Search results for "Picea abies"
showing 10 items of 97 documents
Parastās egles Picea abies L. ietekme uz mālsmilts augsnes virskārtas īpašībām bijušajās lauksaimniecībā izmantojamā zemē Taurenes apkārtnē
2016
Latvijā, kā arī citās Eiropas valstīs pēc 1990. gada strauji palielinājās pamesto lauksaimniecībā izmantojamo zemju(LIZ) platības. Zemju neapsaimniekošanas dēļ uz bijušajām LIZ attīstījās sekundārā sukcesija un apmežošanas process. Apmežošanas izraisa veģetācijas, mikroklimata un augsnes īpašību izmaiņas uz bijušajām LIZ zemēm. Pētījuma mērķis ir noskaidrot egles (Picea abies L.) ietekmi uz augsnes īpašībām (ķīmiskajām, morfoloģiskajām, fizikālajām) Taurenes apkārtnē, Vidzemē. Bakalaura darbā tika apkopotas dabiskās un antropogēnās ietekmes uz bijušo LIZ apmežošanas procesu. Pētījuma rezultāti rāda, ka parastā egle ietekmē apmaiņas katjonu koncentrāciju augsnē un to telpisko izplatību mālsm…
Microbial Community Structure and Density Under Different Tree Species in an Acid Forest Soil (Morvan, France)
2005
Overexploitation of forests to increase wood production has led to the replacement of native forest by large areas of monospecific tree plantations. In the present study, the effects of different monospecific tree cover plantations on density and composition of the indigenous soil microbial community are described. The experimental site of "Breuil-Chenue" in the Morvan (France) was the site of a comparison of a similar mineral soil under Norway spruce (Picea abies), Douglas fir (Pseudotuga menziesii), oak (Quercus sessiflora), and native forest [mixed stand dominated by oak and beech (Fagus sylvatica)]. Sampling was performed during winter (February) at three depths (0-5, 5-10, and 10-15 cm…
Inspired by nature: Fiber networks functionalized with tannic acid and condensed tannin-rich extracts of Norway spruce bark show antimicrobial effica…
2023
This study demonstrated the antibacterial and antiviral potential of condensed tannins and tannic acid when incorporated into fiber networks tested for functional material purposes. Condensed tannins were extracted from industrial bark of Norway spruce by using pressurized hot water extraction (PHWE), followed by purification of extracts by using XADHP7 treatment to obtain sugar-free extract. The chemical composition of the extracts was analyzed by using HPLC, GC‒MS and UHPLC after thiolytic degradation. The test matrices, i.e., lignocellulosic handsheets, were produced and impregnated with tannin-rich extracts, and tannic acid was used as a commercial reference. The antibacterial and antiv…
The accumulation of proline in needles of damaged spruces
1985
Im Rahmen einer vergleichenden physiologischen und cytologischen Charakterisierung geschadigter und schadsymptomfreier Fichten am naturlichen Standort wurden im Spatsommer und Herbst 1984 erste Untersuchungen zum Wasserhaushalt der Baume durchgefuhrt. Messungen des Gesamtwasserpotentials, des osmotischen Potentials, des Gehaltes an verschiedenen Kohlenhydraten und an der freien Aminosaure Prolin deuten auf Veranderungen im Wasserhaushalt geschadigter Fichten. Besonders signifikante Ergebnisse waren beim Prolin zu verzeichnen. Wahrend bei den symptomfreien Fichten der Prolingehalt der Nadeln ungeachtet des Standortes und der Witterungsverhaltnisse konstant niedrig lag, trat bei Schadigung ei…
Photosynthesis and Transpiration in Damaged and Undamaged Spruce Trees
1996
Abstract The investigations presented here focus on the CO2/H2O gas exchange in damaged and undamaged spruce trees while using open-air measurements as well as measurements under defined conditions in the laboratory. The studies were performed at two different sites in the Hunsrück and the Westerwald mountains. In the laboratory the CO2/H2O gas exchange was measured on detached branches under controlled conditions in the course of two years. CO2 saturation curves were also generated. In addition CO2 compensation points were deter mined employing a closed system. In the natural habitat diurnal course measurements of photosynthesis and transpiration as well as light-saturation curves for pho…
Syntheses of Some Biologically Active Compounds from Stilbenes Isolated from the Bark ofPicea abies
1992
From the four stilbenes 1–4 isolated from the bark of Picea abies seven compounds 5–11 were obtained by hydrogenation or permethylation. 1H-, 13C-NMR and mass spectra were used for their characterization. The antileukemic activity of each compound was preliminary tested. Some compounds were further tested for their anti-HIV activity.
Influence of wood harvest on tree-ring time-series of Picea abies in a temperate forest
2012
Tree-ring width data are the prime source of high-resolution climate reconstructions covering recent mil- lennia. Their variations, from year-to-year, are calibrated against regional instrumental data to evaluate the strength of associations with temperature and precipitation records, though the level of variance explained by climatic variables is frequently less than 50%. Among the remaining factors affecting tree growth, the influence of forest management for tree-ring width time-series used to resolve annual climate reconstructions remains relatively unexplored. We here evaluate the impact of conventional single-tree harvesting on tree-ring data using a compilation of circumstantially ma…
Stand structure and spatial pattern of regeneration of Pinus sylvestris in a natural treed mire in Latvia
2009
We examined the regeneration patterns of Pinus sylvestris L. in a natural treed mire in the hemiboreal zone in Latvia. Data on tree stem age and size was collected in 207 fine-scale plots (10 m) and 4 medium-scale plots (400 m). Size structure of living and dead trees was also estimated on transects 180-m and 250-m length and 10-m width. In addition, the vegetation was described in 1-m plots to determine preferred microsites for P. sylvestris establishment. Pinus sylvestris showed continuous regeneration by an inverse J-shaped age and size structure. Pulses of mortality induced by fire were also evident. Regeneration of P. sylvestris was mostly on Sphagnum magellanicam Brid. hummocks free o…
Measurement of Photosynthesis and Transpiration in Spruce Trees with Various Degrees of Damage
1987
Summary In the context of a project on physiological and biochemical characterization of spruce with different degrees of damage, the C02 and H2O gas exchange of 22-year-old spruce from a location in the Hunsru.ck (West Germany) were measured in summer 1985. The measurements were carried out on shoots from 1984 and were set up as a pair comparison, i.e. the measurement data of a tree with symptoms of damage were always compared with a tree in the immediate vicinity which phenotypically showed less damage. Diurnal course measurements in the open air revealed a marked reduction of photosynthesis depending on the degree of damage of the trees. If one plots photosynthetic rate against light int…
Investigation on the Nitrogen Metabolism of Spruce Needles in Relation to the Occurrence of Novel Forest Decline
1988
Summary In order to obtain information on the nitrogen metabolism of undamaged and damaged spruce ( Picea abies ), investigations were performed in 1985 and 1986 on the activity of glutamine synthetase and on the content of free ammonium and soluble proteins in spruce needles. In addition, the chlorophyll content was determined. Needles from the second needle year and the seventh whorl were used. The investigations were carried out in pair comparison on a 20-year-old spruce plantation and in comparison with damage classes on an 80-year-old spruce plantation. Both the pair comparison and the contrasting of different damage groups show an unequivocal decrease of the chlorophyll content correl…