European Journal of Forest Research

, Volume 133, Issue 1, pp 101–110

Estimating light climate in forest with the convex densiometer: operator effect, geometry and relation to diffuse light

  • Olivier Baudry
  • Charlotte Charmetant
  • Catherine Collet
  • Quentin Ponette
Original Paper

DOI: 10.1007/s10342-013-0746-6

Cite this article as:
Baudry, O., Charmetant, C., Collet, C. et al. Eur J Forest Res (2014) 133: 101. doi:10.1007/s10342-013-0746-6

Abstract

Although light is a key factor in forestry, it is surprisingly seldom measured in day-to-day management of European forests. The spherical convex densiometer is a simple instrument that allows to evaluate the canopy openness (CO) by counting the number of ‘canopy’ dots on a grid lying on a convex mirror reflecting the canopy. In this contribution, we compared the performances of this instrument in mixed oak–beech hardwood forests spanning the lower end of the light gradient [1–17 % above canopy photosynthetically active radiation (PAR)] 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 CO 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 conformation on the angle of view, were found to be relatively minor. Densiometer readings were 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.

Keywords

Spherical convex densiometerCanopy opennessHemispherical photographyIndirect light estimationBroadleaf canopy

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Olivier Baudry
    • 1
  • Charlotte Charmetant
    • 1
  • Catherine Collet
    • 2
    • 3
  • Quentin Ponette
    • 1
  1. 1.Earth and Life Institute, Environmental SciencesUniversité catholique de LouvainLouvain-la-NeuveBelgium
  2. 2.INRA, UMR1092, Laboratoire d’Etude des Ressources Forêt Bois (LERFoB)Centre INRA de NancyChampenouxFrance
  3. 3.AgroParisTech, UMR1092, Laboratoire d’Etude des Ressources Forêt Bois (LERFoB)ENGREFNancyFrance