Leaf distribution in large trees and stands of the floodplain forest in southern Moravia     

Cermák J 《Tree physiology》1998,18(11):727-737

Vertical distributions of leaf dry mass (M(d)) and leaf area (A(f)) were related to relative irradiance (I(r); I(r) above the stand = 1) in closed-canopy, old-growth stands of the floodplain forest in southern Moravia composed largely of Quercus, Fraxinus and Tilia species. Foliage area and mass at any given canopy height were converted to solar equivalent leaf area (A(s)) and mass (M(s)) by multiplying actual values at a given level in the canopy by the relative irradiance at that position. Stand leaf area index (LAI) was 5 (7 including shrub and herb layer), and solar equivalent parameters reached about 25% of that amount. In all species, vertical profiles of both relative irradiance and leaf dry mass to area ratio (LMA) were sigmoidal and the two variables were linearly related. The dominant, upper canopy species had a larger proportion of solar equivalent foliage than suppressed understory species. For individual trees of all species, the upper canopy had a larger proportion of solar equivalent foliage than the lower canopy. Light compensation points at both the leaf and whole-tree level were defined according to leaf or tree position, size and structure. I conclude that optimization of A(s) for forest stands may be used as a basis for determining thinning schedules and evaluating tree survival after damage to tree crowns by various factors.  相似文献   

Stilbenes and resin acids in relation to the penetration of Heterobasidion annosum through the bark of Picea abies     

M. Lindberg  L. Lundgren  R. Gref  M. Johansson 《Forest Pathology》1992,22(2):95-106

Concentrations of the stilbene glucosides astringin and isorhapontin, which ranged from 5 to 50 mg/g fresh weight in Picea abies bark, decreased in response to in vivo infection with the root-rot fungus Heterobasidion annosum. The initial concentration of the stilbene astringin was negatively correlated with the depth of hyphal penetration. Resin acid contents increased following infec-tion, but were not correlated with the depth of hyphal penetration. The spatial distribution of stilbene glucosides in spruce stem, root collar and root bark, and the seasonal variations in con-centration, were estimated.  相似文献   

Chitin and glucans detected in the cell walls of Pythium dimorphum—an oomycetous fungus     

F. O. Asiegbu  A. Lnneborg  M. Johansson 《Forest Pathology》1996,26(6):315-321

With aid of fluorescein isothiocyanate (FITC) and gold-labelled lectins, together with antibodies against chitinase and β-1,3-glucanases, the spatial distribution of chitin and glucans in hyphal walls of Pythium dimorphum, a causative agent of root die-back disease of conifer seedlings was studied. Contrary to previous reports, this study revealed that chitin, a polymer of N-acetyl-d -glucosamine, is a component of the cell wall of this oomycetous fungus. However, compared with the other amino sugar, N-acetyl-galactosamine, it is not present in significant amounts. Ultrastructural and labelling studies demonstrated that the chitin region is embedded in or masked by glucan residues.  相似文献   

Irradiance in thinned Norway spruce (Picea abies) stands and the possibilities to prevent suckers of broadleaved trees     

Tord Johansson 《Forest Ecology and Management》1987,20(3-4):307-319

Both incoming shortwave radiation (R_g) and photosynthetically active radiation (PAR) in percentage of full daylight were measured at the same time by point and strip sampling in four plots (0.1 ha) of Picea abies (L.) Karst. The standard deviations (%) of R_g and PAR were, respectively, 11.1 and 9.8 at 64 points, 15.7 and 13.9 at 32 points, and 24.7 and 23.8 at 16 points per plot.

A period of at least 40 s per strip (30 m min⁻¹) gives a CV (coefficient of variation) of 30%. There is no significant difference between relative irradiance (RI) estimated by the point method (64 points) and by the strip method (8 strips). Curves of RI (R_g and PAR) and basal area (m² ha⁻¹), diameter sum (m ha⁻¹) and density (stems ha⁻¹) of fifteen trials with different thinning programmes are presented. Irradiance (R_g) in heavily thinned stands was 3–14% of irradiance on an open place. The irradiance, R_g, in extra-heavily thinned stands is 12–27%, and in unthinned stands, 1–3% that of an open place. The R_g curve lies above the PAR curve in all cases. Some practical implications of the study are presented. Heavy thinning of Norway spruce stands gives RI (R_g) values 10% at basal area of 25m² ha⁻¹ which is necessary to minimize development of suckers of broadleaved trees.  相似文献   

Stand biometry and leaf area distribution in an old olive grove at Andria, southern Italy     

Jan Čermák  Jan Gašpárek  Francesca De Lorenzi  Hamlyn G. Jones 《Annals of Forest Science》2007,64(5):491-501

The objectives of this paper were (1) to provide general biometry data for an 80-year-old olive (Olea europea L., cv. Coratina) grove in Andria, southern Italy, and (2) to compare different methods for estimating leaf area distributions. Stand biometry was represented by a stocking density of 132 trees ha^?1, mean spacing of 8.7 m and mean social area (proportional to spacing and tree size) of about 76 m² per tree. Trunk total circumference averaged 110 cm and after subtraction of missing or dead parts of stems averaged 81 cm, projected area of crowns averaged 17.7 m² and the mean tree height was 4.9 m. Leaf distribution was evaluated using calibrated ground-based side photographs through image analysis and through using a simple canopy-layer model (considering hollow volume within tree crowns) and double-Gaussian curves. The mean leaf size was about 5 cm² (distributed in a log-normal manner over the range of 2 to 12 cm²). Considering whole tree crowns, the mean leaf density was about 2.6 m²m^?3; the maximum leaf area occurred in canopy layers between 1.5 to 3 m, tailing with a steeper slope to the crown base and a less steep slope to the tree-top. The foliated volume of olive crowns (mean 33.2 m³) contained on average 145 thousand leaves of the total area of 72.6 m². The corresponding leaf area index on the stand level (LAI _grove = 0.96), was rather low due to low stocking density. However when taking into account only the projected crown areas (and avoiding free space between trees), the mean LAI reached about 3.5 (range from 1–7). The radial pattern of leaf distribution derived from image analysis indicated peak LAI _rad values at a distance from the stem of about 60 to 70% of crown radius in trees of different size. The applicability of different approaches to the estimation of the necessary allometric parameters is discussed.  相似文献   

Concept and feasibility study for the integrated evaluation of environmental monitoring data in forests     

Sabine Augustin  Jan Evers  Hans-Peter Dietrich  Johannes Eichhorn  Thomas Haussmann  Regina Icke  Ansgar Isenberg  Wolfgang Lux  Monica Musio  Hans Pretzsch  Winfried Riek  Thomas Rötzer  Bernd Schultze  Andreas Schulze  Jörg Schröder  Walter Seidling  Nicole Wellbrock  Klaus von Wilpert  Barbara Wolff 《European Journal of Forest Research》2005,124(4):251-260

In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis (crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative, as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.

Sabine AugustinEmail:

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Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber II: evaluation of models generated on a pixel level     

Nils Lundgren  Olle Hagman  Jan Johansson 《Journal of Wood Science》2006,52(1):39-43

The purpose of this study was to use images from a microwave sensor on a pixel level for simultaneous prediction of moisture content and density of wood. The microwave sensor functions as a line-scan camera with a pixel size of 8mm. Boards of Scots pine (Pinus sylvestris), 25 and 50mm thick, were scanned at three different moisture contents. Dry density and moisture content for each pixel were calculated from measurements with a computed tomography scanner. It was possible to create models for prediction of density on a pixel level. Models for prediction of moisture content had to be based on average values over homogeneous regions. Accuracy will be improved if it is possible to make a classification of knots, heartwood, sapwood, etc., and calibrate different models for different types of wood. The limitations of the sensor used are high noise in amplitude measurements and the restriction to one period for phase measurements.  相似文献   

Quality of timber products from Norway spruce     

M. Perstorper  P. J. Pellicane  I. R. Kliger  G. Johansson 《Wood Science and Technology》1995,29(5):339-352

Summary In a previous paper in this series it was concluded that the warp (twist, crook and bow) of structural timber products is of utmost importance for end-user satisfaction. In this paper, a study of the spatial variation of warp of fast-grown Norway spruce is presented. The material, 372 studs (45 × 70 × 2900 mm²), was cut from different radial and longitudinal positions in trees from two stands.The results indicated that twist and crook were at maximum near the pith. However, twist decreased much more rapidly with the distance from pith compared with crook. Crook associated with core studs was larger in the butt log than in the top log, while twist and bow in core studs appeared not to vary longitudinally. Heartwood formation in the butt log juvenile core did not diminish warp propensity. Twist was rather well correlated to the distance between pith and centroid of cross section. The ratio of grain angle to pith distance was the best parameter to predict twist. Presence of compression wood increased bow and crook significantly, while ring width, density and knot area ratio did not substantially contribute to explain warp variation.A moisture content change from 18% to 12% decreased the overall acceptability, expressed by stud grade yield, from 76% to 43%. Thus, timber products should be delivered at a moisture level close to the one expected in the finalized building in order to avoid excessive warp after delivery.The authors gratefully acknowledge the support from EEC Forest programme, Contract No MA2B-0024, from NUTEK project No 9100554 and from Södra Timber AB  相似文献   

Effects of elevated CO(2) concentration and nutrition on net photosynthesis,stomatal conductance and needle respiration of field-grown Norway spruce trees     

Roberntz P  Stockfors J 《Tree physiology》1998,18(4):233-241

To study the effects of elevated CO(2) on gas exchange, nonstructural carbohydrate and nutrient concentrations in current-year foliage of 30-year-old Norway spruce (Picea abies (L.) Karst.) trees, branches were enclosed in ventilated, transparent plastic bags and flushed with ambient air (mean 370 &mgr;mol CO(2) mol(-1); control) or ambient air + 340 &mgr;mol CO(2) mol(-1) (elevated CO(2)) during two growing seasons. One branch bag was installed on each of 24 selected trees from control and fertilized plots. To reduce the effect of variation among trees, results from each treated branch were compared with those from a control branch on the same whorl of the same tree. Elevated CO(2) increased rates of light-saturated photosynthesis on average by 55% when measured at the treatment CO(2) concentration. The increase was larger in shoots with high needle nitrogen concentrations than in shoots with low needle nitrogen concentrations. However, shoots grown in elevated CO(2) showed a decrease in photosynthetic capacity compared with shoots grown in ambient CO(2). When measured at the internal CO(2) concentration of 200 &mgr;mol CO(2) mol(-1), photosynthetic rates of branches in the elevated CO(2) treatments were reduced by 8 to 32%. The elevated CO(2) treatment caused a 9 to 20% reduction in carboxylation efficiency and an 18% increase in respiration rates. In response to elevated CO(2), starch, fructose and glucose concentrations in the needles increased on average 33%, whereas concentrations of potassium, nitrogen, phosphorus, magnesium and boron decreased. Needle nitrogen concentrations explained 50-60% of the variation in photosynthesis and CO(2) acclimation was greater at low nitrogen concentrations than at high nitrogen concentrations. We conclude that the enhanced photosynthetic rates found in shoots exposed to elevated CO(2) increased carbohydrate concentrations, which may have a negative feedback on the photosynthetic apparatus and stimulate cyanide-resistant respiration. We also infer that the decrease in nutrient concentrations of needles exposed to elevated CO(2) was the result of retranslocation of nutrients to other parts of the branch or tree.  相似文献   

Farmers' production of timber trees in the cacao-coffee region of coastal Ecuador     

Michael F. Mussak  Jan G. Laarman 《Agroforestry Systems》1989,9(2):155-170

The coastal region of Ecuador is an important producer of cacao and coffee. Increasingly, farms and ranches in the region also provide industrial wood for sawmills and other wood processing plants. Most of this wood derives from shade trees and pasture trees. Because little is known of wood supply from farm sources in coastal Ecuador, a survey was conducted of 122 farmers in the subregions of Ventanas, La Troncal, and Babahoyo. The survey indicates an abundance of land for the growing of farm trees, and excellent regeneration of many species on the majority of farms. However, current stocking of farm trees seems well below potential, and fewer than half of interviewed owners deliberately manage farm trees for eventual sale as timber. Only 2.2 percent of gross farm revenue derives from tree sales, even though over half of surveyed farmers have sold trees to industrial buyers at least once. Constraints on production and sales of farm trees for timber include risks of damage to coffee and cacao; perceived incompatibilities with current farming practices; inadequate methods of classification and pricing of farm trees; and insufficient knowledge of the industrial uses of farm trees by agricultural extensionists. These limitations need to be addressed through a strategy of research, development, and information diffusion on selected demonstration farms.

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Resúmen La región costera del Ecuador es una productora importante de cacao y café. Cada vez más, las fincas de la región proveen madera industrial para asseraderos y otros procesores madereros. La mayoría des esta madera viene de árboles de sombra. Dado que se sabe poco de la cantidad de madera provieniente de fincas en la costa del Ecuador se hizo una encuesta a 122 agricultores en las subregiones de Ventanas, La Troncal, y Babahoyo. La encuesta indica que existe una abundancia de terreno disponible para la producción de árboles de sombra y una regeneración excelente de muchas especies en la mayoría de las fincas. Sin embargo, densidades de los árboles de sombra parece bastante debajo de su nivel potencial, y menos de la mitad de los agricultores entrevistados cultivan sus árboles con el fin de venderlos eventualmente. De los entrevistados, un promedio de 2,2 porciento de ingresos brutos anuales provienen de ventas de árboles, a pesar de que más de la mitad de los agricultores han vendido árboles a compradores industriales por lo menos una vez. Limitaciones a la producción y a la venta de estos árboles incluyen el riesgo de daños a las plantas de cacao y cafe; la percibida incompatibilidad con las prácticas agrícolas usuales, métodes inadecuados de clasificar y poner precio a los árboles, y el poco conocimiento de los usos industriales de árboles de sombra por parte de los extensionistas agrícolas. Se necesita enfocar atención a estas limitaciones a través de una estrategia de investigación, desarrollo, y difusión de información en seleccionadas fincas demonstrativas.

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