Sb. Jennings et al., Assessing forest canopies and understorey illumination: canopy closure, canopy cover and other measures, FORESTRY, 72(1), 1999, pp. 59-73
The forest canopy is one of the chief determinants of the microhabitat with
in the forest. It affects plant growth and survival, hence determining the
nature of the vegetation, and wildlife habitat. A plethora of different tec
hniques have been devised to measure the canopy. Evaluation of the literatu
re reveals confusion over what is actually being measured. This paper disti
nguishes two basic types of measurement: canopy cover is the area of the gr
ound covered by a vertical projection of the canopy, while canopy closure i
s the proportion of the sky hemisphere obscured by vegetation when viewed f
rom a single point. The principal techniques used to measure canopy cover,
canopy closure, and a number of related measures are described and discusse
d. The advantages and limitations are outlined and some sampling guidelines
are provided. The authors hope to clarify the nature of the measurements a
nd to provide foresters with sufficient information to select techniques su
itable for their needs.