Spectral Multichannel Monitoring of Radiation within a Mature Mixed Forest

Abstract

A multi-sensor system is described based on fiber optic technology and a diode array spectrometer for near-simultaneous measurement of spectral photon fluence rates (PFR) in the range of 360 nm to 1020 nm with a resolution of 0.8 nm, within a mature Norway spruce (Picea abies [L.] Karst.) - European beech (Fagus sylvatica L.) stand. 126 space-integrating spherical sensors, deployed in a regular grid above and within the canopy and on the forest floor, are sequentially connected to the spectrometer by means of fiber optics. About 1 s per sensor is needed to collect spectral data, store them on hard disk and move the channel multiplexer to the next fiber optic position. Data thus obtained serve to determine vertical profiles of wavelength-dependent photon extinction, especially for spectral ratios and wavebands, characterization of phenological stages, analyses of time series, and meteorological influences such as solar altitude and cloud cover. First measurements during leaf fall 2004 show a non-linear relation of the red/far-red ratio (R/FR) with relative photosynthetic PFR (PPFR_rel). An analysis of relative PFR (PFR_rel) quantifies the frequency of penumbral sunfleck occurrence and the fraction of incoming radiation on the forest floor. In-canopy measurements of daily means of PPFR_rel and R/FR indicate that leaf unfolding and leaf fall can be described by a single sensor, independent of its vertical location within the canopy.

Key words

Solar radiation - photon fluence rate - red/far-red ratio - fiber optic sensor - spectral analysis - forest - beech - spruce.

References

• 1 Aaslyng J. M., Rosenqvist E., Høgh-Schmidt K.. A sensor for microclimatic measurement of photosynthetically active radiation in a plant canopy.  Agricultural and Forest Meteorology. (1999);  96 189-197
• 2 Ammer C.. Growth and biomass partitioning of Fagus sylvatica L. and Quercus robur L. seedlings in response to shading and small changes in the R/FR-ratio of radiation.  Annals of Forest Science. (2003);  60 163-171
• 3 Ammer C.. Untersuchungen zum Einfluss von Fichtenaltbeständen auf die Entwicklung junger Buchen. Aachen; Shaker Verlag (2000)
• 4 Baldocchi D. D., Matt D. R., Hutchinson B. A., McMillen R. T.. Solar radiation within an oak-hickory forest: an evaluation of the extinction coefficients for several radiation components during fully-leafed and leafless periods.  Agricultural and Forest Meteorology. (1984);  32 307-322
• 5 Bernhard G.. Einfluß von Diffusor-Eigenschaften auf die Bestimmung von Bestrahlungsstärken im UV-Bereich: Versuchsaufbau, Messung und Korrekturverfahren. Garmisch-Partenkirchen; IFU Schriftenreihe (1993)
• 6 Björn L. O.. Estimation of fluence rate from irradiance measurements with a cosine-corrected sensor.  Journal of Photochemistry and Photobiology B: Biology. (1995);  29 179-183
• 7 Björn L. O., Vogelmann T. C.. Quantifying light and ultraviolet radiation in plant biology.  Photochemistry and Photobiology. (1996);  64 403-406
• 8 Byrne G. F.. A simple way of improving the angular response of solid-state photodetectors.  Agricultural Meteorology. (1966);  3 367-368
• 9 Capers R. S., Chazdon R. L.. Rapid assessment of understory light availability in a wet tropical forest.  Agricultural and Forest Meteorology. (2004);  123 177-185
• 10 Combes D., Sinoquet H., Varlet-Grancher C.. Preliminary measurement and simulation of the spatial distribution of the Morphogenetically Active Radiation (MAR) within an isolated tree canopy.  Annals of Forest Science. (2000);  57 497-511
• 11 Constabel A. J., Lieffers V. J.. Seasonal patterns of light transmission through boreal mixedwood canopies.  Canadian Journal of Forest Research. (1996);  26 1008-1014
• 12 De Castro F.. Light spectral composition in a tropical forest: measurements and model.  Tree Physiology. (2000);  20 49-56
• 13 Dohrenbusch A.. Überlegungen zur Optimierung der Strahlungsmessung im Wald.  Allgemeine Forst- und Jagdzeitung. (1995);  6 109-114
• 14 Endler J. A.. The color of light and its implications.  Ecological Monographs. (1993);  63 1-27
• 15 Federer C. A., Tanner C. B.. Spectral distribution of light in the forest.  Ecology. (1966);  47 555-560
• 16 Grant R. H.. Partitioning of biologically active radiation in plant canopies.  International Journal of Biometeorology. (1997);  40 26-40
• 17 Gutschick V. P., Barron M. H., Waechter D. A., Wolf M. A.. Portable monitor for solar radiation that accumulates irradiance histograms for 32 leaf-mounted sensors.  Agricultural and Forest Meteorology. (1985);  33 281-290
• 18 Hartmann K. M.. Aktionsspektrometrie. Hoppe, W., Lohmann, W., Markl, H., and Ziegler, H., eds. Biophysik - Ein Lehrbuch. Berlin, Heidelberg, New York; Springer Verlag (1978): 197-222
• 19 Holmes M. G.. Spectral distribution of radiation within plant canopies. Smith, H., ed. Plants and The Daylight Spectrum. London, New York, Toronto, Sydney, San Fransisco; Academic Press (1981): 147-158
• 20 Hutchinson B. A., Matt D. R., McMillen R. T.. Effect of sky brightness distribution upon penetration of diffuse radiation through canopy gaps in a deciduous forest.  Agricultural Meteorology. (1980);  22 137-147
• 21 Lee D. W.. The spectral distribution of radiation in two neotropical rainforests.  Biotropica. (1987);  19 161-166
• 22 McCree K. J.. The action spectrum, absorptance and quantum yield of photosynthesis in crop plants.  Agricultural Meteorology. (1972);  9 191-216
• 23 Messier C., Bellefleur P.. Light quantity and quality on the forest floor of pioneer and climax stages in a birch-beech-sugar maple stand.  Canadian Journal of Forest Research. (1988);  18 615-622
• 24 Monsi M., Saeki T.. Über den Lichtfaktor in den Pflanzengesellschaften und seine Bedeutung für die Stoffproduktion.  Japanese Journal of Botany. (1953);  14 22-52
• 25 Muraoka H., Hirota H., Matsumoto J., Nishimura S., Tang Y., Koizumi H., Washitani I.. On the convertibility of different microsite light availability indices, relative illuminance and relative photon flux density.  Functional Ecology. (2001);  15 798-803
• 26 Ögren E., Sjöström M.. Estimation of the effect of photoinhibition on the carbon gain in leaves of a willow canopy.  Planta. (1990);  181 560-567
• 27 Olesen T.. Daylight spectra (400 - 740 nm) beneath sunny, blue skies in Tasmania, and the effect of a forest canopy.  Australian Journal of Ecology. (1992);  17 451-461
• 28 Palva L., Garam E., Manoochehri F., Seppoenen R., Hari P., Rajala K., Ruotoistenmäki H., Seppälä I.. A novel multipoint measuring system of photosynthetically active radiation.  Agricultural and Forest Meteorology. (1998);  89 141-147
• 29 Reiter I. M.. Space-related resource investments and gains of adult beech (Fagus sylvatica) and spruce (Picea abies) as a quantification of aboveground competitiveness. PhD Thesis, Technical University of Munich. (2004)
• 30 Reitmayer H.. Quantifizierung des spektralen Angebotes photosynthetisch aktiver Strahlung (PAR) innerhalb eines Fichten-Buchen-Mischbestandes. PhD Thesis, Technical University of Munich. (2000)
• 31 Reitmayer H., Werner H., Fabian P.. A novel system for spectral analysis of solar radiation within a mixed beech-spruce stand.  Plant Biology. (2002);  4 228-233
• 32 Ross M. S., Flanagan L. B., La Roi G. H.. Seasonal and successional changes in light quality and quantity in the understory of boreal forest ecosystems.  Canadian Journal of Botany. (1986);  64 2792-2799
• 33 Smith H.. Phytochromes and light signal perception by plants - an emerging synthesis.  Nature. (2000);  407 585-591
• 34 Smith H.. Sensing the light environment: the functions of the phytochrome family. Kendrick, R. E. and Kronenberg, G. H. M., eds. Photomorphogenesis in Plants, 2nd edition. Dordrecht, Boston, London; Kluwer Academic Publishers (1994): 377-416
• 35 Smith H.. Light quality, photoperception, and plant strategy.  Annual Review of Plant Physiology. (1982);  33 481-518
• 36 Smith H., Morgan D. C.. The spectral characteristics of the visible radiation incident upon the surface of the earth. Smith, H., ed. Plants and The Daylight Spectrum. London, New York, Toronto, Sydney, San Fransisco; Academic Press (1981): 3-20
• 37 Wirth R., Weber B., Ryel R. J.. Spatial and temporal variability of canopy structure in a tropical moist forest.  Acta Oecologica. (2001);  22 235-244

Guest Editor: R. Matyssek