water during diurnal cycles of warming and cooling is also unlikely to contribute to refilling significantly. To account for refilling in these cases, it is supposed that the tracheid wall may be chemically active and able to lower the water potential below the value expected by capillarity.     

Identification of QTLs influencing wood property traits in loblolly pine (Pinus taeda L.). I. Physical wood properties

Physical wood property traits for loblolly pine (Pinus taeda L.) were analyzed for the presence of quantitative trait loci (QTLs) in a three-generation outbred pedigree. These traits include wood specific gravity (wsg), volume percentage of latewood (vol%), and microfibril angle (mfa). Phenotypic data were collected for rings 2–11 for wsg and vol%, and rings 3, 5 and 7 for mfa. Both earlywood and latewood were analyzed for each trait. An interval mapping approach designed for an outbred pedigree was used to estimate the number of QTLs, the magnitude of QTL effects, and their genomic position. Nine unique QTLs were detected for composite traits (average of all rings) for wsg, five for vol%, and five for mfa. The majority of these QTLs were verified by analyses of individual-ring traits. Additional QTLs for each trait were also detected by these individual-ring analyses. Most QTLs for wsg were specific to either earlywood or latewood, whereas each QTL for mfa was detected for both earlywood and latewood. Before these QTLs are utilized in a breeding program, they should be verified in larger experiments and in different genetic and environmental backgrounds. Received: 15 February 2000 / Accepted: 31 March 2000     

Identification of QTLs influencing wood property traits in loblolly pine ( Pinus taeda L.). II. Chemical wood properties

Chemical wood property traits were analyzed for the presence of quantitative trait loci (QTLs) in a three-generation outbred pedigree of loblolly pine (Pinus taeda L.). These traits were assayed using pyrolysis molecular beam mass spectrometry and include mass spectrum peak intensities associated with carbohydrates, α-cellulose and hemicellulose sugars, and lignin. Models for projection to latent structures (PLS) were used to also estimate the chemical composition of cell walls (i.e., α-cellulose, galactan and lignin) from mass spectrum data using multivariate regression. Both earlywood and latewood fractions from the fifth annual ring were analyzed for each trait. An interval mapping approach designed for an outbred pedigree was used to estimate the number of QTLs, the magnitude of QTL effects, and their genomic position. Eight unique QTLs influencing cell wall chemistry were detected from multiple peak intensities and/or PLS estimates using the one- and two-QTL models. Significant differences in chemical contents were observed among the populations from North Carolina vs Oklahoma, and results from QTL×environment analyses suggest that QTLs interact with environmental location. QTLs should be verified in larger experiments and in different genetic and environmental backgrounds. QTL mapping will help towards eventually identifying genes having a major effect on chemical wood properties. Received: 19 January 2001 / Accepted: 31 May 2001     

Variation in the amount of triacylglycerols and steryl esters in the outer sapwood of Pinus sylvestris L.

Variation in the amount of triacylglycerols and steryl esters was analysed enzymatically in the outer sapwood of Scots pine (Pinus sylvestris L.). Increment borings were taken at breast height from 40 stems of different diameter. Wood samples from outer sapwood (10 mm from the cambium) were extracted with acetone. Triacylglycerols and steryl esters were separated on TLC and the levels of glycerol and sterol were analysed enzymatically. The average amount of triacylglycerols and steryl esters was approximately 25 and 0.83 mg/g dry weight, respectively. However, variation between the stems studied was fairly large. The sapwood of young and small-diameter stems was not found to store larger amounts of either triacylglycerols or steryl esters than the sapwood of old stems. Neither was there any relationship between the amount of triacylglycerols and steryl esters in the outer sapwood. The possible role of these compounds in heartwood formation is discussed.     

Plastids and glycolipids in the stemwood of Pinus sylvestris L.

Summary The ultrastructure of plastids in xylem ray parenchyma cells of Pinus sylvestris L. was studied and compared with the glycolipid composition of the stemwood. Seasonal changes of the ultrastructure were studied by taking samples regularly throughout the year. The plastids resemble amyloplasts. They usually have one large starch grain, and considerable variation in structure and starch content was observed, especially in the innermost sapwood and in the sapwood-heartwood transition zone. Electron-dense deposits were observed attached to the plastid membranes and envelopes, especially in the transition zone, from April to November. The plastids were aggregated near the nucleus and the starch disappeared during the winter (January–March). The glycolipids, monogalactosyldiacylglycerol (MGDG) and di-galactosyldiacylglycerol (DGDG), were present only in the sapwood, in trace amounts. The glycolipid content was slightly greater in the outer sapwood than in the sapwood-heartwood transition zone. DGDG was the dominant lipid of the two.     

The Circulation of Minerals in Plantations of Pinus sylvestris L.

The dry weights and amounts of sodium, potassium, calcium, magnesium,phosphorus, and nitrogen in the ground flora and organic layersformed over the mineral soil are recorded for an age seriesof plantations of Pinus sylvestris. From these data, the distributionof mineral nutrients within the plantations is deter-mined andcalculations are made of the annual circulation of nutrientsthrough the ecosystem. After 55 years of afforestation the amountof organic matter accumulated over the forest floor is onlyequivalent to the litter fall of the last 6 years. Thus, althoughafforestation results in a progressive accumulation of organicmatter, the woodland community is characterized by a large andrapid transfer of nutrients between the plants and mineral soil.     

Genetic variation of F1 hybrids from controlled crosses between Pinus montana var. rostrata and Pinus sylvestris in morphological needle traits

One hundred and seventeen hybrids, representing ten families from controlled crosses between Pinus montana var. rostrata and Pinus sylvestris, were examined in respect to six morphological traits of two-year-old needles. The biometric data obtained from the measurements provided a basis for multivariate statistical analyses, including discriminant analysis and Mahalanobis distances as principal methods. The analysed families formed two complexes, which were significantly different. The main traits responsible for the distinction were numbers of stomatal rows on both sides of the needles.     

Inheritance of autumn frost hardiness in Pinus sylvestris L. seedlings

Summary Inheritance of frost hardiness was analysed making use of a 12×12 incomplete factorial mating design. Owing to space limitations only 59 families could be tested in four experiments. To link the four experiments, some families were common to two or more experiments. The seedlings were grown in climate chambers under conditions inducing autumn hardening. The plants were exposed to a freezing temperature of –10 °C for three hours at night lengths of 11–13 h. A statistical model was developed for analyses of variance of our data. The genetic variation and the variation due to the cultivation regimes during autumn hardening were of the same magnitude. The additive effects were the most important ones for induction of frost damage. No interaction following long-distance crossing was noted. Mixed model equations were used for ranking of the parents. The results obtained support a polygenic inheritance of frost hardiness. The large within-population variation offers good opportunities for hardiness breeding.     

Effects of soil cadmium on Pinus sylvestris L. seedlings

The effects of Cd on the growth and distribution of Cd and mineral nutrients within plant tissues were investigated for Pinus sylvestris L. seedlings grown in mineral forest soil with increasing levels of Cd addition (0–100 mg kg^–1). Approximately 20% of added Cd was found to be extractable from sandy loam forest soil. Root growth was less affected by Cd than shoot growth, which showed a significant reduction in the 100 mg Cd kg^–1 treatment. Cadmium accumulated in roots up to 325 mg kg^–1. Decreased concentrations of K in needles and Ca in stems with increasing Cd levels suggest a disturbance of mineral nutrition as a result of Cd addition.     

Soluble carbohydrates of Pinus sylvestris L. sapwood and heartwood

Summary The amounts of glucose, fructose, sucrose, arabinose/galactose, raffinose/stachyose and starch were investigated in the outer sapwood, innermost sapwood, transition zone and heartwood of four stems of Pinus sylvestris L. The samples were taken in October and the determination of the compounds was done enzymatically. It was not possible to distinguish arabinose from galactose and raffinose from stachyose. The amounts of glucose, fructose and sucrose were greatest in the outer sapwood and decreased gradually towards the innermost sapwood and the heartwood. In the outermost heartwood glucose, fructose and sucrose were only present in trace amounts. Raffinose/stachyose showed highest concentrations in the outer sapwood and decreased towards the heartwood. In contrast, the concentrations of arabinose/galactose increased towards the heartwood and the greatest amount was found in the inner heartwood. When identified by thin-layer chromatography (TLC), arabinose was found to be present in greater amounts than galactose. The amount of starch decreased markedly towards heartwood. However, the amounts of sugars in all the studied stems was very variable. The changes in the amounts of carbohydrates in the different zones of the stems and the possible relationships of these phenomena with heartwood formation are discussed.     

Group coancestry-controlled selection in a Pinus sylvestris L. breeding program

 Integer Linear Programming was used to maximize genetic gain from selection at a given level of relatedness. Variances and breeding values for total height were available for 296 plus-trees of Pinus sylvestris which had been evaluated by open-pollinated progeny testing at a single test site in northern Sweden. Second-generation breeding and selection scenarios for this breeding population were evaluated using simulated data derived deterministically from normal distributions of estimated breeding values of progeny around mid-parent family means. The study considered two mating designs, assortative and non-assortative single-pair mating, and two selection criteria, individual phenotype and performance of half-sib progeny. Relatedness (group coancestry) was restricted to a level equivalent to that given by within-family selection of 2 trees per family from each of 25 families (the current standard in Sweden). Selection that allows the best-performing families to contribute a greater number of progeny was superior, both when the breeding population size was limited to 50 individuals and when it was allowed to be larger. The selected set giving the greatest average breeding value under restricted group coancestry included the best individual from families that would have been rejected under application of standard within-family selection. We made a comparison of the present value on retrieved gain between phenotypic selection and evaluation by progeny testing. Received: 24 November 1998 / Accepted: 14 December 1998     

The Limits to Xylem Embolism Recovery in Pinus sylvestris L.

In this study we test the hypothesis that, when water supplyis under tension, reversal of cavitation can occur as long aswater continuity is maintained in the vicinity of tracheids.The experiments were conducted on young branches, 7–8mm diameter, of Pinus sylvestris L., freshly collected and allowedto lose water on the bench after being debarked. During dehydration,the volumetric fractions of water (V_w) and gas (V_s) changedsteadily as relative water content () declined. Meanwhile, ultrasonicemissions (UAE) started after a threshold = 90% was reachedand were maximal at = 75%. Before and after dehydration, branchsegments were connected to water-filled tubing and placed from0.2 to 3.6 m above a water source and water inflow and outflowwere recorded. These distances provided a source of water ata potential of –2.0 to –36kPa. We considered thatthe segment water potential would be a function of the surfacetension across the water meniscii at the ends of the embolizedtracheids. Thus, water potentials calculated from tracheid dimensionswould be as low as –43 kPa. Water inflow to segments declinedwhen the distance from the source was increased or the segmentswere very dehydrated. Increasing the distance above the watersource would be expected to increase the water potential differencebut to reduce water uptake. The most dehydrated segments absorbedwater faster at the beginning of the refilling period (2h),but at the end of 16h, was lower and V_g larger than in lessembolized tissue. Recovery of water flow followed a similartrend, and was lowest when embolisms increased. For a narrowrange of , hydraulic conductance was reduced sharply, indicatingthat wide tracheids were still gas-filled. Thus, the numberof tracheids remaining embolized increased when the source waterpotential was low and there was severe embolism. We concludethat embolism can be reversed in P. sylvestris at a rate dependingon the water potential of the source, severity of embolism andhydraulic conductivity. Key words: Pinus sylvestris L., cavitation induction-recovery, embolized tracheids, water content and embolism, matrix potential, capillary, hydraulic conductance