scholarly journals Transmittance of young Norway spruce stand canopy for photosynthetically active radiation during the growing season

2013 ◽  
Vol 61 (1) ◽  
pp. 129-135
Author(s):  
Irena Marková ◽  
Jiří Kubásek
Keyword(s):  
Norway Spruce ◽  
Photosynthetically Active Radiation ◽  
Stand Structure ◽  
Growing Season ◽  
Stand Development ◽  
The Czech Republic ◽  
Active Radiation ◽  
The Mean ◽  
Sky Conditions ◽  
Phenological Phases

Analysis of transmittance of young Norway spruce stand canopy for photosynthetically active radiation (PAR) was made at the study site of Bílý Kříž (the Moravian-Silesian Beskids Mts., the Czech Republic) at different sky conditions during the growing season in 2010. For the description of PAR transmittance different phenological phases of the spruce stand development in clear and overcast days were chosen. The mean daily PAR transmittance of the spruce canopy was significantly higher in overcast days compared with clear ones. Diffuse PAR thus penetrated into lower parts of the canopy more efficiently than direct one. PAR transmittance of young Norway spruce stand canopy was different in individual phenological phases of the spruce stand canopy which was caused by changes in the stand structure during the growing season. Thus monitoring of transmittance of young Norway spruce stand canopy for PAR can help to describe the development of spruce stand canopy.

MVP: a model to simulate the spatial patterns of photosynthetically active radiation under discrete forest canopies

2004 ◽  
Vol 34 (6) ◽  
pp. 1192-1203 ◽  
Author(s):  
Conghe Song ◽  
Lawrence E Band
Keyword(s):  
Spatial Patterns ◽  
Photosynthetically Active Radiation ◽  
Forest Canopy ◽  
Ecological Models ◽  
Computationally Efficient ◽  
Forest Canopies ◽  
Active Radiation ◽  
Beer's Law ◽  
Beer’S Law ◽  
The Mean

The spatial patterns of photosynthetically active radiation (PAR) under forest canopies, including both its mean and spatial variation, are critical factors to numerous understory ecophysiological processes. Currently, Beer's law is the primary algorithm used in ecological models simulating PAR transmission through plant canopies, because more accurate models are too complicated to be used operationally. This study developed a simple and computationally efficient model at a stand scale to simulate both the mean and variation of PAR (MVP) under forest canopies. The model assumes that a forest canopy is composed of individual crowns distributed within upper and lower boundaries with two types of gaps: the between- and within-crown gaps. The between-crown gaps are simulated with geometric optics, and the within-crown gaps are described by Beer's law. The model accounts for the covariance of PAR in space through time, making it possible to simulate both instantaneous and daily accumulated variance of PAR. Validation with observed PAR from the boreal ecosystem–atmosphere study (BOREAS) indicates that the model captures the mean and variance of PAR under forest canopy reasonably well. MVP holds the potential to improve simulation of light interception by forest canopies as well as the treatment of canopy rainfall interception in ecological models.

Modeling the photosynthetically active radiation in South West Amazonia under all sky conditions

2011 ◽  
Vol 108 (3-4) ◽  
pp. 631-640 ◽  
Author(s):  
Leonardo J. G. Aguiar ◽  
Graciela R. Fischer ◽  
Richard J. Ladle ◽  
Ana C. M. Malhado ◽  
Flávio B. Justino ◽  
...  
Keyword(s):  
Photosynthetically Active Radiation ◽  
Active Radiation ◽  
South West ◽  
Sky Conditions

scholarly journals Light Use Efficiency of Aboveground Biomass Production of Norway Spruce Stands

2017 ◽  
Vol 65 (1) ◽  
pp. 9-16
Author(s):  
Michal Bellan ◽  
Irena Marková ◽  
Andrii Zaika ◽  
Jan Krejza
Keyword(s):  
Norway Spruce ◽  
Aboveground Biomass ◽  
Photosynthetically Active Radiation ◽  
Climatic Conditions ◽  
Light Use Efficiency ◽  
Active Radiation ◽  
Spruce Stands ◽  
Use Efficiency ◽  
Study Sites ◽  
Radiation Use

Light use efficiency (LUE or photosynthetically active radiation use efficiency) in production of young spruce stands aboveground biomass was determined at the study sites Rájec (the Drahanská vrchovina Highland) and Bílý Kříž (the Moravian‑Silesian Beskids Mountains) in 2014 and 2015. The LUE value obtained for the investigated spruce stands were in the range of 0.45 – 0.65 g DW MJ–1. The different LUE values were determined for highland and mountain spruce stand. The differences were caused by growth and climatic conditions and by the amount of assimilatory apparatus (LAI).

scholarly journals Phenology of common beech (Fagus sylvatica L.) along the altitudinal gradient in Slovakia (Inner Western Carpathians)

2013 ◽  
Vol 59 (No. 4) ◽  
pp. 176-184 ◽  
Author(s):  
B. Schieber ◽  
R. Janík ◽  
Z. Snopková
Keyword(s):  
Fagus Sylvatica ◽  
Altitudinal Gradient ◽  
Slovak Republic ◽  
Growing Season ◽  
Leaf Fall ◽  
Mean Values ◽  
Common Beech ◽  
Fagus Sylvatica L ◽  
The Mean ◽  
Phenological Phases

The onset and course of selected vegetative phenological phases of beech along the altitudinal gradient in Slovak Republic were studied. Observations were done in the Burda Mts. (200–300 m a.s.l.), Kremnické vrchy Mts. (500 m a.s.l.) and in the Poľana Mts. (900–1,000 m a.s.l., 1,200–1,400 m a.s.l.). Selected spring phenological phases (budburst and leaf unfolding) as well as autumn phenological phases (autumn colouring and leaf fall) were investigated over the period of 5 years (2007–2011). The earliest onset of spring phenological phases during the period of study was found at the lowest-lying sites in the Burda Mts. By contrast, the latest one was observed at the uppermost site in the Poľana Mts. The dynamics of autumn phenological phases had the opposite course compared to spring phenophases. The earliest onset, observed in the uppermost locality in the Poľana Mts., was gradually delayed with decreasing altitude. The phenological gradient, expressing a shift in the onset of spring phenophases along the gradient, reached the mean values of 2.83–3.00 days per 100 m of an increase in altitude. In the case of autumn phenological phases the gradient ranged from –1.00 to –1.78 days per 100 m. On average, the growing season of beech lasted from 128 to 181 days along the altitudinal gradient. Significant correlations (P < 0.001) were calculated between the date of the onset of phenophases and altitude.   

Common Ragweed (Ambrosia artemisiifolia) Interference in Soybeans (Glycine max)

Weed Science ◽  
1981 ◽  
Vol 29 (3) ◽  
pp. 339-342 ◽  
Author(s):  
H. D. Coble ◽  
F. M. Williams ◽  
R. L. Ritter
Keyword(s):  
Glycine Max ◽  
Natural Population ◽  
Photosynthetically Active Radiation ◽  
Yield Loss ◽  
Damage Threshold ◽  
Growing Season ◽  
Ambrosia Artemisiifolia ◽  
Common Ragweed ◽  
Active Radiation ◽  
Naturally Occurring

The influence of common ragweed (Ambrosia artemisiifoliaL.) interference on soybean [Glycine max(L.) Merr. ‘Ransom’] yield was studied in the field utilizing naturally occurring weed populations. The damage-threshold population for a full-season, in-row common ragweed infestation was four weeds/10 m of row, which resulted in an 8% yield loss. Soybeans kept weed-free for 2 weeks or longer after emergence in a dry year produced normal yields, but 4 weeks of weed-free maintenance was required when adequate moisture was available early in the growing season. Soybean yield was not reduced by a natural population of common ragweed if the period of interference was limited to 6 weeks or less after crop emergence. By 8 weeks after emergence, common ragweed height averaged 25 cm taller than soybeans, and the weed canopy intercepted 24% of the photosynthetically active radiation.

scholarly journals A Whole-plant, Open, Gas-exchange System for Measuring Net Photosynthesis of Potted Woody Plants

HortScience ◽  
1996 ◽  
Vol 31 (6) ◽  
pp. 944-946 ◽  
Author(s):  
D.P. Miller ◽  
G.S. Howell ◽  
J.A. Flore
Keyword(s):  
Gas Exchange ◽  
Photosynthetically Active Radiation ◽  
Woody Plants ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Exchange System ◽  
Active Radiation ◽  
Whole Plant ◽  
Short Period ◽  
Gas Exchange System

Chambers were constructed to measure gas exchange of entire potted grapevines (Vitis vinifera L.). The plant enclosures were constructed from Mylar film, which is nearly transparent to photosynthetically active radiation. Maintaining a slight, positive, internal pressure allowed the Mylar chambers to inflate like balloons and required no other means of support. The whole-plant, gas-exchange chamber design and construction were simple and inexpensive. They were assembled easily, equilibrated quickly, and did not require cooling. They allowed for the measurement of many plants in a relatively short period. This system would enable the researcher to make replicated comparisons of treatment influences on whole-plant CO2 assimilation throughout the growing season. While CO2 measurement was the focus of this project, it would be possible to measure whole-plant transpiration with this system.

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