Canadian Forest Service Publications
Solar radiation available over snow pack in a dense pine forest. 1963. Vézina, P.E. s.n., S.l. [Report] 63-Q 6. 9 p.
Issued by: Laurentian Forestry Centre
Catalog ID: 16175
Series: Internal Report (LFC - Québec)
Availability: PDF (download)
This paper reports the results of a study conducted during the 1961-1962 snow caver season to determine the daily levels of solar radiation beneath the canopy of a 21-year-old red pine (Pinus resinosa Ait.) plantation with 66-per cent crown closure situated at Valcartier, near Quebec City. Those levels were computed as the ratio, in per cent, of the daily amount of solar radiation beneath canopy, expressed in langleys, to that in the open. The average daily level cf solar radiation beneath canopy in a 104-day period was 8.0 per cent, and varied from 1 to 28 per cent. It was directly related to the degree of cloudiness, but unrelated to the amount of solar radiation in the open The daily level of solar radiation beneath canopy, however, had the tendency to approach the average level as the amount cf solar radiation in the open increased. This suggested that a short-cut method of estimating the average solar radiation available below s softwood canopy would consist of making observations on a calm, cloudless day, with radiation in the open exceeding 350 langleys. The radiation penetration process is discussed in terms of radiation absorption in the crown cover, and its implication in regeneration silviculture are mentioned.