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  • Articles  (333,353)
  • Springer  (314,617)
  • Nature Publishing Group  (18,736)
  • 1990-1994  (333,353)
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  • 1
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    Gold metallogeny in the Sino-Korean Platform: examples from Hebei province, NE China. (1992)
    Springer
    Details
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/book
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    PAPER (OA)
  • 2
    Electronic Resource
    Electronic Resource
    Molecular mimicry in liver disease (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 377-378 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR — Primary biliary cirrhosis (PBC), an autoimmune chronic cholestatic liver disease, affects mainly women and ulti-mately leads to the destruction of the intra-nepatic bile ducts and death from liver failure. The disease is characterized by the presence of diagnostic serum ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/358377a0
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  • 3
    Electronic Resource
    Electronic Resource
    Fact and fiction in alignment (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 271-271 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - We have discovered a startling similarity between a dinosaur DNA sequence reported in the novel Jurassic Park1 and a partial human brain cDNA sequence from the Venter laboratory described in Nature1 (see figure). The dinosaur sequence (Dinol) consists of duplication, with 117 base pairs from ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/358271c0
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  • 4
    Electronic Resource
    Electronic Resource
    Productivity drive (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 738-738 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - In a recent study on prolific productivity among prominent scientists (MedicalHypotheses, in the press), I have identified eight scientists who have been authors of more than 1,000 research publications, including books, monographs and patents as well as regular papers. They are, in ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/356738b0
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  • 5
    Electronic Resource
    Electronic Resource
    Folding in the egg white (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 278-279 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] PROTEINS seem to find it easy to fold into their three-dimensional conformation - the difficulty is the scientist's, in failing so far to understand how they do it, let alone predict either the pathway or the end state. Three of the more important questions facing the protein folder are these. ...
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    URL: http://dx.doi.org/10.1038/358278a0
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  • 6
    Electronic Resource
    Electronic Resource
    'Neutral' CFCs? (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 738-738 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - The suggestion1 that CFCs may be 'greenhouse neutral' on a global scale may bear on the negotiations at Rio de Janeiro in June aimed at reducing the potential for global warming. Although spatial variations of ozone concentration will complicate the argument2, at first sight the possibility ...
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  • 7
    Electronic Resource
    Electronic Resource
    Text analysis (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 740-740 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ONE of the ma,m contributors to a text's difficulty js its pattern of word choice. In English, this choice is from an estimated 600,000 word-types {terms naving unique orthography), A tog-normal model1 of word choice predtcts that when the words from a large representative ...
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    URL: http://dx.doi.org/10.1038/356740a0
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  • 8
    Electronic Resource
    Electronic Resource
    The growing inaccessibility of science (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 739-740 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THERE is plenty of anecdotal evidence that large areas of the scientific literature are becoming incomprehensible to all but a few initiates. But how persuasive is anecdote? In this article I describe an objective way of looking at the matter and discuss its application to science journals over the ...
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    URL: http://dx.doi.org/10.1038/356739a0
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  • 9
    Electronic Resource
    Electronic Resource
    Evolution of ecological differences in the Old World leaf warblers (1992)
    [s.l.] : Nature Publishing Group
    Nature 357 (1992), S. 176-176 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IN Fig. 2a of the above letter the second and third rows were inadvertently interchanged. In addition, the sequence at position 15176 (ref. 1.) for both Sylvia and P. coronatus should read 'A' and not ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/357176a0
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  • 10
    Electronic Resource
    Electronic Resource
    Guides to experiments (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 743-744 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] RNA EDITING is a bizarre and fascinating form of gene transcript maturation, in which uridine residues are post-transcriptionally inserted into (and occasionally deleted from) mitochondrial RNAs in trypanosomes and related organisms to achieve the mature messenger RNA sequence. The process accounts ...
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    URL: http://dx.doi.org/10.1038/356743a0
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  • 11
    Electronic Resource
    Electronic Resource
    Deep ocean circulation puzzle (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 744-746 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] NOTIONS of the influence deep ocean circulation can have on the climate will have to be revised in the light of papers on pages 757 and 783 of this issue. Lehman and Keigwin1 and Veum et al.2 have examined tracers of ocean circulation in the northern corner of the North Atlantic and find that ...
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  • 12
    Electronic Resource
    Electronic Resource
    Peter Mitchell (1920 - 1992) (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 747-747 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] PETER Mitchell, biochemist and Nobel laureate for chemistry in 1978, died from cancer on 10 April. Mitchell's single-minded purpose was to understand the mechanistic relationships between the metabolism of cells and the transport of solutes across cellular membranes. Clearly they were related, but ...
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  • 13
    Electronic Resource
    Electronic Resource
    Proteases: to each his own (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 748-749 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] PROCESSING of propeptides involves the cleavage of one or more peptide bonds in the inactive precursor resulting in a smaller, sometimes fragmented, active protein. Very often these processing enzymes are unique to a particular pro-peptide and possess unusual specificity aimed at a limited number ...
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  • 14
    Electronic Resource
    Electronic Resource
    Why the recession is still here (1992)
    [s.l.] : Nature Publishing Group
    Nature 357 (1992), S. 1-1 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] FINANCE ministers, the people who decide what taxes we pay, behave even more curiously as a group than singly. The meeting of the finance ministers of seven industrialized nations of the world (known as G-7 for 'Group of Seven') in advance of the annual meeting of the International Monetary Fund ...
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  • 15
    Electronic Resource
    Electronic Resource
    Structure and expression of a human oxytocin receptor (1992)
    [s.l.] : Nature Publishing Group
    Nature 357 (1992), S. 176-176 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] WE have discovered an error in the DNA sequence of our pOTR gene in Fig. \b. The nucleotides 714-717, CGGC should be GGCGGCG. The amino acids underneath should be Ala Ala Ala instead of Ala Gly. Accordingly, the complementary DNA encodes a 389 amino-acid protein with a relative molecular mass of ...
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  • 16
    Electronic Resource
    Electronic Resource
    Protein-DNA interactions at a yeast replication origin (1992)
    [s.l.] : Nature Publishing Group
    Nature 357 (1992), S. 169-172 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] All yeast ARSs contain an exact or close match to the core consensus sequence, 5'-A/TTTTATA/GTTTA/T-3' and this sequence seems essential for origin function. In addition to this element, flanking sequences are important for efficient ARS activity1'2. At ARS1, the core consensus sequence lies in a ...
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  • 17
    Electronic Resource
    Electronic Resource
    Molecular cloning of cDNAs encoding a guanine-nucleotide-releasing factor for Ras p21 (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 351-354 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To clone a GRF for Ras p21, (Ras-GRF), we exploited the fact that GRFs for yeast RAS can activate mammalian Ras11-15. A set of degenerate oligonucleotides was designed to code for all peptides present in two highly conserved regions of three GRFs for yeast RAS, CDC25 (ref. 16) and SDC25 from S. ...
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  • 18
    Electronic Resource
    Electronic Resource
    US drops Imanishi-Kari investigation; Baltimore withdraws Cell retraction (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 177-177 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Washington. US prosecutors announced this week that they are dropping their criminal investigation of Thereza Imanishi-Kari, a Tufts University immunologist accused of scientific misconduct, because the case is too complex and tangled for a jury to reach a conclusion. At the same time, David ...
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  • 19
    Electronic Resource
    Electronic Resource
    British military beckons environmental researchers (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 179-179 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] London. The British Ministry of Defence (MoD) is putting its people, equipment and real estate at the disposal of environmental researchers in a new initiative intended to benefit science. Researchers welcome the opportunity but are scratching their heads to understand such generosity. When the ...
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  • 20
    Electronic Resource
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    US rules out gene patent treaty (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 180-180 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Washington, The chief US science official said last week that the United States will abide by its controversial decision to file applications for patents on gene fragments and will not pursue an international treaty on the issue. D. Allan Bromley, science adviser to the president, said that the ...
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  • 21
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    Chinese researchers promised more (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 182-182 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Beijlng. Prominent Chinese researchers last month heard their government's finance minister promise them more money-sometime. At a meeting on 17 June between Wang Bing-Ojan and the Chinese Academy of Sciences, the finance minister said that the government has adopted a policy, to be implemented ...
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  • 22
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    Cost of brain disorders (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 184-184 
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    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - I was distressed to read the leading article disparaging the report The Costs of Disorders of the Brain. This report argued that the estimated $401 billion annual costs for brain disorders in the United States justifies a substantial increase in funding for brain research. Nature did ...
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  • 23
    Electronic Resource
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    'Blue ostriches' captured (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 185-185 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - The 'blue ostriches', a famous portrayal of a supposed rock painting, is very probably a forgery based upon an engraving (see top figure) in Moffat's Missionary Labour (1842)1. The 'copy' of the mysterious painting (middle fi-gure) was made by G. W. Stow, who was born in England in 1822 ...
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  • 24
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    How to publish the unpalatable? (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 187-187 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] How should a journal, this one perhaps, respond when asked to publish material that contradicts generally accepted views, that the Earth is a rough approximation to an ellipsoid for example? Or that Einstein's relativity is broadly correct (if not widely understood)? The proper response is that a ...
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  • 25
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    The big accelerator in the sky (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 189-190 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE positron, the antimatter counterpart of the electron, was discovered on 2 August 1932, dramatically and unex-pectedly confirming Dirac's new quan-tum theory of the electron. The positron in question was created by a cosmic ray which happened to end its wanderings around the Galaxy in ...
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  • 26
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    Cloning of cDNAs for Fanconi's anaemia by functional complementation (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 763-767 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fanconi's anaemia is a rare autosomal recessive disorder characterized by progressive pan-cytopaenia and a cellular hypersensitivity to DNA crosslinking agents. Four genetic complementation groups have been identified so far, and here we use a functional complementation method to clone ...
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  • 27
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    Superconductivity at 110 K in the infinite-layer compound (Sr 1-x Ca x ) 1-y CuO 2 (1992)
    [s.l.] : Nature Publishing Group
    Nature 356 (1992), S. 775-776 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Samples were prepared starting from metallic compositions of Cal_xSrx:Cu=l-iy:l with 0.4^x^0.7 and O^^^O.l. Typically, a gold capsule was filled with an intimate mixture of Ca0 3Sr0 7CuO2 (low-pressure phase) and fine powder of CuO, pressed almost isostatically up to 6 GPa using a classical ...
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  • 28
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    Sensing the potential (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 200-201 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] BIOSENSORS are portrayed in scientific and popular journals as having immense potential in medicine, clinical chemistry, environmental monitoring and defence. But the image of a biosensor as a miniaturized probe or hand-held 'black box' that provides instantaneous analy-tical results is, ...
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  • 29
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    Moscow, physics and beyond (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 201-202 
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    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IGOR Tamm was one of the generation of Russian theoretical physicists who took what was a moribund and backward subject in their country to its present position of international prominence. From 1934 until his death in 1971 he was head of the theoretical physics depart-ment of the Lebedev ...
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  • 30
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    A double-sided radio jet from the compact Galactic Centre annihilator 1E1740.7–2942 (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 215-217 
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    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] After the first observations with SIGMA, we initiated radio monitoring, at several wavelengths, of 1E1740.7-2942, the dominant hard X-ray source (&30keV) near the Galactic Centre4. The hard X-ray spectrum in its normal state resembles that of Cygnus X-l, one of the best candidates for ...
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  • 31
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    Variability in sea-ice thickness over the North Pole from 1977 to 1990 (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 224-226 
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    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Arctic Ocean is generally regarded as a potentially sensi-tive indicator of global change, especially as the predicted result of continued greenhouse-gas emissions is a global warming with high-latitude amplification1. Such a warming could thus have important consequences for the ...
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  • 32
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    Post-Jurassic mammal-like reptile from the Palaeocene (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 233-235 
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    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Class Reptilia Subclass Synapsida Order Therapsida Suborder Cynodontia Chronoperatidae fam. nov. Type genus Chronopemtes gen. nov. Chronoperates paradoxus gen. et sp. nov. Etymology. Chronos (Greek): time; perates (Greek): wanderer, in reference to the geochronologic gap between this taxon ...
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  • 33
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    Nuclear localization and signalling activity of phosphoinositidase Cβ in Swiss 3T3 cells (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 242-245 
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    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] An analysis of phosphoinositidase C (PIC) activities in the nucleus and cytoplasm of Swiss 3T3 cells using [3H]PtdInsP and [3H]PtdInsP2 as substrates is shown in Fig. 1. Both nuclear and cytoplasmic activities require calcium because the addition of EGTA completely abolishes breakdown. ...
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  • 34
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    Cytotoxic T-lymphocyte activation involves a cascade of signalling and adhesion events (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 253-255 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fluid-phase anti-TCR monoclonal antibody is not a sufficient stimulus to trigger degranulation by cloned cytotoxic T-lymphocytes (CTL), but primes the cells for CDS-dependent adhesion to class I protein, which results in triggering of degranulation3. To determine which signalling events ...
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    Nature; 358.1992, 6383, S.262 (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 262-262 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] PLEASE follow these guidelines so that your manuscript may be handled expeditiously. Nature is an international journal covering all the sciences. Contributors should therefore bear in mind those readers who work in other fields and those for whom English is a second language, and write clearly ...
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    Carbon partitioning in Norway spruce: amounts of fructose 2,6-bisphosphate and of intermediates of starch/sucrose synthesis in relation to needle age and degree of needle loss (1990)
    Springer
    Trees 4 (1990), S. 9-15 
    Details
    ISSN: 1432-2285
    Keywords: Carbon partitioning ; Fructose 2,6-bisphosphate ; Needle development ; Needle loss ; Picea abies ; Starch/sucrose/intermediates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Intermediates involved in carbon partitioning between starch and sucrose [dihydroxyacetone phosphate + glyceraldehyde 3-phosphate (TP), 3-phosphoglyceric acid, fructose 6-phosphate (F6P), fructose 2,6-bisphosphate (F26BP), in addition to glucose, fructose, sucrose and starch] were analysed in lyophilized needles of Norway spruce (Picea abies L. Karst). Samples were taken from all distinct parts of first and second order branches and the analysed data related to season, needle age, needle position and degree of needle loss (control and class 2 approx. 30%–40% needle loss). Positive and inverse correlations of F26BP, an important regulator of carbon partitioning between starch and sucrose, and F6P or TP existed in all samples. F26BP levels were highest in developing needles and gradually decreased during maturation, which is possibly indicative of changes in the relative sink strength during development (switch from import to export of sucrose). In class 2 needles the amount of F26BP was significantly increased. Together with nearly unaltered levels of sucrose but only slightly decreased amounts of starch the results can be taken as evidence for impaired carbon export in our class 2 samples. The data are discussed with respect to needle development and a possible impact of both air pollutants and mineral deficiency at the location from which the samples were taken.
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    URL: http://dx.doi.org/10.1007/BF00226234
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    The ion concentration of dew condensed on Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) needles (1990)
    Springer
    Trees 4 (1990), S. 22-26 
    Details
    ISSN: 1432-2285
    Keywords: Deposition ; Dew ; Pine ; Pinus sylvestris ; Spruce ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dew droplets collected with pipettes from coniferous needles were analysed for their ionic composition. Almost all samples of dew taken from Scots pine trees (Pinus sylvestris) showed significantly higher ion concentrations than those taken from Norway spruce trees (Picea abies). This can be explained by the micromorphology of the needle surface. The higher microscale roughness of the wax layer of a pine needle causes a more efficient flux of atmospheric aerosol particles compared to the spruce needle surface. Dew on coniferous needles is shown to be capable of maintaining pH values below 3 for several hours.
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    URL: http://dx.doi.org/10.1007/BF00226236
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    Vascular differentiation in branch junctions of trees: circular patterns and functional significance (1990)
    Springer
    Trees 4 (1990), S. 49-54 
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    ISSN: 1432-2285
    Keywords: Branch junctions ; Circular vessels ; Pinus ; Quercus ; Vascular differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Regions of spiral vascular tissues and circular vessels occur normally in branch junctions. Their size and frequency increase continuously with age and stem width. This phenomenon is general and was found in all the 15 species studied. The differentiation of narrow spiral vessels with non-functional circular vessels decreases water conductivity through branch junctions leading to hydraulic segmentation of lateral branches from the main stem. Possible hormonal mechanisms controlling circular vascular patterns and narrow vascular elements are discussed.
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    URL: http://dx.doi.org/10.1007/BF00226240
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    Seasonal variation in the monoterpenes in needles of Picea abies (L.) Karst. (1990)
    Springer
    Trees 4 (1990), S. 34-40 
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    ISSN: 1432-2285
    Keywords: Seasonal fluctuation ; Needle ; Picea abies ; (Mono) terpene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This investigation was conducted to obtain information about the fluctuations in composition and amount of needle monoterpenes during the development of spruce needles. Studies conducted with two Norway spruce clones clearly revealed the existence of fluctuations. In juvenile needles, the amounts of the oxygenated terpenes increase constantly with age during the first 2 months of needle growth. The hydrocarbon terpenes dominate within the first weeks, some of them even showing a very distinct first maximum within the first 3 weeks after bud burst. All terpenes, including the oxygenated ones, have a maximum in June/July, which favours the hypothesis of a substitution of the hydrocarbons later on. There are significant changes even in mature needles of Norway spruce. The terpene level of 1-year-old needles of the clonal trees increased from spring to early summer and then dropped again towards winter. In addition, fluctuations in mature needles were shown for a set of ten wild trees. Needles of the same age class, which emerged in 1986, were sampled 4 times from 1986 to 1988. The needle terpene concentrations of the 1 -year-old needles were considerably lower in spring at the time of bud burst than in autumn. The terpene level of older needles thus seems to be influenced by biosynthetic and catabolic activities.
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    URL: http://dx.doi.org/10.1007/BF00226238
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    An analysis of needle yellowing in healthy and chlorotic Norway spruce(Picea abies) in a forest decline area of the Fichtelgebirge(N.E. Bavaria) (1990)
    Springer
    Trees 4 (1990), S. 55-67 
    Details
    ISSN: 1432-2285
    Keywords: Forest decline ; Needle yellowing ; Chlorophylls ; Carotenoids ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a forest decline area (Fichtelgebirge, N.E. Bavaria, FRG), annual time courses of chloroplast pigments in both healthy and chlorotic Norway spruce were studied. The seasonal time courses of green and apparently healthy trees did not generally differ from those reported in the literature for spruce trees of other regions. Chlorophyll content increased from May to October, remained relatively constant or declined slightly during the fall and early winter, and finally decreased markedly from March to early May when pigment is at its minimum before bud break. The annual maximal chlorophyll content increased with needle age from the current year's needles to 4-yearold needles. While carotene content reached its highest concentration in August, the xanthophylls did not peak until February or March. Pigment dynamics of chlorotic trees with lower concentrations, corresponded to those of undamaged trees. Chlorophyll deficits resulted from less pigment formation as well as pigment loss during the growing period. Even when the content of total chlorophyll was low, the ratio of chlorophyll a/chlorophyll b remained almost unchanged. In conjunction with the chlorophyll reductions, a decrease in the chlorophyll/carotenoid ratio and an increase in the xanthophyll/carotene ratio occurred. The periods of needle-chlorophyll reduction did not correlate with those periods of highest concentrations of atmospheric sulphur dioxide, the main air pollutant at the stand. However, chlorophyll formation ceased in the older needle age classes of chlorotic trees when the new flush was sprouting, indicating that nutritional deficiencies affect needle yellowing more than possible direct needle damage by air pollutants.
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    URL: http://dx.doi.org/10.1007/BF00226067
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    Contents of ATP and ADP in needles of Norway spruce in relation to their development, age, and to symptoms of forest decline (1990)
    Springer
    Trees 4 (1990), S. 68-74 
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    ISSN: 1432-2285
    Keywords: ATP ; ADP ; Forest decline ; Needle development ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pool sizes of ATP and ADP were analysed in freeze-stopped, lyophilised homogenates of needles from Norway spruce [Picea abies (L.) Karst.]. Control experiments in which possible changes in adenylate pools during sample acquisition were investigated did not reveal significant differences between needles taken from branches in situ or within a 30-min period after cutting off a branch. In addition, pool sizes of ADP and ATP were not affected by changes in light intensity (between 60 and 1500 μE*-m-2*s-1), which inevitably occur when samples have to be taken from the upper region of older trees. Levels of ATP and ADP showed considerable seasonal changes (May through October) with the highest ratios of ATP/ADP in developing needles. In general, there was a tendency towards increased ratios of ATP/ADP with increasing needle age. This observation was corroborated by analyses of needles from spruce trees of different age and growing under different conditions. Needles from declining trees or from trees specifically fumigated with low concentrations of ozone and sulphur dioxide had significantly increased ratios of ATP/ADP compared to controls. The results are discussed with respect to physiological responses connected with natural senescence and induced ageing.
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    Effects of ozone on starch accumulation in Norway spruce (Picea abies) (1990)
    Springer
    Trees 4 (1990), S. 107-110 
    Details
    ISSN: 1432-2285
    Keywords: Needles ; Ozone ; Picea abies ; Starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fumigation with 100 μg/m3 and 200 μg/m3 ozone in closed-top fumigation chambers induced starch accumulation in chloroplasts of Norway spruce. This accumulation was probably due to a partial inhibition of the starch translocation at night. The intensity of the effect was dependent on the season and the age of the needles. The accumulation was reversed in winter. It is therefore unlikely that such an effect has much significance for plant health.
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    Rhythmic growth fluctuations in forest trees of Central Europe and the Front Range in Colorado (1990)
    Springer
    Trees 4 (1990), S. 99-106 
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    ISSN: 1432-2285
    Keywords: Dendrochronology ; Abrupt growth changes ; Periodicities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth ring sequences in conifers and broadleaved trees show abrupt growth reductions persisting for several years. The frequency and duration of such reductions in almost 10000 trees in forest stands of Central Europe, in particular Switzerland, and in the Front Range, Colorado, USA, is related to species, climate and weather, and geographical unit. The growth reductions in the populations investigated are concentrated in certain periods and, in all species examined, essentially related to periods of drought in the spring and summer months. During the years covered by the study (1850–1985), periods of growth reduction occur in Central Europe, the Front Range, Colorado, and also in the Hudson Valley, New York, at irregular intervals of 6–34 years, and on average every 13–14 years. The growth reduction periods normally do not show synchronism between the three areas investigated. Regionally valid growth periodicities can only be definitely determined through the examination of a very large amount of material comprising a number of species growing in different forest stands and on different sites within a major phytosociological unit. Findings from studies on trees in different climatic areas or on few samples scarcely allow reliable comparisons.
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    Influence of phloem transport on flower abscission in Hibiscus rosa-sinensis (1990)
    Springer
    Trees 4 (1990), S. 128-135 
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    ISSN: 1432-2285
    Keywords: Fruit abscission ; Hibiscus rosa-sinensis ; Microautoradiography ; Phloem transport ; Starch deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Flowering cultivars of Hibiscus rosa-sinensis L. were either cross-pollinated or self-pollinated. Fruit set was observed on 52% of the cross-fertilized flowers, while only 4.6% of the self-fertilized flowers were not abscised. Once during fruit and seed growth, the subtending leaf was exposed to 14CO2, and translocation of labelled photoassimilate was recorded by macro- and microautoradiography. Phloem transport into the raphe occurred in both fruits with fertilized and fruits with non-fertilized ovules. Since empty ovules showed some sink strength, it is assumed that growth of vegetative seed-tissue signalizes the retardation of completion of the abscission process. During fruit growth a considerable amount of starch is deposited in the distal layer of the abscission zone. Part of this starch is consumed during growth of cross-fertilized fruits.
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    Tubule bundle-inclusions in vacuoles of Tamarix aphylla L. mesophyll cells (1990)
    Springer
    Trees 4 (1990), S. 136-141 
    Details
    ISSN: 1432-2285
    Keywords: Mesophyll ; Tamarix aphylla ; Tubule bundles ; Vacuoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Vacuoles of differentiating mesophyll cells of Tamarix aphylla contain an amorphous electron-dense material in which stacks of parallel aligned striations are embedded. Cross-sections of the striations disclosed that they represent profiles of longitudinally sectioned bundles of tubules (tubule outer diameter 9.0 nm, tubule wall thickness 1.8 nm). In advanced mesophyll cell development, the amorphous vacuolar material disappears, whereas the bundles of tubules turn into bundles of double helices (double helix diameter 14.5 nm). Cytochemical treatment of mesophyll cells with the enzymes pepsin and trypsin has revealed that both the bundles of tubules/double helices and the embedding material are constituted of protein. The possible functional role of the vacuolar inclusions is discussed.
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    Endogenous levels of oxygen, carbon dioxide and ethylene in stems of Norway spruce trees during one growing season (1990)
    Springer
    Trees 4 (1990), S. 150-154 
    Details
    ISSN: 1432-2285
    Keywords: Carbon dioxide ; Conifers ; Ethylene ; Gaschromatography ; Mass spectrometry ; Oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The trees sampled in this study came from two stands of Norway spruce, Picea abies (L.) Karst., near Stockholm, Sweden, differing in mean age and height. Holes were bored perpendicular to the stem surface, and gas samples were taken from the outer part of the sapwood throughout one growing season. Endogenous levels of molecular oxygen (O2), carbon dioxide (CO2) and ethylene in the outer sapwood were determined by combined gas chromatography — mass spectrometry (GC-MS) and GC. O2 concentrations began to decrease as growth started in spring. The lowest levels (〈5%) were recorded around mid-summer. In the younger stand concentrations remained below 5% until September. In October, O2 concentrations in the sapwood were similar to those of air. Concentrations of CO2 were below 1% in spring, but began to rise in May, peaking a month later at approximately 10%. Thereafter a slow decrease occurred until October, by which time levels had returned to those recorded in spring. Ethylene concentrations in the older stand reached 75 ppm early in May, while levels in the younger stand peaked at around 30 ppm later in May. Thereafter ethylene levels in both stands started to decrease down to ppb levels. The correlation between determined gas levels and physiological events associated with the seasonal growth cycle in temperate zones is discussed.
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    Nauclea diderrichii: rooting of stem cuttings, clonal variation in shoot dominance, and branch plagiotropism (1990)
    Springer
    Trees 4 (1990), S. 164-169 
    Details
    ISSN: 1432-2285
    Keywords: Apical dominance ; Clonal variation ; Nauclea diderrichii ; Plagiotropism ; Vegetative propagation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nauclea diderrichii (De Wild, and Th. Dur.) Merill (Rubiaceae), an indigenous hardwood of West Africa, is increasingly being grown commercially. This study investigates the potential for vegetative propagation and clonal selection, and raises some fundamental questions about the physiology of apical dominance and of plagiotropism. Rooting ability was high, with up to 100% rooting in 2–4 weeks, when different Indole-3-butyric acid (IBA) concentrations and leaf areas were tested. Auxin applications greatly increased the numbers of roots per cutting. The decapitation of unbranched plants revealed clonal variation in apical dominance and also in the establishment of outright dominance by the two shoots formed from the outgrowth of the axillary buds of the opposite leaves at the top node. Regression analysis of the Dominance Ratio (length of dominant: length of the sub-dominant shoot at the time of achieving dominance) against overall lateral bud activity (r = 0.82), showed that when the two top shoots co-dominate they provide a more powerful source of Correlative Inhibition than when one of the top shoots dominates the other. The imposition of plagiotropism in the axillary bud occurred over a period of a few days as the terminal and axillary buds emerged from the stipule. Growth of accessory buds on intact plants and debranched cuttings was orthotropic. These results are discussed with regard to the role of the leaf in root formation and the understanding of dominance relationships, branching and crown development in trees.
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    Phloem transport in Picea abies (L.) Karst. in mid-winter (1990)
    Springer
    Trees 4 (1990), S. 179-186 
    Details
    ISSN: 1432-2285
    Keywords: 14C translocation ; Microautoradiography ; Phloem loading/unloading ; Picea abies ; Symplastic transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Translocation of 14C assimilates was studied on four different transport systems of Picea abies branches after induced activation in January. 14CO2 assimilation of terminal shoots for 48 h at 25° C resulted in phloem loading and basipetal transport of 14C photosynthate into the following, older shoot generations. 14C import was enhanced, when these older shoot generations were kept in the dark. Microautoradiographs of the labelled terminal shoots showed that 14C assimilates were exported from needles via sieve elements of the leaf traces and loaded into the latest increment of the axial secondary phloem. No 14C label appeared in the obliterated sieve cells or in the tracheids. In addition, 14C photosynthate accumulated densely in the chlorophyllous cells of the cortex and in cells of the resin ducts, indicating certain sink activity. In the darkened 2-year-old shoot, imported 14C photosynthate was concentrated in the functional secondary phloem, while some 14C label was unloaded into the latest xylem increment. When 6-year-old shoots were exposed to 14CO2 for 48 h in the light, 14C assimilates accumulated in the phloem of the leaf trace and in the latest increment of the axial secondary phloem. However, a substantial amount of radioactivity was unloaded into ray cells and phloem parenchyma cells. Thus, the presence of functioning phloem in needles and twigs of P. abies during winter allows long-distance translocation and radial distribution of assimilates according to existing source-sink relations.
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    Hybrid poplar stomata unresponsive to changes in environmental conditions (1990)
    Springer
    Trees 4 (1990), S. 191-197 
    Details
    ISSN: 1432-2285
    Keywords: Unresponsive stomata ; Stomatal conductance ; Hybrid poplar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The factors affecting stomatal conductance (gs) of I-214 (Populus euramericana) and a hybrid poplar, Peace (P. koreana x P. trichocarpa), were examined in the field and under controlled environment conditions. Unusual opening of the stomata was observed with Peace leaves at all positions. Ontogenetic changes in gs were similar between these two poplar species in the light. However, the dark/light ratio of gs in Peace poplar varied from 0.58 to 1.23 with the insertion level while that of I-214 poplar was zero except for the third leaf from the top. The gs of I-214 poplar changed with time of the day, varying from 0.74 mol m-2s-1 in the morning to zero at night, while the gs of Peace poplar changed only from the minimum value of 0.23 mol m-2s-1 at night to the maximum of 0.48 mol m-2s-1 in the morning. Under severe water stress, below -1.5 MPa, which decreased the gs of I-214 poplar to almost zero, the gs of Peace poplar remained about onethird of that observed with well-watered leaves. Exposure to a relatively high concentration of O3 caused the gs of I-214 poplar to decrease nearly to zero but had no effect on the gs of Peace. Stomata of Peace poplar were not affected by ABA and the gs did not change even with 10-4 M ABA, while the gs of I-214 decreased to almost zero on the application of this concentration of ABA.
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    Wind breakage of trees initiated by root delamination (1990)
    Springer
    Trees 4 (1990), S. 225-227 
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    ISSN: 1432-2285
    Keywords: Buttress roots ; Failure mechanism ; Root delamination ; Wind breakage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary There are different types of tree failure under wind loading. Here a special mechanism is discussed by which redirectioning of the tensile forces acting in the tree stem causes a lateral force to become effective away from the stem-root transition contour line. This force leads to delamination of the root followed by development of an axial crack running up the stem, until total stem failure by fibre buckling on the compression side of the stem completes the destruction. It is shown that buttress roots could reduce the danger associated with this failure mechanism.
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    Confocal laser scanning microscopy of fluorescently stained wood cells: a new method for three-dimensional imaging of xylem elements (1991)
    Springer
    Trees 5 (1991), S. 1-4 
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    ISSN: 1432-2285
    Keywords: Confocal laser scanning microscopy ; Wood cell structure ; Three-dimensional imaging ; Lignification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Xylem cells were fluorescently stained with periodic acid — Schiff reaction or with Schiffs reagent alone and studied by confocal laser scanning microscopy. Single images with extremely low depth of focus, series of optical sections, computed stereo scopic images and “shadow casting” images as well as x-z images are obtained. In contrast to scanning electron microscopy, not only are the surfaces imaged, but elements concealed by other structures can be visualized by this system. Quantitative data on cell depth are provided and differences in lignification are detected.
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    Impairment of gas exchange and structure in birch leaves (Betula pendula) caused by low ozone concentrations (1991)
    Springer
    Trees 5 (1991), S. 5-13 
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    ISSN: 1432-2285
    Keywords: Ozone ; Betula pendula ; Leaf gas exchange ; Leaf structure ; Senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Injury caused by low O3 concentrations (0, 0.05, 0.075, 0.1 μl 1-1) was analyzed in the epidermis and mesophyll of fully developed birch leaves by gas exchange experiments and low-temperature SEM: (I) after leaf formation in O3-free and ozonated air, and (II) after transferring control plants into ozonated air. In control leaves, autumnal senescence also was studied in O3-free air (III). As O3 concentration increased, leaves of (I) stayed reduced in size, but showed increased specific weight and stomatal density. The declining photosynthetic capacity, quantum yield and carboxylation efficiency lowered the light saturation of CO2 uptake and the water-use efficiency (WUE). Carbon gain was less limited by the reduced stomatal conductance than by the declining ability of CO2 fixation in the mesophyll. The changes in gas exchange were related to the O3 dose and were mediated by narrowed stomatal pores (overriding the increase in stomatal density) and by progressive collapse of mesophyll cells. The air space in the mesophyll increased, preceded by exudate formation on cell walls. Ozonated leaves, which had developed in O3-free air (II), displayed a similar but more rapid decline than the leaves from (I). In senescent leaves (III), CO2 uptake showed a similar decrease as in leaves with O3 injury but no changes in mesophyll structure and WUE. The nitrogen concentration declined only in senescent leaves in parallel with the rate of CO2 uptake. A thorough understanding of O3 injury and natural senescence requires combined structural and functional analyses of leaves.
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    Ammonium and nitrate uptake rates and rhizosphere pH in non-mycorrhizal roots of Norway spruce [Picea abies (L.) Karst.] (1991)
    Springer
    Trees 5 (1991), S. 14-21 
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    ISSN: 1432-2285
    Keywords: Ammonium ; Calcium ; Nitrate ; Picea abies ; Rhizosphere pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Relationships between root zone temperature, concentrations and uptake rates of NH 4 + and NO 3 − were studied in non-mycorrhizal roots of 4-year-old Norway spruce under controlled environmental conditions. Additionally, in a forest stand NH 4 + and NO 3 − uptake rates along the root axis and changes in the rhizosphere pH were measured. In the concentration (Cmin) range of 100–150 μM uptake rates of NH 4 + were 3–4 times higher than those of NO 3 − The preference for NH 4 + uptake was also reflected in the minimum concentration (Cmin) values. Supplying NH4NO3, the rate of NO 3 − uptake was very low until the NH 4 + concentrations had fallen below about 100 μM. The shift from NH 4 + to NO 3 − uptake was correlated with a corresponding shift from net H+ production to net H+ consumption in the external solution. The uptake rates of NH 4 + were correlated with equimolar net production of H+. With NO 3 − nutrition net consumption of H+ was approximately twice as high as uptake rates of NO 3 − In the forest stand the NO 3 − concentration in the soil solution was more than 10 times higher than the NH 4 + concentration (〈100 μM), and the rhizosphere pH of non-mycorrhizal roots considerably higher than the bulk soil pH. The rhizosphere pH increase was particularly evident in apical root zones where the rates of water and NO 3 − uptake and nitrate reductase activity were also higher. The results are summarized in a model of water and nutrient transport to, and uptake by, non-mycorrhizal roots of Norway spruce in a forest stand. Model calculations indicate that delivery to the roots by mass flow may meet most of the plant demand of nitrogen and calcium, and that non-mycorrhizal root tips have the potential to take up most of the delivered nitrate and calcium.
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    URL: http://dx.doi.org/10.1007/BF00225330
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    Analysis of stand density effects on canopy structure: a conceptual approach (1991)
    Springer
    Trees 5 (1991), S. 44-49 
    Details
    ISSN: 1432-2285
    Keywords: Crown dimensions ; Canopy structure ; Stand density ; Stand structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A few assumptions were used to generate a series of specific, quantitative predictions for the relationships between stand density and various dimensional measures of canopy structure. The predictions, each indicating an increase in mean crown size as density decreased, appeared to be reasonable and intuitive. Predictions were compared to data for two conifer species with different crown forms, Pinus contorta var. latifolia and Abies lasiocarpa. Results of these comparisons were mixed — the linear, directly measured dimensions were consistent with predicted relationships, but dimensions calculated from the linear measures were not. Re-examination of the original assumptions indicated that the model should account for crown shyness (engagement/disengagement) to adequately reflect the influence of stand density on canopy structure. The results also indicated a strong association between stand height and measures of mean crown size. Mean crown size of lodgepole pine was altered much more by density than was mean crown size of subalpine fir, due primarily to the different relative shade tolerances of the two species. Some of the observed differences between species may also reflect the range of densities examined and uneven spacing in the unmanaged natural stands.
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    Regulation of photoassimilate allocation in Pinus sylvestris seedlings by the nutritional status of the mycorrhizal fungus Suillus variegatus (1991)
    Springer
    Trees 5 (1991), S. 36-43 
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    ISSN: 1432-2285
    Keywords: Microautoradiography ; Mycorrhiza ; Pinus sylvestris ; Suillus variegatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seedlings of Pinus sylvestris L. were grown on defined nutrient solutions on carbon filters, either sterile or infected with the basidiomycete Suillus variegatus O. Kuntze. After mycorrhizas were established, the shoot of the seedling was subjected to 14CO2 photosynthesis. 14C-labelled photoassimilates were translocated to both mycorrhizas and non-infected root tips. Microautoradiographs of mycorrhizas indicated that omission of external sugars did not affect the formation of mycorrhizas; 14C-photoassimilates were supplied to cortex, Hartig net and the mantle of hyphae surrounding the rootlet. Nutrient solution containing sugars (malt extract, glucose) enhanced the growth of the fungus. As a consequence, 14C-photoassimilates from the seedling were accumulated in the mantle, but defence mechanisms of the host cannot be excluded. When soluble nitrogen was omitted from the nutrient solution and replaced by chitin precipitated on the filter-bearing mycorrhizas, the fungus appeared strongly labelled in the mantle, where the fungal chitinase provided soluble nitrogen compounds, necessary for the growth of the seedling.
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    Proliferated seed cones and pollen cones in young black spruce (1991)
    Springer
    Trees 5 (1991), S. 65-74 
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    ISSN: 1432-2285
    Keywords: Developmental plasticity ; Seed-cone proliferation ; Pollen-cone proliferation ; Morphological diversity ; Proliferated cone production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The number of proliferated seed cones (PSc) and proliferated pollen cones (PPc) borne by young plantation-grown Picea mariana (Mill.) B.S.P. was established for trees aged 9–17 years from seed. A description and composition of a range of morphological forms of proliferations were produced. Through paired-comparison analyses, compositions of PSc and PPc were compared to those of nearby non-proliferated cones or to vegetative shoots. Between 41% and 88% of trees of different ages that bore seed cones also bore some PSc; 17–58% with pollen cones also had PPc. The total number of PSc represented 2.3–20% of total numbers of seed cones and PSc at each tree age; PPc represented 1.5–5.8% of the total. Proliferated seed cones were greatly diversified in forms ranging from only a few distal needle-like bracts to mainly needles with a few needle-like bracts. A similar range of diversity existed for PPc. Proliferations involving production of distal needles went on to produce a terminal bud. The diversity of morphological forms and their variable occurrence encountered in this study indicate that the developmental pathway of an apical meristem, although defined somewhat by differentiation, has a degree of flexibility. Manifestation of this developmental flexibility throughout a wild population indicates that this phenomenon may be a normal event in P. mariana.
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    URL: http://dx.doi.org/10.1007/BF00227487
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    Fluoride effects on leaf cell ultrastructure of olive trees growing in the vicinity of the Aluminium Factory of Greece (1991)
    Springer
    Trees 5 (1991), S. 83-89 
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    ISSN: 1432-2285
    Keywords: Air pollutants ; Chloroplasts ; Fluoride ; Olive tree leaves ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Leaves of olive trees growing in the vicinity of the Aluminium Factory of Greece were ultrastructurally investigated in order to determine any malformations caused by environmental air pollutants, especially hydrogen fluoride, in comparison with control samples and normal seasonal senescence. Estimation of some elements accumulated by these leaves showed that they contained high amounts of F and Al attributable to the operation of the nearby factory. The most seriously effected cell components were found to be the mesophyll chloroplasts that show a dilation of the intrathylakoid space, increase of the number of plastoglobuli, discoloration of plastoglobuli, accumulation of large starch grains and an overall disorganized appearance of the organelle. The nuclear crystalloid inclusions have unusual shapes, while the vacuoles contain a fibrillar/granular material that increases their electron density. It is concluded that the ultrastructural malformations are caused by a combination of environmental stresses and air pollutants.
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    URL: http://dx.doi.org/10.1007/BF00227489
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    Quantitative and localized element analysis in cross-sections of spruce [Picea abies (L.) Karst.] needles with different degrees of damage (1991)
    Springer
    Trees 5 (1991), S. 95-100 
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    ISSN: 1432-2285
    Keywords: Element content ; Element distribution ; Forest decline ; Micro-PIXE ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Proton-induced X-ray microanalysis (micro-PIXE) permits the simultaneous determination of the content and the distribution of elements with atomic numbers higher than Z = 13 in biological samples. This method was used to investigate element content and localization in cross-sections of 6-month-old spruce needles. It was possible to detect the elements silicon, phosphorus, sulphur, chlorine, potassium, calcium, manganese, iron and zinc in semithin (10 μm) sections of the needles. The localization of the cationic elements like potassium, calcium and manganese was determined in the one-dimensional line scan mode and in the two-dimensional raster scan mode. To demonstrate the usefulness of this method for forest decline research, element content and localization were compared in needles from two trees, which differed in their degree of damage. We were able to detect differences in the amount of cations and in their distribution inside the needles.
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    URL: http://dx.doi.org/10.1007/BF00227491
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    Changes in hydraulic conductivity upon freezing of the xylem of Populus x canadensis Moench “robusta” (1991)
    Springer
    Trees 5 (1991), S. 117-121 
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    ISSN: 1432-2285
    Keywords: Freezing stress ; Hydraulic conductivity ; Populus ; Vessels ; Water conduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The impact of freezing stress on the hydraulic conductivity was studied in 4- to 6-year-old branches of Populus x canadensis Moench “robusta” under gravity flow conditions. In fresh branch segments, the hydraulic conductivity was approximately 3–6×10-2 1 h-1kPa-1m and the specific conductivity approximately 22 1 h-1kPa-1m-1. Depending on the gas content of the solutions fed to the xylem of the segments, their hydraulic conductivity was lowered by a freezing-thawing cycle by 20–50%. However, full recovery of hydraulic conductivity was found after about 2 days. Degassed solutions in contrast showed no impediment to flow after the same treatment. The results give evidence, firstly, that the harmful effect of freezing on functioning of water conducting elements is due to the formation of bubbles in xylem sap containing gas in solution, and secondly, that recovery from this impediment is possible in microporous vessels within a period of about 2 days.
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    URL: http://dx.doi.org/10.1007/BF00227494
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    Preformed and neoformed extension of shoots and sylleptic branching in relation to shoot length in Tsuga canadensis (1991)
    Springer
    Trees 5 (1991), S. 107-116 
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    ISSN: 1432-2285
    Keywords: Architectural model ; Eastern hemlock ; Leaf distribution ; Patterns of vigour ; Shoot development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Shoot systems developed over 3 successive years were investigated on 55 understorey Tsuga canadensis (L.) Carr. trees. Paired comparisons of preformed-leaf content of terminal buds and numbers of leaves produced on new shoots showed that neoformed leaves were produced in large numbers. Parent-shoot character was not useful in predicting numbers of preformed leaves, was better related to total leaves produced, but left the majority of the variation unexplained. This reflected the capacity of any terminal bud to produce a shoot with more or less neoformation, depending on conditions for growth. All shoots over 6 cm long produced sylleptic shoots that bore from two to many leaves and were arranged in a mesitonic pattern along the parent. Some of the longer sylleptic shoots produced lateral buds or second-order sylleptic shoots. Monopodial second-year extensions of sylleptic-shoot axes followed an acrotonic pattern, as did proleptic shoots from the few lateral buds borne on the parent shoots. Such lateral buds were more frequent on shorter parent shoots: they typically occurred near the proximal and distal ends. Duration of shoot extension was positively correlated with shoot length: terminal buds became evident as shoot extension neared cessation.
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    URL: http://dx.doi.org/10.1007/BF00227493
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    Function of spiral grain in trees (1991)
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    Trees 5 (1991), S. 125-135 
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    ISSN: 1432-2285
    Keywords: Transport ; Strength ; Fiber deviations ; Cambial growth ; Reorientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Through spiral grain, conduits for sap lead from each root to all branches. This uniform distribution of sap is indicated by the paths of vessels and tracheids, and has been proven experimentally by means of dyed sap injected into the base of stems or taken up by roots. Trees receiving water only from roots at one side of the root collar nevertheless stay green and continue growing. Spiral grain in bark distributes food from each branch to other flanks of the stem and to most roots. Experimental interruptions of the sap and food conduits caused the cambial zone to reorient new conduit cells in new directions, bypassing the interruption. In particular, spiral grooves cut into the stem surface caused spiral grain. The new cells reorient through division and growth. Although spiral grain is largely under genetic control, trees appear to have a spiral grain especially where needed for distribution of water when root spheres are dry at one side. Compared with straight-grained trees, spiral-grained stems and branches bend and twist more when exposed to strong wind, in this way offering less wind resistance and being less likely to break. Through the bending and twisting, snow slides down from branches rather than breaking them, but the main function of spiral grain is the uniform distribution of supplies from each root to all branches, and from each branch to many roots.
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    Occurrence of unidentified bodies that resemble “plastid initials” in poplar cells after breaking of dormancy in midwinter (1991)
    Springer
    Trees 5 (1991), S. 143-148 
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    ISSN: 1432-2285
    Keywords: Amyloplast ; Dormancy ; Plastid initial ; Plastid proliferation ; Poplar cortical cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Electron-microscopic studies of plastids in cortical cells of poplar (Populus euramericana cv. gelrica) were carried out to examine whether any structural changes were initiated after breaking of dormancy in midwinter under non-growing conditions. After the breaking of dormancy, ultrastructural changes became evident and the profiles of plastids became heterogeneous. Organelles resembling the “plastid initials” proposed by Mühlenthaler and Frey-Wyssling in 1965 were frequently observed concomitant with changes in the plastid envelope. The formation of “plastid initials” appeared to be initiated by the formation of septa in pre-existing plastids. After this stage, narrow connections appeared between the “initials” and the parent plastids. Approximately 50 days after the breaking of dormancy in late March, further heterogeneity in the profiles of plastids was observed. At this stage, young plastids (plastids without starch granules) were frequently observed and the formation of “plastid initials” was hardly ever observed. These observations suggest that the “plastid initials” may be present for only a limited period in the cortical cells of the poplar and may be the precursors of the proplastids. Similar ultrastructural profiles were found in cortical cells of mulberry and in leaf buds of apple trees, suggesting that such changes in the ultrastructure of plastids are a general feature of perennials.
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    Crown profile of foliage area characterized with the Weibull distribution in a hinoki (Chamaecyparis obtusa) stand (1991)
    Springer
    Trees 5 (1991), S. 149-152 
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    ISSN: 1432-2285
    Keywords: Foliage area profile ; Chamaecyparis obtusa (Sieb, et Zucc.) Endl ; Weibull distribution ; Shape parameter ; Scale parameter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Thirten sample trees of various sizes in a 29-year-old hinoki [Chamaecyparis obtusa (Sieb, et Zucc.) Endl.] plantation were felled and subjected to the stratified clip technique. Crown profile of foliage area fitted well with the Weibull distribution. The crown profile tended to be more skewed toward the top of crowns in smaller trees than in larger trees. This tendency was reflected in the value of the shape parameter of the Weibull distribution. The shape parameter ranged from 1.73 to 3.23 and gradually increased up to an asymptotic value with an increase of stem diameter at breast height. The scale parameter of the distribution ranged from 1.0 to 4.2 and tended to increase in proportion to stem diameter at breast height. Foliage area of a tree correlated well with stem diameter at breast height through an ordinary allometric equation. Tree height could be approximated fairly well by a generalized allometric equation as a function of stem diameter at breast height. On the basis of the census of stem diameter at breast height, canopy profile could be constructed synthesizing crown profiles of foliage area for individual trees in the stand. Leaf area index was estimated to be 6.6 ha ha−1.
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    A survey of seasonal bark proteins in eight temperate hardwoods (1991)
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    Trees 5 (1991), S. 153-157 
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    ISSN: 1432-2285
    Keywords: Bark proteins ; Nitrogen storage ; Hardwoods ; Overwintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Bark proteins of eight temperate hardwoods were analyzed by SDS-PAGE at monthly intervals to determine whether an accumulation of specific proteins, potential storage proteins, occurred in the fall at the time of leaf senescence. Storage proteins were identified as proteins that accumulated during the fall and were present in reduced amounts in the summer. Total protein levels were higher in the winter than in the summer in Fagus sylvatica, Fraxinus americana, Tilia americana, Alnus glulinosa, Betula papyrifera and Querus rubra, but not in Gleditsia triacanthos or Robinia pseudoacacia. Betula contained the most abundant storage protein, although in all species minor bands, which fluctuated seasonally, could be identified. With the exception of Alnus and Betula, results generally correlated with previous microscopy studies of these tree species, which showed varying amounts of protein storage vacuoles present in phloem parenchyma cells during the winter, but not during the summer.
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    Tree vigor and height growth in Black Spruce (1991)
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    Trees 5 (1991), S. 158-163 
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    ISSN: 1432-2285
    Keywords: Specific volume increment ; Waring vigor estimates ; Site quality ; Sapwood respiration ; Photosynthate availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationship between tree height and tree vigor was examined in order to test the hypothesis that increased height results in a reduction in photosynthate availability for growth due to an increase in respiratory load of the sapwood. Various vigor indices were measured on black spruce [Picea mariana (Mill.) B. S. P.] trees on a wide range of sites and ages. The relationship between these vigor indices and tree height and site quality were then evaluated through correlation and regression analyses. Vigor indices based on meristematic activity such as specific volume increment and height growth rate were generally more strongly correlated than foliage based indices (i.e. Waring vigor estimates). Both tree height and site index were found to have a significant effect on specific volume increment and height growth rate. However the height effect decreased with a decrease in site quality, and became insignificant (P 〈0.05) on the poorer sites. The full regression model, allowing the height effect to vary between different site quality groups, explained 82% and 72% of the variability in specific volume increment and height growth rate, respectively. The results support the hypothesis that increases in the ratio of respiration to photosynthesis in trees as they increase in size is largely a function of tree height. Possible explanations for the decreased height effect on poor sites are also discussed.
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    Experiments on the water budget of densely and sparsely needled spruces [Picea abies (L.) Karst.] in a declining stand (1991)
    Springer
    Trees 5 (1991), S. 164-170 
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    ISSN: 1432-2285
    Keywords: Forest decline ; Osmotic potential ; Picea abies ; Water content ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The osmotic potentials of needles were compared from numerous trees that had been classified according to needle loss along an altitude profile. With the increasing degree of damage of the trees, the maximum and minimum values deviated more strongly above and below the common mean of all samples. The level of water content of the needles unequivocally reflected the vitality of the trees. Experiments covering a whole vegetation period were performed on a tree pair selected from a natural stand. They were designed to demonstrate differences in water balance between the “healthy” and “damaged” state of the trees. For the “damaged” tree, measurements of the water potentials of single needles showed a greater reduction of potential during the course of the day compared to the “healthy” tree. Recovery in the evenings was slower and often incomplete. The osmotic potentials of “damaged” and “healthy” shoots measured in individual needles also differed both predawn and especially after transpiration stress. Depending on weather and soil desiccation, the differences were more or less pronounced. In the “damaged” tree, the rises in potential after saturation of the twigs fell far short of the “healthy” tree. Reduction of water potential, osmotic potential and relative water content under comparable stress conditions suggest a reduced tolerance of drought by damaged trees. In the context of earlier experiments this result was ascribed to a lack of stomatal control, and long-term pollution effects were thus explained as a specific disturbance of hydroregulation.
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    Root responses of flood-tolerant and flood-sensitive tree species to soil redox conditions (1991)
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    Trees 5 (1991), S. 180-186 
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    ISSN: 1432-2285
    Keywords: Flood-stress ; Root elongation ; Quercus falcata ; Quercus lyrata ; Taxodium distichum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Under controlled rhizotron conditions, roots of Taxodium distichum L., Quercus lyrata Walt, and Q. falcata var. pagodaefolia Ell. were subjected to low soil redox potentials. Root elongation was inhibited at low soil redox potentials. In T. distichum, redox potentials below +200 mV resulted in a significant inhibition of root elongation. In Q. falcata var. pagodaefolia and Q. lyrata, redox potentials below +350 mV resulted in complete cessation of root growth. Studies on root anatomy indicated that low soil redox potenials resulted in a changed cellular structure in the cortex of T. distichum. However, little change was noted in stress roots of oak species. Alcohol dehydrogenase activity in T. distichum roots was approximately doubled compared to control plants, indicating stimulated alcoholic fermentation. In T. distichum, alcoholic fermentation and anatomical changes contribute to flood tolerance but oak species lack these characteristics.
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    The effect of two growth forms of Norway spruce on stand development and radiation interception: a model analysis (1991)
    Springer
    Trees 5 (1991), S. 171-179 
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    ISSN: 1432-2285
    Keywords: Biomass ; Computer simulation ; Picea abies ; Stand dynamics ; Tree architecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Development of tree and canopy structure, and interception of photosynthetically active radiation (PAR) were studied in two model stands of Norway spruce consisting of trees with rapid versus slow site capture. The tree models were derived using Burger's (1953) sample tree material, from which two subpopulations of dominant trees were selected using the rate of horizontal site capture of the tree crowns as the criterion of division. The development of stand structure and interception of PAR were simulated in the two model canopies. The simulation period covered the period from tree age 15–80 years. The average development of the trees in the two subpopulations proved to be very different. The rapidly expanding trees were characterized by low mean within-crown needle area density and a long crown. The slowly expanding trees were smaller but had a higher mean within-crown needle area density. Up to approximately 40 years of age the stand of rapidly expanding trees contained more leaf area and intercepted more radiation than the stand of slowly expanding trees, when canopy cover was held constant. After 40 years of age this relationship was reversed due to the subsequent decline of leaf area in the stand of rapidly expanding trees and the increase in leaf area in the stand of slowly expanding trees. The biological relevancy and silvicultural implications of the simulated patterns of tree and stand development are discussed.
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    Food reserves of Scots pine (Pinus sylvestris L.) (1991)
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    Trees 5 (1991), S. 187-195 
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    ISSN: 1432-2285
    Keywords: Food reserves ; Pinus sylvestris ; Starch ; Sugars ; Triacylglycerol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The amounts of starch, soluble sugars, triacylglycerols, diacylglycerols and free fatty acids were studied in Scots pine (Pinus sylvestris L.) during an annual cycle in current-year needles and in 1-, 2- and 3-year-old needles collected shortly after bud break. Determination of the compounds was performed using specific enzymatic assays, capillary gas chromatography and thin layer chromatography. Newly emerging needles contained relatively large amounts of starch, but only trace amounts of fat. During autumn and winter, fat content rose, while starch content decreased; amounts of both these reserve materials were very high the next spring shortly before bud break and decreased again during shoot elongation. Concentration of intermediates in triacylglycerol biosynthesis (diacylglycerols and free fatty acids), were low in summer and high in winter. The same pattern was observed for fructose and glucose (the predominant soluble sugars), galactose/arabinose and raffinose/melibiose. In contrast, sucrose concentrations were highest in spring and in autumn. Mature needles of different ages collected in May showed significant differences only in their triacylglycerol and starch content. Concentration changes of reserve materials are discussed in relation to season, mobilization and translocation processes, dormancy, frost resistance and the possibility of carbohydrate-fat interconversions.
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    Protein-storing vacuoles in inner bark and leaves of softwoods (1991)
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    Trees 5 (1991), S. 196-202 
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    ISSN: 1432-2285
    Keywords: Protein-storage vacuole ; Protein body ; Softwoods ; Nitrogen storage ; Overwintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The seasonal occurrence of protein-storage vacuoles in parenchyma cells of the inner bark and leaf tissues of seven softwood species was examined. Previously published results showed that these organelles often fill the phloem parenchyma cells of the inner bark tissues in overwintering hardwoods, whereas they are absent from this tissue during the summer. We hypothesize that the organelles are involved in the storage of reduced nitrogen during wintering, in a manner analogous to protein bodies of seeds. A survey of the phloem and cambial parenchyma tissues in six evergreen softwood species (Pinus strobus, P. sylvestris, Picea abies, P. glauca, Abies balsamea, and Thuja occidentalis) and in one deciduous softwood species (Larix decidua) was conducted. There was a large variation in the degree and timing of protein-storage vacuole formation between the individual genera and species. The organelles were not seen in summer samples of inner bark tissues of any of the genera or species examined. Protein-storage vacuoles were common in the bark tissues of Pinus, Abies and Thuja, occasionally seen in Picea, and rarely found in Larix during the winter. One-year-old leaves were also examined, since in all but Larix they are overwintering structures and can act as potential sites of nitrogen storage. Protein-storage vacuoles were present in Pinus and Thuja leaf tissue in both summer and winter, in Abies during winter only, and were absent from Picea leaf tissue at all times. These results indicate that the formation of protein-storage vacuoles prior to overwintering is not a ubiquitous phenomenon in softwoods.
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    URL: http://dx.doi.org/10.1007/BF00227525
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    Formation of heartwood substances in the stem of Robinia pseudoacacia L. (1991)
    Springer
    Trees 5 (1991), S. 203-207 
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    ISSN: 1432-2285
    Keywords: Chalcone synthase ; Heartwood extractives ; Phenylalanine ammonia-lyase ; Robinia pseudoacacia L. ; Sapwood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The activities of two key enzymes in flavonoid biosynthesis, phenylalanine ammonia-lyase (PAL, E.C. 4.3.1.5) and chalcone synthase (CHS, E.C. 2.3.1.74) were determined in the trunkwood of Robinia pseudoacacia L. The trees under investigation were cut at different times of the year (September, November, January and April). At all times PAL is active, both in the youngest wood layer (the outermost growth ring) and at the sapwood heartwood boundary. On the other hand, CHS is active exclusively in the vicinity of the heartwood boundary. The results indicate that PAL is involved both in the formation of lignin (outermost annual ring), and in flavonoid biosynthesis (heartwood boundary). Highest activity of both PAL and CHS could be measured at the sapwood heartwood boundary in the tree felled in November, indicating that heartwood formation was occurring mainly at that time. The flavonoids accumulated in the heartwood are obviously formed in situ and seem to be transported only to a minor extent — if at all — via the phloem and the ray cells to the heartwood.
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    URL: http://dx.doi.org/10.1007/BF00227526
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    Growth patterns and bending mechanics of branches (1991)
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    Trees 5 (1991), S. 232-238 
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    ISSN: 1432-2285
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227530
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    Influence of needle loss, yellowing and mineral content on monoterpenes in the needles of Picea abies (L.) Karst. (1991)
    Springer
    Trees 5 (1991), S. 208-214 
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    ISSN: 1432-2285
    Keywords: Bavaria ; Disease ; Needle ; (Mono)terpenes ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Monoterpenes in needles of Picea abies (L.) Karst. were studied to reveal whether or not the symptoms of forest decline observed in three mountain regions of South Germany (Bavaria) — needle loss and needle yellowing — are related to changes in the amounts of all or individual terpenes. The nutrient supply of the needles was examined in addition to the terpene concentrations, since the disease symptom montane yellowing is often associated with mineral deficiency. At two of the eight locations, trees exhibited Mg-deficiency, at one location K-deficiency was observed, and at another location the S-content of the needles indicated SO2-pollution. Using various statistical methods of analysis, no correlation was observed between the mineral element content of the needles, the percentage of needle loss and either the absolute or percentile terpene amounts stored within the needles. This finding is independent of needle age, date of sampling and terpene pattern. Concerning needle yellowing, the data show a tendency towards a reduction of the terpene concentrations in needles originating from branches with partly yellow needles compared to needles from exclusively green-needled branches. In spite of the fact that only 2-year-old and older needles show the disease symptom of yellowing, the terpene level is reduced even in still green, juvenile and 1-year-old needles. No terpene was found to be an indicator for early recognition of injury.
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    URL: http://dx.doi.org/10.1007/BF00227527
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    Nitrate levels affect the development of the black locust-Rhizobium symbiosis (1991)
    Springer
    Trees 5 (1991), S. 227-231 
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    ISSN: 1432-2285
    Keywords: Robinia pseudoacacia L. ; Nitrate ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Experiments with black locust (Robinia pseudoacacia L.) seedlings grown under strictly controlled laboratory conditions indicated that the availability of nitrate has a marked impact on nitrogen fixation. When nitrate concentrations were very low, both nodulation and seedling growth were impaired, whereas nitrate concentrations high enough to promote plant growth strongly inhibited symbiotic nitrogen fixation. When nitrate was added to the growth medium after infection, nodulation and nitrogen fixation of the seedlings decreased. This effect was even more marked when nitrate was applied before infection with rhizobia. Higher nitrogen concentrations also reduced nodule number and nodule mass when applied simultaneously with the infecting bacteria. The contribution of symbiotic nitrogen fixation to black locust shoot mass by far exceeded its effects on shoot length and root mass. When nitrate availability was very low, specific nitrogen fixation (i. e. nitrogenase activity per nodule wet weight) was improved with increasing nitrogen supply, but rapidly decreased with higher nitrogen concentrations.
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    URL: http://dx.doi.org/10.1007/BF00227529
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    Nitrate reductase in needles, roots and trunk wood of spruce trees [Picea abies (L.) Karst.] (1991)
    Springer
    Trees 5 (1991), S. 215-226 
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    ISSN: 1432-2285
    Keywords: Picea abies ; Nitrate reductase ; Xylem sap ; Fumigation ; Fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrate reductase (EC 1.6.6.2) activity (NRA), as measured by an in vivo assay, is present in needle leaves and mycorrhizal fine root tips of adult Norway spruce [Picea abies (L.) Karst.] in at least equal amounts on a fresh weight basis, in both adult and 5-year-old trees. NRA could also be demonstrated in trunk wood of deroted trees after fertilization with 5 mM $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ , exhibiting a longitudinal profile in the trunk. Inducibility in needles can more efficiently be achieved by NO2 (100 μg·m-3) than by 5 mM nitrate, which is effective only in root-amputated trees. A remarkably high level of needle-NRA in unfertilized trees, which are characterized by a very low level of nitrate in the xylem sap, suggests that NRA in spruce needles may in part be constitutive. Organic-N is a major nitrogen source for the needles even in root-amputated trees, indicating pronounced exchange processes between ray parenchyma and trunk xylem, which in turn are modified by the nitrogen source fed to the trunk stump. Intact trees exhibit a very similar amino acid composition of the xylem sap, regardless of whether $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ or $${\text{NH}}_{{\text{4}}^{\text{ + }} }$$ has been fed. The amino acid pattern of the needles is not thrown out of balance by “flooding” with $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ and $${\text{NH}}_{{\text{4}}^{\text{ + }} }$$ , which occurs in fertilized derooted trees. This indicates a distinct potential for homoeostasis of nitrogen entrance-metabolism (i.e. NRA and glutamine synthetase activity) in the needles. In the ectomycorrhiza/fine root-system (EMC), marked differences in NRA were observed depending on root-tip diameter and along the longitudinal profile of the fine roots. EMC-nitrate reductase is strongly enhanced by $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ . Needle-NRA exhibits a circannual rhythm. An early summer maximum is followed by a December minimum. This activity pattern matches well the transitory increase of soluble nitrogen in spring and the total protein maximum in winter. In an indirect way assimilatory NRA may well contribute to nitrogen overfertilization (by consumption of NOX) as one possible cause of the contemporary decline of spruce populations.
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    URL: http://dx.doi.org/10.1007/BF00227528
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    Small fruit problem in Citrus trees (1991)
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    Trees 5 (1991), S. 239-243 
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    ISSN: 1432-2285
    Keywords: Citrus sinensis ; Fruit ; Photosynthesis ; Respiration ; Transpiration ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Physiological causes of the small fruit problem which occurs in certain trees of orange [Citrus sinensis (L.) Osbeck cv. Valencia] were investigated in terms of water relations and gas exchange of fruits during early fruit development as well as tree carbohydrate reserves. These data from cv. Valencia trees with and without a small fruit potential were compared with those of the large fruited cv. Navel. Neither fruit water potential nor fruit transpiration nor tree carbohydrate reserves appeared to be a cause of the small fruit. Yield records showed the small fruit to be assocaited with a large number of fruit per tree. However, fruits from cv. Valencia trees with a small fruit potential respired faster than either fruits of the same cultivar and size from trees without the physiological disorder or fruits of the same size of cv. Navel and also exceeded the dark respiration of the respective leaves. Hence, the small fruit problem in cv. Valencia was partly attributed to inefficient fruit photosynthesis, causing excessive respiration of each of a larger number of fruits compared to fruits of a tree of the same cultivar but without the physiological disorder. Fruits of cv. Valencia respired more in their 2 months longer lifetime on the tree relative to those of cv. Navel. It is concluded that orchard management methods will have to be investigated to balance the fruit load of the cv. Valencia tree utilizing the carbon available for fruit growth and to minimise stress during the early fruit development.
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    URL: http://dx.doi.org/10.1007/BF00227531
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    Dormancy in peach (Prunus persica L.) flower buds (1991)
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    Trees 5 (1991), S. 244-246 
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    ISSN: 1432-2285
    Keywords: Peach ; Floral buds ; Vegetative buds ; Morphology ; Phenology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Peach buds (floral and vegetative) were periodically collected from midsummer until the spring flowering and sprouted under continuous light, 100% relative humidity and 20–25°C. Treatments with 200 ppm gibberellin A3 (GA3) or chilling (2–4°C for 30 days before planting) were applied. Vegetative buds showed well-defined phenological stages: pre-dormancy, “true dormancy”, and end of dormancy. Both GA3 and chilling treatments shortened the sprouting times of vegetative dormant buds close to those in predormancy. Isolated floral buds were irresponsive under all conditions and did not sprout even with the GA3 or chilling treatments. In a comparative study with buds immediately after collection anatomical analysis demonstrated that vegetative buds were almost completely developed by midsummer/early automn and remained in a resting state until the end of winter. Floral buds developed continuously over the same period. Both types of verticils began to differentiate in midsummer. Sepals and petals developed mainly in late summer, androecious floral parts developed throughout the resting period, while gynoecious floral parts showed differentiation in late winter. The flower was completely formed a few days prior to blossoming. Thus, in isolated peach buds fertile verticils are not sufficiently developed during the resting time to allow sprouting.
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    URL: http://dx.doi.org/10.1007/BF00227532
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    Net assimilation rate and shoot area development in birch (Betula pendula Roth.) at different steady-state values of nutrition and photon flux density (1992)
    Springer
    Trees 6 (1992), S. 1-6 
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    ISSN: 1432-2285
    Keywords: Nitrogen ; Photon flux density ; Growth ; Betula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Small birch plants (Betula pendula Roth.) were grown in a climate chamber at different, exponentially increasing rates of nitrogen supply and at different photon flux densities. This resulted in treatments with relative growth rate equal to the relative rate of increase in nitrogen supply and with different equilibrium values of plant nitrogen concentration. Nitrogen productivity (rate of dry matter increase per plant nitrogen) was largely independent of nitrogen supply and was greater at higher photon flux density. Leaf weight ratio, average specific leaf area (and thus leaf area ratio) were all greater at better nitrogen supply and at lower values of photon flux density. The dependencies were such that the ratio of total projected leaf area to plant nitrogen at a given photon flux density was similar at all rates of nitrogen supply. The ratio was greater at lower values of photon flux density. At a given value of photon flux density, net assimilation rate and net photosynthetic rate per shoot area (measured at the growth climate) were only slightly greater at better rates of nitrogen supply. Values were greater at higher photon flux densities. Acclimation of the total leaf area to plant nitrogen ratio and of net assimilation rate was such that nitrogen productivity was largely saturated with respect to photon flux density at values greater than 230 μmol m-2 s-1. At higher photon flux densities, any potential gain in nitrogen productivity associated with higher net assimilation rates was apparently offset by lower ratios of total leaf area to plant nitrogen.
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    URL: http://dx.doi.org/10.1007/BF00224491
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    The effects of water and multi-nutrient stress on xylem sap chemistry, photosynthesis and transpiration of seedlings of two Eucalypts (1992)
    Springer
    Trees 6 (1992), S. 7-12 
    Details
    ISSN: 1432-2285
    Keywords: Eucalyptus ; Nutrients ; Photosynthesis ; Transpiration ; Xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ten seedlings each of Eucalyptus kitsoniana Maiden and Eucalyptus globulus Labill. were subjected to two levels of water stress and two levels of nutrient stress (macro and micro-nutrients) in a greenhouse for 3 weeks. The objectives were to determine the degree to which seedlings show differences in sap chemistry, photosynthesis and transpiration that relate to the environments in which these two species live. Whole plants were then extracted for xylem sap using a pressure chamber and the sap was analyzed for 14 elements using an inductively coupled plasma spectrometer and a nitrometer. For E. kitsoniana water and nutrient stress, applied separately or in combination, significantly reduced leaf conductance, transpiration, photosynthesis and midday water potential. Nutrient stress alone had less effect than water stress on most functions measured. Water stress alone reduced the root/shoot ratio; the combination of water and nutrient stress increased the root/shoot ratio, primarily because of reduced shoot weight. In E. kitsoniana, water stress alone or in combination with nutrient stress increased the xylem sap concentrations of B and Si. Multi-nutrient stress alone, or in combination with water stress, significantly decreased sap Zn and K. For this species, sap N was decreased by nutrient stress, but increased by water stress. E. globulus had significantly lower transpiration rates and less root mass than E. kitsoniana. Slightly lower leaf conductance and photosynthesis were not significant in E. globulus compared to E. kitsoniana. Water and nutrient stress reduced conductance, transpiration (except for nutrient stress) and photosynthesis, and the effects of water stress on E. globulus were greater than the effects of nutrient stress. Midday water potential was reduced by water stress. Water or nutrient stress alone did not alter seedling root/shoot ratio, but the combination of water and nutrient stress significantly increased the root/shoot ratio for both species. For E. globulus, sap concentrations of Mn, Na, Si and K were increased by water stress (alone or in combination with nutrient stress). Sap N increased with water stress or combined stresses, but decreased under nutrient stress alone. When the two species were compared, E. globulus generally had lower or similar nutrient concentrations in the sap, with Ca, Mg, Mn and P significantly lower than in E. kitsoniana. Seedlings of these two species show strong site adaptations to water and nutrient availability.
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    In vivo pH measurement in the xylem of broad-leaved trees using ion-sensitive field-effect transistors (1992)
    Springer
    Trees 6 (1992), S. 13-18 
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    ISSN: 1432-2285
    Keywords: pH value ; Broad-leaved trees ; Xylem ; ISFET ; Sensor ; pH measurement ; Long-term measurement ; In vivo measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A new method of in vivo pH determination in the xylem of broad-leaved trees using ion-sensitive field effect transistors is developed and its suitability for use is studied. In the first few hours after the sensor had been implanted in the xylem signals could be detected which were generated in response to mechanical damage; particularly strong signal changes are detectable in Populus balsamifera L., Tilia cordata Mill, and Aesculus hippocastanum L. The pH values of the xylem sap extracted from branches corresponded to the values measured by the in vivo method only at certain times. Due to sensor drift the measuring accuracy of long-term experiments lasting up to 3 weeks is restricted. The in vivo measurement of pH in the xylem of poplar branches revealed the ability of the living xylem to buffer the pH of the sap to its own characteristic value.
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    URL: http://dx.doi.org/10.1007/BF00224493
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    Water holdup capacity and residence time of red spruce and balsam fir branches (1992)
    Springer
    Trees 6 (1992), S. 10-27 
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    ISSN: 1432-2285
    Keywords: Throughfall ; Red spruce ; Balsam fir ; Wettability ; Acid precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study examined the throughfall dynamics of high-elevation red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] branches. A site was established at an elevation of 1160 m on Mt. Washington, New Hampshire, USA, and branches were collected from the canopies of mature trees. Throughfall water dynamics of branches collected in September 1988 and March 1989 were determined using a fluorescent tracer in an artificial precipitation apparatus. Water holdup capacities of spruce and fir branches from different canopy positions were similar. Spruce retained more water per unit area than fir. For rain, a three-compartment model that was used to analyze water dynamics showed that the bulk of water initially on the branch experienced very slow turnover, while intercepted water left the branch quickly. There did not appear to be any difference in throughfall dynamics between spruce and fir. Our results suggest that the initial composition of rain and mobilized dry deposition will influence the composition of water in contact with the branch for a relatively long time, as branch water composition will respond slowly to changes in precipitation composition. These predictions require field testing where sequential sampling of throughfall and precipitation occurs on a time scale equivalent to 0.1–0.2 mm of precipitation.
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    Gas exchange and canopy structure of 9-year-old loblolly pine, pitch pine and pitch x loblolly hybrids (1992)
    Springer
    Trees 6 (1992), S. 28-31 
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    ISSN: 1432-2285
    Keywords: Canopy leaf surface area ; Gas exchange ; Pinus rigida x taeda ; Silhouette area ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seasonal gas exchange and canopy structure were compared among 9-year-old loblolly pine (Pinus taeda L.), pitch pine (Pinus rigida Mill.), and pitch x loblolly hybrids (Pinus rigida x taeda) growing in an F2 plantation located in Critz, Va., USA. Leaf net photosynthesis, conductance, internal CO2 concentration (ci), water use efficiency (WUE; photosynthesis/conductance), dark respiration and the ratio of net photosynthesis/respiration did not vary among or within the three taxa. Significant differences in volume production, crown length, total crown leaf surface area and the silhouette area of shade shoots among the taxa were observed. The loblolly-South Carolina source had greater volume and crown surface area than the pitch pine, and the hybrid taxa were intermediate between the two. Although the silhouette area ratio of shade foliage varied among taxa, it was not related to volume. A strong relationship between total leaf surface area and volume was observed. Leaf conductance, ci, WUE and leaf water potential were the physiological parameters significantly and positively correlated with volume. This study suggests that the amount of needle surface in the canopy is more important in early stand volume growth than the leaf carbon exchange rate and the degree of needle self-shading in the lower canopy.
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    Partition coefficients of plant cuticles for monoterpenes (1992)
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    Trees 6 (1992), S. 32-36 
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    ISSN: 1432-2285
    Keywords: Abies ; Cuticle ; Monoterpene ; Octanol/water partition coefficient ; Picea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Cuticle/water partition coefficients (Kc/w) for d-limonene, α-pinene and β-pinene were determined by an extrapolation and a desorption method. The sorption experiments were carried out with isolated angiosperm and gymnosperm cuticles and with [14C]-labelled monoterpenes, which were obtained biosynthetically. Both methods were suitable for the determination of the Kc/w of volatile hydrophobic compounds. For the angiosperm cuticles the partition coefficients are of the order of 104, which indicates a high accumulation of monoterpenes in the cuticle. The values of the conifer cuticles of Picea abies (L.) Karst. and Abies alba Mill., however, are lower due to their high lignin content. This is proved by the increase of the partition coefficients after removal of polar and phenolic components. The Kc/w can be estimated with good accuracy from the octanol/water partition coefficient, which was determined experimentally.
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    Localization of a storage protein in the wood ray parenchyma cells of Taxodium distichum (L.) L. C. Rich. by immunogold labeling (1992)
    Springer
    Trees 6 (1992), S. 37-40 
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    ISSN: 1432-2285
    Keywords: Taxodium distichum ; Immunoblotting ; Immunogold labeling ; Ultrastructure of wood ray cells ; Protein storing vacuoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ultrastructural investigations showed the occurrence of electron-dense intravacuolar aggregations in wood ray cells of Taxodium distichum (L.) L. C. Rich, during the dormant season. Such aggregations were missing in summer. By SDS-PAGE of the crude protein extract of Taxodium, a prominent protein of about 35 kDa was detected before budbreak. This protein disappeared at the time when the new shoots had fully grown out. An antibody was raised against this “storage protein”. In the immunoblot the antibody reacted specifically with the 35 kDa protein. At the electron-microscope level, by immunogold labeling, the electron-dense intravacuolar aggregations were identified as the specific storage sites for the 35 kDa protein. Thus, these vacuoles proved to be “protein storing vacuoles”.
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    Physiological responses of Pinus sylvestris to atmospheric ammonia (1992)
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    Trees 6 (1992), S. 48-53 
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    ISSN: 1432-2285
    Keywords: Air pollution ; Ammonia ; Assimilation of carbon dioxide ; Transpiration ; Drought stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Young saplings of Pinus sylvestris were fumigated for 3 months with ammonia in concentrations ranging from 0 to 240 μg m-3. Despite the much higher concentrations than normal in the field, no visible damage occurred. Photosynthesis, dark respiration, transpiration and biomass production were stimulated. At 240 μg m-3 with high irradiance (PAR: 950 μmol m-2 s-1), net photosynthesis was stimulated by 24% and dark respiration by 76%. Intitial light use efficiency was not significantly affected. Transpiration increased, both in the dark and at 950 μmol m-2 s-1 by 40% and 57%, respectively. In the presence of ammonia, stomatal control was less efficient. Though growth of roots was not affected by NH3, that of current year needles was stimulated, resulting in an increased mass ratio of needles to roots. The nitrogen content of the needles increased, but the contents of other mineral components did not change significantly. Due to increased transpiration per unit of needle area and increased mass of needles per tree, water loss per tree was about twice as high in the treatment with 240 μg m-3 as in the control. Towards the end of fumigation, a 10-day period without water supply followed and then the water potential of the shoots was measured as an indicator of water demand. This demand was higher with higher concentrations of NH3, suggesting a higher risk of injury from drought.
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    Changes in chlorophyll fluorescence and chlorophyll content in suppressed Norway spruce [Picea abies (L.) Karst.] in response to release cutting (1992)
    Springer
    Trees 6 (1992), S. 41-47 
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    ISSN: 1432-2285
    Keywords: Release cutting ; Chlorophyll fluorescence ; Chlorophyll ; Stress reactions ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In order to study physiological strain caused by release cutting, suppressed Norway spruce on mesic and moist sites was completely released from overstory birch, or 500 birches per hectare were left as a shelter. The treatments were conducted in late June in 1988 and in 1989. The spruce's reaction to the environmental change was monitored by measurements of fast chlorophyll fluorescence kinetics and analysis of chlorophyll content. This was done before treatment, 1 week after treatment, 2 months after treatment, and twice during the following growth period. Complete release resulted in a more pronounced decrease in the ratio of variable fluorescence to maximal fluorescence (Fv/Fm) than partial release. There was also a tendency for the build-up of chlorophyll content in needles to be more affected when the spruce was completely released. Released spruces on moist sites tended to be more affected by the release than released spruces on mesic sites. The results suggest that in this kind of stand the risk of damage to the spruces is greatest when the spruces are completely released on moist sites. Furthermore, it is shown that the weather conditions prevailing shortly before and after the release have a large influence on the spruce's reaction to the release. The results also indicate some adjustment to the new environment in mature needles.
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    Phytoalexins of woody plants (1992)
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    Trees 6 (1992), S. 55-68 
    Details
    ISSN: 1432-2285
    Keywords: Woody plants ; Host-pathogen systems ; Phytoalexins ; Stress metabolites ; Antimicrobial activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Phytoalexins accumulated in selected woody plants in response to microbial attack or stress are reviewed and listed with respect to their chemical structure and probable biogenetic origin. The host-pathogen systems from which they have been isolated are described. The review also considers the antimicrobial activity of the phytoalexins to the causal pathogens and other microorganisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226582
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  • 88
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    Seasonal growth, δ13C in leaves and stem, and phloem structure of birch (Betula pendula) under low ozone concentrations (1992)
    Springer
    Trees 6 (1992), S. 69-76 
    Details
    ISSN: 1432-2285
    Keywords: Ozone ; Betula pendula ; Growth analysis ; δ13C ; Phloem structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The growth of potted birch cuttings (one clone of Betula pendula) was studied under low O3 concentrations (0, 0.050, 0.075, 0.100 μl l-1) throughout an entire growing season. With increasing O3 dose, 20–50% of all leaves formed were prematurely shed, while 40–70% of the remaining foliage displayed advanced discoloration by the end of the season. Ozonation affected the S, P and N concentration of leaves and increased δ13C in leaves and stem, while the CO2 assimilation rate declined with increasing CO2 concentration in mesophyll intercellulars. While whole-plant production correlated negatively with the O3 dose, ozone increased the specific leaf weight (i.e. leaf weight/leaf area, SLW) but decreased the ratios of stem weight/stem length and root/shoot biomass. Neither the latter ratio nor SLW changed in experimentally defoliated control plants, whereas in ozonated plants starch accumulated along leaf veins and phloem tissue was deformed in the leaf petioles and the stem. Only in early summer was the relative growth rate higher in the ozonated than in the control plants. The ratio of whole-plant biomass production versus total foliage area formed was lowered under O3 stress. However, when relating biomass to the actual foliage area present due to leaf loss, this ratio did not differ between treatments. Similarly the ratio of actual foliage area versus basal stem area in cross-section did not differ. Overall, whole-plant production was strongly determined by O3-caused changes in crown structure and began to be limited at O3 doses (approximately 180 μl l-1 h) similar to those of rural sites in Central Europe.
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    URL: http://dx.doi.org/10.1007/BF00226583
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  • 89
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    Root system analysis of seedlings of seven tree species from a tropical dry forest in Mexico (1992)
    Springer
    Trees 6 (1992), S. 77-82 
    Details
    ISSN: 1432-2285
    Keywords: Tropical deciduous forest ; Tree seedlings ; Root morphology ; Growth analysis ; Legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Root attributes of tree seedlings of seven species from the tropical deciduous forest along the Pacific Coast of Mexico are described using morphometirc root system analysis. Mean relative growth rate, root/shoot ratios, specific root length, root density, mean number of roots tips and root length/leaf area ratio were determined in seedlings grown for 35 days inside growth chambers. All the species had low relative growth rates, low root/shoot ratios and low root densities (〈0.5 cm/cm3). The species associated with disturbed habitats, in contrast to the species characteristic of undisturbed areas, presented small seeds, a dichotomous root branching pattern and large specific root length. No relationship was found between seed size and mean relative growth rate among the species studied.
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    URL: http://dx.doi.org/10.1007/BF00226584
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  • 90
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    Interactions between Cylindrocarpon destructans and ectomycorrhizas of Picea abies with Laccaria laccata and Paxillus involutes (1992)
    Springer
    Trees 6 (1992), S. 83-90 
    Details
    ISSN: 1432-2285
    Keywords: Cylindrocarpon destructans ; Picea abies ; Laccaria laccata ; Paxillus involutus ; Protection by mycorrhizas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In paired cultures with two mycorrhizal fungi, the root pathogen Cylindrocarpon destructans (Zinsm.) Scholten had an inhibitional effect on mycelial growth of Laccaria laccata (Scop, ex Fr.) Bk. & Br. but was inhibited itself by Paxillus involutes (Batsch.) Fr. A similar pathogen-symbiont interaction scheme was observed in triaxenic cultures with Picea abies Karst. seedlings but only in the vicinity of the mycorrhizal root tips. Both mycorrhizas similarly increased the endogenous plant resistance against the infection of C. destructans. This suggests that direct pathogen-symbiont interactions are an important factor for population dynamics in the mycorrhizo sphere. Moreover, endogenous plant resistance constitutes one of the key factors for an effective defence against pathogenic fungi.
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    URL: http://dx.doi.org/10.1007/BF00226585
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  • 91
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    Changes in photosynthetic activity of buds and stem tissues of Fagus sylvatica during winter (1992)
    Springer
    Trees 6 (1992), S. 91-95 
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    ISSN: 1432-2285
    Keywords: Fagus sylvatica ; Chlorophyll fluorescence ; Dormancy ; Photosynthesis ; Seasonal variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The photosynthetic activity of leafless twigs and buds of Fagus sylvatica was determined by in vivo chlorophyll fluorescence from November to May. Measurements were made on the day of sampling, and during exposure to warm temperatures until reactivation was attained. Under the same conditions, bud development and growth were forced by exposure of cut twigs to 25/18° C at long-day conditions, and bud swelling and bud burst were monitored. Winter inactivation of photosynthesis results in a reduction of the photochemical efficiency of PS II, as indicated by lowering of FV/FM, from January through March. The greatest reduction is in cortical chlorenchyma, the least in folded leaflets and primordia of buds. Restoration of photosynthetic activity, brought about by warming, needed 3–4 weeks in cortex and 1–2 weeks in buds during the coldest period of winter. Frequency distributions based on three types of chlorophyll fluorescence transients, defined by quantitative fluorescence parameters, have proved to be a valuable method for a differentiated expression of the unequal functional activation states of parallel samples. The seasonal course of winter inactivation of photosynthesis did not correspond entirely with the depth of bud dormancy as revealed by the forcing treatments; inactivation of photosynthesis may be more closely synchronized with changes in frost hardiness; possible causes are discussed. We suggest, therefore, that a distinction should be made between inactivation of metabolic processes and depth of dormancy, even though these processes are inherently interrelated.
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    URL: http://dx.doi.org/10.1007/BF00226586
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  • 92
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    Seasonal changes in CO2 and H2O gas exchange of young European beech (Fagus sylvatica L.) (1992)
    Springer
    Trees 6 (1992), S. 96-102 
    Details
    ISSN: 1432-2285
    Keywords: Fagus sylvatica L ; Photosynthesis ; Transpiration ; Diurnal and annual courses ; Quantum yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The CO2 and H2O gas exchange of young beech trees (Fagus sylvatica L.) were measured over a growing season. Of particular interest was the adaptation of gas exchange to the low level of photon flux density in the understorey of the old beech. The recorded diurnal courses were subdivided into several classes of irradiance. The most frequent class was from only 30–40 μE * m-2 * s-1. Even at the highest irradiance values, no light saturation in assimilation occurred. The light compensation point lies below 3 μE * m-2 * s-1, because net dark respiration values are very low. Calculated from the initial slope of the light response curves a mean value of 0.02 mol CO2 * mol photons-1 shows a very efficient use of light be the young trees. At the optimal phase of assimilation, the relationship between the daily sum of irradiance and net photosynthesis is highly significantly correlated. Under the local climatic situation, the stomatal opening primarily depends on irradiance. In response to a change in irradiance, stomatal opening also changes rapidly. Therefore, there is only a loose relationship between transpiration rate and vapour pressure saturation deficit. Towards autumn, the transpiration coefficient (E/A-ratio, estimated under light saturation) increases strongly because net photosynthesis decreases simultaneously.
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    URL: http://dx.doi.org/10.1007/BF00226587
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  • 93
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    Determination of water sorption by cuticles isolated from fir tree needles (1992)
    Springer
    Trees 6 (1992), S. 109-114 
    Details
    ISSN: 1432-2285
    Keywords: Water content ; Water permeability ; Partition coefficient ; Sorption isotherm ; Plant cuticle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The water sorption by isolated cuticles from needles of Abies alba was measured between 4% and 80% relative humidity using a magnetic suspension microbalance. The sorption isotherms were not linear and sorption increased more rapidly at the lowest and highest values of relative humidity. The mean values, calculated for 1- to 5-year-old adaxial cuticles developed from 1984 to 1988, increased from 2.9% to 17.1% of the dehydrated weight, and from 4% to 80% relative humidity. Results did not depend on the age of needles and the comparison between healthy and declining trees revealed no major difference in water sorption by cuticles isolated from these two types of trees. Data are discussed in relation to cuticular permeability and one determinant of water permeability, the partition coefficient relating the equilibrium water concentration of the cuticle to that of the surrounding atmosphere, was calculated.
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    URL: http://dx.doi.org/10.1007/BF00226589
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  • 94
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    Tree-ring element analysis of Korean pine (Pinus koraiensis Sieb. et Zucc.) and Mongolian oak (Quercus mongolica Fisch. ex Turcz.) from Changbai Mountain, north-east China (1992)
    Springer
    Trees 6 (1992), S. 103-108 
    Details
    ISSN: 1432-2285
    Keywords: Nutrient elements ; Pinus koraiensis Sieb. et Zucc ; Quercus Mongolica Fisch. ex Turcz ; Trace elements ; Tree rings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tree-ring analysis of 17 elements (Pb, Cd, Cu, Zn, As, Cr, Ti, Ni, V, Mn, Fe, Al, Ca, Mg, K, Na and P) was performed on Korean pine (Pinus koraiensis Sieb. et Zucc.) and Mongolian oak (Quercus mongolica Fisch. ex Turcz.) specimens from Changbai Mountain, a remote nature reserve in north-east China. The radial distribution patterns of Pb, Cu, Cr, Ti, Ni, V, As and Fe for both Korean pine and Mongolian oak were similar: concentrations remained generally constant in tree-ring intervals spanning approximately 200 years. These temporal patterns were in accordance with the known stability of the local ecological environment during this period. However, the other elements showed characteristic distribution patterns that differed between Korean pine and Mongolian oak. These patterns can only be interpreted in terms of physiological results; specifically they appeared to be related to the sapwood-heartwood conversion.
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    URL: http://dx.doi.org/10.1007/BF00226588
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  • 95
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    The effects of ultraviolet-B radiation on loblolly pine (1992)
    Springer
    Trees 6 (1992), S. 115-120 
    Details
    ISSN: 1432-2285
    Keywords: Growth ; Loblolly pine ; Ozone depletion ; Pinus taeda ; Ultraviolet-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Depletion of stratospheric ozone and the resulting increase in ultraviolet-B (UV-B) radiation may negatively impact the productivity of terrestrial ecosystems. This concern has led to a number of studies that report the influence of supplementing UV-B radiation on plant growth and development. However, only two of these field studies have included tree species and both were singleseason experiments. In this study, loblolly pine (Pinus taeda L.) from seven seed sources was grown under natural and supplemental levels of UV-B radiation. Irradiation treatments were continued for three seasons on plants from four of the seven groups and for 1 year only for three groups. The supplemental irradiances simulated those that would be anticipated with stratospheric ozone reductions of 16% and 25% over Beltsville, Md. The effects of UV-B radiation during the 1st year on plant growth varied among the seed sources. The growth of plants from two of the seven seed sources tested showed significant reductions following a single irradiation season and plants from one group tended to be larger under increased UV-B radiation. However, after 3 years of supplemental irradiation, plant biomass was reduced in all four groups by 12–20% at the highest simulated ozone depletion. These results suggest that the effects of UV-B radiation may accumulate in trees and that increased UV-B radiation could significantly reduce the growth of loblolly pine over its lifetime. However, they also point to a need for multiple season research in any analysis of potential consequences of global change on the long-term growth of trees.
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    URL: http://dx.doi.org/10.1007/BF00202426
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  • 96
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    Structural aspects of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] tuberculate ectomycorrhizae (1992)
    Springer
    Trees 6 (1992), S. 137-146 
    Details
    ISSN: 1432-2285
    Keywords: Pseudotsuga ; Tubercles ; Ectomycorrhiza ; Calcium oxalate ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tubercles of Pseudotsuga menziesii consisted of clusters of ectomycorrhizae surrounded by a peridiumlike rind. Energy dispersive spectroscopy demonstrated that crystals found in the zone of loose hyphae extending from the inner rind to the mantle of each root probably contain calcium oxalate. Inner mantle and Hartig net hyphae showed a labyrinthine branching pattern and stored carbohydrates and protein. The Hartig net formed up to inner cortical cells which had thickened, darkly stained walls. Bacteria were located either along with hyphae within the rind or as colonies on the surface of the tubercle.
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    URL: http://dx.doi.org/10.1007/BF00202429
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  • 97
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    Assessment of transpiration estimates for Picea abies trees during a growing season (1992)
    Springer
    Trees 6 (1992), S. 121-127 
    Details
    ISSN: 1432-2285
    Keywords: Heat balance method ; Canopy conductance ; Sap-flow rate ; Penman-Monteith equation ; Scaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The tree-trunk heat balance method with internal heating and sensing of temperature was used to estimate sap-flow rate of spruce trees in a stand in southern Sweden. Sap-flow rate values were scaled up to stand transpiration and utilised for calculation of canopy conductance. The calculated values provided the basis for a function relating canopy conductance to vapour pressure deficit, which was implemented in the Penman-Monteith equation. The stand was mostly growing in non-limiting soil water conditions (irrigation regime applied during dry periods). The whole-season transpiration was assessed by two different approaches and then compared: the sap-flow rate measurements were scaled to stand transpiration and the adapted Penman-Monteith estimate. They gave similar results: the transpiration totals differed by 3% and the coefficient of determination of the linear regression was r2 = 0.89. Similarly good was the assessment for a set of rainy days. The Penman-Monteith estimate adapted in this way proved to be reasonably precise and reliable in this forest stand and usable even in wet conditions. The seasonal transpiration of the spruce stand was 392 mm according to the adapted Penman-Monteith equation. Mean daily transpiration was 1.8 mm and daily maximum transpiration was 4.8–4.9 mm as estimated by sap-flow rate measurements.
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    URL: http://dx.doi.org/10.1007/BF00202427
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    The influence of ozone on the stomatal and non-stomatal limitation of photosynthesis in Norway spruce, Picea abies (L.) Karst, exposed to soil moisture deficit (1992)
    Springer
    Trees 6 (1992), S. 128-136 
    Details
    ISSN: 1432-2285
    Keywords: Norway spruce ; Ozone ; Photosynthesis ; Stomatal limitation of photosynthesis ; Drought stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Norway spruce, Picea abies (L.) Karst., was exposed to charcoal-filtered air (CF) and non-filtered air + ozone (NF+) and periods of soil moisture deficit from 1985 to 1988 in open-top chambers. Net photosynthesis, stomatal conductance, needle water potential and various shoot properties were measured on 1-year-old shoots during a period of soil moisture deficit. The gas exchange was measured at saturating photosynthetic photon flux density and across a range of CO2 concentrations. The soil moisture deficit induced a mild drought stress in the plants, expressed by a pre-dawn needle water potential of approximately-0.9 MPa and a substantial reduction in net photosynthesis and gas phase conductance. In the CF treatment, intercellular CO2 concentration was reduced, but was unaffected in the NF+ treatment. Furthermore, net photosynthesis declined more in response to the soil moisture deficit in the NF+ treatment than in the CF treatment. This is suggested to be attributed to the carboxylation efficiency at the operating point, which was decreased by 47% and 64% in shoots from the CF and the NF+ treatments, respectively. Stomatal limitation of net photosynthesis was increased by drought by 24–45% in the CF treatment, while it was unaffected in the NF+ treatment. Thus, our results imply that the coupling between the stomatal conductance and the photosynthetic rate was changed and that the marginal cost of water per given amount of carbon gain will increase in trees exposed to ozone, during periods of drought.
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    URL: http://dx.doi.org/10.1007/BF00202428
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    Longevity and senescence of needles in Pinus cembra L. (1992)
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    Trees 6 (1992), S. 156-161 
    Details
    ISSN: 1432-2285
    Keywords: Pinus cembra ; Needle longevity ; Needle senescence ; Nutrient elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Needle development has been investigated in Pinus cembra at several locations in the Grisons. Special attention has been paid to longevity and senescence. Despite large variations from one tree to another, longevity (up to 12 years) appeared to increase with increasing altitude. With increasing age, contents of nutrients such as N, P, K and, to a lesser extent, Mg and S tend to decrease. Photosynthetic activity did not decline with increasing age of short shoots. Senescence begins in mid-August in needles of the oldest age classes. It is associated with the mobilization and withdrawal of large proportions of N, P, K and also Mg and S, but Ca appears to be immobile. The extent of yellowing is irregular in individual trees but needle losses on a large scale are followed by reduced losses in subsequent years.
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    URL: http://dx.doi.org/10.1007/BF00202431
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    Food reserves of scots pine (Pinus sylvestris L.) (1992)
    Springer
    Trees 6 (1992), S. 147-155 
    Details
    ISSN: 1432-2285
    Keywords: Pinus sylvestris ; Starch ; Sugars ; Triacylglycerols ; Xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Starch, soluble sugars, triacylglycerols, diacylglycerols and free fatty acids were measured in 30-year-old Scots pine (Pinus sylvestris L.) trees during an annual cycle in the sapwood (youngest ten xylem rings). The radial distribution of carbohydrates and lipids was studied in the trunkwood of 90 -to 150-year-old Scots pine trees collected at the end of the growing season. Determination of the compounds was performed using specific enzymatic assays, capillary gas chromatography and thin layer chromatography. The amounts of glucose, fructose, sucrose, and galactose/arabinose in the sapwood were slightly higher in winter than in summer. Raffinose/stachyose increased up to 5-fold during the cold period. At the beginning of the growing season starch amounts rose, and then decreased in summer and autumn. No concentration changes were observed in the total amounts of diacylglycerols and fatty acids throughout the year. Triacylglycerol levels were slightly higher in February than in summer and autumn. Relative frequencies of individual fatty acids were similar in all lipid fractions. Glucose, fructose, sucrose, starch and triacylglycerols disappeared almost entirely at the transition zone from sapwood to heartwood. In contrast, free fatty acids and galactose/arabinose rose in centripetal direction, and diacylglycerols remained constant across trunk cross-sections. The relative amounts of individual fatty acids changed markedly in the free fatty acid fraction and in the triacylglycerols when crossing the sapwood-heartwood boundary. Concentration changes of reserve materials are discussed in relation to season, mobilization and translocation processes, dormancy, frost resistance, and heartwood formation. The results are compared to those found in needles.
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    URL: http://dx.doi.org/10.1007/BF00202430
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