Stand structure of an uneven-aged fir–beech forest with an irregular diameter structure: modeling the development of the Belevine forest, Croatia     

Juro Čavlović  Mario Božić  Andrej Boncina 《European Journal of Forest Research》2006,125(4):325-333

This study focuses on the problem of irregular diameter structure in a silver fir–beech selection (plenter) forest with a “surplus” of large diameter trees and a lack of natural regeneration and small diameter trees. We sampled 274 plots (900 m² each) in the Belevine research site (266.24 ha) in the mountain region Gorski Kotar (Croatia), where diameter (dbh) distribution, diameter increment, and natural regeneration were analyzed in detail. A low density of natural regeneration, weak annual recruitment of small (10 cm dbh) diameter trees (only five trees per hectare), delayed diameter growth of trees, and a low annual rate of trees reaching the next dbh class were attributed to the current irregular dbh structure. The stand development prediction for the next 50 years is based on a simulation model, which considers the current diameter structure, increment, recruitment, and future cutting regime. Intensive cutting in the first of five 10-year cutting cycles (intensity higher of 25%) is needed to initiate natural regeneration and to accelerate growth of young silver fir trees. In the next 50 years, the irregular diameter structure will be gradually improved.  相似文献   

Effect of dietary Schizochytrium microalga oil and fish oil on plasma cholesterol level in rats          下载免费PDF全文

T. Komprda  O. Škultéty  S. Křížková  G. Zorníková  V. Rozíková  R. Krobot 《Journal of animal physiology and animal nutrition》2015,99(2):308-316

The purpose of the study was to test the hypothesis that the dietary oils with different content of n‐3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) affect plasma lipid level in rats in a different degree. The diets with 6% of fish oil (FO) and Schizochytrium microalga oil (SchO; EPA+DHA content in the diets 9.5 + 12.3 and 2.6 + 29.5% of the sum of total fatty acids, respectively) were used; the diet with 6% of safflower oil (high content of n‐6 PUFA linoleic acid, 65.5%; EPA+DHA content 0.7 + 0.9%) was used as a control. The difference between FO and SchO was established only in the case of plasma triacylglycerol (TAG) level: plasma TAG of the FO‐fed rats did not differ from the control rats (p > 0.05), while SchO decreased (p < 0.05) plasma TAG to 46% of the control. On the other hand, FO and SchO decreased (p < 0.05) total plasma cholesterol (TC) in rats in the same extent, to 73% of the control. Regarding the underlying mechanisms for the TC decrease, both SchO and FO up‐regulated hepatic Insig‐1 gene (181 and 133% of the control; p < 0.05), which tended (p = 0.15 and p = 0.19 respectively) to decrease the amount of hepatic nSREBP‐2 protein (61 and 66% of the control). However, neither SchO nor FO influenced hepatic 3‐hydroxy‐3‐methyl‐glutaryl‐CoA reductase gene expression (p > 0.05); SchO (but not FO) increased (p < 0.05) low‐density lipoprotein receptor mRNA in the liver. It was concluded that the decrease of total plasma cholesterol might be caused by an increased cholesterol uptake from plasma into the cells (in the case of SchO), but also by other (in the present study not tested) mechanisms.  相似文献   

Forgotten role of fires in Central European forests: critical importance of early post-fire successional stages for bees and wasps (Hymenoptera: Aculeata)     

Petr Bogusch  Lukáš Blažej  Miloš Trýzna  Petr Heneberg 《European Journal of Forest Research》2015,134(1):153-166

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Can the structure of dormant cambium and the widths of phloem and xylem increments be used as indicators for tree vitality?     

Jožica Gričar  Špela Jagodic  Bogoslav Šefc  Jelena Trajković  Klemen Eler 《European Journal of Forest Research》2014,133(3):551-562

We investigated the structure and width of the dormant cambium and of the increments of phloem and xylem of Quercus robur to estimate their potential as indicators for tree vitality. The samples were taken from three woodlands, two in Slovenia [Krakovo forest (KRA) and Murska Suma (MUS)] and one in Croatia [Kobiljak (KOB)], with reported tree decline. The number of dormant cells seems to reflect the initial capacity of the cambium to accomplish cell division. With the exception of two trees at KRA, cell production was always higher on the xylem side than on the phloem side. The annual phloem increments were narrower, less variable among trees and with clear lower and upper limits. With increased cambial cell productivity, the share of the xylem in the total annual radial increment increased following a curvilinear function. In trees with an annual radial increment >3.5 mm, the xylem size represented more than 90 % of the total radial growth. The anatomical variables analyzed show that the most limiting environmental conditions seem to prevail at KRA, whereas the conditions at MUS seem to be most favorable in terms of radial growth. Analysis of the width and structure of xylem and phloem increments, the number of dormant cambial cells and their inter-relationships can provide additional information on the vitality of oaks.  相似文献   

Compensatory Growth Responses During Reproductive Phase of Cowpea after Relief of Water Stress   总被引：1，自引：0，他引：1  

V. Bala Subramanian  M. Maheswari 《Journal of Agronomy and Crop Science》1992,168(2):85-90

Unpredictable drought affects growth and yield of dryland cowpea ( Vigna unguiculata [L.] Walp.) during rainy season. With the objective of identifying compensatory growth responses after relief of water stress, pot-grown plants (cv. C-752) were water-stressed at flowering, and physiological responses, short term dry matter partitioning upon relief of water stress, and productivity at maturity were studied. Water stress decreased, to varying degrees, leaf water potential, stomatal conductance, photosynthesis rate and transpiration rate. Recovery in assimilation lagged behind that in water relations. Assimilate supply seemed to be limiting early pod growth upon relief of water stress due to low photosynthesis rate, reduced leaf area per pod, and increased partitioning to leaf expansion. However, later pod growth was not limited by assimilate supply and final dry matter per pod was similar in both non-stressed and stress-affected plant. Cowpea exhibited the following growth responses during pod-fill stage upon relief of water stress: 1. increase in leaf area, 2. shift in dry matter partitioning in favour of leaf expansion, 3. extended green leaf duration, and 4. increase in pod number. These partially compensating physiological responses probably ensure reasonable productivity of dryland cowpea during rainy season.  相似文献   

Collection of plant-genetic resources in the Georgian SSR 1986     

Rusudan K. Beridze  Peter Hanelt  Džulietta Mandžgaladze  Klaus Pistrick 《Genetic Resources and Crop Evolution》1987,35(2):335-353

Summary After having finished in 1985 the collection of plant-genetic resources in Western Georgia (the results have been summarized in some tables) joint activities for the collection of indigenous taxa of cultivated plants began for Eastern regions of the Georgian SSR in 1986. The mission took place within the rayon Dueti, which is highly differentiated in geographical respect and stretches beyond the main ridge of the Great Caucasus. Althogether 265 samples could be collected, grain legumes and vegetables represent the most numerous groups but the amount of cereal accessions is not much less; this contrasts sharply with the results from the missions in Western Georgia. The gene-erosion is very advanced in Dueti too, especially for cereals.Triticum carthlicum, T. dicoccon and naked barleys have disappeared within the last decades from the fields. However in isolated settlements the cultivation of old local races ofT. aestivum as well as of barley and rye had been maintained up till now. For breeding purposes and botanically interesting material could be collected also from vegetables, spice plants and grain legumes. Some examples have been shortly characterized.

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Sammlung pflanzen-genetischer Ressourcen in der Georgischen SSR 1986

Zusammenfassung Nachdem 1985 die Sammlungen pflanzen-genetischer Ressourcen in Westgeorgien abgeschlossen wurden (in einigen Tabellen werden die Sammelergebnisse kurz zusammengefaßt), wurde 1986 die gemeinsame Sammeltätigkeit zur Erfassung indigener Kulturpflanzen-Sippen in östlichen Gebieten der Georgischen SSR aufgenommen. Die Reise führte in den Rayon Dueti, der geographisch sehr differenziert ist und bis jenseits des Kaukasus-Hauptkammes reicht. Es konnten insgesamt 265 Proben gesammelt werden, unter denen Körnerleguminosen und Gemüse den Hauptanteil einnehmen, denen aber die Getreide (im Gegensatz zu den Sammelergebnissen in Westgeorgien) nur wenig nachstehen. Die Generosion ist auch hier vor allem bei den Getreiden sehr weit fortgeschritten;Triticum carthlicum, T. dicoccon sowie Nacktgersten sind in den letzten Jahrzehnten aus dem Anbau verschwunden. Jedoch hat sich in entlegenen Siedlungen noch die Kultur alter Lokalsorten vonTr. aestivum sowie von Gerste und Roggen erhalten. Auch von Gemüsen, Gewürzpflanzen und Körnerleguminosen konnte botanisch und züchterisch interessantes Material gesammelt werden. Einige Beispiele davon werden kurz charakterisiert.

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- 1986

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Absence of geographical structure of morphological variation in <Emphasis Type="Italic">Juniperus oxycedrus</Emphasis> L. subsp. <Emphasis Type="Italic">oxycedrus</Emphasis> in the Balkan Peninsula     

Robert Brus  Dalibor Ballian  Peter Zhelev  Marija Pandža  Martin Bobinac  Jane Acevski  Yannis Raftoyannis  Kristjan Jarni 《European Journal of Forest Research》2011,130(4):657-670

We examined leaf and mature seed cone variation of Juniperus oxycedrus L. subsp. oxycedrus in 12 natural populations across the species range in the Balkan Peninsula. We measured 10 morphological traits from a minimum of 100 leaves in each of 190 individuals, and two morphological traits from 30–50 seed cones in each of 94 females. High phenotypic variation was found, but no geographical structure or cline across populations was detected for any of the studied traits. Mean values of comparable leaf and cone morphological traits did not differ considerably from values reported elsewhere. Gender dimorphism in leaf morphology was detected, but it was not distributed uniformly throughout the studied area. An ANOVA model with both nested and crossed effects revealed that the largest proportion of the total variation was, as expected, contained within populations, partly as among-tree variation (18–47%, depending on the trait) and partly as within-tree variation (33–77%), which was remarkably high. Gender dimorphism explained only 0–3% of the total variation. Differences among populations (2–23%) were significant for all studied traits except one; however, PCA showed no clear geographical differentiation of the studied populations. This lack of phylogeographical structure may be the consequence of repeatedly occurring colonisation-retreat scenarios and suggests the existence of several small refugial populations scattered over a large part of the Balkan Peninsula in the Pleistocene. Further research including palaeobotanical and molecular genetic studies will be needed to better understand the forces that shaped current variation patterns of J. oxycedrus L. subsp. oxycedrus in the Balkan Peninsula.  相似文献   

Identifying the Growth Limiting Physiochemical Parameter for Chives Grown in Biologically Treated Graywater     

Bala Vairavan  W. Andrew Jackson  Cary Green  Audra Morse 《Water, air, and soil pollution》2007,184(1-4):5-15

Plants can play an important role in wastewater treatment and water reuse in terrestrial and space systems. Chive growth in biologically treated graywater, simulating the anticipated early planetary base graywater, was evaluated in this study for NASA. Phytotoxicity due to physiochemical parameters such as ammonium-nitrogen (NH₄ ⁺-N), nitrite-nitrogen (NO₂ ^?-N), pH, and sodium (Na⁺) was assessed using a series of hydroponic experiments in an environmentally controlled growth chamber. Nitrification in wastewater was observed in all graywater treatments, which converted NO₂ ^?-N (a toxic form of nitrogen) and NH₄ ⁺-N (toxic at high concentrations) to nitrate-nitrogen (NO₃ ^?-N) (preferred N form for plant uptake). Irrespective of the increase in the NO₃ ^–-N concentration due to nitrification, chives in the wastewater treatments typically had poor or no growth. The high levels of Na⁺ present in the graywater treatments affected potassium uptake and may have affected other nutrient uptake. The impact of nitrification on wastewater pH and NO₂ ^?-N toxicity is believed to be the critical factor affecting chive growth and may hinder the use high nitrogen waste streams for plant growth unless NO₂ ^?-N concentrations are controlled during biological treatment of graywater.  相似文献   

Spatial and vertical distribution of <Superscript>137</Superscript>Cs in soils in the erosive area of southeastern Serbia (Pčinja and South Morava River Basins)     

Jelena Petrović  Snežana Dragović  Ranko Dragović  Milan Đorđević  Mrđan Đokić  Mirjana Ćujić 《Journal of Soils and Sediments》2016,16(4):1168-1175

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INCREASED CADMIUM AVAILABILITY TO CROPS ON A SEWAGE-SLUDGE AMENDED SOIL     

Tichý  R.  Ný  V.  Kužel  S.  Kolář  L. 《Water, air, and soil pollution》1997,94(3-4):361-372

Analysis of spatial distribution of sewage-sludge born cadmium on the experimental plot revealed positive correlation of total cadmium and organic matter. Soil pH fluctuated randomly on the field. ‘Bioavailable’ concentrations, as determined by NH₄-acetate extraction, were closely correlated to the total cadmium levels, and only negligible effects of pH and/or organic matter fluctuations were recorded. Desorption model using modified Freundlich isotherm was applied to predict risks of cadmium solubilization at different conditions. Simulations revealed that the organic matter content within the ranges found at the experimental field cannot support a proper immobilization of cadmium at pH-range observed at the field. The phenomenon was explained by ineffective care for the soil in the past.  相似文献