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61.
Zusammenfassung Ziel des Projekts ist die Erarbeitung spektraler Rückstrahlungscharakteristiken von Einzelb?umen und Bestandesoberfl?chen
zur Erfassung und kontinuierlichen Beobachtung von Vitalit?tsunterschieden bzw. Sch?digungen an Waldb?umen, insbesondere an
Fichten. (Ammer et al. 1983;Hildebrandt 1976). Die für die Spektroradiometermessungen wichtigen objektunabh?ngigen Einflu?parameter wie Sonnenstand, Me?richtung,
Neigungswinkel, ?ffnungswinkel und Beleuchtungsverh?ltnisse sind durch eine Vielzahl von Voruntersuchungen bestimmt worden.
Erste Me?ergebnisse an Testfl?chen im H?glwald und im Erbersberger Forst lassen deutliche Reaktionen im Spektralverhalten
erkennen, die auf Vitalit?ts- und ph?nologische Unterschiede zurückgeführt werden k?nnen.
Beitrag Nr. 16 der H?glwald-Serie 1986 相似文献
Judging vigor of spruces on the basis of spectral reflection measurements
Summary Objective of the research project is the evaluation of characteristic spectral signatures for single trees and stands to assess and continuously monitor differences in vigor, or damages of trees, respectively, especially for spruce. The object-independent parameters which are important for the spectro-radiometer measurements, such as angle and elevation of the sun, inclination, measuring direction, angle of view, and illumination have been determined by numerous previous investigations. First results from the testsites “H?glwald” and “Ebersberger Forst” show distinct differences in the spectral curves which can be related to different degrees of vigor and phenology.
Beitrag Nr. 16 der H?glwald-Serie 1986 相似文献
62.
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.63.
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 下载免费PDF全文
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