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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'cover photography'

Category : Research note

article id 1518, category Research note
Francesco Chianucci. (2015). A note on estimating canopy cover from digital cover and hemispherical photography. Silva Fennica vol. 50 no. 1 article id 1518.
Keywords: forest canopy; foliage cover; crown cover; fisheye photography; cover photography
Highlights: Comparison of fisheye (DHP) and cover (DCP) photography for estimating canopy cover; Digital photographic estimates validated against artificial images with known cover; Accuracy of cover estimates from DHP is influenced by mean gap size and actual cover; Accuracy of cover estimates from DCP is not influenced by mean gap size and actual cover.
Abstract | Full text in HTML | Full text in PDF | Author Info

Fast and accurate estimates of canopy cover are central for a wide range of forestry studies. As direct measurements are impractical, indirect optical methods have often been used in forestry to estimate canopy cover. In this paper the accuracy of canopy cover estimates from two widely used canopy photographic methods, hemispherical photography (DHP) and cover photography (DCP) was evaluated. Canopy cover was approximated in DHP as the complement of gap fraction data at narrow viewing zenith angle range (0°–15°), which was comparable with that of DCP. The methodology was tested using artificial images with known canopy cover; this allowed exploring the influence of actual canopy cover and mean gap size on canopy cover estimation from photography. DCP provided robust estimates of canopy cover, whose accuracy was not influenced by variation in actual canopy cover and mean gap size, based on comparison with artificial images; by contrast, the accuracy of cover estimates from DHP was influenced by both actual canopy cover and mean gap size, because of the lower ability of DHP to detect small gaps within crown. The results were replicated in both DHP and DCP images collected in real forest canopies. Finally, the influence of canopy cover on foliage clumping index and leaf area index was evaluated using a theoretical gap fraction model. The main findings indicate that DCP can overcome the limits of indirect techniques for obtaining unbiased and precise estimates of canopy cover, which are comparable to those obtainable from direct, more labour-intensive techniques, being therefore highly suitable for routine monitoring and inventory purposes.

  • Chianucci, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy ORCID E-mail: (email)

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