Spectral Distribution of Light in Forests of the Douglas Fir Zone of Southern British Columbia

Freyman, S.

doi:10.4141/cjps68-057

Cited by 11 publications

(10 citation statements)

References 1 publication

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“…In addition to these fundamental considerations, the time of year and nearby physical structures both interact with radiation and can significantly alter the incident irradiance at a given location (Federer & Tanner, 1966;Grace, 1983;Smith, 1982). One such factor is the position under a forest canopy (Coombe, 1957;Dengel, Grace, & MacArthur, 2015;Freyman, 1968;Hutchison & Matt, 1977;Urban et al, 2007;Vezina & Boulter, 1966). Transitions between shade and sunflecks involve changes in the irradiance received by plants and its spectral composition, where they mediate physiological responses to optimize exploitation of brief favorable light conditions (Campany, Tjoelker, von Caemmerer, & Duursma, 2016;Chen, Zhang, Li, & Cao, 2011).…”

Section: Introductionmentioning

confidence: 99%

Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

Hartikainen

Jach

Grané

et al. 2018

Ecology and Evolution

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Forest canopies create dynamic light environments in their understorey, where spectral composition changes among patterns of shade and sunflecks, and through the seasons with canopy phenology and sun angle. Plants use spectral composition as a cue to adjust their growth strategy for optimal resource use. Quantifying the ever‐changing nature of the understorey light environment is technically challenging with respect to data collection. Thus, to capture the simultaneous variation occurring in multiple regions of the solar spectrum, we recorded spectral irradiance from forest understoreys over the wavelength range 300–800 nm using an array spectroradiometer. It is also methodologically challenging to analyze solar spectra because of their multi‐scale nature and multivariate lay‐out. To compare spectra, we therefore used a novel method termed thick pen transform (TPT), which is simple and visually interpretable. This enabled us to show that sunlight position in the forest understorey (i.e., shade, semi‐shade, or sunfleck) was the most important factor in determining shape similarity of spectral irradiance. Likewise, the contributions of stand identity and time of year could be distinguished. Spectra from sunflecks were consistently the most similar, irrespective of differences in global irradiance. On average, the degree of cross‐dependence increased with increasing scale, sometimes shifting from negative (dissimilar) to positive (similar) values. We conclude that the interplay of sunlight position, stand identity, and date cannot be ignored when quantifying and comparing spectral composition in forest understoreys. Technological advances mean that array spectroradiometers, which can record spectra contiguously over very short time intervals, are being widely adopted, not only to measure irradiance under pollution, clouds, atmospheric changes, and in biological systems, but also spectral changes at small scales in the photonics industry. We consider that TPT is an applicable method for spectral analysis in any field and can be a useful tool to analyze large datasets in general.

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Section: Introductionmentioning

confidence: 99%

Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

Hartikainen

Jach

Grané

et al. 2018

Ecology and Evolution

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“…Whilst daylight has an altnost uniform distribution of radiation between 400 and 800 nm, all shadelight spectra show high attenuation of radiation in the 400-700 nm waveband and far less attenuation in the non-photosynthetically active far-red (700-800 nm) region. In general, coniferous canopies have been shown to be fairly neutral with respect to absorption in the photosynthetically-active waveband from 400-700 nm, although some show a minor peak in the blue waveband (Coombe, 1957;Federer & Tanner, 1966;Freyman, 1968;Morgan & Smith, 1981a), while broadleaf deciduous canopies have a characteristic minor peak in the green waveband (Tasker & Smith, 1977).…”

Section: Introductionmentioning

confidence: 99%

Some observations on the spectral distribution characteristics of short‐wave radiation within Pinus radiata D. Don canopies

Morgan¹,

Warrington²,

Rook

1985

Plant Cell & Environment

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Measurements of the photosynthetic photon flux density (400-700 nni) and of the spectral distribution of photon flux density across the 370-800 nm waveband, were made under both clear and overcast sky conditions above and at various positions within two Pinus radiata canopies of diflerent stocking but similar leaf area indices. The spectra obtained for the daylight conditions (i.e. above forest canopy) were generally similar to those published previously. The spectra for shadelight within the forest canopy showed no blue peak which was characteristic of previously reported measurements which were restricted to the difluse radiation component. There was almost neutral absorption within the 400-700 nm waveband, and typical lower attenuation in the 700-800 nm waveband. The blue: red ratio was largely unchanged by either canopy type or sky conditions and varied between 0.57 and 0.81. The red: far-red ratio in shadelight was between 0.22 and 0.41 under clear sky and between 0.68 and 0.95 under overcast sky conditions. Values for daylight were between 1.16-1.22. Calculated phytochrome photoequilibrium values in shadelight were approximately 0.35 under clear sky and 0.46 under overcast sky conditions. In each case there appeared to be no dilTerences between the two canopies with respect to these minimum values.A.Vr-u' ()/v/.

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“…Various factors are known to affect the spectral quality of photosynthetically active radiation (PAR; 400-700 nm) in the terrestrial environment, such as the transit of the sun across the sky (Robertson 1966;Vézina & Boulter 1966;Evans 1969;Holmes & Smith 1977a;Olesen 1992), cloud formations (Federer & Tanner 1966;Robertson 1966;Vézina & Boulter 1966;Stoutjesdijk 1972b;Morgan et al 1985); the reflective properties of topographical features (Kimes 1983); and the canopy structure of overtopping vegetation (Coombe 1957;Atzet & Waring 1970;Stoutjesdijk 1972aStoutjesdijk , 1972bGoodfellow & Barkham 1974;Holmes & Smith 1977b;Morgan et al 1985;Olesen 1992), including the relative proportions of woody stems and leaves (Vézina & Boulter 1966;Tasker & Smith 1977;Hughes et al 1985), the extent of flowering (Yates & Steven 1987) and species composition (Coombe 1957;Federer & Tanner 1966;Robertson 1966;Vézina & Boulter 1966;Freyman 1968;Tasker & Smith 1977).…”

Section: Introductionmentioning

confidence: 99%

Is there a representative wavelength for photosynthetically active radiation in the terrestrial environment?

Olesen

2000

Austral Ecology

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The spectral quality of photosynthetically active radiation (PAR; 400-700 nm) incident at an open site and on a forest floor was analysed to determine whether narrowband (1 nm) wavelengths could be used to estimate total incident PAR. The narrowband estimates were not as good as the broadband estimates based on silicon photovoltaic sensors, but the variance at 530 nm was sufficiently small for narrowband sensors to be considered as low-cost and light-weight alternatives to broadband sensors.

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Spectral Distribution of Light in Forests of the Douglas Fir Zone of Southern British Columbia

Abstract: not available

Cited by 11 publications

References 1 publication

Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

Some observations on the spectral distribution characteristics of short‐wave radiation within Pinus radiata D. Don canopies

Is there a representative wavelength for photosynthetically active radiation in the terrestrial environment?

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