The Effect of Season Upon Registrations of Stand Mean Height, Crown Closure and Tree Species on Aerial Photos

1991

28 S.

23 Lit. Ang.

Unselbständiges Werk

200037941

Stand mean height, crown closure and the mixture of tree species are estimated in 33 Norway spruce and Scots pine stands by 5 interpreters. They used a stereoplotter of the second order, and panchromatic aerial photos taken the 13th of May and the 2nd of August. For 3 of the interpreters, the systematic error in mean height measurements is larger in the May photos than in the August photos. Differences in photo estimated crown closure are found between the 2 seasons. These differences are, however, mainly dependent on the persons carrying out the interpretations. The May photos have lead to the best results regarding interpretation of the mixture of tree species. In both the May photos and the August photos, the interpretation results are best in pure stands.