Basal sweep and compression wood in young Scots pine trees

This study demonstrates the correlation between stem form and compression wood content in 36 sampled trees from a 6-yr-old container grown Scots pine ( Pinus sylvestris L.) plantation in central Sweden. Root analyses were carried out to examine causes for the high incidences of basal sweep. On the sampled trees basal sweep, stem sweep and maximum bow-height were measured. Discs were cut at different heights and the compression wood content was analysed using digital image analysis. Pith eccentricity and out-of-roundness were calculated for each disc as well as per stem. Compression wood and pith eccentricity was most pronounced near the stem base, where sweep tends to be high. In general, pith eccentricity increased with degree of basal sweep. As a conclusion, expression of basal sweep can be used to predict compression wood content in young Scots pine trees. This study also shows the importance of anchoring of a tree to prevent basal sweep formation due to instability.     

Effects of SO2 on photosynthesis and peroxidase activity in Scots pine needles

Short-term exposure to high concentrations of SO₂ caused a temporary decrease in the photosynthetic rate, while both short-term and long-term exposure to low concentrations of SO₂ increased photo-synthesis after the exposure. Low SO₂ concentrations did not cause any change in peroxidase activity. Thus peroxidase activity does not seem a suitable method in monitoring latent injury caused by low SO₂ concentrations.     

Annual pattern of photosynthesis in Scots pine in the boreal zone

To detect seasonal changes in photosynthetic rate in the field, a set of 18,000 photosynthetic measurements made between April and October on three shoots of Scots pine growing near the northern timberline was studied. The measurements were analyzed in the framework of an optimal stomatal control model of photosynthesis, in which irradiance (photosynthetically active radiation, I), air humidity and ambient temperature are driving variables. All driving variables were monitored concomitantly with gas exchange measurements throughout the growing season. The model has nine parameters, of which six were assumed to be constant over the growing season and were fixed based on previous information. The three variable parameters were the initial slope (alpha) and saturation value (gamma) of the light-response curve of carboxylation efficiency in the intercellular cavity, and the cost of transpiration (lambda), in carbon units, regulating the degree of stomatal opening. These parameters could not be estimated independently, nor could their values be satisfactorily found by standard nonlinear regression techniques. A Monte Carlo based simulation procedure was devised to analyze the best-fit parameters and their mutual correlations near the minimum of the residual sum of squares. This was accomplished by replacing the saturation value of the light-response curve with a linearity parameter that determined the shape of the curve. In the best fit solutions, only alpha and lambda varied from day to day, whereas the shape of the curve was constant (i.e., gamma was proportional to alpha). Both alpha and lambda showed consistent patterns from spring to autumn, but the seasonal variation was considerably greater for alpha than for lambda. The optimal stomatal control model with the seven fixed and two daily parameter values gave a good overall fit for photosynthetic rate over the season (PEV > 95%).     

Predicting lumber grade and by-product yields for Scots pine trees

The purpose of this study was to develop models for estimating yields of lumber grades and by-products of individual Scots pine (Pinus sylvestris L.) trees using stem and crown dimensions as explanatory variables. Two separate data sets were used: (1) one simulated by the process-based growth model, PipeQual, which provides information about stem form and branch properties. The model was used to predict the 3D structure of Scots pine stems from thinning regimes of varying intensity and rotation periods and (2) an empirical data set with detailed 3D measurements of stem structure. The stems were sawn using the WoodCim sawing simulator and the yields and grades of the individual sawn pieces, as well as by-products, were recorded. The sawn timber was classified on A, B, C and D-grades for side and centre boards separately (Nordic Timber grading). By-products were pulpwood, sawmill chips, sawdust and bark.     

Effects of timing of soil frost thawing on Scots pine

Effects of the timing of soil thawing in the spring on Scots pine (Pinus sylvestris L.) were studied under controlled laboratory conditions. Sixteen 6-year-old saplings were lifted from the field, replanted in containers and placed in four treatments in controlled environment (CE) chambers with four replicate saplings per chamber. The saplings were held in the CE chambers during one simulated winter and one simulated growing season. The soil was frozen to -2 degrees C during a second simulated winter in the CE chambers, and the soil thawing treatments began at the end of the second simulated winter. Soil thawing began at various times before (no delay in thawing) and after (delay in thawing) chamber air conditions were changed from simulated winter to simulated summer. Delayed soil thawing subjected saplings to stress, with the severity of stress depending on the length of the delay in thawing. If there was no delay or only a short delay in soil thawing, stress was minor and reversible. A 2-week delay in soil thawing led to death of the saplings. Stress was apparent as decreases in the variable to maximal chlorophyll fluorescence ratio (Fv/Fm), chlorophyll a/b ratio and needle water potential. In needles of stressed saplings, apoplastic electrical resistance first decreased and then increased and there were anomalies in the electrical impedance spectra of the stems. Stress from the soil thawing treatments affected both root and shoot growth.     

Fatty acids of ozone-exposed Scots pine and poplar trees and of damaged field-grown Norway spruce trees

In foliage of Pinus sylvestris, Populus euramericana, and Picea abies the fatty acid composition was analyzed. Whereas clonal material of pine and poplar in controlled ozone fumigations did not show any significant differences as compared to controls, such differences were obtained in fieldgrown spruces showing needle loss.     

Transpiration of Scots pine in Flanders growing on soil with irregular substratum

An investigation was carried out to compare the water balance of Scots pine in Flanders growing on soils with contrasted water availability. Based on sap flow measurements transpiration of Scots pine was determined for two small plots on cover sands resting on a clayey substratum of varying depths (shallow and deep). Soil water content (SWC) was relatively low (0.12–0.21 m³ m⁻³) in the upper topsoil (0–0.75 m) in both plots. However, it was always higher in the shallow plot (by 3–27%) than in the deep plot. The difference between SWC in both plots was more pronounced in the deeper soil layers (0.75–1.5 m). Sap flow was measured in seven sample pine trees on each plot from May to October 2000 using the heat field deformation (HFD) method. Transpiration of the individual trees in the deep plot was 22% lower than in trees in the shallow plot. The difference decreased to 15% after scaling up to the stand level due to a higher density of trees growing in the deep plot. It was hypothesized that higher water uptake in the shallow plot was possibly caused by structural differences between the root systems of trees growing in plots with variable soil texture. The sapwood in shallow-plot trees was 1 cm less deep than in trees growing in the deep plot (as measured by biometric and sap flow pattern methods). Sap flow radial patterns suggested a higher involvement of sinker roots for water uptake in the deep clayey substratum plot. This was in agreement with higher activity of the inner xylem in trees on the deep plot under higher evaporative demands. However, the fraction of the inner xylem to the whole-tree water supply was nearly three-fold lower than the outer xylem, which appeared to provide water presumably from the superficial roots. The fraction of these roots, estimated according to sap flow radial patterns, was around 10% higher in trees on the shallow plot. This caused 30% higher sap flow in the stem outer xylem there. Transpiration of the pine stands was limited under high evaporative demands in both plots by the low availability of soil water. The limitation was greater in the deep plot and persisted throughout the whole growing season.     

Level of sugars in Scots pine trees of different sensitivity to fluoride and sulphur dioxide

On the average there is in the needles of the studied pines 1.9 and 4.9% of reducing sugars in the fresh and dry weight of wintertime needles respectively. There is 1.4% glucose of needle fresh weight (3.0% of needle dry weight) while for fructose the corresponding values are 0.8 and 2.1%. The relative ratio of glucose to fructose was on the average 1.33. Trees more tolerant to fluorides and sulphur dioxide emitted from the phosphate fertilizers factory have a statistically significant lower level of directly reducing sugars in the dry weight of needles (37.1 mg/g) compared to sensitive trees (50.5 mg/g). The control (more tolerant trees) accumulate more glucose and fructose than sensitive ones.     

Coherent response of a group of plantation-grown Scots pine trees to wind loading

Wind-induced motion of 29 neighbouring trees growing in a Scots pine plantation was measured over the period 14 March to 24 March 2008. The bi-orthogonal decomposition (BOD) of the complex tree motion field into a limited number of spatio-temporal modes provided the basis for the analysis of the response behaviour to wind excitation of the group of sample trees. It is shown that the first BOD-mode was the most energetic and differed from all other BOD-modes. The BOD-results as well as the results from wavelet analysis of the temporal eigenvectors of the BOD-modes demonstrate that two concomitant low-frequency components in the streamwise wind velocity component stimulated coherent response of the sample trees at the tree group level. However, in the range of the wind speed measured close to the top of the Scots pine forest canopy (hourly mean wind speed values lower than 6 m s⁻¹), the wind loads associated with these low-frequency airflow structures were too low to harmonise the motion of the sample trees completely. It is shown that instantaneous single tree responses to wind excitation were highly irregular in magnitude and direction. Results from Fourier and wavelet analysis demonstrate that sway in the first mode dominated the wind-induced sway behaviour at the tree level.     

Spatial optimization for dispersion of remnant trees in seed-tree cuttings and retention-tree stands of Scots pine

Abstract

In this study, optimal spatial patterns for seed-tree cuttings and green-tree retention in Scots pine stands were investigated. The optimization approach is based on functions that describe the effects of single, retained trees on Scots pine regeneration. Two spatial optimization techniques were applied to this intrastand-level problem. The model approach assumes smooth, non-convex optimization problems with a convex set of feasible solutions. These problems were solved with a deterministic optimization algorithm with 500 initial tree position sets, also taking into account different forest management objectives such as high, homogeneous seed and seedling density. This required the use of multicriteria optimization procedures. The best spatial patterns identified differed significantly according to the objective functions considered. This was demonstrated by aggregation index values of stem maps and from visualization. Thus, the objective functions must be defined carefully to obtain best solutions for the management aims. A small degree of clumping in seed-tree cuttings did not appear detrimental to seedling density objectives. Therefore, short-term retention trees should be selected primarily by phenotype, not solely by a specific distribution scheme.     

Delayed soil thawing affects root and shoot functioning and growth in Scots pine

In boreal regions, soil can remain frozen after the start of the growing season. We compared relationships between root characteristics and water relations in Scots pine (Pinus sylvestris L.) saplings subjected to soil frost treatments before and during the first week of the growing period in a controlled environment experiment. Delayed soil thawing delayed the onset of sap flow or totally blocked it if soil thawing lagged the start of the growing period by 7 days. This effect was reflected in the electrical impedance of needles and trunks and in the relative electrolyte leakage of needles. Prolonged soil frost reduced or completely inhibited root growth. In unfrozen soil, limited trunk sap flow was observed despite unfavorable aboveground growing conditions (low temperature, low irradiance, short photoperiod). Following the earliest soil thaw, sap flow varied during the growing season, depending on light and temperature conditions, phenological stage of the plant and the amount of live needles in the canopy. The results suggest that delayed soil thawing can reduce tree growth, and if prolonged, it can be lethal.     

Plant size, not age, regulates growth and gas exchange in grafted Scots pine trees

We studied the effect of scion donor-tree age on the physiology and growth of 6- to 7-year-old grafted Scots pine (Pinus sylvestris L.) trees (4 and 5 years after grafting). Physiological measurements included photosynthethetic rate, stomatal conductance, transpiration, whole plant hydraulic conductance, needle nitrogen concentration and carbon isotope composition. Growth measurements included total and component biomasses, relative growth rates and growth efficiency. Scion donor trees ranged in age from 36 to 269 years at the time of grafting. Hydraulic conductance was measured gravimetrically, applying the Ohm's law analogy, and directly, with a high-pressure flow meter. We found no effect of scion donor-tree age on any of the variables measured. There was, however, great variation within scion donor-tree age groups, which was related to the size of the grafted trees. Differences in size may have been caused by variable initial grafting success, but there was no indication that grafting success and age were related. At the stem level, hydraulic conductance scaled with total leaf area so that total conductance per unit leaf area did not vary with crown size. However, leaf specific hydraulic conductance (gravimetric), transpiration, photosynthesis and stomatal conductance declined with increasing total tree leaf area and needle width. We hypothesize that needle width is inversely related to mesophyll conductance. We conclude that canopy and needle size and not scion donor-tree age determined gas exchange in our grafted trees.     

Seasonal changes in amino acids, protein and total nitrogen in needles of fertilized Scots pine trees

Seasonal changes in amino acids, protein and total nitrogen in needles of 30-year-old, fertilized Scots pine (Pinus sylvestris L.) trees growing in Northern Sweden were investigated over two years in field experiments. The studied plots had been fertilized annually for 17 years with (i) a high level of N, (ii) a medium level of N, or (iii) a medium level of N, P and K. Trees growing on unfertilized plots served as controls. In control trees, glutamine, glutamic acid, gamma-aminobutyric acid, aspartic acid and proline represented 50-70% of the total free amino acids determined. Arginine was present only in low concentrations in control trees throughout the year, but it was usually the most abundant amino acid in fertilized trees. Glutamine concentrations were high during the spring and summer in both years of study, whereas proline concentrations were high in the spring but otherwise low throughout the year. In the first year of study, glutamic acid concentrations were high during the spring and summer, whereas gamma-aminobutyric acid was present in high concentrations during the winter months. This pattern was less pronounced in the second year of investigation. The concentrations of most amino acids, except glutamic acid, increased in response to fertilization. Nitrogen fertilization increased the foliar concentration of arginine from < 1 micromol g(dw) (-1) in control trees to a maximum of 110 micromol g(dw) (-1). Trees fertilized with nitrogen, phosphorus and potassium had significantly lower arginine concentrations than trees fertilized with the same amount of nitrogen only. Protein concentrations were similar in all fertilized trees but higher than those in control trees. For all treatments, protein concentrations were high in winter and at a minimum in early spring. In summer, the protein concentration remained almost constant except for a temporary decrease which coincided with the expansion of new shoots. Apart from arginine, the amino acid composition of proteins was similar in all treatments.     

Effect of heavy metal pollution of forest soil on radial growth of Scots pine

A field experiment with artificial soil contamination by the heavy metals copper and nickel was established in Kola Peninsula, northern Russia. To study the effect of soil contamination by heavy metals without SO₂ air pollution on the Scots pine trees growth the experiment was located outside the range of forest damage due to emissions from a copper–nickel smelter. Retardation in tree diameter growth over 15 years after contamination with 20 kg of metallurgical dust per 100 m² plot was 54%, 10 kg 27%, 5 kg 16% and 2.5 kg 7%, respectively, compared with growth in control plots. Thus, decreasing Scots pine growth due to heavy metal pollution was demonstrated.     

The effects of soil and air temperature on CO2 exchange and net biomass accumulation in Norway spruce, Scots pine and silver birch seedlings

Soil temperature is proposed to affect the photosynthetic rate and carbon allocation in boreal trees through sink limitation. The aim of this study was to investigate the effect of temperature on CO(2) exchange, biomass partitioning and ectomycorrhizal (ECM) fungi of boreal tree species. We measured carbon allocation, above- and below-ground CO(2) exchange and the species composition of associated ECM fungi in the rhizosphere of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies K.) and silver birch (Betula pendula Roth) seedlings grown in soil maintained at 7-12, 12-15 and 16-22 °C. We found increased root biomass and photosynthetic rate at higher soil temperatures, but simultaneously with photosynthesis rate, higher temperature generally increased soil respiration as well as shoot, and root and rhizosphere respiration. The net CO(2) exchange and seedling biomass did not increase significantly with increasing temperature due to a concomitant increase in carbon assimilation and respiration rates. The 2-month-long growth period in different soil temperatures did not alter the ECM fungi species composition and the below-ground carbon sink strength did not seem to be directly related to ECM biomass and species composition in any of the tree species. Ectomycorrhizal species composition and number of mycorrhiza did not explain the CO(2) exchange results at different temperatures.     

Dielectric spectroscopy of Scots pine

Dielectric properties of Scots pine (42 trees) were compared with density, moisture content (MC), and resin acid content (RAC) (of heartwood). The samples were measured in frozen, green, conditioned and non-conditioned dry moisture states to evaluate the potential of dielectric spectroscopy in determining the wood characteristics at different stages of wood processing. Heartwood and sapwood parts of each sample were measured separately, and through-transmission measurement was conducted in longitudinal and tangential direction at frequencies from 1 MHz to 1 GHz. The MC and density correlated significantly with the dielectric parameters in both measurement directions but especially in longitudinal direction. The RAC of the heartwood correlated significantly with tanδ and ε″/(ε′ ? 1) of the green samples measured in the tangential direction at frequencies above 200 MHz. The correlation at 1 GHz was ?0.56 for green samples, ?0.66 for conditioned samples and ?0.61 for non-conditioned samples (P < 0.001, for all). The study suggests that the extractives also affect radio-frequency dielectric responses, which might be used for extractive analyses of pine heartwood.     

Effects of needle age, long-term temperature and CO(2) treatments on the photosynthesis of Scots pine

Naturally regenerated 20-25-year-old Scots pine (Pinus sylvestris L.) trees were grown in open-top chambers in the presence of an elevated temperature or CO(2) concentration, or both. The elevated temperature treatment was administered year-round for 3 years. The CO(2) treatment was applied between April 15 and September 15 for 2 years. The photosynthetic responses of 1- and 2-year-old needles to varying photon flux densities (0-1500 micro mol m(-2) s(-1)) and CO(2) concentrations (350, 700 and 1400 micro mol mol(-1)) during measurement were determined. The CO(2) treatment alone increased maximum photosynthetic rate and light-use efficiency, but decreased dark respiration rate, light compensation and light saturation regardless of needle age. In contrast, the temperature treatment decreased maximum photosynthetic rate and photosynthetic efficiency, but increased dark respiration rate, light compensation and light saturation. The aging of needles affected the photosynthetic performance of the shoots; values of all parameters except photosynthetic efficiency were less in 2- than in 1-year-old needles. The CO(2) treatment decreased and the temperature treatment enhanced the reduction in maximum photosynthesis due to needle aging.     

Fine root biomass of Scots pine stands differing in age and soil fertility in southern Finland

The biomass of small and large fine roots (相似文献