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Wyszukujesz frazę "light condition" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Comparison of four methods for estimating relative solar radiation in managed and old-growth silver fir-beech forest
Autorzy:
Rozenbergar, D.
Kolar, U.
Cater, M.
Diaci, J.
Powiązania:
https://bibliotekanauki.pl/articles/41259.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
solar radiation
old-growth silver fir forest
beech forest
forest
light condition
forestry
hemispheric photography
Opis:
Methods based on the principle of hemispherical canopy projection, including hemispherical photography (digital andfilm), sensors like LAI 2000 (zenith cutoff anle 74,1°) andstable horizontoscope, represent less accurate, yet significantly less expensive andtime-consuming techniques for radiation measurements comparedto long-term measurement with a network of photosynthetically active radiation (PAR) sensors. With measurements taken at a single point in time they can provide reliable estimates of relative diffuse andd irect solar radiation andcan also be usedto estimate the light climate in different times of the year. The four above mentioned methods for solar radiation estimation were applied at the same points in gaps and under adjacent canopies in unevenaged, mixed Dinaric fir-beech and pure beech montane forests. Locations covereda range of radiation andstandstructure conditions. Data analyses showedgoodreliability of all four methods over the whole range (2–80%) of radiation conditions. The most comparable results come from LAI 2000 andfilm hemispherical photography (all R > 0.90). Digital hemispherical photography is an accurate andreliable (R = 0.89) replacement for film hemispherical photography, but the higher values estimatedfor direct radiation should be taken into account. Compared to the other three methods, the stable horizontoscope gives less accurate results, especially under canopies with poorly defined gaps. Our study showed that all four methods tested are suitable for estimating the solar radiation climate in gaps and stands with heterogeneous vertical structures, andhave potential value as a tool in decision making when practicing silviculture.
Źródło:
Dendrobiology; 2011, 65
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Responses in young Quercus petraea: coppices and standards under favourable and drought conditions
Autorzy:
Stojanovic, M.
Cater, M.
Pokorny, R.
Powiązania:
https://bibliotekanauki.pl/articles/41121.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
plant response
young plant
Quercus petraea
sessile oak
durmast oak zob.sessile oak
coppice
standard
favourable condition
drought condition
drought response
light condition
Opis:
Assimilation and photosynthetic efficiency (maximal quantum yield) of young oaks were compared in coppice and standard sessile oak stands of comparable age (100 years) under different light intensity categories: under minimum light – ISF < 20%, low light – 20%30% during favourable and drought conditions. Measurements of maximal assimilation rates were performed at a constant temperature of the measurement block (20°C), a CO2 concentration of 400 μmol/l, flow 500 μmol/s and different light intensities: 0, 50, 250, 600, 1200 and 1800 μmol/m2s during three consecutive growing seasons (2012, 2013 and 2014). In every category at least 8 young naturally regenerated seedlings and sprouts of different coppice stools were measured. The quantum yield in optimal conditions in standards was highest in the category of closed canopy, while in coppices in medium light category. During severe drought in 2013 the drop in efficiency of standards was evident in all categories, while in coppices no differences in efficiency were observed between favourable 2012 and 2013 with expressed drought stress, proving the advantage of young coppices over standards in this particular light category. However, the beneficial effects of restoration coppicing are not guaranteed. It is our belief that in time such advantage might decrease; it would be therefore interesting to compare responses in time and define, when response abilities of both studied systems become equal.
Źródło:
Dendrobiology; 2016, 76
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of cutting off distal ends of Quercus robur acorns on seedling growth and their infection by the fungus Erysiphe alphitoides in different light conditions
Autorzy:
Giertych, M.J.
Suszka, J.
Powiązania:
https://bibliotekanauki.pl/articles/41420.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
oak
pedunculate oak
container nursery
oak powdery mildew
Quercus robur
seedling growth
plant infection
fungi
Erysiphe alphitoides
light condition
phenology
Opis:
Quercus robur seedlings are very often infested by oak powdery mildew caused by Erysiphe alphitoides. This disease attacks primary leaves with high insolation. In our experiment seedling growth in different light conditions was observed. Seedlings were derived from intact seeds or from seeds where the distal ends of acorns were cut off. Acorns were sown in pots at four light conditions (2%, 8% and 30% light transmittance and in full sunlight). For half of the seedlings we reduced the influence of powdery mildew by using a fungicide. Height of seedlings, shoot dry mass and the degree of damage caused by Erysiphe alphitoides were measured. The highest damages were in full light conditions and the lowest in the 30% light treatment. The influence of acorn reduction on powdery mildew infection was not significant (p=0.0763), however, in the full light conditions the seedlings from cut acorns were ca. 30% less damaged. The cutting of acorns also alters the height of seedlings and shoot mass. The tallest seedlings were from cut seeds growing in the 30% light treatment. The influence of the fungicide was lowest in the 30% light treatment where the decrease in damage was only ca. 10%. For nursery practice we can say that oak seedling production from cut off acorns under 30% light transmittance should give the best results of seedling growth even without the fungicide application.
Źródło:
Dendrobiology; 2010, 64
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of sunlight on phenolic compounds accumulation in coniferous plants
Autorzy:
Brzezinska, E
Kozlowska, M
Powiązania:
https://bibliotekanauki.pl/articles/41493.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
light condition
one-year-old shoot
two-year-old shoot
needle
common yew
Taxus baccata
American arborvitae
Thuja occidentalis
common juniper zob.juniper
juniper
Juniperus communis
urban garden
phenol
total phenol content
accumulation
coniferous plant
sunlight
flavone
Opis:
The effect of light conditions on the accumulation of phenolic compounds was investigated in the needles of one-year and two-year old shoots, collected from perennial specimens of common yew (Taxus baccata L.), American arborvitae (Thuja occidentalis L.) and common juniper (Juniperus communis L.), growing in an urban garden. The content of total phenols and flavones was partially related to the light requirement or light tolerance of conifer tree. In Taxus needles, a shade-loving species, higher accumulation of phenolic metabolites was observed under shaded condition (in two-year old shoots) and was linked with the growth intensity in spring. In Thuja and particularly in Juniperus, the level of phenolics was related to the insolation intensity, probably so as a part of the adaptation mechanism.
Źródło:
Dendrobiology; 2008, 59; 3-7
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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