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51.
Barbara Moser Christoph Bachofen Jonathan D. Müller Marek Metslaid Thomas Wohlgemuth 《Annals of Forest Science》2016,73(4):959-970
Key message
Pinus sylvestris seedlings quickly expand their roots to deeper soil layers while Pseudotsuga menziesii concentrates its root system in the topsoil, thereby running the risk of desiccation during long dry spells, as indicated by lower survival after simulated summer drought.Context
Pseudotsuga menziesii (Douglas-fir) is regarded as a promising species to maintain the productivity of Central European lowland forests given the projected increase of long dry spells.Aims
Will the species be able to regenerate from seed and spread outside plantations in a drier temperate Europe?Methods
We measured the relative growth rate, biomass allocation, root architecture, and phenotypic plasticity of Pseudotsuga menziesii seedlings sown in a common garden and grown under current precipitation and prolonged drought, respectively. The species’ competitive ability with respect to Pinus sylvestris L., the most drought-tolerant native conifer in Central Europe, was assessed during three growing seasons.Results
Pinus sylvestris seedlings had higher relative growth rates than did Pseudotsuga menziesii seedlings, first in terms of aboveground biomass and later in terms of shoot height. This resulted in heavier and taller seedlings after three growing seasons under both moist and dry conditions. Shorter vertical roots corresponded with lower survival of Pseudotsuga menziesii seedlings under dry conditions.Conclusion
Fast root proliferation allows Pinus sylvestris seedlings to reach deeper water pools that are less rapidly depleted during transient drought. By contrast, the shallow root system might put Pseudotsuga menziesii seedlings at the risk of desiccation during prolonged dry spells.52.
Sabine Augustin Jan Evers Hans-Peter Dietrich Johannes Eichhorn Thomas Haussmann Regina Icke Ansgar Isenberg Wolfgang Lux Monica Musio Hans Pretzsch Winfried Riek Thomas Rötzer Bernd Schultze Andreas Schulze Jörg Schröder Walter Seidling Nicole Wellbrock Klaus von Wilpert Barbara Wolff 《European Journal of Forest Research》2005,124(4):251-260
In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and
other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system
in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse
effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary
air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring
was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and
feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal
Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives
of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification
and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading
to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected
level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis
(crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative,
as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the
extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.
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53.
Jennifer D. Knoepp Barbara C. Reynolds D.A. Crossley Wayne T. Swank 《Forest Ecology and Management》2005,220(1-3):300-312
Soil nutrient concentrations decreased in an aggrading southern Appalachian forest over a 20-year period. Construction of nutrient budgets showed significant nutrient sequestration aboveground including increased forest floor mass. We hypothesized that the changes in forest floor mass resulted from decreased litter decomposition rates because of decreased litter quality. In 1992 and 1993, we repeated a litter decomposition experiment conducted in 1969 and 1970 to test this hypothesis. In addition, we examined microarthropod populations and functional groups as litter decomposed. For four of the five species tested, first-year decomposition rates were about the same in both experiments. Initial litter nutrient concentrations of P were lower in all tree species in the most recent sampling. N, Ca, and Mg concentrations also declined in some species. These declines often resulted in decreased nutrient release rates during decomposition. Microarthropod populations differed significantly among litter species, as well as between years (probably resulting from differences in growing-season rainfall). For some litter species we found significant relationships between microarthropod populations and nutrient concentration (primarily C and N); however, most r2-values were low. Data suggest that changes in forest floor mass probably resulted from decreased litter quality and that those changes may have an effect on microarthropod populations. 相似文献
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Surface Electromyography of the Vastus Lateralis,Biceps Femoris,and Gluteus Medius Muscle in Sound Dogs During Walking and Specific Physiotherapeutic Exercises 
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