Potential of the spherical densiometer to estimate light availability in temperate broadleaved forests
(2013) Communications in Agricultural and Applied Biological Sciences — Vol. 78, n° 1, p. 121-125 (2013)
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- Assessment of light availability is frequently needed in various fields of environmental and ecological sciences. In forest management, light controls a lot of ecosystem processes and is a key factor in stand regeneration. Surprisingly, it is very seldom measured in day to day management of European forests. The spherical densiometer is a very simple instrument that allows to evaluate the canopy cover by counting the number of ‘canopy’ dots on a grid lying on a convex mirror reflecting the canopy. In this contribution, we compared performances of this tool in mixed hardwood forests to two reference techniques: PAR measurements and fish-eye photography, based on a detailed analysis of its functioning. Discrepancies between the densiometer and the fish-eye estimates of canopy openness were due to a combination of differences in dot resolution, dot counting and portion of the hemisphere considered. By contrast, the various effects of operator on densiometer estimates, including the influence of morphology on the angle of view, were found to be relatively minor. Densiometer reading was closely related to the relative light intensity assessed by PAR sensors in overcast conditions, which suggests that the use of this inexpensive tool should be expanded.
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Citations
Baudry, O., Charmetant, C., Collet, C., & Ponette, Q. (2013). Potential of the spherical densiometer to estimate light availability in temperate broadleaved forests. Communications in Agricultural and Applied Biological Sciences, 78(1), 121-125. https://hdl.handle.net/2078.5/33647 (Original work published 2013)